Languishing Pluto mission kept alive by Congress

Artist's concept of the Pluto Express orbiter.

By Richard Stenger
CNN

(CNN) -- A robotic mission to Pluto received a boost from Congress this week, despite lackluster support from NASA and the Bush administration for the proposal.

Members of the House and Senate conference committee, negotiating the fiscal year 2002 budget for NASA, approved $30 million to move forward with the Pluto-Kuiper Belt project.

The congressional action earmarked the funds to develop the launch vehicle and the scientific instruments for the mission, designed to send a probe to the last unexplored planet in the solar system. Moreover, it directed NASA to select mission scientists.

"The strong support for space exploration in the Congress is very welcome, especially at a time when there are so many other budget pressures," said Louis Friedman, director of the Planetary Society, an international group of space enthusiasts.

Last year, NASA announced it was canceling the project, citing cost overruns and technical delays. But months later, following protests from planetary scientists, the agency said it would reconsider the mission. In April of this year, however, President Bush unveiled a proposed 2002 budget that did not include funds for the Pluto mission.

"If Congress had not restored the funding, the opportunity for reaching the last unvisited planet in our solar system would have been lost for a generation," said Friedman in a statement.

Friedman cautioned that the project still could suffer the budget ax, unless NASA figures out a way to reign in the cost, currently projected at more than $500 million.

The probe was originally slated to lift off in 2004. The revised timetable would likely push back the departure to 2006, the last launch opportunity in more than a decade that would allow a spacecraft to use the gravity of Jupiter to boost itself to Pluto, according to planetary scientists.

Timing is critical for another reason as well. Pluto has a highly irregular orbit and is currently heading away from the sun.

A later launch could push the arrival date so far in the future that most of Pluto's tenuous atmosphere might be frozen by the time the a spacecraft reaches the system, Friedman said. It won't thaw out again for two centuries.

The Pluto-Kuiper Express would also fly by Pluto's moon Charon and the Kuiper Belt, a ring of icy objects beyond the planets that may hold clues about how the solar system formed. The one-way trip from Earth to Pluto is expected to take from 10 to 12 years.