NASA Postpones Mission to Pluto

Sept. 22, 2000 -- NASA has halted work on a planned mission to the solar system’s only unexplored planet, indefinitely delaying a trip to distant Pluto while engineers try to design a more affordable spacecraft.

The delay of the Pluto-Kuiper Express was the result ofspiraling costs in the Outer Planets Program and to avoid thebudget crunch blamed for last year’s Mars probe losses, said EdWeiler, NASA’s associate administrator for space science.

When it was first approved in 1996, “there was a lot ofengineering optimism and a lot of technologies that were assumed tobe simple to evolve,” he said Thursday. “Like the Mars program,things didn’t work out the way they were supposed to.”

Europa Comes First

The agency is making a priority of the Europa Orbiter, an OuterPlanets mission to be launched in January 2006. Scientists believethe Jovian moon might contain a subsurface ocean, a key ingredientto life.

“The Europa Orbiter is a high-priority mission because one ofthe themes of NASA space science is the search for life,” Weilersaid at conference of the American Institute of Aeronautics andAstronautics in Long Beach.

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

“Since I can’t deficit spend like other forms of government andhave to balance my budget, I have only one choice: I have decidedto delay Pluto indefinitely and move forward with ... the EuropaOrbiter,” Weiler said.

Last week, Weiler sent an order to stop work on the Pluto-KuiperExpress, which was being developed along with other Outer Planetsprobes at Jet Propulsion Laboratory in Pasadena, Calif.

Work continues on the other spacecraft at JPL, including theEuropa Orbiter and a solar probe, which is to be launched in 2007or 2008, said Doug Stetson, the lab’s manager of solar systemexploration.

Pluto: By 2020

The Pluto probe was originally scheduled to explore the planetby 2012. In addition to Pluto and its moon Charon, the probe wouldhave studied the Edgeworth-Kuiper Disk of asteroid-size rocksoutside Pluto’s orbit.

In the work-stop order, engineers were told to come up with amore affordable design that could explore Pluto by 2020.

Engineers were about a year into the probe’s development, havingalready come up with a basic design and issued some contracts,Stetson said. Some of the work can probably be used in anext-generation Pluto craft.

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

“What we’re doing right now is assessing the options that willallow us to do a Pluto mission probably around the end of thedecade, with a goal of arriving at Pluto by the year 2020,”Stetson said.

Uncertain Plutonian Future

Pluto, which was discovered only in 1930 and is now movingfarther from the sun, may not be in the best condition for study inthe near future, said Ellis Miner of the American AstronomicalSociety’s Division for Planetary Sciences.

“At some point, whatever tenuous atmosphere it might have wouldfreeze onto the surface,” he said. “One of the reasons we wantedto get there as quickly as possible is we would like to be able tostudy that atmosphere before that happens.”

Once the atmosphere freezes to the surface, it is not likely tothaw until the 2230s. It takes nearly 250 years to orbit the sun.

With a diameter of 1,430 miles, Pluto is less than half the sizeof any other planet and only two-thirds as big as Earth’s moon. Atclosest approach to the sun, the planet is still 2.7 billion milesaway from the star.