Testimony Date: 05/26/2022
Congress Session Name: 117th Congress (Second Session)
Witness: Robin Canup, Philip R. Christensen
Witness Credentials:
Robin Canup, Assistant Vice President, Planetary Science Directorate, Southwest Research Institute, and Co-chair, The Planetary Science and Astrobiology Decadal Survey, 2023-2032, Space Studies Board, Division on Engineering and Physical Sciences, The National Academies of Sciences, Engineering, and Medicine
and
Philip R. Christensen, Regents Professor, School of Earth and Space Exploration, Arizona State University, and Co-chair, The Planetary Science and Astrobiology Decadal Survey, 2023-2032, Space Studies Board, Division on Engineering and Physical Sciences, The National Academies of Sciences, Engineering, and Medicine
Chamber: House
Committee: Space and Aeronautics Subcommittee, Committee on Science, Space, and Technology
The Planetary Science and Astrobiology Decadal Survey
Statement of
Robin Canup, Ph.D.
Assistant Vice President
Planetary Science Directorate
Southwest Research Institute
and
Co-chair, The Planetary Science and Astrobiology Decadal Survey, 2023-2032
Space Studies Board
Division on Engineering and Physical Sciences
The National Academies of Sciences, Engineering, and Medicine
before the
Subcommittee on Space and Aeronautics
Committee on Science, Space, and Technology
United States House of Representatives
May 26, 2022
Good morning Chairman Beyer, Ranking Member Babin, and members of the Subcommittee. My name is Robin Canup, and I am Assistant Vice President of the Planetary Science Directorate at Southwest Research Institute. I served as co-chair of the National Academies of Sciences, Engineering, and Medicine’s Decadal Survey in Planetary Science and Astrobiology. We are deeply appreciative of the opportunity to speak to you about our Decadal Report, “Origins, Worlds, and Life”.1
A Prior Decade of Unprecedented Success and Continued US Leadership in Space Exploration
Ten years ago, Dr. Steven Squyres came here and argued for an ambitious program of planetary exploration. Thanks to the generosity of Congress, that program became a reality and has ushered in the past decade of unprecedented success. Collection of samples at Mars for return to Earth and Europa Clipper, the top priority large (Flagship) missions from the prior decadal survey, are now underway, and will revolutionize our understanding of the early habitable martian environment, and of the habitability of an icy ocean world. These have been accompanied by a vibrant program of small and medium missions, as well as new partnerships between NASA and the private sector that are increasing access to space and its affordability.
Against this backdrop of incredible accomplishments, and with awareness of efforts being undertaken by other space agencies around the world, we put forth an aspirational plan for the next decade to ensure groundbreaking scientific advances and our nation’s continued leadership in solar system exploration.
Priority Science Questions: The Motivating Rationale for Planetary Science and Astrobiology
We began our task by defining the most important scientific questions that motivate our endeavors, which fall within three scientific themes.
The first theme, “Origins”, addresses how the primordial disk of gas and solids that orbited our young Sun evolved to yield the outer giant planet systems and Kuiper belt objects, and the inner asteroids and terrestrial planets, including the Earth-Moon system.
The second theme, “Worlds and Processes”, considers ongoing gravitational interactions and bombardment; the interiors and surfaces of solid planets as well as their atmospheres and climates; the properties of gas-dominated Jupiter and Saturn and the ice giants Uranus and Neptune; and the many diverse systems of moons and rings.
The third theme, “Life and Habitability”, addresses how life on Earth emerged and evolved; the existence of habitable environments across our solar system; and the central question of whether life formed elsewhere and how to detect evidence of it.
Related to all three themes is the study of planets orbiting other stars, which can help us better understand whether Earthlike planets are common or rare in the universe.
Insuring the Vitality and Success of NASA’s Most Valuable Resource: Its People
Answering such fundamental questions requires a highly-skilled and creative workforce. Broad access and participation, as well as equitable processes, are needed to recruit, retain, and nurture the best talent to work in our field. Our report makes numerous recommendations to enhance diversity, equity, inclusion and accessibility in our profession, including actions to minimize the effects of bias in processes, enhance outreach to underrepresented communities, and to foster respectful work environments.
Research and Analysis: The Foundation for the Advancement of Knowledge
Basic Research & Analysis provides the intellectual foundation to ensure NASA’s activities are optimized to advance scientific knowledge. The openly-competed R&A programs support broad access into our profession, and their highly competitive nature drives innovation. While NASA’s planetary program has grown substantially in the past decade, the per-year fractional investment in R&A activities has decreased, from nearly 15% in 2013 to less than 8% currently. It is essential to the continued success of the nation’s planetary and astrobiology program that this trend be reversed, and that a minimum of 10% of the annual program be invested in R&A activities.
Importance and Priority of Mars Sample Return
The committee reaffirms the scientific and strategic importance of Mars Sample Return (MSR), and recommends that it be completed as soon as is practically possible as the highest priority of NASA’s robotic exploration efforts. We provide specific guidance to ensure that the level of investment in MSR remains consistent with long-term programmatic balance across NASA’s planetary portfolio.
The Pivotal Role of Science in Human Exploration
One of the most exciting recommendations in our report involves increased cooperation between NASA’s science and human exploration endeavors. The Artemis program calls for landing humans on the Moon within the 2020s, with increasingly sustained operations on the lunar surface. The committee strongly supports the visionary Artemis program, and argues that it is imperative that it be accompanied by a similarly visionary scientific program. To not do so would be a missed opportunity for NASA and the nation that would undermine the tremendous potential value of the Artemis program
The Endurance-A Mission: A ground-breaking robotic-human partnership to achieve transformative science at the Moon
To this end, the committee prioritizes a transformative robotic-human partnership: the Endurance- A lunar rover mission. This rover would complete a 1000-km traverse across the South Pole Aiken basin on the Moon’s far side, collecting 100 kg of samples to address the highest priority science objectives. Endurance-A would then deliver these samples to a location on the lunar surface for return to Earth by Artemis astronauts.
The Endurance-A mission would revolutionize our understanding of the Moon and the history of the early solar system that is recorded in its most ancient impact basin. Its sample set would provide a lasting legacy for future generations. We recognize the challenges of integrating science into human exploration plans, but find that overcoming such challenges is strongly justified by the tremendous value of human-robotic partnerships to the agency and nation. We make numerous recommendations to assist NASA in this endeavor.
Thank you for the invitation to testify. I will be happy to answer any questions the Subcommittee might have.
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ENDNOTES
1. The Summary of the National Academies of Sciences, Engineering, and Medicine’s Origins, Worlds, and Life A Decadal Strategy for Planetary Science and Astrobiology 2023-2032 was provided to the Subcommittee as an attachment to Dr. Canup’s testimony.
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An archived webcast of the hearing can be found on the House Science, Space, and Technology’s Website.
Statement of
Philip R. Christensen, Ph.D.
Regents Professor, School of Earth and Space Exploration
Arizona State University
and
Co-chair, The Planetary Science and Astrobiology Decadal Survey, 2023-2032
Space Studies Board
Division on Engineering and Physical Sciences
The National Academies of Sciences, Engineering, and Medicine
before the
Subcommittee on Space and Aeronautics
Committee on Science, Space, and Technology
United States House of Representatives
May 26, 2022
Chairman Beyer, Ranking Member Babin, and distinguished members of the Subcommittee thank you very much for the opportunity to speak to you today. My name is Philp Christensen, and I am a Regents professor in the School of Earth and Space Exploration at Arizona State University and Co-Chair of the National Academies of Sciences, Engineering, and Medicine’s Decadal Survey in Planetary Science and Astrobiology.1
New Flagship Missions
One of the most important, exciting, and challenging tasks that our committee was given was to identify and prioritize the large, or “Flagship” - planetary science missions that NASA should undertake in the coming decade. As you heard from my co-chair Dr. Canup, there is a remarkable array of key science questions that we would like to answer, and the Flagship missions provide the best means to make fundamental progress toward answering those questions. We carefully studied a half dozen potential missions and selected the Uranus orbiter and probe as our top priority. Uranus is a member of the “ice-giant” class of planets – so called because they have far more ice, and likely rock, than the “gas giants” Jupiter and Saturn. The ice giants may be among the most common class of planets in the universe, yet they remain the only planetary bodies in our solar system that have never been studied with a dedicated orbital tour. Uranus is one of the most intriguing bodies in the solar system. Its low internal energy, active atmospheric dynamics, and complex magnetic field all present major puzzles. A primordial giant impact may have produced the planet’s extreme axial tilt and possibly its rings and satellites. It is unclear when and where Uranus formed – it may have swapped positions with Neptune during early solar system migration. This migration would have significantly affected the inner solar system, including the early Earth at the time when life may have been emerging – we need to understand this process much better. Uranus’s largest ice-rock moons show surprising evidence of geological activity and are potential ocean worlds. The Uranus orbiter and probe will address a broad range of science questions across the entire Uranian system – from its origin, its interior, atmosphere, and magnetosphere, to its moons and rings. The mission would launch on an existing rocket, with optimal launch opportunities in 2031 and 2032 that utilize a Jupiter gravity assist to shorten cruise time. Finally, there is strong international interest in an ice giant mission, which offers the opportunity for partnership like the highly successful NASA-ESA collaboration on the Cassini/Huygens spacecraft to the saturnian system. Our committee strongly recommends that NASA begin the development of this mission as soon as possible with the goal of launching in 2031.
Our second priority Flagship, which we also advocate starting in the coming decade, is the Enceladus orbiter and lander mission. Enceladus is a small, icy moon of Saturn with active plumes that bring water from its subsurface ocean to the surface. These plumes deliver ocean water, and whatever is in it, to the surface where we can study it. The Orbilander mission will not only determine whether an ocean world could support life but will directly address perhaps the most fundamental question in solar system science: is there life beyond Earth? The Cassini spacecraft sampled the plumes, so we know that they contain water, methane, ammonia, and other simple organic molecules. However, the Cassini fly through velocity was high, causing the breakup of large organic molecules associated with life. The Orbilander will first orbit Enceladus at much lower velocity than Cassini and then will land and spend two years on the surface directly beneath an active plume. This mission design will provide much better measurements of the fresh plume materials as they rain down upon the lander. In addition to the search for evidence of life, Orbilander will obtain geochemical and geophysical context for the life detection experiments, such as the conditions in the ocean and the dynamics of the interior.
Medium-class New Frontiers Missions
In addition to the Flagship missions, our committee evaluated more than 25 medium-class, or New Frontiers, mission concepts and prioritized the most promising candidates for the coming decade. New Frontiers missions are competitively selected and provide the science engineering community with the opportunity to bring forward their most innovative and exciting exploration concepts. I’m sure you can appreciate how difficult it was for us to make our final selections from this amazing suite of candidates, but we have an exceptional set of nine themes.
- The Centaur Orbiter and Lander would study one of the compositionally primitive members of the Kuiper Belt – the ice-rich bodies formed in the outermost solar system - that has been captured into orbit between Jupiter and Neptune. Such objects provide crucial information on the nature of the compositional reservoirs in the protoplanetary disk.
- The Ceres Sample Return would return samples to Earth from the largest asteroid and most ice rich body in the inner solar system and investigate how it formed and assess its habitability.
- The Comet Surface Sample Return would return samples for detailed analyses to understand comet formation and activity, the mechanisms of primordial mixing in the early solar nebula, and the role of comets in delivery of water and organics to Earth.
- The Enceladus Multiple Flyby would characterize the habitability of the subsurface ocean and look for evidence of life via analysis of fresh plume material. This mission would not provide the detailed results of the Orbilander, but we considered the search for life at Enceladus to be of such importance to warrant an alternative mission pathway.
- The Lunar Geophysical Network would examine the Moon with a global, long-lived network of geophysical landers to better understand the Moon’s geological processes, bulk composition, distribution of heat-producing elements, and interior state and thermal evolution.
- The Saturn Probe would obtain direct measurements of Saturn’s atmosphere from an entry probe in order to understand conditions in the protosolar nebula, constrain giant planet formation mechanisms, including when and where Saturn formed, and study what governs the diversity of giant planet climates, circulations, and meteorology.
- The Titan Orbiter would characterize Titan’s ice shell and subsurface ocean, its dense nitrogen atmosphere, and study its methane seas and hydrological cycle to assess its potential habitability and prebiotic chemistry relevant to the early Earth.
- The Venus In Situ Explorer would investigate global atmospheric cycles, surface- atmosphere interactions, and surface properties that cannot be characterized from orbit or from a single descent profile, in order to better understand the origin and evolution of terrestrial planets, including our Earth.
- The Triton Ocean World Surveyor would orbit Neptune and complete numerous flybys of Triton, a captured Kuiper Belt Object that has a geologically young surface and active plumes and is a potential ocean world.
Our recommended program for the decade would include the selection of three New Frontiers missions, each of which will provide breakthroughs in our understanding of the solar system that we live in.
Planetary Defense
Planetary defense is an international enterprise aimed at providing protection to the people of the world from devastating asteroid and comet impacts. By using the knowledge and tools gained through planetary science and exploration, it is now possible to develop realistic and cost-effective detection and mitigation strategies against these natural disasters. As awareness of the hazard posed to life and property by Earth-approaching asteroids and comets has grown, NASA, NSF, and other government agencies are pursuing activities in support of planetary defense. Advancement in planetary defense will require enhancements in asteroid detection and characterization, an assessment of potential mitigation techniques, and the ability to rapidly characterize newly identified hazardous objects. Our report recommends that NASA should fully support the development and timely launch, of the NEO Surveyor mission to achieve the highest priority planetary defense goal of asteroid detection (and characterization?). Furthermore, we recommend a follow-on rapid-response, reconnaissance mission targeted to an approximately 100- m diameter asteroid – the class that poses the highest probability of a destructive Earth impact - to better prepare for a short-warning-time threat.
A Balanced Planetary Exploration Portfolio for the Coming Decade
Our report outlines a prioritized portfolio of research activities that will significantly advance the frontiers of planetary science and astrobiology in the coming decade. Our recommended program defines an integrated suite of flight projects, research activities, and technology development that will produce transformative advances in our knowledge and understanding. This program follows directly from our priority science questions and captures the highest priorities of the planetary science community. It is balanced across activities of varied scale and scientific focus and includes key areas for cooperation with NASA’s human exploration program and U.S. agency, industry, and international partners. The recommended program is both aspirational and inspirational and enables the robust training and development of a diverse science and engineering workforce, drives technology development, and maintains strong U.S. leadership in space exploration across the solar system.
Thank you for the opportunity to testify. I welcome any questions the Subcommittee might have.
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ENDNOTES
1. The Summary of the National Academies of Sciences, Engineering, and Medicine’s Origins, Worlds, and Life A Decadal Strategy for Planetary Science and Astrobiology 2023-2032 was provided to the Subcommittee as an attachment to Dr. Christensen’s testimony.
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An archived webcast of the hearing can be found on the House Science, Space, and Technology’s Website.