ESA News
http://www.esa.int

14 March 2008

Jules Verne demonstrates flawless Collision Avoidance Manoeuvre

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 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.

"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-Francois 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.

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