Jules Verne
Demonstrates Flawless Collision Avoidance Manoeuvre
(14 March 2008) Mission controllers
received confirmation shortly after 10:45 CET (09:45 UT) this morning that
Jules Verne ATV had successfully demonstrated the critical Collision Avoidance
Manoeuvre.
The crucial test began at 08:57 CET (07:57 UT), and
included placing the spacecraft into a minimally functioning 'survival'
mode.
The in-flight Collision Avoidance Manoeuvre, or CAM, demonstration
was necessary to prove that the spacecraft could reliably move away from the
ISS in case of any problems during the final rendezvous and docking with the
International Space Station. Upon detection of a critical failure or an unsafe
situation, the spacecraft's Monitoring and Safing Unit (MSU) is designed to
isolate the ATV's nominal systems and issue a CAM command.
"It went
perfectly - the MSU commanded ATV exactly as expected. After that, we had a
perfect recovery of the spacecraft, from sun-pointing safe mode, and we reset
the on-board computers. ATV is back in cruise mode," said Alberto Novelli,
ESA's Mission Director at the ATV Control Centre in Toulouse,
France.
The Automated Transfer Vehicle (ATV) is the first fully automatic re-supply spacecraft of its kind. ESA's Jules Verne ATV is the first European space supplier for the ISS. Its launch is scheduled on 9 March from Europe's spaceport in Kourou, French Guiana. (courtesy: ESA - D.Ducros)
The complex procedure involved shutting down
all of the normal control systems and placing the spacecraft into 'last-chance'
survival mode. After the manoeuvre was positively demonstrated and confirmed,
controllers implemented a lengthy 'exit-from-survival' recovery process that
brought all systems back into nominal operation.
"The performance was
absolutely flawless. We know now that it is completely safe for us to go to the
Station because we always have an independent way to get away from it. This
demonstrates that our back-up 'spacecraft within a spacecraft' works perfectly
- it's good to have this tool in our back pocket," said John Ellwood, ESA's ATV
Project Manager.
An enhanced team of some 60 mission controllers from
ESA and French space agency CNES watched this morning's test intently from the
ATV Control Centre. If any problems had occurred during survival mode, it would
have been very difficult to recover the spacecraft.
Mission controllers followed today's demonstration from the ATV Control Centre (courtesy: ESA)
"This independent mode relies on separate
computers, separate software, separate batteries, separate trajectory
monitoring sensors and separate thrusters. The only item shared with the ATV's
main system is propellant," explained ESA astronaut Jean-François
Clervoy, senior advisor to the ATV project.
The test was conducted with
ATV orbiting well away from the ISS, and included a 200-second thruster burn,
which took place as the spacecraft passed over northern Africa. A final orbit
determination will be done later today.
The CAM demonstration was also
monitored closely by ESA's ISS partners, with NASA operations personnel seated
on console in the ATV Control Centre. The US and Russian ISS control centres
and ESA's Columbus Control Centre also monitored the test. One important result
of the demonstration was to prove to the partners that the CAM functionality
was reliable and could assure the safety of the Station and crew members. The
CAM demonstration results are now being analysed by the ISS
partners.
Additional demonstrations of Jules Verne's functionality are
scheduled later in the month, with actual rendezvous and docking planned for 3
April 2008.
(source: ESA)
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