Planetary Science Division Corner

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Planetary Science Decadal Survey

Download Visions and Voyages for Planetary Science in the Decade 2013-2022 (PDF - 9.7 MB), this document sets out priorities for which planetary missions should be undertaken in the next ten years. For links to presentations on this subject from the LPSC meeting, presentations on this subject by Jim Green, and the Decadal Survey town hall schedule across the nation see

The Planetary Science Decadal Survey is organized by the National Research Council at the request of NASA and NSF. Its objective is to set clear priorities for solar system exploration for the coming decade. NASA and Congress and the Office of Management and Budget highly value the decadal survey process for establishing NASA's science priorities.

The distinguishing characteristic of the decadal survey process is that it is based on broad input from the science community. The goal is to establish a true community consensus regarding the key science questions for the next decade, and the suite of missions that should address them.

What makes the decadal a powerful document is the strong science focus and commitment by the community to follow it. It is the guide we use at NASA Headquarters, the current Administration and Congress. It is that important!

For more information and to download white papers and view presentations follow this link to

Strategic Goal:
Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space.

The Intellectual Foundation

Solar system exploration is a grand human enterprise that seeks to discover the nature and origin of the celestial bodies among which we live and to explore whether life exists beyond Earth. The scientific foundation for this enterprise is described in the NRC's Decadal Survey in Planetary Science New Frontiers in the Solar System: An Integrated Exploration Strategy (NRC, 2003). The quest to understand our origins is universal. How did we get here? Are we alone? What does the future hold? Modern science, and especially space science, provides extraordinary opportunities to pursue these questions. The tools that are available and that will become available in the coming years will enable us to develop an astoundingly vast range of mission opportunities. We are at the leading edge of a journey of exploration that will yield a profound new understanding of our home, the Earth, and of ourselves. Robotic exploration is the key precursor for the expansion of humanity into our solar system.

These grand themes are captured in five fundamental science questions in the planetary science community's 2006 Solar System Exploration Roadmap that form the basis for NASA's approach to the exploration of the solar system:

  • How did the Sun's family of planets and minor bodies originate?
  • How did the solar system evolve to its current diverse state?
  • What are the characteristics of the solar system that led to the origin of life?
  • How did life begin and evolve on Earth and has it evolved elsewhere in the solar system?
  • What are the hazards and resources in the solar system environment that will affect the extension of human presence in space?

The theme guiding these questions is habitability - the capacity of an environment (which could cover an entire planet) to support life. This concept includes the existence of liquid water as well as the availability of energy and organic molecules. There is also a temporal component since these clement conditions must exist long enough for life to originate, evolve or migrate to the environment (from, perhaps, another environment). Beyond local conditions, habitability also encompasses issues related to the architecture of planetary systems (e.g., how does planetary architecture influence impact rates on planets close enough to the parent star to support liquid water?), and, to a lesser extent, stellar physics (e.g., is high metallicity a prerequisite for habitable planets to form?), and galactic structure (e.g., can habitable planets exist in environments near gamma-ray bursts or supernovae?).

The fundamental science questions transcend the traditional boundaries of astronomy, physics, chemistry, biology, and geology. To address them requires multi-disciplinary approaches and NASA has pioneered this by providing crucial, early support for planetary science (in the 1960s and 1970s) and astrobiology (in the 1990s). As described in the Research and Analysis (R&A) section below, however, funds available for multi-disciplinary research over the next five years are less than expected one year ago.

In order to progress in addressing the five fundamental science questions, NASA relies on a balanced program of R&A, technology development, data and sample curation programs, and missions of various sizes. The R&A programs not only leverage NASA's investments by analyzing the data and samples returned by missions, but also serve as the wellspring for new science questions and new mission concepts. These concepts are realized through the development of new technologies. Data and samples returned to Earth by missions are carefully curated and disseminated to researchers and the results of NASA-funded research are communicated to the public through a vigorous program of public outreach, and both formal and informal education.

NASA seeks regular input from the scientific community in developing its approach to addressing these questions. Input is provided through chartered bodies such as the Space Studies Board of the National Research Council, the Committee on Planetary Exploration (COMPLEX), advisory committees and community-led groups (e.g., Mars Exploration Program Assessment Group, MEPAG). All of their comments and recommendations have been considered in light of budgetary realities, and the resulting plan for the exploration of the solar system is described here. Additionally, the science community has been deeply involved in the creation of New Frontiers in the Solar System: An Integrated Exploration Strategy (hereafter called the NRC Decadal Survey), the 2003 Solar System Exploration Roadmap, the 2006 Solar System Exploration Roadmap and the 2006 Mars Architecture. The earlier documents had a profound influence on the Vision for Space Exploration which stated that NASA will: (1) conduct robotic exploration of Mars to search for evidence of life, to understand the history of the solar system, and to prepare for future human exploration; and, (2) conduct robotic exploration across the solar system for scientific purposes and to support human exploration. In particular, explore Jupiter's moons, asteroids and other bodies to search for evidence of life, to understand the history of the solar system and to search for resources. Recommendations from all of these documents have been incorporated into this plan.

Science Objectives and Outcomes: Solar System Destinations and Missions

Planetary Science missions are grouped by their respective targets of investigation. Missions to Mercury, Venus, and the Moon are considered to be Inner Solar System Missions. Missions to Mars are also considered Inner Solar System Missions but are described in a separate section since the Mars Exploration Program is an integrated campaign of exploration, technology development and public engagement. Missions to the other planets (Jupiter and beyond) and their moons are classified as Outer Solar System Missions. Finally, missions to comets and asteroids are described as Small Bodies Missions.

In exploring any particular solar system object, NASA has followed a general paradigm of "flyby, orbit, land, rove, and return." This prescription has been followed most completely for investigations of the Moon and Mars. In contrast, the first flyby of Pluto and its large satellite, Charon, will be performed by the New Horizons mission and will not occur until July 2015. A complete campaign may not be performed for each interesting object in the solar system; not all scientific questions can be studied at all objects and there are high technological and financial hurdles to overcome for some missions and certain destinations. Moreover, a healthy program of solar system exploration requires a balance between detailed investigations of a particular target and broader reconnaissance of a variety of similar targets.

In addition to a description of the missions themselves, each sub-section here presents specific goals that are addressed by the various missions that investigate that area.

Program Elements

A strong scientific and technical community is required to envision, develop and implement solar system exploration missions, and to interpret and apply results from these missions for the benefit of society. The data and samples returned from missions must be archived and curated and the results widely disseminated. In this section, the elements of the Planetary Science program that nurture and support missions are described.

A sketch of the relationship between the various crosscutting elements and missions
Figure 5.1: A sketch of the relationship between the various crosscutting elements and missions. Basic research and analysis lead to new science questions about the solar system. New instruments and technologies provide new technical capabilities. Combined, the capabilities and questions generate new mission concepts, some of which are developed into flight missions. Flight missions, in turn, generate new data and, possibly, new samples. They also prove new technologies. The data and samples become the object of new research and analysis.

Research and Analysis

Discoveries and concepts developed in the R&A Program are the genesis of scientific priorities, missions, instrumentation, and investigations. The R&A Program is the primary interface with NASA for university faculty and graduate students; it allows training of the next generation of mission team members, principal investigators, and project scientists. Although not always tied to specific missions, the tasks funded by the R&A Program add value to missions in the form of post-mission data analysis, observations required for mission design, mission observation support, and joint scientific campaigns. Increasingly this support has expanded to include international, multi-disciplinary campaigns in conjunction with spacecraft observations, greatly increasing the value of data from all platforms through combining current observations and comparing different data types. A recent example is the massive campaign organized to support observations and characterization of the Deep Impact encounter with comet Tempel 1. Computational and theoretical resources were devoted to the problem and a large fraction of the available Earth and space-based observational assets of the world's scientific community supported the campaign, included networks of amateur astronomers. Funded at less than 10 percent of the total funds expended annually on the robotic exploration of the solar system, R&A Program greatly leverages NASA's significant investment in missions.

Due to the broad nature of the fundamental science questions addressed by the exploration of our solar system, the various elements of the Planetary Science R&A program cover an extraordinarily broad range of scientific investigations. In particular, the R&A program supports two, necessary multi-disciplinary sciences: planetary science and astrobiology. Planetary science grew from the discoveries of the space missions of the 1970s and forms the foundation for the scientific exploration of the solar system. NASA remains the primary funding source for planetary science research. Astrobiology is a new field, started by NASA a decade ago, that brings together scientists from diverse disciplines including Earth and planetary science, astrophysics, heliophysics, microbiology, evolutionary biology, and cosmochemistry to develop the scientific foundation needed to pursue the search for evidence of life and habitability in the solar system and beyond. Astrobiology and the missions it supports bring modern science to bear on questions that, in one form or another, are as old as humanity itself: How does life begin and evolve? Does life exist elsewhere in the universe? What is the future of life on Earth and beyond?

In addition to planetary science and astrobiology, the R&A Program also the study of the origins of the solar system and the interrogation of those materials left over from the birth of planets: asteroids, meteorites, comets and interplanetary dust particles. An additional component is the analysis of data returned and archived by missions.

Recent changes to NASA's budget, including cuts to the R&A Program, however, have adversely affected NASA's ability to analyze data and materials returned from missions and to lay the foundations for future missions. These cuts have also reduced NASA's financial support for astrobiology research by about half. As part of the budget formulation process, NASA will annually reassess the balance of investment among R&A, missions, and technology development.

Data Curation, Dissemination and Analysis

The outcomes of planetary exploration missions are of two sorts: data recorded and transmitted to Earth by spacecraft, and samples that are returned to Earth by various means. The curation, dissemination and analysis of these require rather different approaches.

The Planetary Data System (PDS) is the active data archive for NASA's Planetary Science Division. It is a distributed archive, with datasets archived at a number of Science Discipline Nodes (Atmospheres, Geosciences, Imaging, Planetary Plasma Interactions, and Small Bodies). The Science Discipline Node Principal Investigators maintain a strict set of PDS compliance standards to ensure the integrity and long-term usability of the datasets, and to determine the appropriate formats for data product deliveries from NASA and International flight projects.

Support functions (Engineering, Navigation Ancillary Information Facility, and Radio Science) assist the Science Discipline Nodes through infrastructure development and flight project support. In addition, a number of Science Subnodes and Data Nodes interface with the Science Discipline Nodes to provide access to specific sets of data, often for short periods of time. Geographically dispersed mirrors of data are maintained within the PDS to ensure continuity of operations and a "deep archive" is held at NASA's National Space Science Data Center (NSSDC).

Data from particular ESMD missions, such as the Lunar Reconnaissance Orbiter, will also be archived by the PDS by agreement between SMD and ESMD.

The Johnson Space Center (JSC) Astromaterials Curation Facility provides services for all returned planetary materials that do not require planetary protection laboratories. This facility has been in operation since the Apollo lunar samples were returned. Later, meteorites collected by U.S. teams in Antarctica and interplanetary dust collected in the stratosphere were added to the collections. In 2004 and 2006 the Genesis and Stardust missions returned the first solar system materials from outside Earth's atmosphere since Apollo. Special new clean-room laboratories were constructed for both the Genesis solar wind samples and Stardust comet samples. These samples are currently being studied in laboratories worldwide.

In the next decades we anticipate missions to collect samples from the Moon, Mars, comets and asteroids. Each of these new sample collections will require new curation laboratories, while the facilities for the older collections will require routine maintenance and upgrades. Samples to be returned from Mars pose even greater challenges due to special planetary protection requirements. It is imperative that attention be paid to curation facilities to assure that new samples will be available for analysis in laboratories around the world and that the remaining samples are available for further investigations with new advanced instruments for many years to come.

Planetary Protection

Planetary protection refers to the practice of protecting solar system bodies from biological contamination from Earth, and protecting Earth from possible life forms that could be returned from elsewhere. Planetary protection practices preserve our ability to study other worlds as they exist in their natural state-avoiding contamination that would obscure our ability to find extraterrestrial life, if it exists, while ensuring prudent precautions to protect Earth's biosphere. NASA's planetary protection policy also is a component in the U.S. adherence to the 1967 United Nations Outer Space Treaty, which requires that states party to the treaty "shall pursue studies of outer space, including the moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination," and also to avoid "adverse changes in the environment of Earth resulting from the introduction of extraterrestrial matter."

For NASA, planetary protection requirements for each mission and target body are based on the advice of the National Research Council's Space Studies Board for strategic issues and with the NASA Advisory Council's Planetary Protection Subcommittee for implementation issues under NASA and international guidelines. Each mission is categorized according to the type of encounter it will have (e.g., flyby, orbiter, or lander) and the nature of its destination (e.g., a planet, moon, comet, or asteroid). If the target body has the potential to provide clues about life or prebiotic chemical evolution, a spacecraft going there must meet a higher level of cleanliness, and some operating restrictions will be imposed. Spacecraft going to target bodies with the potential to support Earth life must undergo stringent cleaning and sterilization processes, and greater operating restrictions. Missions returning samples to Earth may be either "unrestricted" in their return phase, or may be subject to stringent precautions to protect the Earth's biosphere if it is thought that life could exist on the target body.

The NRC decadal survey offered several recommendations on the need for ongoing improvements in the ability to respond to planetary protection requirements to solar system exploration missions. Missions to outer satellites were considered a challenge due to the presence of subsurface oceans potentially containing life as well as organic compounds and potential prebiotic chemistry. In preparation for future Mars sample-return missions, it was recommended that a sample-analysis program be established with a suitable investment well in advance of the mission. Clearly, the challenges of implementing planetary protection constraints for solar system exploration missions are only beginning.

The NRC has recently (2005) provided recommendations about planetary protection requirements to prevent Mars forward contamination, taking into account new results from the Mars Global Surveyor, Mars Odyssey, and Mars Exploration Rover missions. This report emphasized the importance of a strong research program for planetary protection in understanding microbial diversity, spacecraft sterilization, and Martian environmental conditions conducive to life-while emphasizing the need for additional resources to be invested in adopting molecular microbiological methods to account for potential biological contamination. The report also endorsed the concept of "special regions" on Mars that may support Earth life (as put forth by NASA and COSPAR), and recommended that NASA explicitly define conditions and data sets that describe these regions, while maintaining strict spacecraft cleanliness standards to avoid their contamination during future Mars missions.

Planetary Research and Analysis FY08 Funds for ROSES 07 pie chart