Then, in August 2005, the U.S. will launch the "Mars Reconnaissance Orbiter", which was first proposed for the 2003 opportunity but passed over then for the rovers. This new mission is a virtual certainty; its startup funds will come out of the current FY 2000 budget.
It will be based on the overall design of the current Mars Global Surveyor, but JPL will have nothing to do with its construction, which will be carried out by a private company picked through competitive bidding. It will spend 3-5 years mapping Mars, and serve as a communications relay for Mars landers for up to a decade.
MRO's three main instruments -- although they won't be picked in detail until next year -- are all connected with important missing gaps in the data to be provided by MGS, Mars Odyssey, and the 2003 European Mars Express orbiter.
The first is a new extremely high-resolution telescopic camera, even better than the current telescopic camera on MGS. It will photograph a fraction of a percent of Mars' surface with a resolution of a mere 20 cm/pixel -- as good as the naked eye a few hundred meters up.
New technology should make the camera far smaller and lighter than was possible even a few years ago -- and its CCD may be fully 4000 pixels on a side, allowing each image to cover 800 meters square.
The second experiment will recover the detailed mapping of Mars' weather lost when Mars Climate Orbiter failed, including constant mapping of temperatures, humidity, and dust and ice clouds at half a dozen different altitudes simultaneously.
But the new device, with its new technology, will weigh only a small fraction as much as the bulky 100-kg "PMIRR" instrument on MCO (and it will also carry out the wide-angle photography of weather patterns planned for the two tiny cameras also lost on MCO).
The highest-ranked instrument, though, is a mapping near-IR spectrometer to take spectra of Mars' surface in the short wavelengths of reflected sunlight, thus detecting a different set of minerals than those detected by the earlier orbiters using the longer-wavelength spectra of thermal IR emissions.
A near-IR mapper was originally one of the highest-priority instruments on the original Mars Observer, but had to be cancelled due to spacecraft development slip-ups. A similar mapper will be flown on Mars Express, but it has a top resolution of only 400 meters (for a few percent of the surface).
The instrument on MRO will be much sharper-eyed -- capable, in fact, of mapping 1 percent of Mars' surface with a resolution of only 50 meters -- and thus mapping a wide variety of geologically and biologically important minerals in very sharp detail. (If there's room, MRO may also carry a UV spectrometer to study the escape processes of Mars' atmospheric gases, and perhaps also a small radar sounder provided by Italy to follow up on Mars Express' radar sounder, which will make the first attempt to probe 1 km or more below Mars' surface to look for subsurface ice and liquid water.)
After MRO, the preliminary mapping of Mars' surface from orbit will be complete -- what chief Mars Exploration Program Scientist Jim Garvin describes as the "Seek" phase of the new three-part Mars exploration plan -- and the time will come to return to the second, "In-Situ Study" phase begun by the earlier Mars landers.
2007 is currently planned to be a first-class extravaganza of Mars exploration, not only by the U.S. but by France and Italy as its partners.
Its centerpiece will be a large "smart lander" -- a full-fledged soft lander with throttleable rocket engines, so large that it must be launched by a Delta 4 or Atlas 5 booster.
It will test two crucial new technologies for Mars exploration: a control system to steer its atmospheric entry path to allow a landing within a few kilometers of its target point (whereas current landers routinely miss by 50 km), and a landing hazard-avoidance system (probably using scanning laser radar) which will construct 3-D maps of the surface on the way down so that the craft, during its final descent on its rocket engines, can steer itself up to 80 meters to the side to avoid dangerous rocks or slopes.
And the lander's landing gear design (which hasn't yet been picked) will be much more resistant both to impacts on boulders and to the danger of tipping over. (It may perhaps consist of a complete crushable bottom on the probe -- to which the rocket engines will be attached -- and outriggers sticking out to the sides.)
The lander itself -- like the new Pathfinder landers that will carry the 2003 Mars rovers -- will itself carry no scientific instruments. Instead, it will serve as the carrier for a new, radically enlarged Mars rover -- "the size of a John Deere tractor" -- which will operate for two years or more, crawl for a hundred km or more across the surface, and carry as much as 300 kg of scientific instruments, allowing an extremely thorough in-situ study of Mars' surface and a survey for evidence of fossils. (Kenneth Nealson and Stamatios Krimigis noted that many people may not be full aware of just how much more sophisticated, sensitive and lightweight in-situ analysis instruments -- including biological ones -- have become in recent years.)
Continue to Part Three of this Report
