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

Over the past decade the Mars science community, as represented by the Mars Exploration
Program Analysis Group (MEPAG), has formulated three major science themes that pertain to
understanding Mars as a planetary system:
• Life—Understand the potential for life elsewhere in the universe;
• Climate—Characterize the present and past climate and climate processes; and
• Geology—Understand the geological processes affecting Mars’s interior, crust, and surface.
From these themes, MEPAG has derived key, overarching science questions that drive future
Mars exploration. These include the following:
• What are the nature, ages, and origin of the diverse suite of geologic units and aqueous
environments evident from orbital and landed data, and were any of them habitable?
• How, when, and why did environments vary through Mars history, and did any of them host
life or its precursors?
• What are the inventory and dynamics of carbon compounds and trace gases in the atmosphere
and surface, and what are the processes that govern their origin, evolution, and fate?
• What is the present climate and how has it evolved on time scales of 10 million years, 100
million years, and 1 billion years?
• What are the internal structure and dynamics and how have these evolved over time?
The next decade holds great promise for Mars exploration. The MSL rover (Box 6.1), scheduled
for launch in 2011, will significantly advance our knowledge of surface mineralogy and chemistry at a
site specifically selected to provide insight into aqueous processes. The MAVEN mission currently in
development and the ESA/NASA ExoMars Trace Gas Orbiter (TGO) will provide major new insights
into the state and evolution of the Mars atmosphere. Following these missions the highest priority science
goal will be to address in detail the questions of habitability and the potential origin and evolution of life
on Mars.
The major focus of the next decade will be to initiate a Mars sample-return campaign, beginning
with a rover mission to collect and cache samples, followed by missions to retrieve these samples and
return them to Earth. It is widely accepted within the Mars science community that analysis of carefully
selected samples from sites that have the highest scientific potential that are returned to Earth for intense
study using advanced analytical techniques will provide the highest scientific return on investment for
understanding Mars as a planetary system.
These samples can be collected and returned to Earth in a sequence of three missions that collect
the samples, place them into Mars orbit, and return them to Earth. This modular approach is
scientifically, technically, and programmatically robust, with each mission possessing a small number of
discrete engineering challenges, and multiple sample caches providing resiliency against failure of
subsequent elements. This modular approach also allows the sample return campaign to proceed at a pace
determined by prioritization within the solar system objectives and by available funding. The study of
Mars as an integrated system is so scientifically compelling that it will continue well beyond the coming
decade, with future missions implementing geophysical and atmospheric networks, providing in situ
studies of diverse sites, and additional sample returns that build on the coming decade’s discoveries.
All three of the crosscutting science themes for the exploration of the solar system include Mars,
and studying Mars is vital to answering a number of the priority questions in each of them. The Building
New Worlds theme includes the question “what governed the accretion, supply of water, chemistry, and
internal differentiation of the inner planets and the evolution of their atmospheres, and what roles did
bombardment by large projectiles play?” Mars is central to the Planetary Habitats theme which also
includes two questions: “what were the primordial sources of organic matter, and where does organic
synthesis continue today?” and “beyond Earth, are there modern habitats elsewhere in the solar system
with necessary conditions, organic matter, water, energy, and nutrients to sustain life, and do organisms
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