by Staff Writers
Paris, France (ESA) Mar 31, 2008
International Space Station managers gave the go-ahead on yesterday for Jules Verne ATV to proceed with the second of two demonstration days in the lead up to a first ISS docking attempt later in the week. On Monday, Demonstration Day 2 will see ATV approach to within 11 m of the ISS.
"Having tested very successfully on Saturday the first part of the rendezvous, in particular using the relative GPS between that on Jules Verne and on the Russian Service Module of the ISS, we now have the go-ahead to the test the second part of the rendezvous which uses the optical sensors." said John Ellwood, ESA's ATV Project Manager.
"This will be very interesting, but we have a lot of confidence based on the great performance of Jules Verne during the first demonstration day."
The first demonstration day proves Jules Verne ATV can perform relative navigation with the ISS using relative GPS to successfully and safely manoeuvre the spacecraft to a point located 3.5 km behind the ISS and at the same orbital altitude.
Jules Verne ATV performed flawlessly during the manoeuvres, moving to within visible distance of the Space Station. Saturday's demonstration also confirmed Jules Verne is able to establish a continuous two-way data link with the ISS.
Demonstration Day 1 ended with an Escape command sent from the ATV Control Centre in Toulouse, France, successfully sending Jules Verne ATV away from the Space Station.
During Demonstration Day 2, scheduled to start at 14:26 CEST (12:26 UT) on Monday 31 March, Jules Verne ATV will approach to a point just 11 m away from the docking port on the Russian Service Module Zvezda. ATV will also navigate for the first time using a laser-based optical system.
Data collected during Demonstration Day 2 will be made available to ISS managers for their go-ahead to proceed with a first docking attempt on Thursday. Jules Verne ATV is scheduled to dock with ISS at 16:41 CEST (14:41 UT) on 3 April.
Jules Verne demonstrates key capabilities
"All systems were completely nominal, which is very satisfying for this first day of really testing the rendezvous capability of the spacecraft," said John Ellwood, ESA ATV Project Manager.
Today's demonstration also confirmed Jules Verne is able to establish a continuous two-way data link with the ISS. Using the high-rate S-band communication link, which was switched on at a distance of 40 km from the ISS, Jules Verne for the first time conducted relative GPS (Global Positioning Satellite) measurements with the Station.
Relative GPS is a navigation technique executed by computers between the ATV's GPS receiver and the ISS GPS receiver that enables ATV to navigate relative to the Station with very high accuracy.
For both the flight control team in Toulouse and the ISS flight crew, this 64 kilobits/sec transmission rate also made it possible to test all the crucial data and communication connections between the two spacecraft, including some monitoring capability on both sides to send and receive communications.
When Jules Verne reached the closest holding position, at 3.5 km from the ISS, the bus-sized spaceship turned on its external tracking lights and activated the Russian-built Kurs rendezvous radar with equipment on both spacecraft.
The robust and historical Kurs system, a concept which has been used for decades, provides relative distance and velocity with independent data for the crew monitoring during Jules Verne's final approach to the Station.
During the demonstration the astronauts on board ISS reported they were able to see Jules Verne with the naked eye. The spacecraft could also be seen via screens inside the ATV Control Centre.
"For the flight control team the sight of the ATV thrusters firing was particularly exciting and brought the whole thing to life," said Bob Chesson, Head of ESA's human spaceflight operations. "It was fantastic to be reunited with Jules Verne and to see it performing so perfectly which is very promising for the days to come."
Data collected throughout the first demonstration day will now be analysed by the ESA JADOR (Jules Verne ATV Demonstration Objectives Report) team. A report will be submitted to the ISS Mission Management Team. After an assessment and authorisation on 30 March, ATV can proceed to Demonstration Day 2 on Monday (including an approach to within 11 m of the ISS).
"The first analysis from the JADOR are looking pretty good. We are going to spend some hours now analysing them further. We are quite confident," said Alberto Novelli, ESA's Mission Director at ATV-CC.
Jules Verne ATV
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