Habitability Versus Searching for Life -- the Phoenix Mission
I'm Dr. Deborah Bass, Deputy Project Scientist for Phoenix. I have been working to create operations processes and jobs and train the science team in how to carry out those jobs. In addition to that, I work very closely with the engineering team on Phoenix to make sure decisions are made that benefit science as much as possible!
Phoenix is not searching for life. That potential discovery is for a future
mission that has specific life-detection instruments. But I keep
getting asked about whether Phoenix will find life on Mars, so I've
thought quite a bit about what Phoenix is and is not doing.
What Phoenix is planning to investigate is whether the arctic region on
Mars could have supported life, either now or in the past. That is a
search for "habitability." It is looking for the right environment
and ingredients for life. Look at it this way. To even start making
chocolate chip cookies, you have to be sure you have the flour, the
eggs, the butter and the chocolate chips! They wouldn't be chocolate
chip cookies without the chips, you know! That means Phoenix is
investigating whether life could have been possible in the Martian
Arctic. At any rate, the things necessary for life as we know it are an energy
source, organic materials and liquid water.
The energy source is easy -- sunlight for example, which plants on Earth
use to convert carbon dioxide into oxygen. Obviously we know Mars has sunlight!
Other Mars spacecraft have found evidence of molecules called
sulfates. Sulfates happen to also be a good energy source -- organisms
on Earth at the bottom of deep ocean trenches use sulfates for
chemical energy sources. Phoenix will be looking for these sulfates at
its landing site too.
Previous spacecraft have shown that water seems to have been all over
Mars in the past in liquid form. Phoenix is going to study its landing
site for evidence of water ice and whether that water ice ever
thawed. It is that liquid water that is necessary for life. It is
possible that life might still be around in some kind of frozen,
dormant form. But remember that Phoenix is not going to try to detect
those microbes; rather, it will look at whether they *could* have existed at some
point. Click here to watch a video about 'Looking for Life in All the Right Places.'
Organic materials are molecules that contain the building blocks of
Life -- carbon, oxygen, nitrogen, hydrogen. Mars doesn't appear to have
organic materials on its surface, but it might be possible that there
are organics preserved beneath the surface in the water ice. Turns out
that ice is a good preserver of organic materials on Earth, which
means that the Martian polar region is probably the best place to look
for organics on Mars!
Habitability -- was Mars ever "just right" for life? That's what Phoenix is
hoping to discover -- a complicated and important search, if I do say so.
To learn more about the spacecraft and the mission, check out the following sites:
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