Mars Reconnaissance Orbiter

For starters, a pair of much, much better mass spectrometers- one of
them is a negative ion mass spec, which is handy for examining C14/C11,
O17/O16, and O18/O16 ratios.

Such ratios are commonly used to determine whether compounds are
biological in origin, and could be useful in settling the debate over
the unexpectedly concentrated levels of methane found in some regions
of Mars' atomosphere are from geochemical or biochemical processes.

(Living oragnisms preferentially use some isotopes of compounds over
others.)

MRO can cover massive amounts of territory with better than has been
previously available resolution. That is not to take a single thing
away from the rovers, they are wonderful machines. But the Rovers also
have limitations, especially in terms of the amount of surface area
that can be explored.

John

Indeed. A rover is a really great tool for looking at a very specific
area you want to examine in greater detail, while the MRO and other
orbiters are good for wider coverage studies of Mars, and can provide a
larger context view to what is being studied on the surface with the
rovers. Both ways are very complimentary to one another, that is why
you have Odyssey doing joint atmospheric TES and mini-TES observations
with the rovers whenever possible. The various orbiters, particularly
the MRO, can scout the potential routes ahead for the rovers by giving
a detailed overhead view of the landing site. Many of the sites
examined in detail by the rovers so far have been the result of this.
It also gives the rover drivers advanced knowledge of areas where it
might not be so healthy for the rovers to go, and alternative routes
can be planned. On top of that, some of the science being done from the
orbiters, like the Mars Climate Sounder instrument, work best when they
have a high altitude to scan Mars' atmosphere from.
-Mike

...Personally, I think I need to set up a site where we all pitch our
predictions for when each rover finally either croaks or are finally
retired due to budget cuts or some other ****up on the ground outside
of technical gaffes. I give Spirit at least another year, and
Opportunity about another 7-9 months past that based on current
performance. Spirit's wheel problem will eventually result in a
totally locked wheel that will put extra strain on the other five by
having to drag it along, and eventually burn those motors out quicker
than if the wheel were free-spinning. Opportunity will no doubt have a
similar failure, but so far no signs of any.

It's not likely given the terrain that Opportunity's wheels will wear
out before Spirit's. Spirit has to go over very rocky ground, and now
up and down fairly steep hills and through the little valleys between
them. Opportunity, by contrast, has only mostly to go over flat terrain
(occasionally the rover has to crawl around on the steep sides of a
crater, but not that often), having to be a little bit careful for sand
dunes, like Purgatory, that can trap it. Another factor in
Opportunity's longevity over Spirit is that wheel issue happened on on
Spirit first, and steps were taken then on Opportunity (driving the
rover backwards, for instance) to ensure the lubricants in the wheel
motors stay evenly distributed.

Opportunity's big issue, though, is the stuck heater switch, which
drains the batteries at night. However the "Deep Sleep" mode seems to
be keeping that in check

The date, of course, will vary depending on whether or not they run
the damn things through another dust devil bath...

Well, that particular way of cleaning the solar arrays is more likely
on Spirit than Opportunity. But Opportunity gets the "Frost bath"
during the martian winters, so it all kind of evens out. Another
Opportunity advantage is that the Meridani Planum site it landed at is
somewhat nearer to the martian equator than Spirit's Gusev Crater site,
so that rover does not quite suffer as badly in terms of reduced
sunlight during the winter months on Mars.
-Mike