QUESTION:
Why is going to Mars important? How will doing so improve things for us on
Earth? If you didn't find the rock in the Allan Hills ice field of
Antarctica, would you still be interested in the planet Mars?

ANSWER from Mark Adler on January 30, 1997:
Good question.  Tough question.  Different people will have different answers  
to this question, so here's mine.  (By "going to Mars" I'll assume you mean,  
for example, the missions we just launched to Mars, and those to be launched  
in the next several years.)

The most immediate benefit is the personal enjoyment of the public as they  
participate in the exploration of Mars.  That of course depends on us reaching  
out to the public so that they can be part of it.  (Hey, that's what I'm  
doing right now!)

The most tangible benefit, in my mind, is a scientific understanding of how  
another planet has changed since it formed and an understanding of how it  
works today so that we can better understand Earth.  It is very difficult,  
some would say impossible, to understand an incredibly complicated system like  
Earth without another example to look at.  Mars is that other example.

For example, a very long time ago Mars had water running on its surface like  
Earth does today.  But now there can be no liquid water on Mars since its  
atmosphere is so thin and cold.  What happened?  We don't know exactly.  If we  
can figure that out, then we will be smarter about how these things work, and  
will better understand, for example, what the impact of humans could be on  
Earth's climate.  Also Mars is unique in that much of its early history was  
preserved, whereas on Earth wind and water erosion and plate tectonics has  
erased much of its early history.  So Mars can teach us about what Earth was  
like long ago, so that we can begin to understand how Earth came to be like it  
is today.

The third major benefit is only a possibility.  But if it happens, then it  
will have a major impact on our view of ourselves in the universe.  That is if  
we discover clear signs of life on Mars sometime in its past.  If that life  
came about separately from Earth, then we can say that there must be life in  
lots of places in the universe and that somewhere else, someone may be asking  
the same questions.

There are numerous other benefits.  Not the least of which to me is that Mars  
exploration pays for my food and shelter!  :-)  Seriously, there is the  
benefit of national prestige, which is very real to the politicians who fund  
this stuff.  There is the harder to quantify benefit of science for unknown  
gains in the future.  When we look back to what scientific discoveries have  
most affected our lives, in many cases there would have been no way to tell at  
the time which discoveries those would be!  Another benefit is the  
development of new spacecraft technologies for Mars exploration that can  
applied to spacecraft that directly affect us on Earth, such as communications  
and weather satellites.  It's possible that some technologies developed for  
Mars exploration might have direct applications on Earth.  For example the  
robotic technology being developed for wheeled rovers that are given goals  
instead of step-by-step directions.

I'm sure there are some that I've forgotten.  In short, there are a lot of  
benefits, but the biggies in my opinion are: the public enjoyment of  
exploration, understanding Earth, and the possibility of discovering that life  
isn't unique to Earth and so that we are probably not alone.

mark

ANSWER from Donna Shirley on January 30, 1997:
1. To find out why Mars is like it is - cold and dry - when it was 
once warmer and wetter.  This is to find out if the earth might 
become like Mars or Venus if we mess with environment too much.

2. To see if life ever developed on Mars (the second most likely place
in the solar system besides the earth).

3. To prepare to someday send people to colonize Mars.

ANSWER from Jack Farmer on January 31, 1997:
We visited Mars several times in the 1970's with robotic missions called
Mariner 9 (an orbiter) and Viking (2 orbiters and 2 landers).  We would
like to go back to better understand how the Earth and Solar System
originated, and to see if life ever developed elsewhere, beyond Earth.
Mars is really the best place to go to study such things for basically two
reasons:

1) The surface of Mars is very old and preserves a record of the earliest
events that shaped the inner solar system (this early rock record has been
lost on Earth because of plate tectonics and weathering and erosion).

2) Mars was more Earth-like early in its history and is the other planet in
our solar system most likely to have supported extensive liquid water
environments where life could have developed and survived.  During the
early history of Mars, at the time life first developed on Earth, the
planet had water at the surface where it formed extensive valley networks
and may have even pooled to form large lakes.  If life developed here on
Earth, we have to ask "Why not on Mars?".

For a number of reasons, very early in the planet's history (around 3
billion years ago) Mars appears to have lost its atmosphere, eventually
refrigerating to form an icy cold desert.  The surface of Mars today is far
too harsh for life to exist mainly because liquid water is unstable there
and can only exist as vapor in the atmosphere or as ice (Mars has ice caps
at both poles).

If life still exists on Mars, it is likely to lie deep underground where
the temperatures and pressures are high enough for water to still be
liquid.  The way to really know for sure is to return to Mars and search
for evidence of ancient  life (as fossils preserved in rocks), or to drill
deep beneath the surface to find zones of liquid water where living
orgnanisms may be present.  Deep drilling is likely to require human
missions.  We just launched two robotic missions to Mars in the Fall, and
although neither will provide a definitive answer to the life question,
they will open up new ways of looking at the planet and help us decide
where to go next.  Eventually we want to return samples to the Earth and
send astronauts to the red planet to explore the deep subsurface.  - Jack
Farmer

Jack D. Farmer, PhD.
NASA Ames Research Center

ANSWER from Jack Farmer on April 3, 1997:
There are many reasons, but perhaps the most compelling these days is to
search for evidence of past or present life.  Of the other planets in the
inner solar system, Mars offers the greatest chance for  having developed
life.  True, the present surface of Mars is a dry, frozen environment and
not aplace we think of as conducive to life.  But early in its history,
Mars was warmer with liquid water at the surface.  We think that during
that time, life may have developed and flourished.  But today the
atmospheric density of Mars is ~1/1000 of that on Earth and liquid water is
unstable. Today water is only present in two forms at the surface of Mars :
ice (found at high latitudes as ground ice and as glacial ice on the
northern polar cap) and as atmospheric vapor.

As Mars lost its atmosphere it also lost the possibility for liquid water
when and why this happened is still open to debate, but we think it is
mostly explained by the fact that Mars never developed plate tectonics and
so the crust has never been recycled to release gases back into the
atmosphere. Another reason to go back to Mars is to try and understand the
climate and atmospheric history and why the planet lost its atmosphere.
This could help us better understand our own planetary history and future!

If life developed on Mars during the early clement period, it is likely to
have become extinct in surface environments.  And if life was present
early, it is likely to have left behind its traces as fossils in rocks.
One strategy we are promoting to search for past life is to explore the
ancient water-deposited sedimentary rocks found in the oldest terranes of
Mars.  These areas are mostly found in the heavily cratered southern
highlands of Mars.

The search for extant life on Mars we must take a different approach than
that we will takle in searching for past life as a fossil record. Twenty
years ago we sent two landers to the surface of Mars to look for living
organisms.  Those missions discovered no evidence for life on the present
surface of Mars.  But we also believe that when Mars lost its atmosphere,
the zone of liquid water likely retreated underground.  There could be vast
amounts of water on Mars today as subsurface groundwater, and this
comprises an important potential habitat for extant life.  To get there we
will have to drill 100's to 1000's of meters down and that is complicated
enough to require humans.

This gets us to another reason to go to Mars.  In the long term, we want to
send humans and colonize the Martian surface.  This is important because
human astronauts on Mars could do a much better job of exploring (using
their robotic partners of course!) than could ever be accomplished using
robots alone.  Mars is such an important place for us Earthlings because it
has rocks at its surface that extend back to much earlier periods in solar
system history than here on Earth.  That record can tell us a lot about how
the Earth formed and how life got started here. So Mars holds many secrets
of great importance to us for helping us better understand ourselves and
our history.  Getting there will produce many technological advances and
spin-offs that will benefit us all.  It is a small investment to make
considering all that we will gain in return!
- Jack Farmer

ANSWER from Bruce Jakosky on April 28, 1997:
Mars has always been one of the most interesting planets.  When we began
to explore it in detail over twenty years ago, we discovered large volcanos,
giant valleys, and evidence that there once had been abundant liquid water.
Even without the meteorites that have come from Mars, Mars is interesting.
We can look at its geology and its history, and understand more about how
planets work.  This helps us to understand our own planet.

And, because Mars has had liquid water, it is possible that it may have
life.  Although we sent the Viking spacecraft to Mars in 1976 to look for
life, and didn't find any, it may have been looking in the wrong places.
If we can find a location where there is liquid water today, we might find
life.  And, if we go look at places where water existed in the past, we might
find evidence that life existed in the past.

The Mars meteorites are a real treasure trove of information--they tell us
a lot about the red planet.  And, with all of the recent interest in
possible life, the public has become aware of the excitement about Mars
and its history.  These rocks are helping us to learn about Mars, but they
are only part of a program of exploration that includes telescopic
observations, theoretical analyses, and spacecraft exploration.  With luck,
we'll be able to bring rocks back to Earth from Mars, and learn even more.