How Does Life Begin and Develop?
Goal
1
How
Life Arose on Earth
Goal
2
Organization of Matter into Living Systems
Goal
4
Coevolution of the Biosphere and the Earth
Does Life Exist Elsewhere in the Universe?
Goal
7
Signature of Life on Other Worlds
Goal
8
Life on Mars and Europa
What is Life's Future on Earth and Beyond?
Goal
9
Environmental Change on Earth
Goal
10
Terrestrial Life in Space
Question: Does Life Exist Elsewhere in the Universe?
Goal
5: Establish Limits for Life in Environments That Provide Analogues for
Conditions on Other Worlds
Investigate
the adaptation of life to the full range of habitable environments on
our own planet, past and present, and use these as analogues for conditions
on other bodies in our solar system, such as Mars or Europa.
Life is found on the Earth anywhere liquid water is present, including such extreme environments as the interior of nuclear reactors, ice-covered Antarctic lakes, suboceanic hydrothermal vents, and deep subsurface rocks. To understand the possible environments for life on other worlds, we must investigate the full range of habitable environments on our own planet, both today and in the past. We will investigate these extreme environments not only for what they can tell us about the adaptability of life on this planet, but also as analogues for conditions on other bodies in our solar system, such as Mars or Europa.
Background
To understand the potential for life on other worlds, we should begin by investigating the limits to life on our own planet. The tolerance for extreme conditions shown by terrestrial life is much broader than previously thought. Recent research on some of the Earth's smallest inhabitants has shown them to be remarkably versatile in their choice of lifestyles, with communities of microorganisms thriving in such extreme environments as nuclear reactors, perennially ice-covered Antarctic lakes, the interiors of rocks, hydrothermal springs and deep subsurface aquifers. Some extreme environments, such as those near marine hydrothermal vents, have actually been suggested as possible sites for the origin of life on Earth. Investigation of extremophile organisms and their habitats provide first-order scientific return in their own right (e.g., adaptive mechanisms, origin and evolution of life) as well as analogue environments for Mars and Europa exploration (Goal 8). It is also of interest to identify terrestrial environments that do not support life, such as glacial ice fields, and to ask why life has not adapted to fill all environmental niches that are energetically possible. Such studies can also assist in identifying the chemical or morphological signatures of life in environments that differ significantly from that of the bulk of the Earth's surface (Goal 7).