QUESTION:
The  design of expensive projects like space explorations necessitates the
creation of systems which are virtually foolproof. For instance, probably a
lot of research has gone into making sure that the fuel achieves a lift-off
with precise motion vectors instead of exploding. This implies that a lot of
machinery on space vehicles is very well designed for its specific function.

However, another factor to consider is that space-lifting a unit mass is
also very expensive, which would imply that the system should also be
designed to deliver the maximum bang for the buck per unit mass, if you'd
pardon the pun.

The nature of my question is -- how much of the Pathfinder, and the space
program in general, tries to achieve the latter?

For instance, the lander has a CPU which performs a multitude of tasks that
are preprogrammed. However, if need arises, it can be reprogrammed to handle
new situations with improved algorithms, etc. So, how about the rest of the
structure? What other uses can be had for the airbags? the rover ramps? the
actuator motors of the petal? The lasers on the rover? The calibration
targets on the lander? Any unused micro-explosives? If only the optical
systems were more configurable, you could use the same lens components to
build a microscope/telescope/panaromic camera!

In summary, how malleable is the engineering architecture of the space
vehicles? How multipurpose are their various components? Any plans for
putting general-purpose robotic tool-arms on later missions to perform
surgery for future missions (An arm that heals a ship could also
manipulate/crush/sample rocks for material analysis)?

ANSWER from Charles Whetsel on July 21, 1997:
There are a lot of examples of multi-purpose equipment being used in the
Mars Exploration Program.  As a contingency plan, the Pathfinder operations
team had practiced a set of maneuver with the deployment petals that could
have been used to effectively "crawl" the lander a short distance across the
surface of Mars (to get off of a boulder, for example).  Another good
example on Mars Pathfinder are the accelerometers: Even though these were
required for engineering purposes (to determine when to deploy the
parachute, when to inflate the airbags, etc.) the atmospheric science
community has already started to analyze the data to determine what new
information about the density of the Martian atmosphere at different
altitudes can be learned.

Similarly, Mars Global Surveyor and many other planetary spacecraft have
been equipped with a special mode for their radio transmitters that also
enables atmoshperic science to be conducted.  Since the radio must be used
anyway to send data and pictures back to earth, the radio scientists get
their measurements essentially for free.  Every time the spacecraft passes
behind the planet in it's orbit (many times per day) by leaving the radio
transmitter on for a few minutes longer, the scientists are able to watch
the effect of the atmosphere on the radio beam as it sinks deeper and deeper
into the atmosphere and finally winks out below the surface of the planet. 
The same observation is made in reverse as the beam emerges on the other
side of the occultation.

On the Mars Surveyor '98 Lander, we will have a robotic arm attached to the
lander instead of a rover.  This arm will not only dig in the Martian soil
and carry soil samples back to the lander for analysis, but will also be
equipped with a small camera at the wrist of the arm for close-up images of
both the surface or perhaps of the lander itself, if required for
troubleshooting purposes.

Charles Whetsel
Chief Engineer
Mars Surveyor Operations