Watch the video animation of Deep Space 1 flying by an asteroid.
The still-unexplained glitch occurred two months after the spacecraft had completed its primary mission of flight testing a dozen innovative technologies. But with the spacecraft in otherwise excellent health and nearly a full tank of propellant aboard the malfunction dashed scientists hopes of making bonus flybys of two separate comets.
"The typical response at that point would have been to declare the mission over. We could have retired the spacecraft and been proud of its prior accomplishments. But as the hero of one of my favorite movies said, Never give up, never surrender," said Rayman, quoting the recent Hollywood sci-fi parody Galaxy Quest.
Now, with its advanced ion-propulsion engine chugging away again and its science camera functioning as a jury-rigged navigational instrument mission members at NASAs Jet Propulsion Laboratory (JPL) and spacecraft-builder Spectrum Astro Inc. are confident the spacecraft can make one of the two rendezvous. Barring any future catastrophes, Deep Space 1 should wing by the comet Borrelly a little over a year from now.
"We really hope to continue thrusting until we get to Borrelly," said Mike Matranga, of Spectrum Astro, the lead engineer for the flight computer that runs the ion engine. "Weve got plenty of gas, for goodness sake."
The fix came not a moment too soon: had the spacecraft not resumed thrusting by July 5, it could well have missed its shot at meeting Borrelly.
"It wasnt drop-dead," Rayman said of the date, "but it was drop-comatose."
The innovative repair required engineers to write new software to press the spacecrafts science camera into a navigational role for which it had not been designed. NASA began uploading the software, broken down into 90 files, on May 30.
The extremely tight schedule grew even tighter on June 3 when a problem familiar to many computer users cropped up.
On that date, a glitch aboard Deep Space 1 forced the spacecraft to reboot its computer, deleting in the process 81 of the files that had already been uploaded.
"At that point, I felt like we had conducted this heroic effort and we had done a great job and it looked as if we were going to lose it," said Rayman, part of the 10-member core team working to save Deep Space 1.
However, NASA allocated the mission more time on its Deep Space Network of antennas, which allowed the team to redouble its efforts to send the spacecraft commands across a distance more than twice that separating the Earth from the sun.
By June 8, the new software was in place and ready to be tested. Four days later, the spacecraft found and locked onto a star other than the sun for the first time. With that step, the probe gained full knowledge of its orientation in space for the first time since November.
"Hats off to JPL for their stick-to-it-tiveness and being able to rewrite the software," Matranga said.
On June 21, NASA sent commands to switch on the engine for the first time since last fall. On June 28, Deep Space 1 began its first full week of thrusting toward the spot in space where it will meet up with Borrelly. Between now and September 2001, the spacecraft will keep its ion-propulsion engine on for the equivalent of about 225 days, picking out every month or so a new guide star to point toward en route to its cosmic rendezvous.
"Its really exciting to me to think about this small craft, hundreds of millions of kilometers (miles) away and we are not only able to make a detailed diagnosis of its problem, but build a new system that works," Rayman said. "Its really amazing humans can do this."
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