[meteorite-list] NASA Reinstates Cancelled Asteroid Mission

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Mar 28 01:45:53 2006
Message-ID: <200603280105.k2S154J16301_at_zagami.jpl.nasa.gov>

http://space.com/news/060327_dawn_mission.html

NASA Reinstates Cancelled Asteroid Mission
By Tariq Malik
space.com
27 March, 2006

NASA's once-canceled Dawn mission to visit a pair of asteroids
has been reinstated following a mission review, space agency
officials said Monday.

NASA initially canceled the Dawn mission, which calls for an
ion-powered spacecraft to visit two large asteroids, earlier this
month only to reverse that decision, which drew ire and opposition
from planetary scientists at this month's 37th Lunar and Planetary
Science Conference (LPSC).

After an in-depth study of the cost overruns and technical challenges
plaguing Dawn's development, NASA officials concluded that the mission
should proceed towards a summer 2007 launch target.

"When you're doing deep planetary missions...there are always pretty tall
challenges," NASA associate administrator Rex Geveden told reporters in
a Monday teleconference. "And it looks like Dawn is ready to take those
on and beat them."

The decision buoyed Dawn mission scientists, who had mourned the
project's cancellation earlier this month.

"This mission goes up and down, but I'm happy," Dawn team member Lucy
McFadden, of the Department of Astronomy at the University of Maryland
in College Park, Maryland, told SPACE.com. "I want to get to work and
get this thing off the ground."

Dawn's new light

NASA first approved the Dawn mission in 2001 as part of its low-cost
Discovery mission program.

The spacecraft"s novel ion propulsion system draws on technology
demonstrated by NASA's Deep Space 1 probe, though Dawn would mark the
agency's first science mission to employ such an engine. Europe's
SMART-1 probe currently circling the moon also uses ion propulsion.

"This is, in fact, quite an ambitious mission," said Colleen Hartman,
NASA's deputy associate administrator for science mission directorate,
during the teleconference. "The things we're doing here are tough,
they're not easy."

Dawn is destined to rendezvous and orbit both Vesta and Ceres, two of
the largest asteroids in the Asteroid Belt, in 2011 and 2015,
respectively.

"Getting to Ceres and Vesta will be opening up our eyes to new worlds,"
McFadden said, adding that the large asteroids formed quickly in the
early Solar System and harbor many mysteries for scientists, including
their surface composition and features. "We just have the barest hint
from maps that we've derived from the Hubble Space Telescope on their
surface features."

During its development, the cost Dawn's mission swelled from an initial
$373 million to $446 million due to technical challenges, NASA officials
said. That cost overrun - and a 14-month launch delay from its intended
summer 2006 target - prompted NASA's March 2 decision to scrap the
mission, which came after $257 million had already been spent, the
agency said.

An additional $14 million would have been required to cancel the mission
completely, NASA said.

Off again, on again

Technical challenges revolving around Dawn's propulsion system, xenon
fuel tank and thermal stresses - among others - contributed to its
cancellation, NASA officials said, adding that those concerns have since
been addressed by additional data.

"What we had here was a very gut-wrenching decision," Hartman said. "And
we're very happy to be going forward."

But a review process instituted by NASA chief Michael Griffin to
evaluate the cancellation of NASA space missions proved successful for
Dawn's supporters.

"The science mission directorate decided to terminate it, and the appeal
[was] to see if we continue to fund Dawn or go on with that
termination," said Andrew Dantzler, director of NASA's solar system
division at the agency's Washington, D.C. headquarters, during an
interview last week.

NASA officials said Monday that the process is likely not one that will
occur often, adding that Dawn has accrued about $5 million in additional
costs since the agency ordered mission managers and scientists to stand
down last fall when cancellation discussions began in earnest.

"We revisited a number of technical and financial challenges and the
work being done to address them," NASA associate administrator Rex
Geveden said in an earlier statement. "Our review determined the project
team has made substantive progress - we have confidence the mission will
succeed."

The funds to save the project likely prevented other programs from
moving ahead, Hartman added.

"These are hard choices and sometimes future missions or current
missions have to sacrifice," Geveden added during the teleconference.

Meanwhile, Dawn scientists and engineers have their work cut out for
them before they can launch the spacecraft toward its asteroid targets
atop a Delta 2 rocket. About half of the spacecraft's hardware, which
includes support components and science experiments, is complete, NASA
officials said.

"I want to get to both of them," McFadden said of Vesta and Ceres. "I
can't believe I have to wait until 2015."
Received on Mon 27 Mar 2006 08:05:04 PM PST