Andrew Yee[_1_]
March 24th 08, 02:26 AM
ESA News
http://www.esa.int
12 March 2008
Successful manoeuvres position Jules Verne ATV for crucial tests
Jules Verne ATV successfully performed two boosts today, bringing the
spacecraft to an altitude of 303 km -- half-way between the insertion orbit
reached after last Sunday's launch and the orbit of the International Space
Station.
The boosts used two of the four main engines on the Automated Transfer
Vehicle. Each boost lasted for approximately 2 minutes and provided a change
in velocity of just over 6 m/s. Today's burns came on top of two burns
conducted by mission controllers at ESA's ATV Control Centre yesterday.
"Everything is working perfectly now on both the main and redundant
propulsion chains," explains John Ellwood, ESA's ATV Project Manager. "The
same chain -- Propulsion Configuration A -- that we switched to on Monday
was used to perform the two boosts yesterday and the two boosts today."
"The entire spacecraft is working beautifully and the actual degree of
control during these boosts has been even better than expected," adds
Ellwood. The burns on Tuesday were later determined to have performed to
within 0.3% of the target.
The manoeuvres overall boosted the altitude of Jules Verne by approximately
20 km and have positioned the ATV behind and below the ISS, which is at an
altitude of 340 km, with the two orbiting craft separated by a phase angle
of approximately 280 degrees.
Following today's first burn at 13:20 CET [1220 UTC], the second burn, at
14:01 CET [1301 UTC], was commanded and monitored using ESA's own Artemis
relay satellite, due to a gap in TDRS relay satellite coverage at that time,
making the manoeuvre an all-European activity.
In the next two days the ATV team will try out one of the spacecraft's main
safety features -- the Collision Avoidance Manoeuvre, or CAM. Jules Verne
ATV is equipped with a completely independent system with which ATV can be
given a boost away from the Space Station if necessary during the craft's
automated docking procedure.
A CAM would be executed using a completely independent control system,
sensors and thrusters, managed by a separate computer which in turn uses
software developed completely separately from the rest of the ATV.
"This is a manoeuvre which, if everything else has failed, really is a
'back-up of back-ups.' If things are really going wrong, it's our ultimate
safety system," explains Ellwood.
A test of the CAM system is scheduled for 13 March, starting at 11:00 CET
[1000 UTC] and running through an extensive series of procedures during a
window extending until approximately 17:00 CET [1600 UTC]. Mission
controllers will then analyse results and confirm that everything is as
expected.
An actual demonstration of the Collision Avoidance Manoeuvre is scheduled
for Friday, 14 March, beginning at 08:56 CET [0756 UTC].
"The CAM demonstration is a really critical activity, as it involves turning
off the spacecraft's nominal systems and actually flying the spacecraft
while relying on the back-up CAM system. We will all be monitoring the
spacecraft very closely on Friday," says Bob Chesson, the Head of ESA's
Human Spaceflight Operations team.
The intense activity for the Jules Verne team comes soon after a successful
recovery operation conducted on the night of 10 March, in which a propulsion
drive chain was re-established after having been automatically shut-down
soon after launch.
The recovery was a complex operation, involving engineers from prime
contractor Astrium, ESA's ATV project team and the joint ESA-CNES mission
control team at the ATV Control Centre.
"We were very concerned, but Jules Verne is fine now. I don't think I've
ever seen such close and strong cooperation among so many teams of people
done in such an efficient way done so effectively. It was incredible to
watch these guys in action," says Chesson.
[NOTE: Images and weblinks supporting this release are available at
http://www.esa.int/esaCP/SEMN1FM5NDF_index_1.html ]
http://www.esa.int
12 March 2008
Successful manoeuvres position Jules Verne ATV for crucial tests
Jules Verne ATV successfully performed two boosts today, bringing the
spacecraft to an altitude of 303 km -- half-way between the insertion orbit
reached after last Sunday's launch and the orbit of the International Space
Station.
The boosts used two of the four main engines on the Automated Transfer
Vehicle. Each boost lasted for approximately 2 minutes and provided a change
in velocity of just over 6 m/s. Today's burns came on top of two burns
conducted by mission controllers at ESA's ATV Control Centre yesterday.
"Everything is working perfectly now on both the main and redundant
propulsion chains," explains John Ellwood, ESA's ATV Project Manager. "The
same chain -- Propulsion Configuration A -- that we switched to on Monday
was used to perform the two boosts yesterday and the two boosts today."
"The entire spacecraft is working beautifully and the actual degree of
control during these boosts has been even better than expected," adds
Ellwood. The burns on Tuesday were later determined to have performed to
within 0.3% of the target.
The manoeuvres overall boosted the altitude of Jules Verne by approximately
20 km and have positioned the ATV behind and below the ISS, which is at an
altitude of 340 km, with the two orbiting craft separated by a phase angle
of approximately 280 degrees.
Following today's first burn at 13:20 CET [1220 UTC], the second burn, at
14:01 CET [1301 UTC], was commanded and monitored using ESA's own Artemis
relay satellite, due to a gap in TDRS relay satellite coverage at that time,
making the manoeuvre an all-European activity.
In the next two days the ATV team will try out one of the spacecraft's main
safety features -- the Collision Avoidance Manoeuvre, or CAM. Jules Verne
ATV is equipped with a completely independent system with which ATV can be
given a boost away from the Space Station if necessary during the craft's
automated docking procedure.
A CAM would be executed using a completely independent control system,
sensors and thrusters, managed by a separate computer which in turn uses
software developed completely separately from the rest of the ATV.
"This is a manoeuvre which, if everything else has failed, really is a
'back-up of back-ups.' If things are really going wrong, it's our ultimate
safety system," explains Ellwood.
A test of the CAM system is scheduled for 13 March, starting at 11:00 CET
[1000 UTC] and running through an extensive series of procedures during a
window extending until approximately 17:00 CET [1600 UTC]. Mission
controllers will then analyse results and confirm that everything is as
expected.
An actual demonstration of the Collision Avoidance Manoeuvre is scheduled
for Friday, 14 March, beginning at 08:56 CET [0756 UTC].
"The CAM demonstration is a really critical activity, as it involves turning
off the spacecraft's nominal systems and actually flying the spacecraft
while relying on the back-up CAM system. We will all be monitoring the
spacecraft very closely on Friday," says Bob Chesson, the Head of ESA's
Human Spaceflight Operations team.
The intense activity for the Jules Verne team comes soon after a successful
recovery operation conducted on the night of 10 March, in which a propulsion
drive chain was re-established after having been automatically shut-down
soon after launch.
The recovery was a complex operation, involving engineers from prime
contractor Astrium, ESA's ATV project team and the joint ESA-CNES mission
control team at the ATV Control Centre.
"We were very concerned, but Jules Verne is fine now. I don't think I've
ever seen such close and strong cooperation among so many teams of people
done in such an efficient way done so effectively. It was incredible to
watch these guys in action," says Chesson.
[NOTE: Images and weblinks supporting this release are available at
http://www.esa.int/esaCP/SEMN1FM5NDF_index_1.html ]