QUESTION:
Is there was any way for the Pathfinder to transmit sound from Mars, and if
not, why was that ability not included? Are there plans to include this
feature in future missions?

ANSWER from Bridget Landry on July 15, 1997:
That's an interesting question!  There are no microphones on Pathfinder, so
it can't record any sounds.  I think part of the reason that this decision
was made was that the air on Mars is so thin (about 1/2% of Earth's
atmosphere at the surface) that I'm not sure how well it would transmit
sound.  Also, there is not that much to be learned from sound, particularly
in an environment where the only forms of life we might expect to find would
be bacterial/microbial.  On other missions (one that I am working on, which
is planning to go to Europa, an icy moon of Jupiter) there are plans to use
sound as a seismic tool, to determine the structure and thickness of the ice
crust.  Such a technique could work on Mars, as well; Pathfinder just didn't
choose that path.

Thanks for your question!

Bridget

ANSWER from Guy Beutelschies on July 19, 1997:
Since there is nothing alive on the surface to make noise, we decided
against putting an audio reciever onboard.  Getting the sound of wind was
not important enough to justify the cost.  There are no plans that I know of
on any future Mars missions.

Guy Beutelschies	Mars Pathfinder Flight Engineer

ANSWER from Mary Urquhart on July 18, 1997:
Pathfinder, like all spacecraft, is limited by mass restrictions because of
the cost of launch.  Only equipment necssary to the spacecraft or that has
specific scientific value is put on the spacecraft, and even then there is
is often a great deal of competition among scientists for the selection of
instruments.  I agree that it might be fun to hear the wind when it isn't
calm, but a microphone wouldn't have any real scientific value. The imaging
equipment, on the other hand, all serves scientific and/or spacecraft
operation purposes as well as providing a great show for all of us back on
Earth!

Mary Urquhart                                    
Laboratory for Atmospheric and Space Physics  
University of Colorado at Boulder

ANSWER from Mark Adler on August 11, 1997:
Actually it requires quite a bit of bandwidth compared to our transmission
rates, even for low quality audio.  Our current data rate from Mars is
around 8 kilobits per second.  Voice communication over telephone lines uses
64 kilobits per second.  Compact disc quality stereo audio uses 1400
kilobits per second.  More recent technology to compress CD quality audio
can get that down to around 200 kilobits per second.  Still a long way from
8 kilobits per second.

Nevertheless, we are putting a microphone on our next Mars lander, launching
at the beginning of 1999 and landing later that year.  Because of the data
rate limitations, we will only be able to return short snippets of recorded
sound.  Even so, as you suggest, there will be great public interest in
hearing those snippets.

I can already see the "Winds of Mars" relaxation CD...

mark