Cameron Park - Nov. 15, 2000
In my previous report on the Oct. 30-31 meeting of NASA's Solar System Exploration Subcommittee -- the group of a dozen planetary scientists who advise NASA on the scientific value of its proposed Solar System exploration missions -- I noted that they were very pleased with the design of NASA's newly announced plan for Mars exploration.
But exactly the opposite was true of the overall new form of its Outer Planets exploration program. In fact, it would not be saying too much to report that they were scandalized -- and they spent most of the two-day meeting planning how to try to repair the situation. Unfortunately, it now appears that their recommendations will be for naught.
The problem is threefold:
(1) Two years ago, NASA made a surprise decision to reverse the planned launch order of the first two missions in the new Outer Planets Program.
The SSES had recommended that the "Pluto-Kuiper Express" -- the first lightweight flyby probe of the last unexplored planet and its moon Charon, with an optional extension to study at least one smaller Kuiper Belt object -- should be launched first, in Nov. 2003, to take advantage of an opportunity for a gravity-assist flyby of Jupiter.
Then the Europa Orbiter -- a mission to orbit Jupiter's moon to try to establish firmly whether it still has a subsurface ocean of liquid water, and where the best landing sites are for future landers to study Europa's biological potential -- was to be launched in Dec. 2004.
Europa Orbiter requires considerably more sophisticated new technology developments than Pluto Express -- its weight must be trimmed to an absolute minimum for it to be launched on an acceptably small booster, and its electronics must be resistant to a very high dose of radiation from Jupiter's inner radiation belts.
Moreover, there was only one more opportunity for a decade to reach Pluto via a Jupiter gravity-assist -- in 2004 -- and if the Pluto probe slipped more than a year, its arrival at Pluto might be delayed for up to a decade, by which time Pluto's faint but scientifically important atmosphere might very well have frozen out on the planet's surface as it moved farther from the Sun.
For all these reasons, the SSES at the time officially recommended that the Pluto probe be launched first. But in February 1998, when NASA released its FY 1999 budget request, all observers were surprised to see that the order of the two had been reversed -- the more sophisticated Europa probe would be launched first in 2003, and the Pluto probe would follow at the last available Jupiter opportunity in 2004.
In an earlier article, I speculated that this sudden switch might be the personal work of NASA Administrator Dan Goldin, given his personal fascination with astrobiology and with good PR for NASA -- and three different scientists at the SSES meeting have now confirmed that the switch was entirely his own decision, on the grounds that (to quote Goldin's reported comment): "Nobody gives a damn about Pluto."
The new plan was for a single spacecraft bus and avionics design to be developed for the Europa mission, then used again for the simpler Pluto mission and the third mission in the program: the Solar Probe, which was to be launched in 2007 to make an extremely close flyby of the Sun through its actual corona.
Despite the vast differences in these three missions, the same general bus design was thought usable by all of them -- and this duplication would save money. At the time, it was widely thought that the launch deadlines for the missions could be met easily despite the switch. But the consequences of this move proved disastrous, for:
(2) Murphy's Law stepped in -- the problems of developing the Europa Orbiter proved much greater than expected, both in time and money.
At the SSES meeting, JPL's Outer Planets Program manager John McNamee confirmed that the Jet Propulsion Laboratory's cost estimates for both the Europa and Pluto missions had literally exploded upwards this year -- from a total of $807 million to $1.369 billion -- a rise of $250 million in the cost of the Pluto probe, and $300 million in that of the Europa probe.
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