How Does Life Begin and Develop?
Objective
1
Sources of 0rganics on Earth
Objective
2
Origin of Life's Cellular Components
Objective
4
Genomic Clues to Evolution
Objective
5
Linking Planetary and Biological Evolution
Does Life Exist Elsewhere in the Universe?
Objective
7
The Extremes of Life
Objective
8
Past and Present Life on Mars
Objective
9
Life's Precursors and Habitats in the Outer Solar System
Objective
10
Natural Migration of Life
Objective
11
Origin of Habitable Planets
Objective
12
Effects of Climate and Geology on Habitability
Objective
13
Extrasolar Biomarkers
What is Life's Future on Earth
and Beyond?
Objective
14
Ecosystem Response to Rapid Environmental Change
Objective
15
Earth's Future Habitability
Objective
16
Bringing Life with Us beyond Earth
Objective
17
Planetary Protection
Question: Does Life Exist Elsewhere in the Universe?
Past and Present Life on Mars
Objective 8: Search
for evidence of ancient climates, extinct life and potential habitats
for extant life on Mars.
The requirements for life on Earth imply that liquid water is the critical requirement for life on other worlds of the Solar System. Operationally, the search for past or present life is therefore a search for past or present environments where liquid water may be (or may have been) found. There is direct evidence that Mars once had liquid water on its surface, and indirect evidence that even today there may be subsurface Martian aquifers and/or hydrothermal systems. The search for fossils -- either biochemical or structural- would focus on aquatic depositional environments, such as sedimentary deposits from former lakes or hydrothermal systems. Chemical analyses of samples formed under habitable conditions can offer insights into biologically-relevant chemistry that may have occurred in these environments. Both the selection of sites bearing evidence of habitable environments (past and present) and the in-situ analysis of surface materials will enable a sample return program that effectively addresses astrobiology goals.
Implementation
Near- to mid-term:
- Continue to collect martian
meteorites and conduct comprehensive analyses of them. o Improve methodologies
for identifying biomarkers.
- Conduct global visual and
spectral reconnaissance of Mars to identify paleolakes and sites of
past hydrothermal activity by determining the presence of fluvial features,
shorelines, and precipitates such as carbonates, phosphates, silica
and evaporites.
- Locate, sample and characterize
geologic deposits that record evidence of the early Mars climate and
potential biosphere.
- Develop geophysical methods
to remotely characterize the potential for subsurface liquid water on
Mars. o Working with external agencies and industry, develop technologies
capable of accessing and retrieving samples from deep (>5km) below the
martian surface.
- Develop technologies for accessing broad areas of the Martian surface.
Future extensions:
- On Mars access to sediments deposited in lakes as well as potential subsurface hydrospheres requires sampling capabilities beyond the current state-of-the-art. To reach paleolake sediments it would be necessary to get through the aeolian dust which may extend to depths of 10 meters, and access to depths of 5 or more kilometers may be required for hydrospheres. The long terms goals in the search for extant and extinct life on Mars thus rely in large extent upon broadening the sphere of Martian exploration through advanced mobility and drilling technologies. Even in the short term, greater access will allow sample returns with greater relevance to life. These returned samples will help us look more effectively for life elsewhere. In the long term, increasing the sphere of exploration will set the stage for the human assisted search for past or present life on Mars.