Cameron Park - October 19, 2000

On Sept. 13, NASA space science chief Ed Weiler announced that the long-awaited 2004 launch of the "Pluto-Kuiper Express" mission would be the subject of a "stop work" order due to limited funds for space science, and the impact PKE was having on the Europa Orbiter mission scheduled for launch in 2006.

This was followed, on Sept. 29, by an announcement by Doug Stetson (manager of JPL's Solar System Exploration Office) that the earliest that NASA might now launch a Pluto mission would be "2009 or 2010". But as Jupiter would not be available for a gravity-assist flyby to catapult the little probe out to Pluto, an alternative means of propelling it rapidly into the outer Solar System would have to be used - such as "solar-electric propulsion or solar sails" - with a planned arrival at Pluto "no later than 2020".

However, the planetary science community was infuriated by the first decision, and unmollified by the second. Pluto Express -- unlike most space science missions -- will suffer an actual and serious scientific data loss if its arrival at Pluto is significantly delayed, since Pluto is currently moving away from the Sun on its elliptical orbit and its thin atmosphere (one of the main subjects of the mission) will soon begin freezing out onto its surface.

As Stetson himself said, we don't clearly understand how fast that will occur -- and it's quite possible that the atmosphere may freeze out as early as 2015.

Moreover, the simple fact is that a Pluto mission which has to depend on advanced deep-space propulsion techniques rather than a Jupiter gravity assist will not only likely take longer than the 8-year flight planned for Pluto Express, but will be considerably more expensive.

For these reasons, the Division of Planetary Sciences of the American Astronomical Society (the nation's major body of planetary scientists) took the unusual step on Sept. 21 of issuing an official statement criticizing NASA for cancelling the mission, and urging that "NASA and the US Congress find a way to fund this important mission, but not at the expense of other equally important planetary missions or its basic research and analysis programs... If this mission is delayed beyond the 2004 launch, the opportunity to study the tenuous Pluto atmosphere may be lost for centuries."

Nevertheless, NASA is sticking to its guns thus far; public affairs officer Don Savage stated on Oct. 16 that "things have not changed". However, something unusual is happening, according to the Los Angeles Times (in an Oct. 15 story reprinted in the Washington Post): The decision "is stirring up something of a public revolt.

In just two weeks the Planetary Society, a Pasadena-based group of space exploration enthusiasts, has received 10,000 letters protesting the suspension of the mission. And a Pennsylvania teenager is collecting signatures via PlutoMission.com to petition NASA to change its decision.

"A lot of Americans have a lot of faith in the space program. It really lets people down when they cancel a mission," said Ted Nichols II, a 17-year-old high school senior and amateur astronomer from near Harrisburg, Pa., who created the PlutoMission.com Website.

"Nichols and Louis Friedman [executive director of the Planetary Society] are surprised at the potent public response to Pluto. It may be because the distant planet has 'the mystery of the edge," surmises Friedman. Doug Stetson... thinks it may be because most people dislike unfinished business. "There's a real desire to complete the first wave of exploration," he said."

The public discontent might be greater, however, if more was known about the rather strange process by which the cancellation decision was reached.

According to SpaceDaily sources in the planetary science community, "The decision to cancel Pluto Kuiper Express rather than the Europa Orbiter was not discussed with any of the science advisory boards that NASA supposedly consults", and "planetary scientists who objected to the cancellation were allegedly threatened with loss of future NASA funding."

Other scientists are willing to comment publicly. Dr. Alan Stern of the Southwest Research Institute -- arguably the leading scientific expert on Pluto -- said "No one I know in the scientific community has confidence in the 2009 plan. It's scientifically riskier, and the addition of solar-electric propulsion is a new cost driver that will make the mission more, not less expensive."

NASA's original plan was to incorporate both the Pluto Express and Europa Orbiter missions into its new "Outer Planets/Solar Probe Program", a new generation of missions -- also including the later "Solar Probe", which would make an extremely close flyby of the Sun -- which would utilize similar spacecraft buses using new advanced "X2000" technology making them both extremely lightweight and highly radiation-resistant.

The original plan was to launch Pluto Express first in 2003, and Europa Orbiter in 2004 -- but in 1998 NASA unexpectedly reversed the order of the two launches, despite the facts that Europa Orbiter required considerably more sophisticated technology and Pluto Express could not tolerate any further delay beyond 2004 in order to use Jupiter for a gravity assist.

The suspicion at the time was that this decision was made by NASA Headquarters -- and perhaps by Administrator Dan Goldin himself -- because of an excessive obsession with astrobiology missions in the belief that they have more PR pizazz with the general public.

However, the new X2000 technologies took more time and money to develop than expected. Earlier this year, NASA decided to delay the launch of Europa Orbiter into 2006 -- but even then, it soon became clear that a Pluto probe using those technologies simply could not be launched in 2004 with the amount of funding available.

The mission could perhaps have been saved by transferring NASA's planned spending on Europa Orbiter during Fiscal 2001 into the Pluto project; but NASA instead decided to cancel Pluto Express and try to save the 2006 launch of Europa Orbiter -- despite the fact that Europa Orbiter, unlike the Pluto probe, could tolerate a launch delay of any length with no loss of science data or increase in total cost.

This may, again, be due to an excessive fixation with astrobiological missions and public PR on NASA's part -- especially when you consider that at virtually the same time, NASA astonished the scientific community by making a snap decision to launch a second rover to Mars in 2003, for which it had to immediately scrape up $200 million by siphoning it out of its other programs.

Admittedly, the problems with the X2000 technology development might have prevented a launch of Pluto Express in 2004 even if Europa Orbiter had been deprived of all its funding this year. (JPL states that "the total cost of finishing Pluto-Kuiper Express between now and 2004 is about $600 million.") And it's considered unlikely by almost everyone that Congress can be persuaded to cough up the additional $150 million or so needed this year.

But (as noted in an earlier "SpaceDaily" article), those advanced lightweight and radiation-resistant technologies -- which are undoubtedly necessary for Europa Orbiter and Solar Probe -- are not necessary for a Pluto flyby mission.

A Pluto probe will be exposed to a tremendously lesser dose of radiation during its brief Jupiter flyby than Europa Orbiter will. And an examination of the weights of other near-future NASA solar system probes with technical requirements similar to those of Pluto Express makes it clear that a Pluto spacecraft similar to one of NASA's "Discovery" inner Solar System missions could definitely be constructed that would weigh only 350-400 kg -- light enough to be launched to Pluto in 2004 by the already-developed Atlas 3 booster -- while retaining the scientific capabilities of Pluto Express, without the need for any of the new X2000 technologies.

This would also likely make it possible to fund a 2004 Pluto mission without the need to ask Congress for any increase in NASA funding whatsoever -- and also without reversing that rather curious decision to suddenly fund a new $200 million Mars rover mission out of nowhere.

Moreover, if the design for such a Pluto spacecraft was selected using techniques similar to the Discovery Program's strategy of picking a mission out of a list of candidates proposed by various independent scientific and engineering teams, it might set a promising precedent for the future -- since one complaint this writer has repeatedly heard from planetary scientists is that NASA has no similar program for missions to the outer Solar System (or, for that matter, Mars), and that the spacecraft designed for those programs by centralized decision makers without competition tend to be both more expensive and less well-designed than those which the competitive Discovery process selects.

None of this is at all likely to happen, however, without an increase in pressure on both NASA and Congress from both the scientific community and the general public -- nor will a 2004 Pluto mission using any technique be saved without such pressure.