DARPA's Orbital Express Encounters Serious Sensor Flight Computer Anomaly

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15 May 2007 Update from Jan Walker, DARPA PAO:

"During Scenario 3-1 execution on the evening of May 11, Orbital Express encountered a serious sensor flight computer anomaly on the ASTRO while stationkeeping at 10 meters separation distance from the NextSat. Onboard fault protection reacted immediately, placing the ASTRO into an abort trajectory which carried it to a hold-point 120 meters from the NextSat. The Orbital Express team has spent the past several days recovering from this fault and from problems associated with loss of relative navigation at the longer-than-anticipated separation distances for this scenario. The ASTRO has since coasted at distances of up to several kilometers from the NextSat. Both vehicles are safe. The ASTRO powered up its redundant sensor flight computer and is processing sensor data nominally. The team is in the process of developing a recovery scenario for ingress and remate, and hopes to execute this ingress in the next several days."

Editor's 14 May 2007 note: At this point ASTRO and NextSat should be a few meters apart. Some observers are suggesting that they are kilometers apart. No word from DARPA.

OE observed with Nextsat, SeeSat-L

"... NEXTSAT appeared to trail by about 0.5 deg, when at a range of about 600 km, which indicates a distance of about 5 km."

Orbital Express -- Mission Updates, Boeing

5-May At roughly 6 pm MST, Boeing engineers command the spacecraft to begin performing Scenario 2-1. Scenario 2-1 is to be the first unmated operation where the two spacecraft depart to ten meters. It is at this distance that ASTRO will station-keep until communication constraints are met. Once the constraints are met, the ASTRO performs the final approach and capture. The entire operation is performed at Autonomy Level 4. It is at this level that ground control simply witnesses the operation. At the predicted time, 11:22 pm, ASTRO separates from NextSat and begins to back away to ten meters. ASTRO station-keeps exactly as predicted and returns down the corridor to capture NextSat within two minutes of predicted time of capture. ASTRO uses approximately 50% of predicted propellant allocated for the operation. Boeing engineers and the management team are elated to witness the flawless operation from beginning to end, setting the bar exponentially higher for all subsequent operations.


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