NASA stops work on Pluto mission

Artist's concept of the Pluto Express orbiter

LONG BEACH, California (AP) -- NASA has stopped working on its planned mission to Pluto, indefinitely delaying a trip to the solar system's only unexplored planet while engineers try to design a less expensive spacecraft.

The delay of the Pluto-Kuiper Express resulted from spiraling costs in the Outer Planets Program, said Ed Weiler, the National Aeronautics and Space Administration's associate administrator for space science.

When it was approved in 1996, "there was a lot of engineering optimism and a lot of technologies that were assumed to be simple to evolve," he said Thursday.

A Hubble Space Telescope view of Pluto (left) and its moon, Charon

But things didn't work out the way they were supposed to, he added.

The agency still is focusing on launching an orbiter to Europa, Jupiter's fourth-largest moon, in January 2006. Scientists believe the moon might contain a subsurface ocean, a key ingredient to life.

"The Europa Orbiter is a high-priority mission because one of the themes of NASA space science is the search for life," Weiler said at a conference of the American Institute of Aeronautics and Astronautics.

The Pluto and Europa missions were supposed to cost about $800 million combined. Largely because of the rising cost of launch vehicles and radioactive power supplies, the cost has risen to $1.3 billion.

"Since I can't deficit-spend like other forms of government and have to balance my budget, I have only one choice: I have decided to delay Pluto indefinitely and move forward with ... the Europa Orbiter," Weiler said.

Last week, Weiler sent an order to stop work on the Pluto-Kuiper Express, which was being developed along with other Outer Planets probes at the Jet Propulsion Laboratory in Pasadena, California.

Work continues on the other spacecraft, including the Europa Orbiter and a solar probe, which is to be launched in 2007 or 2008, said Doug Stetson, the lab's manager of solar system exploration.

The Pluto probe was scheduled to explore the planet by 2012. Besides Pluto and its moon Charon, the probe would have studied the Edgeworth-Kuiper Disk of asteroid-size rocks outside Pluto's orbit.

Weiler told engineers to develop a cheaper design that could explore Pluto by 2020.

Engineers were about a year into the probe's development, having already come up with a basic design and issued some contracts, Stetson said. Some of the work can probably be used.

The biggest change in a new design will likely be in propulsion, with a futuristic ion engine replacing the costly chemical engines used in most previous spacecraft, he said.

Pluto, which was discovered only in 1930 and is now moving farther from the sun, may not be in the best condition for study in the near future, said Ellis Miner of the American Astronomical Society's Division for Planetary Sciences.

"At some point, whatever tenuous atmosphere it might have would freeze onto the surface," he said. "One of the reasons we wanted to get there as quickly as possible is we would like to be able to study that atmosphere before that happens."

Once the atmosphere freezes to the surface, it is not likely to thaw until the 2230s.

Copyright 2000 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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Pluto-Kuiper Express
NASA Jet Propulsion Laboratory

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