The remainder of the decade's program has run into additional problems -- not linked to the U.S., but to difficulties and likely program cancellations in the Mars projects of three different European nations, two of them partnered with the U.S.. And a whole series of additional factors -- including the massive cost of a Mars sample return mission -- are forcing the U.S. to radically revise its post-2009 Mars program, including the form of the first sample-return mission.

Taking them in order of planned launch date: first, the little "Beagle 2" hard-lander intended to be carried to Mars in 2003 aboard the European Space Agency's Mars Express orbiter has continued to run into serious problems which might force it to be removed from that mission. Beagle 2 is being built on a remarkably low shoe-string budget -- only 62 million U.S. dollars -- by a consortium of universities led by Colin Pillinger of Britain's Open University, with about half its funding from the British government.

Beagle's planned cost has been the source of complaints from the very start by those skeptical that a successful hard-lander -- especially one with such sophisticated surface experiments -- can be built and tested for such a super-low cost. The ESA came reasonably close to eliminating it from the mission during a review last spring -- and there have been some continuing problems since.

ESA's science chief David Southwood confirmed this in a press conference last week, saying that "The prime responsibility for Beagle is with the British government, and I believe that in recent weeks they have had to find more money" -- although he added that the ESA is "doing its utmost to make sure that Beagle will there on the launch pad with [Mars Express]."

At the NASA Advisory Council meeting, JPL's Mars project director Firouz Naderi confirmed an earlier report in "Die Zeit" that one of the main problems has been with Beagle's shock-absorbing airbags. To save mass and money, the little lander -- unlike America's Martian hard landers -- depends only on a parachute and airbags for its landing, rather than carrying a package of solid rockets to fire at the last second and remove a lot of its remaining descent speed. But, since a parachute can only remove a limited amount of descent speed in Mars' faint atmosphere, this means that Beagle will hit at over 100 km/hour -- and so its airbags must be particularly tough and rip-proof.

According to Naderi, some recent tests run of the airbags at JPL itself at ESA's request revealed a serious tendency for them to rupture. However, Southwood has since told SpaceDaily that Beagle's entry and landing subsystem "has since been redesigned to use the airbags as qualified", and that a new parachute design which is part of this has been successfully tested. He expressed confidence that Beagle 2 will indeed be fully completed and successfully tested by the deadline at the end of next January.

If Beagle actually should be cancelled for 2003, it's possible that it could be flown to Mars later, but at the moment there seems to be no other Mars-bound spacecraft in the near future on which it could piggyback. The possibility can't quite be ruled out that none of the three Mars landers planned for the 2003 opportunity will be launched, and that Mars Express (which continues to go smoothly) will be the only spacecraft sent to Mars next year -- but both NASA and the ESA insist that the odds are still very much against such a calamity.

By contrast, the sophisticated Mars Reconnaissance Orbiter ("MRO") which the U.S. plans to launch to Mars in 2005 -- including a super-high powered camera system to photograph 2 percent of Mars' surface with resolutions as small as 25 cm -- is going smoothly in its early development, and has recently undergone a successful Project Design Review. There is, however, a problem with the only one of its science instruments to be provided by a foreign country: the "SHARAD" subsurface radar sounder to be provided by Italy's "ASI" space agency.

The new government of Silvio Berlusconi has shifted Italy's emphasis from deep space science to Earth-oriented science satellites, with several consequences. For one thing, ASI will decide in the next few weeks whether it will provide copies of the two IR spectrometers ("VIRTIS" and "PFS") that are the crucial core of the science payload that would be carried by the ESA's proposed 2005 "Venus Express" orbiter.

Upon this decision rests the question of whether this mission -- a unique opportunity to do very detailed studies of Venus' atmosphere for only one-third of the usual cost of such a mission, using a near duplicate of Mars Express -- can be flown by ESA. If the mission is delayed until the next Venus launch opportunity in 2007, its cost will rise so much, due to the difficulty of keeping the various Mars Express equipment sources on line, that it will probably be cancelled.

Another consequence is that the ASI is now uncertain whether it will provide the SHARAD sounder which it had promised to MRO, which would follow up the "MARSIS" radar sounder on Mars Express with a shallower-depth but much higher resolution search for permafrost layers and pocket of liquid water up to 300 meters below Mars' surface.

Naderi told this reporter that ASI still says that it is highly probable that SHARAD will be provided; but the final decision, again, won't come until the end of September. If SHARAD is cancelled, there probably isn't time to provide any substitute instrument for MRO. (This, however, would still leave most of MRO's science payload intact.) But, as we'll see, this is actually the least important likely Mars-related cancellation by Italy.

The planned 2007 U.S. mission to Mars -- the first "Mars Scout" mission, selected (like the Discovery Program missions to other Solar System targets) from low-cost competitive proposals by various university and corporate teams -- continues to go well. 20 plausible proposals were submitted by the early August deadline, many of them very promising-looking.

Three or four finalists are to be announced on Dec. 4 for more detailed government-funded study, with the final choice to be made next August. The finalists include a wide variety of orbiters and landers, including several missions that would use the 2001 Mars Surveyor soft lander that was built but never launched.