[House Hearing, 115 Congress]
[From the U.S. Government Publishing Office]
PLANETARY FLAGSHIP MISSIONS:
MARS ROVER 2020 AND EUROPA CLIPPER
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HEARING
BEFORE THE
SUBCOMMITTEE ON SPACE
COMMITTEE ON SCIENCE, SPACE, AND TECHNOLOGY
HOUSE OF REPRESENTATIVES
ONE HUNDRED FIFTEENTH CONGRESS
FIRST SESSION
__________
JULY 18, 2017
__________
Serial No. 115-22
__________
Printed for the use of the Committee on Science, Space, and Technology
[GRAPHIC(S) NOT AVAILABLE IN TIFF FORMAT]
Available via the World Wide Web: http://science.house.gov
______
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COMMITTEE ON SCIENCE, SPACE, AND TECHNOLOGY
HON. LAMAR S. SMITH, Texas, Chair
FRANK D. LUCAS, Oklahoma EDDIE BERNICE JOHNSON, Texas
DANA ROHRABACHER, California ZOE LOFGREN, California
MO BROOKS, Alabama DANIEL LIPINSKI, Illinois
RANDY HULTGREN, Illinois SUZANNE BONAMICI, Oregon
BILL POSEY, Florida AMI BERA, California
THOMAS MASSIE, Kentucky ELIZABETH H. ESTY, Connecticut
JIM BRIDENSTINE, Oklahoma MARC A. VEASEY, Texas
RANDY K. WEBER, Texas DONALD S. BEYER, JR., Virginia
STEPHEN KNIGHT, California JACKY ROSEN, Nevada
BRIAN BABIN, Texas JERRY MCNERNEY, California
BARBARA COMSTOCK, Virginia ED PERLMUTTER, Colorado
BARRY LOUDERMILK, Georgia PAUL TONKO, New York
RALPH LEE ABRAHAM, Louisiana BILL FOSTER, Illinois
DRAIN LaHOOD, Illinois MARK TAKANO, California
DANIEL WEBSTER, Florida COLLEEN HANABUSA, Hawaii
JIM BANKS, Indiana CHARLIE CRIST, Florida
ANDY BIGGS, Arizona
ROGER W. MARSHALL, Kansas
NEAL P. DUNN, Florida
CLAY HIGGINS, Louisiana
RALPH NORMAN, South Carolina
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Subcommittee on Space
HON. BRIAN BABIN, Texas, Chair
DANA ROHRABACHER, California AMI BERA, California, Ranking
FRANK D. LUCAS, Oklahoma Member
MO BROOKS, Alabama ZOE LOFGREN, California
BILL POSEY, Florida DONALD S. BEYER, JR., Virginia
JIM BRIDENSTINE, Oklahoma MARC A. VEASEY, Texas
STEPHEN KNIGHT, California DANIEL LIPINSKI, Illinois
BARBARA COMSTOCK, Virginia ED PERLMUTTER, Colorado
RALPH LEE ABRAHAM, Louisiana CHARLIE CRIST, Florida
DANIEL WEBSTER, Florida BILL FOSTER, Illinois
JIM BANKS, Indiana EDDIE BERNICE JOHNSON, Texas
ANDY BIGGS, Arizona
NEAL P. DUNN, Florida
CLAY HIGGINS, Louisiana
LAMAR S. SMITH, Texas
C O N T E N T S
July 18, 2017
Page
Witness List..................................................... 2
Hearing Charter.................................................. 3
Opening Statements
Statement by Representative Brian Babin, Chairman, Subcommittee
on Space, Committee on Science, Space, and Technology, U.S.
House of Representatives....................................... 4
Written Statement............................................ 6
Statement by Representative Ami Bera, Ranking Member,
Subcommittee on Space, Committee on Science, Space, and
Technology, U.S. House of Representatives...................... 8
Written Statement............................................ 9
Statement by Representative Eddie Bernice Johnson, Ranking
Member, Committee on Science, Space, and Technology, U.S. House
of Representatives............................................. 11
Written Statement............................................ 13
Statement by Representative Lamar S. Smith, Chairman, Committee
on Science, Space, and Technology, U.S. House of
Representatives................................................ 14
Written Statement............................................ 15
Witnesses:
Dr. Jim Green, Planetary Science Division Director, Science
Mission Directorate, NASA
Oral Statement............................................... 17
Written Statement............................................ 20
Dr. Kenneth Farley, Mars Rover 2020 Project Scientist; Professor
of Geochemistry, California Institute of Technology
Oral Statement............................................... 25
Written Statement............................................ 27
Dr. Robert Pappalardo, Europa Clipper Project Scientist, Jet
Propulsion Laboratory, California Institute of Technology
Oral Statement............................................... 30
Written Statement............................................ 32
Dr. Linda T. Elkins-Tanton, Director and Foundation Professor,
School of Earth and Space Exploration, Arizona State
University; Principal Investigator, NASA Psyche Mission
Oral Statement............................................... 36
Written Statement............................................ 38
Dr. William B. McKinnon, Co-Chair, National Academy of Sciences,
Committee on Astrobiology and Planetary Science; Professor of
Earth and Planetary Sciences, Washington University in St.
Louis
Oral Statement............................................... 43
Written Statement............................................ 45
Discussion....................................................... 58
Appendix I: Answers to Post-Hearing Questions
Dr. Jim Green, Planetary Science Division Director, Science
Mission Directorate, NASA...................................... 74
Dr. Kenneth Farley, Mars Rover 2020 Project Scientist; Professor
of Geochemistry, California Institute of Technology............ 78
Dr. Robert Pappalardo, Europa Clipper Project Scientist, Jet
Propulsion Laboratory, California Institute of Technology...... 79
Dr. Linda T. Elkins-Tanton, Director and Foundation Professor,
School of Earth and Space Exploration, Arizona State
University; Principal Investigator, NASA Psyche Mission........ 80
Appendix II: Additional Material for the Record
Responses submitted by NASA...................................... 84
PLANETARY FLAGSHIP MISSIONS:
MARS ROVER 2020 AND EUROPA CLIPPER
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TUESDAY, JULY 18, 2017
House of Representatives,
Subcommittee on Space,
Committee on Science, Space, and Technology,
Washington, D.C.
The Subcommittee met, pursuant to call, at 10:09 a.m., in
Room 2318 of the Rayburn House Office Building, Hon. Brian
Babin [Chairman of the Subcommittee] presiding.
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Chairman Babin. The Subcommittee on Space will come to
order.
Without objection, the Chair is authorized to declare
recesses of the Subcommittee at any time.
And welcome to today's hearing titled ``Planetary Flagship
Missions: Mars Rover 2020 and Europa Clipper.'' I recognize
myself for five minutes for an opening statement.
NASA's planetary science flagships are the crown jewels of
our robotic exploration of the solar system. Viking, Voyager,
Galileo, Cassini, Chandra, and Mars Science Laboratory are
programs that have inspired generations of Americans. One need
only visit a local elementary school to see the wonder in
children's eyes as they learn about the great discoveries of
these flagship missions. Mars Rover 2020 and the Europa Clipper
will be no less amazing.
Upholding such a legacy is not easy. From its original
recommendation by the National Academies, through formulation
and development, and ultimately launch and mission operations,
there is much work to be done to ensure mission success, that
the taxpayers' money is being appropriately spent, and that the
national interest is met.
Today's hearing serves an important oversight purpose. Our
witnesses will provide important testimony on the Mars Rover
2020 and the Europa Clipper, from both a programmatic and
science perspective. The hearing will also provide an
opportunity for Committee members to learn about the science
that these missions will conduct and how it will benefit our
nation.
I have full faith that NASA and its hard working men and
women will carry out its planetary science flagship missions
successfully. That said, NASA is entering the most critical
stage of the Mars Rover 2020 development and is undertaking the
development of the Europa Clipper, and possibly a Europa
Lander, at the same time.
For Mars Rover 2020, the NASA Inspector General reported
concerns regarding an overly optimistic schedule for Mars Rover
2020 based largely on technology development challenges. I look
forward to hearing from Dr. Green about these issues and how
NASA is addressing them.
A fundamental oversight question that needs to be addressed
is how developing and operating these flagship missions at the
same time, including a possible lander, will affect the
Planetary Science Division and broader Science Mission
Directorate portfolio. NASA must remain vigilant to protect
against potential cost growth or mission creep that could
impact other activities.
The Consolidated Appropriations Act of 2017 funded and
requires a Europa lander mission to complement the Clipper. The
Act directed NASA to launch the Clipper in 2022 and a lander in
2024.
In the fiscal year 2018 President's budget, his request
does not include funding for a Europa lander. NASA says that
because the Planetary Science division already supports two
other large strategic missions, Mars Rover 2020 and Europa
Clipper, it cannot accommodate a Europa lander without
significant impacts to other programs, and while a Europa
lander is not included in the fiscal year 2018 budget request
from the Administration, it has become an established concept
for the future. NASA's Europa Lander Science Definition Team
conducted a study on the topic in 2016 to evaluate landing on
Europa and assess the science value and engineering design of a
future lander mission. More recently, NASA released a community
announcement to ask scientists what instruments would befit a
Europa lander and NASA continues to work on lander design
concepts.
I strongly support NASA and its efforts with the Mars Rover
2020 and Europa Clipper. I also believe there is great value in
exploring the possibility of a Europa lander. However, it is
critical that as Congress and NASA moves forward, we do our due
diligence to assure not only flagship mission success, but also
the success of the entire Planetary Science portfolio. I'd like
to highlight the importance of sufficient research and analysis
funding so that scientists can actually study the data derived
from these missions.
I want to thank the witnesses for being here today and I
look forward to your testimonies.
[The prepared statement of Mr. Babin follows:]
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Chairman Babin. And now I recognize the Ranking Member, the
gentleman from California, for an opening statement. Mr. Bera.
Mr. Bera. Thank you, Mr. Chairman. And I had to look back
there. I see my old friend, our former colleague, Congressman
Matt Salmon, in the audience. We miss you, Matt. Thanks for
being here.
Chairman Babin. I just saw him too.
Mr. Bera. You know, thank you for holding this hearing,
``Planetary Flagship Missions: Mars Rover 2020 and Europa
Clipper.'' I think for both of us, we've talked about this, and
for many of us of a generation that grew up in the space race,
just the imagination, thinking about, you know, whether it was
going to the moon or beyond, the Apollo missions to Skylab to
Apollo-Soyuz to the space shuttle programs captured our
imagination, and to a new generation of our kids and grandkids,
they continue to capture our imagination of going beyond.
We live in a time where we've sent spacecraft to explore
the moon, all eight planets, Pluto, several asteroids and
comets. And just last week, the NASA Juno spacecraft provided
us an amazing view of Jupiter's mysterious Great Red Spot. So,
you know, these missions are incredibly important because it
allows us to know that we're part of something bigger, and now
we've got Voyager One that is traveling through interstellar
space. The reach of our scientific exploration is truly
inspiring.
And to maximize the scientific return on investment for
planetary exploration, NASA develops both large and small
missions to visit a range of destinations throughout our solar
system. We're here to talk about large flagship missions like
Mars 2020 and Europa Clipper missions because they play an
important role in using complex instruments to help us
understand the challenge of exploring hard-to-reach locations
but we spend less time talking about the smaller missions, like
the Psyche mission that's represented on our panel. These are
launched more frequently in response to new discoveries. These
missions also provide opportunities for students to engage in
mission design, development, and operation. So the mixture of
both the large planetary missions but also the small is an
intentional mix and it provides significant value and has
through the history of NASA's planetary science program.
We also know that NASA's planetary missions have greatly
advanced our understanding of the solar system and its
potential to harbor life beyond Earth. Now, imagine if we were
to identify life beyond Earth. That would be disruptive for all
of humanity in a way of answering that seminal question, are we
alone? And, you know, life may not be in the form of human
life. It may be microbiotic life, et cetera, but even that
discovery would be dramatic and change how we viewed ourselves
in the context of our universe.
So I look forward to learning more about the role of large
and small planetary missions and the importance of supporting
this balanced mission size and, you know, I want to acknowledge
the panel here. I also want to acknowledge the long-term
commitments that we make as a body to fund this discovery, and
it's incredibly important to us.
So with that, I'll yield back
[The prepared statement of Mr. Bera follows:]
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Chairman Babin. Thank you, Mr. Bera.
I now recognize the Ranking Member of the full Committee
for a statement. Ms. Johnson.
Ms. Johnson. Thank you very much, Mr. Chairman.
Before I get into my formal statement, I just want to take
a moment to say that this Friday marks 48 years of Apollo 11
moon landing, and as we look forward to inspiring our younger
generation, whom I know many are sitting right out there, for
the exciting future missions to Mars, Europa and asteroids,
just remember that just 48 years ago this Friday, we had a
previous generation of young people. America has an impressive
legacy of accomplishment in both robotic and human space
exploration, and I hope that we can continue to build on it. I
hope that your minds will be just as inspired for our future as
we have seen for our past. Now for my formal statement.
Let me welcome all of our witnesses. I look forward to your
testimony.
Mr. Chairman, I thank you for holding this hearing on
planetary flagship missions. Through our investigations in
NASA's planetary science program, NASA has been able to explore
every planet in the solar system, as well as Pluto;
continuously operate missions to Mars for the past two decades;
and discover an expanding realm of potentially habitable bodies
both within and beyond the solar system. With each discovery,
NASA is advancing knowledge, pushing technological boundaries,
and inspiring future generations to pursue science and
technology education and careers. That is why I have often
referred to NASA's science program as one of America's crown
jewels.
And we will hear this morning even more exciting planetary
science missions lie ahead. As I speak, NASA is developing two
planetary flagship missions. The Mars 2020 Rover will assess
the habitability of Mars and look for signs of past life. In
addition, the Europa Clipper mission will investigate the ice
shell of Jupiter's moon Europa and its underlying ocean,
helping scientists to assess whether it can support life.
These, like previous flagships, are very challenging missions.
Mars 2020 will drill, collect, and cache samples of Martian
rocks and soils, and Europa Clipper must withstand the intense
radiation environment of Jupiter. Fortunately, NASA has decades
of experience with flagship missions to draw on.
With that in mind, I hope our witnesses can discuss the
lessons learned from previous flagships and how we are using
that knowledge in developing the Mars 2020 and Europa Clipper
missions.
Mr. Chairman, a discussion of flagship missions would be
incomplete without mentioning the importance of balance in
mission sizes, a critical element of a robust portfolio for
both the National Academies and NASA Authorization Acts have
repeatedly emphasized.
To that end, I am pleased that this morning's discussion
will also include smaller, Discovery-class missions, and their
role in maintaining a productive and balanced planetary science
program. Looking ahead, opportunities for new and exciting
planetary science missions abound. Maintaining balance will
take discipline among NASA, the scientific community, and
Congress.
Before I close, I want to take a moment to thank the
talented, dedicated and committed workforce of NASA and its
university, industry, and international partners. Our Nation's
inspiring achievements in planetary science would not be
possible without all of you.
I thank you, Mr. Chairman, and yield back.
[The prepared statement of Ms. Johnson follows:]
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Chairman Babin. Thank you, Ms. Johnson.
I now recognize our Chairman of our full Committee, Mr.
Smith from Texas.
Chairman Smith. Thank you, Mr. Chairman.
The exploration of our solar system captures Americans'
interests, inspires us to pursue extraordinary goals, and keeps
us on the forefront of scientific achievement.
Planetary missions teach us about how our solar system
works and provide clues about how it was formed. They discover
the locations of minerals and potential water sources on
asteroids, comets, moons, and planets that could be used on
future human missions or, in the case of minerals, extracted
for use here on Earth.
Planetary science also helps address a fundamental question
of science: Is there life elsewhere in the universe? Within our
own solar system, scientists have found strong evidence that
other planetary systems could in fact host life.
Europa, one of Jupiter's many moons, may have the necessary
ingredients for life: water and energy. Its ocean lies beneath
an icy surface and may be two times the volume of all Earth's
oceans. Tidal forces drive active geological processes within
Europa's ocean interior and provide energy. Scientists see
similar activity in hydrothermal vents on Earth's ocean floor.
The Europa Clipper mission, a flagship mission recommended
by the National Academy of Sciences, will be an important
mission to address the scientific question of whether there is
life elsewhere in the universe. It will advance our
understanding of planetary science as it explores the
characteristics of Europa's oceans, ice surface, and other
geological activity.
Congress directed NASA to work on a Europa lander to
complement the Europa Clipper. NASA's Europa Lander Science
Definition Team conducted a study on the topic in 2016. The
study found that the mission could analyze the biological
potential of Europa's ocean by directly examining both Europa's
surface and sub-surface. This is a very exciting concept that
warrants NASA's continued efforts.
Closer to Earth, Mars Rover 2020 will also study the
habitability of Mars. It builds upon the discoveries from the
Mars Curiosity rover and the two Mars Exploration rovers,
Spirit and Opportunity. The mission not only seeks signs of
habitable conditions in Mars' past, but also searches for signs
of past microbial life itself. It will also test new technology
that could benefit future robotic and human exploration of
Mars. One of its instruments, MOXIE, will test a method for
producing oxygen from the Martian atmosphere. Oxygen production
on Mars will be critical for future human missions.
I appreciate NASA's planetary science exploration efforts
and the Trump Administration's support of American leadership
in space. Other than national security agencies, NASA received
the most favorable budget request from the Trump
Administration. As a result, we can look forward to NASA
undertaking a bold and ambitious agenda.
I thank our witnesses and look forward to their testimony,
and I'll yield back, Mr. Chairman.
[The prepared statement of Mr. Smith follows:]
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Chairman Babin. Thank you, Mr. Chairman.
Now let me introduce our witnesses. We have a distinguished
panel this morning.
Our first witness today is Dr. Jim Green, the Director of
the Planetary Science Division of the Science Mission
Directorate at NASA. Welcome. Dr. Green has served as the Chief
of the Space Science Data Operations Office at Goddard Space
Center as well as the Co-Investigator and Deputy Project
Scientist on the IMAGE mission. He received his Ph.D. in space
physics from the University of Iowa. Welcome.
Our second witness today is Dr. Ken Farley, the Mars Rover
2020 Project Scientist. He is also a Professor of Geochemistry
at the California Institute of Technology. He received his
bachelor of science in chemistry from Yale and a doctorate in
earth science from the Scripps Institution of Oceanography from
the University of California in San Diego. Welcome.
Our third witness today is Dr. Robert Pappalardo, the
Europa Clipper Project Scientist at JPL at the California
Institute of Technology. Dr. Pappalardo received his bachelor
of arts in geological sciences from Cornell University as well
as Ph.D. in geology from Arizona State University. Maybe that's
why we see Representative Matt Salmon back there.
Dr. Linda T. Elkins-Tanton, our fourth witness today,
Director and Foundation Professor at the School of Earth and
Space Exploration at Arizona State University. She is also the
Principal Investigator for the NASA Psyche Mission. She
received her bachelor's of science and her master's of science
as well as her Ph.D. from MIT.
Our fifth witness today is Dr. William B. McKinnon. He is
Co-Chair of National Academy of Sciences' Committee on
Astrobiology and Planetary Science. He is also a Professor of
Earth and Planetary Sciences at Washington University in St.
Louis. He received his bachelor of science degree in Earth and
planetary sciences from MIT and his Ph.D. in planetary science
and geophysics from Cal Tech.
I would like to now recognize Dr. Green for five minutes to
present his testimony.
TESTIMONY OF DR. JIM GREEN,
PLANETARY SCIENCE DIVISION DIRECTOR,
SCIENCE MISSION DIRECTORATE, NASA
Dr. Green. Chairman Babin and the Members of the Committee,
thank you so very much for giving us the opportunity to come
and talk about certainly my favorite subject: planetary
science. In my opening statement, I'd like to explain how
missions like Mars 2020 and the Europa Clipper fit into an
overall planetary exploration portfolio.
[Chart]
In my first chart, as you see, this is an overview of the
current planetary missions. They're in a variety of
formulation, implementation and currently operating missions
that we have.
This is a tremendously exciting time in planetary science.
All our operating missions are making revolutionary discoveries
and all are rewriting the textbooks.
For instance, just two years ago, we had a fabulous fly-by
of the New Horizon spacecraft through the Pluto system. With
that mission, the United States becomes the first and only
Nation to reach every major body in the solar system from
Mercury to Pluto. Dr. Bill McKinnon on the panel is a New
Horizons Co-Investigator.
Today, NASA has numerous missions exploring and operating
through the solar system such as the lunar reconnaissance
orbiter, which is bringing us back to the moon and making
exciting discoveries.
The indomitable Mars Curiosity and Opportunity rovers along
with our orbiters at Mars continue to make almost daily new
discoveries about the red planet. For example, from our Maven
mission, it has revealed that solar wind interactions with the
upper atmosphere of Mars over time has literally stripped away
most of that atmosphere, transforming Mars from what we believe
was once a planet that could have supported life in its distant
past to now a frigid, arid world.
Adding to our Mars missions, Insight lander will be
launched in May 2018 and land in November 2018. Insight is
designed to study the interior of Mars along with understanding
its present-day level of global seismic activity.
In 2020, a new Mars rover will be launched carrying seven
state-of-the-art instruments to conduct advanced geological
research and search for signs of ancient Mars life. For the
very first time, we will create high-grade rock core samples
for potential return to Earth for further analysis. I look
forward to Dr. Farley's testimony, which will provide
additional information on that mission.
Between Mars and Jupiter is a major asteroid belt where
NASA's Dawn mission is currently studying the dwarf planet
Ceres and finding evidence of past cryovolcanism.
This year, NASA selected two discovery missions, Lucy and
Psyche, which will respectively visit six Jupiter mysterious
Trojan asteroids and study a unique metal asteroid that may
actually be an exposed planetary core called Psyche. Dr. Linda
Elkins-Tanton is here today to tell much more about the Psyche
mission.
NASA's robotic rendezvous and sample return mission that
visits the Bennu asteroid is called OSIRIS-Rex. It will get a
gravity assist by Earth in September and it will reach that
potentially hazardous asteroid in August of next year.
Examinations of objects like Bennu will allow our scientists to
investigate how planets formed and how materials like water and
organics actually were delivered in early impacts in addition
to looking at the effects of potential planetary defense.
In our outer solar system, Jupiter's mission Juno, which
got into polar orbit our very first time in polar orbit at
Jupiter last July. Since then Juno has been observing the cloud
tops and into the interior of the planet, finding in the
northern and southern polar regions that that planet is
maintaining huge nearly Earth-size cyclones.
After 13 years of orbiting Saturn, our Cassini spacecraft
is making a daring dive between the planet's atmosphere and the
first ring, and it will lead to plunging that spacecraft into
Saturn on September 15 as it runs out of fuel. Cassini has
given us a powerful insight into the planet's internal
structure, atmosphere and rings in addition to unbelievable
views of Titan and Enceladus.
And if I may go on and summarize, finally, NASA recognizes
there is still much to learn. With your support, we will
continue to tackle solar system exploration goals identified as
top priorities by the scientific community and delineated in
the National Academies' Planetary Decadal.
Again, thank you so much for the opportunity to testify
today and I look forward to responding to your questions.
[The prepared statement of Dr. Green follows:]
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Chairman Babin. Thank you, Dr. Green.
I now recognize Dr. Farley for five minutes to present your
testimony.
TESTIMONY OF DR. KENNETH FARLEY,
MARS ROVER 2020 PROJECT SCIENTIST;
PROFESSOR OF GEOCHEMISTRY,
CALIFORNIA INSTITUTE OF TECHNOLOGY
Dr. Farley. Thank you for the opportunity to testify today
on the Mars 2020 mission.
Mars 2020 will seek evidence of past life in a fossil
Earth-like environment that existed in the first billion years
after the dawn of the solar system. This flagship mission will
engage many hundreds of scientists and the American public in a
very challenging journey through one of the most intriguing
landscapes in the solar system and some of the most profound
scientific questions of our time.
Today Mars is too cold, too dry, and too exposed to harmful
radiation to plausibly nurture life on its surface. However,
more than two decades of sustained and strategic NASA-led
exploration have shown that the red planet was once very
different. Imagery from the Mars Odyssey and Mars
Reconnaissance Orbiters reveals that prior to about 3.6 billion
years ago, Mars had rivers, lakes, and possibly a vast northern
ocean. Sophisticated analyses made on the planet's surface,
most notably by the Spirit and Curiosity rovers, have richly
documented ancient environments with all conditions believed
necessary to sustain life. In that same early time period,
conditions here on Earth were broadly similar, and life had
already originated, evolved, and spread across the surface.
However, unlike Earth, with its active erosion and plate
tectonics, the geologic record of ancient Mars is exquisitely
preserved for study, allowing us to seek answers to grand
questions including how early climate and habitability evolve
on rocky planets, the nature of prebiotic environments that
might ultimately spawn life, and whether life is unique to
Earth. Seeking the signs of life in an ancient habitable
environment is the central goal of the Mars 2020 mission.
Thanks to a wealth of images from the Mars Reconnaissance
Orbiter, the science community has narrowed the possible Mars
2020 landing sites down to three very different settings that
on Earth are both habitable and inhabited: an ancient river and
lake system, a fossil hot spring similar to those at
Yellowstone National Park, and a setting where warm water once
circulated through shallow subsurface rocks. Once on Mars, the
rover will use its on-board instruments to investigate the
local geology, to characterize the habitable environments the
rover traverses, and to look for evidence of ancient life.
Using Earth as a guide, we expect that any Martian life
existing at that time was primitive, consisting only of
microbes. Truly definitive discovery of microbial biosignatures
by instruments on board the rover is unlikely, and can best be
undertaken using the full arsenal of terrestrial laboratories.
For this reason the Mars 2020 rover will prepare a complete
suite of samples for possible return to Earth by a future
mission.
Mars 2020 starts with the designs of the remarkably
successful Mars Science Laboratory (MSL) and the Curiosity
rover. To this platform a suite of very capable new science
instruments is being added to explore the structure, chemistry,
and mineralogy of the surface all the way from the regional
scale down to the microscopic scale. In addition, the mission
is developing advanced new capabilities for landing in rugged
terrain, for autonomous navigation and science observation, and
for robotic coring and caching of samples. These are critical
steps towards unleashing the full capabilities of robotic solar
system investigation.
The mission will also test new technologies beneficial to
future human Mars exploration, most notably a device to
demonstrate conversion of carbon dioxide in the Martian
atmosphere into oxygen for use as a component of rocket
propellant. The mission is currently in the implementation
phase (Phase C) with a substantial amount of hardware already
completed. Launch will occur in the summer of 2020, with
arrival on Mars on February 18, 2021. The rover will be landed
using the spectacular sky-crane system pioneered by MSL, and
will explore the Martian surface for at least two years. In
that period the rover will core and cache at least twenty rock
samples, each about the size and shape of a piece of chalkboard
chalk. These will be thoroughly documented and placed on the
surface, accessible to retrieval by a future mission or even by
human explorers. By collecting and caching a diverse suite of
high-science-value rock samples, Mars 2020 fulfills the highest
priority objectives of the Mars and planetary science
communities as described in the most recent Planetary Science
Decadal Survey.
Mars 2020 will investigate a planet known with detail
sufficient to compellingly address, for the first time, well-
posed and profound scientific questions that would forever
elude answers from Earth-bound study. Going well beyond
observations on the Martian surface, return of the cache to
terrestrial laboratories would provide future generations of
scientists across many disciplines access to samples that would
transform our understanding of Mars, the solar system, and
life. There is still an enormous amount to learn about Mars,
and the deeper we penetrate, the richer the scientific tapestry
becomes. Mars 2020 makes the next big step in this decades-long
journey, and provides new focus and foundation for human
exploration of Mars. It's an honor and a privilege for me to
play a part in such a grand and ambitious undertaking.
I look forward to your questions.
[The prepared statement of Dr. Farley follows:]
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Chairman Babin. Thank you, Dr. Farley.
I now recognize Dr. Pappalardo for five minutes to present
your testimony.
TESTIMONY OF DR. ROBERT PAPPALARDO,
EUROPA CLIPPER PROJECT SCIENTIST,
JET PROPULSION LABORATORY,
CALIFORNIA INSTITUTE OF TECHNOLOGY
Dr. Pappalardo. Chairman Smith, Chairman Babin, Ranking
Member Bera and other Members of the Committee, I'm delighted
to appear before you to describe recent progress in NASA's
Europa Clipper mission.
The ice-covered world Europa--moon of Jupiter similar in
size to Earth's moon--shows a landscape of cracks, ridges, and
jumbled, chaotic terrains indicative of a tumultuous past. The
Galileo spacecraft, which orbited Jupiter beginning in the late
1990s, provided images, compositional information, and gravity
and magnetic data that point to a remarkable conclusion: Europa
likely has a global ocean of liquid water beneath its icy
carapace, maintained by tidal flexing and heating. From what we
know of the tenacity of life, Europa could be one of the best
places in the solar system to search for life beyond Earth.
For these reasons, future detailed investigation of Europa
is one of the top priorities for planetary exploration, as
expressed in the National Research Council's 2011 Planetary
Science Decadal Survey. The Europa Clipper mission responds
directly to the Decadal Survey in its top-level goal: explore
Europa to investigate its habitability, and in its science
objectives to understand Europa's ice shell and ocean,
composition, geology, and recent or current activity. The last
of these categories includes the possibility that Europa may
have active plumes that spew water vapor into space, and which
could directly reveal Europa's internal composition and
suitability for life. This tantalizing evidence for plumes is
provided by the Hubble Space Telescope, searching at the
extreme of its detection limits.
In the tradition of the 19th century trading ships for
which this mission was recently named, the Europa Clipper will
sail past the Jovian moon at a rapid clip as frequently as
every two weeks. providing many opportunities to investigate
Europa from as close as 16 miles above the surface. During each
flyby, the spacecraft will spend just a short time within the
challenging radiation environment near Europa. The prime
mission plan includes 40 to 45 flybys of Europa from Jupiter
orbit, during which the spacecraft will interrogate the moon in
unprecedented detail. This will include imaging to understand
its geological history; compositional analyses including direct
sampling of materials knocked off the surface; ice-penetrating
radar to examine the 3D structure of its icy shell; and
gravity, magnetic, and plasma measurements to understand its
hidden interior and interactions with the Jupiter environment.
The mission can also lay the foundation for future exploration
of Europa, providing critical global context and scouting
potential landing sites for a potential future landed mission.
As its Project Scientist, I represent the science and
scientific integrity of the Europa Clipper mission, ensuring it
will address the top-level goal and objectives. I first
testified before this Committee two years ago, just after NASA
had competitively selected nine science instruments for the
mission, and had given the green light to begin Phase A, known
as mission formulation. In February of this year, NASA
completed its second major milestone review, so today we're in
Phase B, refining details of how the instruments will achieve
the mission's science, and developing preliminary yet detailed
design plans for the spacecraft and its subsystems, including
the science instruments.
Progress on the instrument suite has been outstanding.
Instrument concepts have been reviewed; designs have matured;
subsystem vendors are being selected; prototype parts are being
built; detectors are being tested; and additional tests are
being conducted to ensure robustness against the harsh
radiation environment in Europa's vicinity.
Beginning this fall and into next spring, each spacecraft
subsystem and each instrument will undergo a preliminary design
review to assure that the defined science can be achieved by
the instruments and spacecraft in combination. These Phase B
reviews are in preparation for the mission to proceed to Phase
C around October 2018. It's also at this key decision point
that NASA would make a final commitment as to a launch
readiness date and baseline mission cost. Then during Phase C,
flight hardware would be built.
The members of the mission's science team are working
cooperatively together to define the synergistic science which
I see as this mission's hallmark. No one instrument can
definitively affirm the ocean's existence or tell us
convincingly of Europa's composition. Instead, each instrument
technique provides a piece of the puzzle, and from the combined
science data, Europa scientists will mature a complete picture
of how Europa works as a complex system from its submerged
rocky core to its ocean to the capping ice shell and surface,
to its thin atmosphere, and the surrounding environment of
Jovian space.
The clipper ships of the late 19th century were an
expression of speed and grace in the golden age of sail. We're
now in a golden age of solar system discovery, and the Europa
Clipper mission will return to us untold scientific riches.
Thank you, and I look forward to your questions.
[The prepared statement of Dr. Pappalardo follows:]
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Chairman Babin. Thank you, Dr. Pappalardo.
I now recognize Dr. Elkins-Tanton for five minutes to
present her testimony.
TESTIMONY OF DR. LINDA T. ELKINS-TANTON,
DIRECTOR AND FOUNDATION PROFESSOR,
SCHOOL OF EARTH AND SPACE EXPLORATION,
ARIZONA STATE UNIVERSITY;
PRINCIPAL INVESTIGATOR, NASA PSYCHE MISSION
Dr. Elkins-Tanton. Chairman Babin, Chairman Smith, Ranking
Member Bera, and the Members of the Committee, thank you so
much for the opportunity to speak today. Today I'll be
testifying in my personal capacity.
Any discussion of NASA's planetary science program would be
incomplete without also talking about the balance between
flagships and smaller planetary missions, and so today I'm
going to talk about three things. I'm going to talk about the
newly selected Psyche mission, I'm going to talk about
portfolio balance, and I'm going to talk about our inevitable
space future.
I am the Principal Investigator of the Psyche mission,
which in January was selected as the 14th in the NASA's
Discovery program. The spacecraft is scheduled to launch in
August of 2022 to rendezvous with the asteroid Psyche in
January of 2026, and to orbit Psyche for 22 months. Psyche is a
metal world with a diameter about the same as the width of
Massachusetts and with a surface area larger than the area of
Texas. Humankind has explored rocky worlds and we have explored
icy worlds and we have explored worlds covered with gas but we
have never before explored a metal world. This is a first.
We think that Psyche is the core of a small early-formed
planet that was bombarded in the early solar system and had its
rocky exterior knocked off so that only its metal core remains
showing today. Computer models of planetary formation indicate
that this is rare, and indeed, Psyche is the only large, round
metal object in our solar system, so it's not just unique, it's
improbable.
The science we hope to achieve in the mission is first to
determine whether indeed Psyche is a core, or if it is some
previously undiscovered kind of material. We'll be comparing
what we learn at Psyche to models of the Earth's core to better
understand that unreachable part of our own planet. And for the
first time, we'll be investigating the morphology of a metal
body. What do craters into metal look like? Could Psyche have
glittering cliffs of metal and green pyroxene crystals? We
don't know yet. No one knows yet. At Psyche, we will also take
the first steps toward our space resource future because we're
pretty confident that Psyche almost entirely consists of iron,
nickel, copper, and a variety of trace metals.
Now, I strongly support the Planetary Decadal Survey's
conclusion about the necessity for having a balanced mission
portfolio combining small and mid-sized missions on a regular
tempo with flagships. Tempo is critical. Tempo maintains our
workforce and it also saves our institutional memory, but each
size of mission comes with its own challenges and its own its
own advantages. For smaller missions like Psyche, usually
keeping costs down and keeping risk down means that we're going
to use trusted high-heritage components whereas flagship
missions give us the opportunity for innovation and new
technology development, and we need both of those things. We
need our trusted technology today and we need new technology
for the future.
Flagship missions can also engage a broader swath of the
community through competed calls for instruments. These calls
can bring new groups onto missions that would otherwise not be
involved but then the project scientist has the challenge of
organizing and uniting otherwise disconnected sub-teams. It's
an interesting challenge. In fact, all lead scientists have to
build, inspire and lead large interdisciplinary teams, and
normally engineers and scientists are not taught these skills,
so we are trying to change that at ASU now.
Exploration is a human imperative. It is stamped on our
DNA, and space is the future of exploration for humankind.
Every time we do this most extreme of technological miracles
and we send a rocket off of our Earth to make discoveries in
space, we encourage people all around the world to make a
bolder step in their own lives and in their own communities. So
space exploration is therefore an opportunity for us to create
a better educated, more united society.
At ASU I'm also co-chair with President Michael Crow of our
new Interplanetary Initiative. In this initiative, we're
bringing together not just the technological but the
educational and the social aspects that we need for our space
future, and indeed, education is the single most critical thing
for humanity's future. Both at ASU and at our startup, Beagle
Learning, we are working on next-generation learning. We need
to produce a critical mass of people who are attracted to the
unknown, who are learning how to ask better questions, who are
willing to pursue answers through partial solutions, and who
know how to build teams and to lead. All this ideation is
initiated by the vision and the process of NASA, and in fact,
space exploration will bring us to a better future here on
Earth as well as eventually on the moon and Mars and beyond.
Thank you very much.
[The prepared statement of Dr. Elkins-Tanton follows:]
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Chairman Babin. Thank you, Dr. Elkins-Tanton.
Now I'd like to recognize Dr. McKinnon for five minutes for
your testimony.
TESTIMONY OF DR. WILLIAM B. MCKINNON,
CO-CHAIR, NATIONAL ACADEMY OF SCIENCES,
COMMITTEE ON ASTROBIOLOGY AND PLANETARY SCIENCE;
PROFESSOR OF EARTH AND PLANETARY SCIENCES,
WASHINGTON UNIVERSITY IN ST. LOUIS
Dr. McKinnon. Good morning, Mr. Chairman, Members of the
Committee.
So I'm here today because I'm a Co-Chair of the Committee
on Astrobiology and Planetary Sciences, or CAPS, for the
National Academies, but I wish to say that my testimony today
is my own and is not an official report from CAPS or the
Academies. Nevertheless, I hope you find my remarks useful.
So I'd like to focus on the Planetary Science Decadal
Survey and its relation to flagship and other planetary
missions. Obviously decadal surveys are carried out about every
ten years for various space science disciplines and the
Committees and the panels that carry out the decadal are drawn
from the broad community associated with the discipline in
question. Decadal survey recommendations to the government play
a critical role in defining our country's agenda in a given
science area for ten years or even longer.
Now, the Planetary Science Decadal Survey was tasked in
particular, among many things, to create a prioritized list of
flight investigations because missions lie at the heart of
planetary exploration. Such a prioritization is based first and
foremost on science, especially science per dollar, but also on
programmatic balance among mission targets and balance among
mission types--small, medium and large. Indeed, a balanced mix
of discovery, new frontiers and flagship missions enable both a
steady stream of new discoveries and the capability to address
larger challenges such as sample return missions or outer solar
system exploration.
Prioritization also considers technological readiness, the
availability of trajectory opportunities, understanding of cost
and technological risk, and the fiscal climate. Anyway, these
prioritizations take in the sense that decadal surveys succeed
because the consensus they represent is compelling.
Now, in terms of science, increasingly central to NASA's
exploration of the solar system is the emerging science of
astrobiology, prominent examples being the scientific program
of the Curiosity Mars Rover, the Mars 2020 rover, the
development of the Europa Clipper mission, and the planning for
the potential future landing on the surface of Europa and the
inclusion of ocean worlds in the recent new frontiers call.
Indeed, in the most recent Planetary Decadal Survey,
astrobiology was a driving scientific rationale for the two top
mission recommendations now being implemented as Mars 2020 and
Europa Clipper. Now, my personal assessment, and as the CAPS
leadership has previously reported to the Space Studies Board,
is that NASA's Planetary Science Division is doing well and the
Decadal Survey's priorities and recommendations are being
pursued. Mars 2020 and Europa Clipper in particular are, I
believe, responsive to the Decadal Survey in science and cost.
Now, regarding NASA's plans to explore Europa, CAPS, as
well as the ongoing Academies' planetary mid-term review will
continue to consider the aspects of--consider the impacts of
the evolution of this program. Presently, NASA has been
directed to add a lander to the Europa exploration program. The
development of any large mission like that is of course a
programmatic challenge and can have unwelcome or worse effects
on a broad cost-contained program. But this challenge must be
balanced against the scientific opportunity afforded by the
promise of addressing one of the greatest of scientific
questions: is there extant life beyond Earth?
As I said, these are all issues I expect CAPS will continue
to consider and will also be surely considered by the next
decadal as well.
So to finish up, Mr. Chairman, as a second grader I watched
the liftoff of John Glenn and Friendship 7 in our auditorium,
and as a teenager at home I watched Neil Armstrong walk on the
moon. Over the past 60 years, I have seen NASA's exploration of
the solar system from Mercury out to Pluto and beyond,
revolutionize our conception of ourselves and our planet, but I
believe given our ongoing discoveries and characterization of
planets around other stars, thousands of them we know about
now, and the very real possibility of detecting extant life in
our solar system that we are approaching an even greater
revolution, a true paradigm shift in our understanding of our
place and our destiny in the universe.
Thank you very much.
[The prepared statement of Dr. McKinnon follows:]
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Chairman Babin. Thank you, Dr. McKinnon. All fascinating
testimonies. I really appreciate it. The Chair now recognizes
himself for five minutes.
Dr. Green, in the near future, NASA's Planetary Science
Division may be running three flagship missions at the same
time: the Mars rover for launch in 2020, the Europa Clipper for
launch in 2022, and potentially a Europa lander for launch in
the 2024 time frame. I greatly support this investment and
NASA's renewed focus on deep space exploration. At the same
time, from an acquisition perspective, this is a great deal of
work. What is NASA doing to address the risks of cost and
schedule slips associated with this cadence of flagship
missions?
Dr. Green. Planetary Science I think has tackled a number
of those topics and is doing quite well because we started to
implement a couple very important and new procedures.
Typically, strategic missions in the past based on a science
rationale that's almost at any cost. In Planetary Science, we
begin the--we have begun the process in particular with Mars
2020 to have a cost-constrained environment. As was recognized
on the Planetary Decadal, both the Mars Cacher and the Europa
Clipper were unaffordable, and we took on a process early in
this decade to begin to determine what science we can do at
that reasonable cost. We're leveraging on Mars 2020 the
architecture for Curiosity. We've done a lot of work on the
planning of the Europa Clipper where we're looking at descope
options, and so some of these processes are incredibly
important for us to follow through on.
Chairman Babin. Okay. Thank you very much.
And now the next question to Dr. McKinnon. To what extent
do the Mars Rover 2020 and Europa Clipper missions align with
the Decadal Survey recommendations?
Dr. McKinnon. Well, the original survey considered two
flagship-class missions, Mars astrobiology Explorer-Cacher and
a Europa Jupiter orbiter mission, a mission to orbit Europa
itself, and in both cases the Decadal Survey concluded based on
a very detailed cost and technical evaluation that these
missions were probably too expensive to be carried out in the
decade in question. And so basically they said these were our
priority missions but they needed to be descoped. They needed
to be reduced in cost and perhaps reduced--and certainly
reduced in risk. And in both cases, I think they've done that.
As an example, the Europa mission doesn't orbit Europa anymore
but it orbits Jupiter but repeatedly passes by Europa dozens of
times and basically recovers all of the science, and in fact,
in my own view actually does an even better job because it
avoids so much of the radiation that's near Jupiter and it
allows in its long looping orbits around Jupiter that Dr.
Pappalardo can tell you about, it can radio back all the data
that it collects every time, and it does it within a very
reasonable cost cap.
Chairman Babin. Thank you very much.
Now, I also would like to ask Dr. Farley and Dr.
Pappalardo, the exploration of Mars and Europa are inspiring
and truly amazing. As Project Scientists for Mars Rover 2020
and the Europa Clipper, can you share with us what excites you
about these exploration efforts, and what are the greatest
scientific discoveries that you're hoping to achieve?
Dr. Farley. Well, I think the most exciting thing about
Mars is that, as I mentioned in my testimony, the surface of
Mars is--carries a rock record from a time period which is
completely obliterated on Earth. There is no substantial rock
record that is older than about 3.6 billion years on Earth.
Those rocks are present on the surface of Mars, and they will
tell us a lot both about the way rocky planets evolve and also
about things like habitable environments, and for me, linking
this to the life question, I think the really exciting thing
is, we will potentially be looking at an environment that was
capable of having life originate, and that's of course one of
the great questions. It's a great scientific question that is
extremely difficult to treat as a science question because
there's no evidence, no substantial evidence to compare it
against. By going to Mars, we may actually be able to find
environments like that and learn something really profound
about the way life works.
Chairman Babin. Thank you very much.
And Dr. Pappalardo?
Dr. Pappalardo. For Europa, we want to understand, is this
really a habitable environment, Europa's ocean, lakes within
the ice shell, and we think we know how Europa works but
planetary scientists are always surprised when we actually go
there with new instruments to test hypotheses. So we're going
to both test hypotheses and explore and expect to be surprised.
What I would love to see is some sort of oasis, that is, a
place where there's liquid water near the surface, there's
evidence of heat coming out, there are organics at the surface
somewhere where we'd want to follow up with future exploration.
Chairman Babin. Fascinating. Thank you. My time is up so
I'd now like to recognize the gentleman from California, Dr.
Bera.
Mr. Bera. Thank you, Mr. Chairman.
Dr. Elkins-Tanton--and I think each of you in your opening
statements alluded to the fact that exploration is part of our
DNA, you know, this natural curiosity, this desire for
discovery, and the universe is, you know, unlimited in its
possibilities of what we can learn. That brings us back down to
Congress where we have to operate in the confines of limits.
Each of you has talked about the Decadal Survey and alluded to
a bit of the roadmap for some of our bigger missions and laying
out some of the parameters for some of the medium-size
missions.
Dr. Elkins-Tanton, as you talked about the Psyche mission
and alluded to the importance of, you know, some of our smaller
missions, how those--you know, what we discover, you know,
they're able to be launched at a lower cost, et cetera. You
know, there's some worry in that limited environment of
Congress that we potentially focus on the big missions at the
expense of the smaller missions, and we've got to found the
right balance. Maybe if you want to expand on your comments and
the importance of some of the smaller missions.
Dr. Elkins-Tanton. Thank you very much. Indeed, I think
this is well recognized at NASA, and I've heard Jim Green talk
about a cadence, a process for deep exploration in space that
you might fly by, you might orbit, you might land, and then you
might rove, and indeed, you wouldn't spend all the money that
you would have to spend to do a flagship mission on a body that
we know little about, and so the smaller missions form a
framework and they set the stage for the kinds of bigger
expeditions that we want to do, and as my colleagues here have
mentioned, every time we do something in space, it surprises
us, and so we must try these smaller missions to find out where
the biggest surprises are and then put our money on making the
big, big discoveries.
Mr. Bera. Dr. Green, do you want to expand on the
importance of the smaller missions?
Dr. Green. Indeed, the smaller missions are really our
pioneers. They do go out and do some initial exploration. You
know, smaller missions in the discovery framework is really the
heart of that exploration process. You know, I mentioned
several of them in my testimony like Dawn. Others that have
come and gone while I've been at NASA headquarters include
Messenger, another wonderful mission. Grail went to the moon,
Messenger went to Mercury, and Grail studied the moon in new
and unique ways.
And so indeed, the discovery line is really quite important
for us, and then the next line is new frontiers. This is where
we can now concentrate on the next level of detail. So
important for us to make decisions on what our next flagships
will be.
Mr. Bera. Great. Switching now to Mars and, you know, our
telecommunications infrastructure and Mars, my understanding
right now is that the Mars Reconnaissance Orbiter handles the
majority of our telecommunications relay for Curiosity Rover,
but the MRO was launched 12 years ago. As we look at Mars Rover
2020, you know, I guess, Dr. Green or Dr. Farley, would you
like to kind of comment on, you know, will we still be relying
on the MRO to relay that information back or are we thinking
about, you know, what next steps for telecommunications?
Dr. Green. Well, telecommunications for any surface assets
indeed go through our orbiters, and right now we have a
wonderful network including MRO is Mars Odyssey, and also with
partnership from ESA, other missions that are also orbiting
Mars have that telecommunication capability. So in addition to
those two, we also have with ESA the Mars Express mission and
now the newly inserted into orbit, the Trace Gas Orbiter from
ESA. Now, we also have Maven, which is not prime
telecommunication capability but may become more dependent on
using Maven as our aging assets occur. So indeed, supporting
telecommunications is a real critical element of allowing us to
now when Mars 2020 gets down on the ground be able to relay
that data back so we take careful operations of all those
missions and partner with other agencies.
Mr. Bera. Great. Dr. Farley, do you want to expand or----
Dr. Farley. I'll just say Mars 2020 has a very large demand
to downlink data. We have a huge number of cameras. It's quite
extraordinary. There's more than 20 cameras on the rover. And
we will need downlink. As you point out, MRO is an aging asset
but as Dr. Green pointed out, there are contingency plans to
get us the data volume we need.
Mr. Bera. Great. Thank you. And I'll yield back.
Chairman Babin. You bet. Thank you. Good questions.
I now recognize the gentleman from California, Mr.
Rohrabacher.
Mr. Rohrabacher. Thank you very much, Mr. Chairman. It was
noted earlier that one of the purposes of, or one of the
benefits, I should say, of your activities is that you have
these robots all over the universe and beyond that you are
inspiring people with our capabilities.
And Mr. Chairman, let me just note that I've been around
for a while, and I think that when we were deciding about the
shuttle and we were deciding about Space Station, a lot of
times the discussion was only on the immediate scientific
payback, but I believe those two space projects have inspired
generations of Americans now, and who knows how much more
productive our people are, how much more visionary they are
because of these investments in the shuttle and the space
station, which were very expensive projects, I might add.
And back to expensive projects, let me just note that one
thing that I find--one of our witnesses mentioned that the
Decadal Survey was supposed to prioritize and it just seems to
me standing back and listening to everything that we haven't
had that prioritization and maybe we should--there's been--when
you have so many projects at one time, it indicates that there
hasn't been a real finding out of what priorities we need, and
I'm certainly not an expert enough to tell you what those
priorities should be.
Let me ask some specific concepts or ideas about the
engineering that I don't know about. What type--well, first of
all, is there any one of these missions that plan to--we know
we've landed the robots on Mars. Do we plan to actually bring
some material from Mars back to Earth before we plan to send
human beings there and bring them back?
Dr. Green. Indeed, the Mars 2020 mission, which is going to
core rock, providing a detailed look at the past Mars, the
geological records in that rock, we are currently looking at a
variety of architectures, and----
Mr. Rohrabacher. Right, but we are going to bring them
back?
Dr. Green. Our intention would be indeed that as the
importance of these samples are noted based on the analysis
that we do in situ that indeed we would plan on bringing
samples back from Mars.
Mr. Rohrabacher. Okay. The reason I ask that is, it seems
to me that rather silly to think that if we can't bring back
rocks that we're going to bring back people, and certainly if
we aren't comfortable with the idea that we can bring back
rocks, we should be focusing on getting that done before we
talk about bringing people back.
The exploration, to me, that's the most inspiring. I just
have to tell you that when we talk about going out and visiting
those places where nobody has been, what type of fuel are we
using? There was a mention about one of the things when we run
out of fuel, it's going to land into Europa or something like
that. What type of fuel is now being used in these various
projects? We know you have to have a big rocket to get them
going, but if they're going to keep going into the universe,
what fuel do they use?
Dr. Farley. Yeah, Mars 2020 while it's on the surface will
use a short-lived plutonium isotope so it's a nuclear power
source.
Mr. Rohrabacher. Any other----
Dr. Elkins-Tanton. May I add to that? During cruise and
while orbiting Psyche, our spacecraft will use solar electric
propulsion, and this to me is so--it's in our heart at space
age. You see the little blue plumes of the ions being shot out
the back and it's all run by solar power, and in fact, this is
another good proof of this technology which is eventually going
to be critical for getting people to Mars.
Mr. Rohrabacher. Yeah, I remember the solar sail project,
which also was very exciting. These new concepts that--and
you--and let me just note, Mr. Chairman, the fact that we can
actually provide a fuel for something that far away indicates
that maybe we have some knowledge that's going to really help
us here.
But one last thought. I would hope that--again, I think the
Moon is close by and whatever we can actually get a benefit of
going back there, we should before you take the next step.
However, the most important thing was, if Mars--can I ask
permission for one minute for this question? And that is, you
have indicated that Mars was totally different thousands of
years ago. Is it possible that there was a civilization on Mars
thousands of years ago?
Dr. Farley. So the evidence is that Mars was different
billions of years ago, not thousands of years ago.
Mr. Rohrabacher. Well, yes.
Dr. Farley. And there would be--there's no evidence that
I'm aware of that----
Mr. Rohrabacher. Would you rule that out? See, there's some
people--well, anyway----
Dr. Farley. I would say that is extremely unlikely.
Mr. Rohrabacher. Okay. Well, thank you all, and thanks for
the good job you're doing. God bless.
Chairman Babin. Thank you, Mr. Rohrabacher. I'm looking
forward to finding out what's up there, that's for sure. And
just last month, we had a great hearing in here on in-space
propulsion, which was super, super interesting.
Okay. Now I recognize the gentleman from Colorado, Mr. Ed
Perlmutter.
Mr. Perlmutter. Thanks, Dr. Babin.
And good morning, and thank you for your testimony today,
and a truism in life is, everything's relative, and when we're
talking about small, medium and flagship projects that you all
are undertaking, you know, to Mrs. McGillicuty from Lakewood,
Colorado, they're all major undertakings, and Dr. McKinnon and
Dr. Elkins-Tanton, I mean, we're here for I dipped into the
future far as human eyes could see, saw the vision of the world
and all the wonder that would be. And all of you are working on
kind of the ultimate question of humanity, why are we here and
what else is out there. And so I just appreciate your
willingness to take on kind of the nuts and bolts for us to
start knowing the unknown, and this Committee is so exciting to
all of us here and to hear the work you're doing, we appreciate
it.
Now, I'd like to start with Dr. Farley. One of the things
that I am focused on is trying to get our astronauts to Mars
by--you guessed it--2033, all right, and so first question I
have is for you. How will this rover, you know, 2020, our
mission in 2020, how will that help us, inform us to get humans
to Mars by 2033?
Dr. Farley. Well, I think it's important to note that Mars
2020 has a very strong collaborative involvement from the human
side of NASA, and that is manifested in several different ways.
Most notably, you heard about the MOXIE demonstration of in
situ resource utilization. In addition, we have a weather
station, which will characterize the environment, will also
characterize dust, and dust on Mars is a big concern for human
explorers, and in addition, during entry, descent and landing,
we'll have a very sophisticated observation package.
Understanding what goes on during EDL is absolutely critical
and almost impossible to simulate either on a computer or in an
analog experiment on Earth, so this is very important data, and
as Dr. Green mentioned in answer to the question of, you know,
bringing rocks back before people back, it's a very sensible
thing to do. Obviously there's no commitment to do that but
there will be a tempting target to learn from when those
samples come back.
Mr. Perlmutter. Dr. Elkins-Tanton, where the heck is
Psyche, I mean other than up here or wherever it might be?
Dr. Elkins-Tanton. Psyche is in the outer main asteroid
belt between Mars and Jupiter. It's about three times farther
from the sun than the Earth is.
Mr. Perlmutter. Okay. Dr. Pappalardo, my question to you,
you know, often I talk about Star Trek or Star Wars or Men in
Black but what you're doing reminds me of 2001: A Space Odyssey
and, you know, our mission at that point to get to Jupiter. So
explain to me in this investigation, study of Europa, what are
the--I mean, what do you really--what do you see already and
what do you expect to see from this mission?
Dr. Pappalardo. Let me preface by saying I'm a big Trekkie.
And our Europa science team of about 130 people we have as our
mascot, our totem, a giant monolith that we tote around our
meetings.
So we have tantalizing hints from the Galileo mission about
what Europa is like. At high resolution we have precious little
data. We have one six-meter-per-pixel image. We have ten-meter-
per-pixel images that you can count on your hands and toes to
get an idea of what Europa is like, and so this creates this
picture of what we think it's like, an ice shell probably about
20 kilometers thick above a saltwater ocean and then the rocky
mantle below. But, you know, right now it's kind of a uniform
picture whereas any world you explore in more detail and then
you find out how it varies from place to place. We've seen this
happen with our understanding of Mars where we first thought it
was a cratered ball because we saw the cratered part of it and
then we started understanding more and more, and now it's at
the outcrop scale we see differences. So we're going to
understand how Europa works as a world. We're kind of in our
level of understanding that we were before plate tectonics on
Earth where we don't really get how all the little pieces we
see at the global scale fit together and we're going to find
more little pieces as we explore with Europa Clipper.
Mr. Perlmutter. Thank you----
Dr. McKinnon. If I could----
Mr. Perlmutter. --Mr. Chair, and I yield back.
Dr. McKinnon. I'll just pipe in just for a second.
Mr. Perlmutter. Oh, I'm sorry.
Dr. McKinnon. We're--you know, we have tantalizing evidence
from the Hubble space telescope that Europa's venting material
into space, and we hope when we get there we'll be able to
confirm that and literally fly through it and sample it and
analyze it.
Mr. Perlmutter. Thank you, Doctor.
Chairman Babin. Thank you. Good questions and great
answers.
I now recognize the gentleman from Oklahoma, Mr. Lucas.
Mr. Lucas. Thank you, Mr. Chairman, and I share my
colleagues' enthusiasm up here and clearly the enthusiasm of
the panel.
Let's visit mechanically for a moment, Dr. Farley, about
the nature of the rover programs. A lot of citizens back home
are very sensitive about how we spend their money. Could you
take me through a discussion about Mars Rover 2020, the
advances and the technology and the science gathering used in
that compared, say, to Curiosity as I explain to my
constituents back home why it's important we do this?
Dr. Farley. Okay. Well, in reference to Curiosity, the
reason this mission can be done in a cost-constrained way is to
take advantage of the platform that the Mars Science Laboratory
developed. It should not be underestimated how difficult any
new undertaking in space is. So we start off with that, and
this allows us to actually focus on the stuff that is new, and
there are new science instruments that will make new kinds of
observations, and I think those--they will be directed towards
characterizing samples that will form the basis of a discussion
as to whether those samples should be brought back, and if
those samples are brought back, I think they will revolutionize
our understanding of many different things.
If you look at the history of our understanding of many
aspects of the solar system, it was completely changed by the
return of the lunar samples, and that of course is an
abiological world. My expectation is, if samples come back from
Mars, this will be a revolution that goes way beyond sort of
planetary science and geology. It will actually extend into
asking and looking at samples for the first time to address
questions about what life not as we know might look like, and
I'll just put it out there as a profound question for which we
don't have an answer, how does one look for life as we don't
know it? And we may have samples in our collection in 20-some
years where we will need to answer that question. I think the
public will be fascinated by that question.
Mr. Lucas. Dr. Pappalardo, discussing the plumes just a
moment ago, tell us mechanically about what it will be involved
in being able to use the Clipper in a way to verify their
existence, whether it's navigating the flybys or the sensors on
board. Expand for just a moment on that if you would.
Dr. Pappalardo. Well, first, there're continuing
observation with the Hubble Space Telescope so we hope, expect
to have new data before we arrive so we can understand if
they're real, if they're periodic in some way. But say we don't
or say they're sporadic and we need to understand them better.
We would use the time--we have a big looping first orbit. We
would use that time to monitor and try to understand whether
there is evidence of plumes, both from imaging and from
ultraviolet observations where we could see the glow from such
plumes. And then during the mission, we're planning on
monitoring the whole time when we're a little farther from
Europa to look for plumes. And then if there are plumes, then
we will certainly want to target them. Whether it be in the
primary mission or the extended mission, we'll figure that out,
but we'll want to fly through as low as possible, meaning about
25 kilometers, 16 miles off the deck if we can, depending on
the location, depending on whether we can or not, and for that
matter, how much particulates because you can damage--you can
risk the spacecraft, and by flying through, we'd be able to
sample that stuff directly and get a direct sampling of what's
in the interior of Europa. We don't know for sure. Assuming the
plumes are real, we don't know for sure if they're coming from
the ocean or from lakes within the ice shell, and we would
analyze the gas and the dust that's coming off to say a lot
about what the interior composition of Europa is like.
This is analogous to what Cassini has done at Enceladus at
Saturn, which does have plumes that spew into space.
Mr. Lucas. So an incredible amount of prep, an incredible
amount of skill in maneuvering the mission, and just a little
bit of luck would be a good thing too.
Dr. Pappalardo. And we have a group of scientists. We're
thinking that through as we meet and discuss the possibilities
and working with the engineers to do so.
Mr. Lucas. Absolutely. Thank you, Doctor.
Yield back, Mr. Chairman.
Chairman Babin. Thank you.
I now recognize the gentleman from Virginia, Mr. Beyer.
Mr. Beyer. Dr. Babin, thank you very much, and thanks to
all of you for being here.
Dr. Farley, a relative softball question, but in your
testimony, you say that past life Mars 2020 seek evidence of
past life in a fossil-like Earth-like environment that existed
in the first billion years after the dawn of the solar system--
some of the most profound scientific questions of our time. Why
are they profound?
Dr. Farley. Well, the two questions that I was alluding to
there are the, is there life beyond Earth, and I will just make
the general observation from my interaction in the science
community, the discovery of thousands of extrasolar planets has
converted this question from something where most scientists
that I knew would say it doesn't seem that likely to wow, it
seems really unlikely that we are alone. The only way I think
you could really put some scientific evidence to that is, if
you look in a habitable place, is it inhabited? There may be
lots and lots of habitable places out there, and that goes to
the question of the spark that makes life happen, and so that I
think is a really profound question that we will go after. Is
life out there? Was it out there? And what is necessary--what
are the environments like where life might evolve, and those
are really profound questions.
Mr. Beyer. Thank you very much.
Moving from life to metal, Dr. Elkins-Tanton, a couple of
quick questions. How do we know that it's metal? Is it a
spectrometer or whatever? How do you know it's the only one in
the solar system? Why did you name it Psyche? And do you really
think it used to be a planet and the rock and the like was
stripped off of it, that it was like Earth or Mars or Venus?
Dr. Elkins-Tanton. Right. Okay. Let's see if I can remember
this and get it all in your time. So the first question is how
do we know it's metal. We've never seen Psyche visually as more
than a dot of light but we get radar returns from Arecibo,
which seems to me to be also just a technological miracle. We
can actually send radar from Arecibo, get the returns, see that
the radar has interacted with the material of Psyche in a way
that it only interacts with metal, so that's a really key one.
We can also see its reflected spectra consistent with metal and
its density consistent with metal but the radar returns are the
key. So we're pretty certain it's metal. There are other
smaller metal asteroids like Cleopatra, which is shaped like a
dog bone. If you haven't seen it, you should google it. It's a
great one. But they're all much smaller. They seem to be the
shrapnel of leftover from planetary collisions. All the really
heavy, rocky, metallic material is either in the inner solar
system or in the asteroid belt or hidden inside ices and gases
in the outer solar system. So we're pretty sure that what we
see in the asteroid belt is it for metal and Psyche's the only
big round one.
Now, Psyche was discovered in, I believe, 1852 maybe--I
might have the date wrong--by an astronomer in Naples, and he
named it Psyche. It was the 16th body found in the asteroid
belt by a group of astronomers called the Celestial Police who
were trying to set right to the solar system and find the
planet that was there, and they didn't, and they were naming
them all after gods and goddesses, and so Psyche's number came
and there it is, Psyche.
There was one more question. What was it?
Mr. Beyer. Did it used to be a planet?
Dr. Elkins-Tanton. Oh, we're pretty sure it was but, you
know, true to my scientific training, everywhere I've been in
the world and given talks on Psyche, I've asked scientists what
else could it possibly be. If it's not the core of a planet,
how do we make this? And our best other guess is that it could
be material that had all the oxygen stripped off it by heat
very close to the young sun. Theoretically, people think that
kind of material could exist but we've never found an example
of it, and so if it's not a core, that would actually be more
exciting. It would be something we've never seen before.
Mr. Beyer. Exciting either way.
Dr. Elkins-Tanton. Thank you. I think so.
Mr. Beyer. And I want to point out that Jules Verne did
think we could do a journey to the center of that Earth.
Dr. Elkins-Tanton. I visited that Icelandic volcano. It
didn't work for me.
Mr. Beyer. Dr. Green, you talked about looking for evidence
of organic materials on Ceres and that Bennu--I hope I
pronounced it right--is believed to contain water and organic
compounds such as amino acids. Have we gone beyond amino acids
to proteins to nucleic acids? Are we going to leap to DNA and
RNA?
Dr. Green. Well, of course, we would call that an ever-
increasing knowledge about potentially the right stuff that
life either is made of or produces as a byproduct. That's all
part of what would be a ladder of life but the only way we can
definitively determine what's really at Bennu is to bring
samples back, and that indeed is planned. When we get into
orbit around Bennu, as we start getting August of next year,
we'll be studying it for about 500 or so days picking the right
location, going down, sucking up material, perhaps as much as a
kilogram, and then bringing that material back, and that's when
we'll do the detailed look at what's in it. It'd be great to
find more complex amino acids and other organics.
Chairman Babin. Thank you, Mr. Beyer.
I now recognize the gentleman from Florida, Dr. Dunn.
Mr. Dunn. Thank you very much, Mr. Chairman. I think the
Space Subcommittee always seems to be most inherently
optimistic committee of the House, and you know, the can-do
attitude of our panelists is absolutely infectious. I can only
hope that you'll expose yourselves to the Senate sometime soon.
I want to frame my questions to the panel with this
thought. The proof of life that is truly extraterrestrial life
is an event that is on the level with the first Moon landing,
so long after posterity's forgotten all of the proceedings of
this Committee and relegated the history of our planetary
explorations to the dusty bookshelves, everyone will remember
the event that proved extraterrestrial life.
So with that thought, Dr. Farley, let's say everything
works out perfectly on the Mars 2020 lander. You obtain
appropriate terrestrial samples. What would you consider to be
the elements of a biosignature, you know, a biotic chemistry,
if you will?
Dr. Farley. So I'll give two different answers to that. One
is, what can we detect with the rover and what could we defect
if we bring samples back, and with the rover, we have the
capability to make a map at the scale of about a postage stamp
of the distribution of organic matter. That's one of our key
observational capabilities, to take a rock and make a map of
organic matter, and on that same postage stamp-size piece of
material, we can also map the elemental composition. And when
one looks at ancient terrestrial rocks, this co-registration of
organic matter and elemental composition is the key to
identifying on a planet where you already know there's life to
identify the most ancient life on Earth. So we will make those
kinds of observations, but just like with the terrestrial case,
those kinds of observation are seldom definitive. They're the
kind of thing people argue about for decades, and if we bring
samples back, they're a far greater diversity of observations
we can make. Dr. Green was talking about different--making
observations of the ladder of life, looking for more and more
complex organic molecules whose composition is only reasonably
associated with life as opposed to abiological processes.
Mr. Dunn. I guess I kind of thought the problem with
bringing it back is everybody always wonders about
contamination, you know, did you sterilize the ship so
thoroughly on the way out and the way back that you can be
certain that this came from Mars. So if you do a test as they
did on the Viking, they are in in situ on Mars, and if you
could design a better test, a better chemical test, what would
that be and would it involve, as you and I spoke before the
meeting, stereoisomers and----
Dr. Farley. So one of the complications of looking for
ancient life is that there will be degradation of organic
molecules.
Mr. Dunn. You're looking for ancient life. I'm looking for
life today.
Dr. Farley. Right. We have no capability on the rover to
look for extant life at the microbial scale. We can't tell the
difference between live and dead, but if those samples came
back, as I mentioned before, I think there will be a lot of
interest in actually developing technologies, and they would
include things like stereochemistry and that sort of thing.
Mr. Dunn. So would you elaborate? Because I'm not sure
everybody on the Committee is thinking about stereochemistry.
What's the significance of discovering an ongoing biochemical
or chemical process, a biotic process that has, you know,
solely left- or right-handed metabolite?
Dr. Farley. Sure. So one of the key ways that one
identifies molecules that are involved in life is that all life
has a preference for a particular handedness of one of the
organic molecules. There's two different confirmations that
these organic molecules could be in and most abiological
processes produce them in equal abundance whereas life because
it has a machinery involved, very specific machinery, tends to
produce a specific chirality, a specific confirmation of these
organic molecules. So this is really a critical observation for
establishing that life is involved. There are very, very few
abiological processes that would produce stereochemically
specific molecules.
Mr. Dunn. So production of a stereospecific metabolite
would be a pretty strong presumptive proof of life, extant
life, on Mars if you ran it the way the Vikings rover ran that?
What the Viking rover did is run that test without
stereoisomers.
Dr. Farley. Right.
Mr. Dunn. So if you ran the same test and checked for
stereoisomers by having left- or right-handed substrates----
Dr. Farley. Yes, that would be a very important test, and
I'm aware that there are instruments under development for
actually making those kind of measurements in space.
Mr. Dunn. I agree there are. I'm out of time. I would say
that that's about a 2-kilogram package. I look forward to
talking to you outside of the Committee structure, and I yield
back.
Chairman Babin. Thank you. You remember a lot from your
training, Dr. Dunn.
Let's see. Another gentleman from Florida, Mr. Posey.
Mr. Posey. Thank you, Mr. Chairman.
Dr. Green, traditionally, planetary exploration was a
public sector endeavor that taxpayers took care of. Today the
U.S. private sector companies are beginning to invest and
develop planetary exploration programs. What is NASA doing to
facilitate and encourage private sector investment and
participation in planetary exploration?
Dr. Green. I believe there's a whole range of things that
we've been involved in. If you take an example of the concept
of going to asteroids and being able to extract certain metals
and other compounds of interest, the first thing that they're
going to need to know is, where are they, what is their
characteristics, how to get to them, and indeed, we are doing
an extensive finding project where we'll find our small bodies,
we'll catalog and characterize them, and all that information
will be critical, and we've discussed that openly in many
different meetings working with that sector.
Another sector is a series of commercial opportunities
going to the moon. Now, this could be a really important
element for scientists to be able to work with the commercial
entities and be able to obtain rides to be able to bring back
material or examine certain regions on the moon that are
extremely important. The moon is still quite valuable in terms
of being able to provide us an enormous amount of science that
be done. It's been a witness plate of over 4 billion years of
impacts and can tell us a lot about what's happened to our
environment and what's happened to the Earth. So those
partnerships are beginning. There are some that are done
through a Space Act agreement and others are done through
collaborations and discussions at a variety of venues.
Mr. Posey. Thank you very much. That's a good answer.
Given the important role of robotic planetary missions in
advancing human exploration capabilities, how can the current
and future planetary missions be integrated into the human
exploration roadmap, which we've asked NASA to produce?
Dr. Green. Well, of course, from my perspective, planetary
scientists are really the guides. You know, they're really the
ones that go out first. Human exploration is not Star Trek.
It's not ``go where no human has gone before.'' In our program,
and NASA is really all about sending humans to locations beyond
low-Earth orbit out into the solar system, be able to live,
work, but also return, and all those require not only where
you're going but the characteristics so how to get there, what
are the kind of science and other activities one can do on
station, and then of course the challenges of entry, descent
and landing for any of the bodies they choose to go to.
We pioneer a lot of that, you know, in terms of being able
to look at those environments, collect that information, but
also pioneer some of the initial technologies that allow us to
get our rovers and other machinery at various locations,
whether it's the moon or Mars.
Mr. Posey. Can you describe the infrastructure that
missions will be putting in place around Mars and Europa to
support future missions? For example, will NASA be able to use
the Europa Clipper to support future Europa missions, namely
the lander?
Dr. Green. Yeah, actually as Lindy mentioned earlier, in
planetary science, we really have a very important paradigm
that we follow. It's flyby, orbit, land, rove, but also return
those samples. And indeed, the Europa Clipper gives us that
opportunity to do a detailed examination of Europa that
provides high-resolution imaging that gets us right to where we
want to go that makes the next mission, which would be
notionally a lander, to be able to land safely and perform the
science that we wanted to do. So indeed, each of these missions
are very much related and depend on the success of the previous
mission.
Mr. Posey. Thank you very much. I yield back, Mr. Chairman.
Chairman Babin. Yes, sir. Thank you, Mr. Posey.
And another gentleman from Florida, Mr. Webster.
Mr. Webster. Thank you, Mr. Chairman.
Dr. Green, is there any interest in going to the outer
planets to do the same level of investigation and so forth, or
is that just too expensive and too far?
Dr. Green. Well, indeed, when one looks at the science
that's been delineated by the community and the National
Academies' Planetary Decadal, we have an extensive desire to be
able to go out to the outer reaches of our solar system where
our planets like Neptune and Uranus reside. Neptune and Uranus,
although they are big what look like giant planets like Saturn
and Jupiter, they actually are very different in many ways.
They have a whole series of different compositions associated
with them. We call them the ice giants. You know, they're not
completely hydrogen and helium. They have ammonias and a whole
series of other elements that they have obtained in that
accretion process that we know very little about and so being
able to go out to Uranus and Neptune are extremely important.
We just completed a major study and have worked with the
scientific community to determine what are the characteristics
of the measurements we want to make in those regions but also
how do we be able--how are we able to get out there perhaps in
the second half of the next decade and really get into orbit
and analyze that environment.
Mr. Webster. Is that desire which you spoke of funded?
Dr. Green. Right now that's only at the study level. The
Planetary Decadal is quite clear that the top things that we
should be doing we are doing but, you know, you have to
prepare, you have to spend some time on your future or you
don't have that future, and so while we do this planning, while
we do this mission concepts and studies, those are indeed
laying the groundwork for our future work.
Mr. Webster. Is Voyager still broadcasting?
Dr. Green. Yes. Both Voyagers are still broadcasting. Now,
they're very far away. They're more than 120 astronomical units
away where one astronomical unit is the distance between the
Sun and the Earth, so they're very far out there, and
therefore--and they have little power left although it's a
radioisotope power. It's a long-lasting power system. They're
sending back a handful of bits whenever we can turn our big
telescopes and bring that data back but they're doing a
marvelous job, really exploring that outer reaches of the
heliosphere we call it.
Mr. Webster. What's their wattage?
Dr. Green. I would only guess but I would believe it's on
the order of tens of watts. That's all that's left.
Mr. Webster. And then what would be the final date that it
won't be able to broadcast anymore? You're saying it's
diminishing now, right? Is that what you said?
Dr. Green. Yeah, it uses--utilizes radioisotope, plutonium
238, which decays over time, and how that works is, you bring a
mass of plutonium together, it's radioactive. You shield that
and that radioactive capability where the nucleus of the atom
blows apart heats and that heats a sleeve that's around this
material and then that heat through a thermal couple is used to
charge a battery and then you run your experiments off of it.
And so over time as the radioisotope decays, then there's
little heat involved, and now you have major power management
activities that you have to do, which they're doing to really
keep the spacecraft going because not only is it providing
power but it's also providing warmth for the instruments and
the spacecraft subsystems.
I can't give you, although I'll take for the record and get
back to you on exactly what our prediction is when it will
really have not enough power to sustain itself or it'll be at a
distance far enough away that we will not be able to track it.
Mr. Webster. Thank you very much. Yield back.
Dr. McKinnon. If I could add just one thing to do that,
that the New Horizons spacecraft, which passed by Pluto and is
on its way to another body in about a year and a half, will
also leave the solar system and it's also powered by a similar
radioisotope heating system and we anticipate that we'll be
able to contact and operate the spacecraft into the 2030s.
Chairman Babin. Thank you for those fascinating questions.
I want to ask one more question. Why do we think that Mars
lost its atmosphere billions of years ago? And Mars is farther
away from the sun than Earth, and I'm just going to--Dr.
Farley, would you take a stab at that?
Dr. Farley. There may be others here that know more than I
do about this but this is one of the central purposes of the
Maven mission, to try to understand why the atmosphere was
apparently lost, and one of the leading candidates is that the
planet uses hydrogen, and--to space, and that causes--that
hydrogen is produced by the breakdown of water, and so you
break up the water molecule and the hydrogen escapes. You
cannot re-form the water molecule so that's a way to desiccate
it by interaction with the solar wind, and one of the jet
reasons for that is that Mars apparently lost its magnetic
field very early in its history whereas Earth did not so the
magnetic field protects the Earth from the radiation from the
sun that causes this to happen.
Chairman Babin. Thank you. Anybody else?
Dr. Elkins-Tanton. Yeah, I'd like to add to that. I've
worked on that directly. And so this is part of our interest in
Psyche as a core is to understand the magnetic field, but to
add to what Ken has said, it's also possible--another
hypothesis is that when Mars was very young and still hot, its
atmosphere would have been inflated through heat to be further
away and less well bound to the body itself, and the more
active young sun could actually have stripped it at that time.
And so we don't know exactly when it was stripped or the
processes, and that's another thing we'd like to learn to find
out how applicable it is to the Earth.
Chairman Babin. Great. Those are fascinating answers. Thank
you so much. I think I'm the only member left here.
But I want to say how much I appreciate all of you
fascinating and well-educated scientists for being here, and we
appreciable your valuable testimony. And also, the record will
remain open for two weeks for additional comments if any
Members would like to submit those.
So with that, this hearing is adjourned. Thank you.
[Whereupon, at 11:44 a.m., the Subcommittee was adjourned.]
Appendix I
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Answers to Post-Hearing Questions
Appendix II
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Additional Material for the Record
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