[meteorite-list] NASA Restarts Once-Dead Dawn Asteroid Mission

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Mar 28 16:02:16 2006
Message-ID: <200603281639.k2SGdBD28030_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/news/n0603/27dawnrestart/

NASA restarts once-dead Dawn asteroid mission
BY STEPHEN CLARK
SPACEFLIGHT NOW
March 27, 2006

Less than a month after falling victim to budget and technical concerns,
the Dawn asteroid explorer was brought back from the grave Monday by a
decision to restore funding to the mission and launch the probe by next
summer.

NASA announced the reinstatement, a complete reversal of the decision
three weeks ago to kill the mission, after an appeal from project
officials at the Jet Propulsion Laboratory. The objections prompted yet
another review of Dawn, which had undergone a series of investigations
since October that assessed the state of the mission after various
problems and cost overruns came to light.

Last fall, NASA's Science Mission Directorate chartered an independent
assessment team to determine the status of the obstacles facing the
mission. In the meantime, the project was ordered to stand down as the
spacecraft was undergoing final assembly at an Orbital Sciences Corp.
factory. For more details on the history of the saga, see Spaceflight
Now's earlier story <http://www.spaceflightnow.com/news/n0603/03dawn/>.

The results from that review board eventually led to the cancellation of
Dawn on March 2. Findings included an estimated total cost of $446
million, a 20 percent increase over the capped cost of $373 million.

By early March, about $257 million had already been spent in mission
development, planning, and construction. An additional $14 million would
have been necessary to formally terminate Dawn, while the stand down
itself was an expense of approximately $5 million.

"When we looked at the stand down information at that time, we felt in
the Science Mission Directorate that there was too much risk still left
on the table to go forward," Colleen Hartman, the directorate's deputy
associate administrator, told reporters Monday in explaining why Dawn
had been cancelled earlier this month. "There is approximately a 20
percent increase (in cost). The information on the table at the time was
insufficient for us to feel comfortable going forward. Since that time
there was additional information provided."

The most recent review team included only upper level management from
NASA headquarters, and they weighed the decision process, the
conclusions of the initial assessment team, and the project's rebuttal.
They met last Thursday to discuss the matters, and made a final decision
over the weekend to reverse the cancellation order.

The group - chaired by Rex Geveden, NASA's associate administrator at
agency headquarters - found that the most prominent technical problems
no longer stood in the way of Dawn. Testing of composite xenon tanks
caused ruptures at lower than expected pressures, but engineers will
likely load less xenon propellant than first planned. An issue involving
test failures of two power units that provide electricity to the craft's
ion propulsion system is also on track to being resolved.

"Those failures are now understood and have to do with transient thermal
conditions that are a function of the test configuration," Geveden said.
"So we believe, fundamentally, that there is not a flight hardware issue
with those units, but rather a test configuration issue. There is a
hurdle to clear with that one - those need to go through 500-hour-life
testing. That's still out there, but the technical resolution path seems
pretty clear."

Another problem centering on thermal and structural concerns during a
test has also been addressed, said Geveden. "That had to do with a test
configuration situation and that one can be kind of finessed by adding
some heaters and managing the thermal environment in the test in a more
sophisticated way."

"In all of those cases there's work to do, but the way forward looks
pretty clear. I think the risk posture on this mission is not atypical
for this kind of mission. When you are doing deep planetary missions and
dealing with the environments and the temperature regimes and the
complication of integrating a suite of instruments, there are always
pretty tall challenges. And it looks like Dawn is prepared to take those
on and beat them."

Future costs are also thought be under control with improved management
and the technical remedies. Also, President Bush's planned fiscal year
2007 budget features enough margin to carry out the project, including
the overruns, but officials couldn't say where funding to cover the
extra costs will be coming from.

"Every time something overruns like this it obviously has to come from a
pot of money," Hartman said. "The pot of money doesn't change, and
somebody is requiring more from it. So as you know there's less for
something else. I can't track each dollar and tell you where that dollar
came from. We optimized the program and other things got less."

"Cost overruns are pretty typical because the amount of technical
uncertainty is normally high, and trying to estimate the cost on the
front-end of those missions is very hard to do," said Geveden.

"So you get to this stage of a mission where you are maybe two-thirds of
the way through the developmental stage and you have sunk half of the
cost. You have to really trade off the remaining cost the mission (and)
the scientific value against that remaining cost and judge that against
applying that money to new-start missions. That is the kind of difficult
trade we had to make. I take cost overruns deadly seriously, as does the
Science Mission Directorate, and that's the reason this mission was
under review for cancellation and that's the reason why consideration of
cancellation was, in my opinion, a very legitimate thing to do."

But Monday's decision doesn't mean Dawn is completely out of danger.

"Reinstatement does not excuse past performance nor guarantee
unequivocal future support," Geveden wrote in a letter to Science
Mission Directorate associate administrator Mary Cleave and JPL director
Charles Elachi. "JPL and the Dawn project are, therefore, required to
fully commit appropriate resources and management to the successful
completion of this mission."

Dawn principal investigator Chris Russell has long criticized NASA's
decision to halt mission preparations and has vigorously defended the
mission since its cancellation.

"The stand down spent money but did not progress us meaningfully toward
launch," Russell said last week. "Also we now have to rehire folks and
retrain to get to launch. So this whole process has wasted money - it
defies logic what they did."

Dawn is now expected to be ready for launch between June and August of
2007 aboard a Boeing Delta 2 rocket from Cape Canaveral, Florida. The
basic mission plan remains unchanged after the delays of the past few
months, and Dawn will reach Mars in early 2009 to receive a crucial
gravity assist that will send its path arcing into the asteroid belt.

The spacecraft will reach asteroid Vesta in October 2011, where it will
spend over six months orbiting to conduct science observations. After
departing Vesta, Dawn will arrive at asteroid Ceres by August 2015 to
investigate the solar system's largest minor planet.

"The things we are doing here are tough. They are not easy," Hartman
said. "This is a tough business. To have something last this long and
reach two destinations and explore them with this resolution and
specificity is a very difficult job."

Dawn will carry three primary instruments provided by a team of
international scientists. A framing camera built by the German Aerospace
Center, DLR, and the Max Planck Institute for Aeronomy will return
imagery of the surface of both asteroids. An Italian-built visible and
infrared mapping spectrometer will map the two bodies and determine
chemical compositions. The Los Alamos National Laboratory in New Mexico
is responsible for a gamma ray and neutron detector.

"Because (Vesta and Ceres) basically remained intact since their
formation, we're going to be measuring things like their mass, their
shape, their volume, their spin rate, and in order to do that we'll be
using both imagery, laser altimetry, and gravity measurements onboard,"
explained Hartman.

Hartman said NASA's Science Mission Directorate never lost sight of the
science that will come from Dawn. She described the review process as
very "gut-wrenching," and said that NASA is pleased to be going forward
with the mission.

"Understanding the major asteroids is a critical part of our exploration
program as it is the only way to piece together what happened 4.6
billion years ago (in the early solar system)," Russell said. "Vesta is
a rocky planet with an iron core like the Earth. It is one of the
building blocks that formed the terrestrial planets. Ceres we now know
is an ice planet over a rocky core. The water ice may be liquid inside.
Thus it is probably a better place to find life than (Jupiter's moon)
Europa. If we could get to Ceres and prove this to the community, then
the pressure for a Europa mission would go away and a Ceres lander would
be the order of the day."
Received on Tue 28 Mar 2006 11:39:10 AM PST