Vision and Voyages for Planetary Science in the - Solar System ...

impacts on Earth have played in mass extinction events, and they still pose a modern day hazard. “How
have the myriad chemical and physical properties that shaped the solar system operated, interacted, and
evolved over time?” is a question that is directly addressed by the study of their role in accretion and
subsequent bombardment through time, in particular as these bodies are believed to have served an
important role in delivering organic materials and water to the inner planets, particularly Earth.
and
SCIENCE GOALS FOR THE STUDY OF PRIMITIVE BODIES
The goals for research on primitive bodies for the next decade are twofold:
• Decipher the record in primitive bodies of epochs and processes not obtainable elsewhere,
• Understand the role of primitive bodies as building blocks for planets and life.
DECIPHER THE RECORD IN PRIMITIVE BODIES
OF EPOCHS AND PROCESSES NOT OBTAINED ELSEWHERE
Primitive bodies, be they asteroids, comets, KBOs, possibly the martian moons, meteorites or
IDPs—are thought to have formed earlier than the planets in the hierarchical assembly of solar system
bodies. Because they witnessed, or participated in, many of the formative processes in the early solar
nebula, they can provide unique constraints on physical conditions and cosmochemical abundances. Such
constraints come, in part, from observations and remote-sensing measurements made from nearby
spacecraft. Because we can visit only a small number of the myriad, highly diverse primitive bodies, we
must also observe them using Earth-based telescopes. Constraints on nebular processes, as well as
absolute dating of events in the early solar system, also come from laboratory analyses of samples of
these bodies, whether collected and returned to Earth by spacecraft missions or obtained by the vagaries
of celestial mechanics. The least-processed of these samples contain small amounts of tiny presolar
grains, whose properties and compositions constrain astrophysical processes that predate the solar system.
TABLE 4.1 Major Accomplishments by Telescopes and Space-based Studies of Primitive Bodies in the
Past Decade
Major Accomplishment Mission and/or Technique
Detailed orbital characterization of an asteroid, including successful landing Near-Earth Asteroid Rendezvous
Sampled a near-Earth asteroid and returned the sample to Earth; determined Hayabusa
that small asteroids can be rubble piles
Determined the density of a comet nucleus via the first controlled cratering Deep Impact
experiment on a primitive body
Return of comet dust for analysis in terrestrial laboratories Stardust
First reconnaissance of a possible former trans-Neptune object in the form of Cassini
Saturn’s distant satellite, Phoebe
Discovered that binary objects are common among near-Earth and main belt
asteroids and Kuiper belt objects, and that comets occur within the main
asteroid belt.
Ground- and space-based
telescopes and radar studies
PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION
4-2