123 lift-off!

The European Space Agency’s Jules Verne Automated Transfer Vehicle might have had a flawless launch but, as noted on the Jules Verne blog, the onboard computers switched to the second of four propulsion chains after detecting a potential problem. It’ll have to wait a while to dock at the International Space Station as NASA’s Space Shuttle Endeavour lifted off last night from Kennedy Space Center, Florida, in a spectacular night launch. Footage from ReelNASA
Another view of the launch [new video with footage all the way to orbit]

And some additional information on that potential problem for ESA’s ATV from the comments zone at the Jules Verne blog

Posted by: Michiel Straathof • Anomaly 10-03-2008 • 09:29:20
“However the spacecraft on board computers detected a slight difference in pressure between the oxidizer and the fuel that compose the propellant. This caused the ATV to immediately switch over to the second of four propulsion chains, as it is designed to do.”

What exactly does that mean?

Posted by: Nuno Silva • RE: Anomaly 10-03-2008 • 12:39:25
Means that for monitoring purposes one compares pressure from the ergol tanks in order to detect possible failures. This is compared with conservative thresholds: one prefers to declare an healthy equipment failed than the other way around.
ATV has 4 propulsive chains but it has been qualified to perform the entire mission with 3. With 2 it can only cope with security constraints.
So, with 3 chains, ATV is only using 3/4 of the thrusters.
Astrium colleagues are looking at it in the control centre (ATV-CC). Either is a false alarm and the “failed” chain can be manually reintegrated, either the problem is real but can solved, either the problem is real and can’t be solved (in this last case we can also perform the entire mission).

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