Computer Science – Performance
Scientific paper
Oct 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003xmm..pres...20.&link_type=abstract
XMM Press Release SNR 20-2003
Computer Science
Performance
Scientific paper
Mars Express in orbit around Mars hi-res
Size hi-res: 592 kb Credits: ESA - Illustration by Medialab
Mars Express in orbit around Mars Mars Express will left Earth for Mars in June 2003 when the positions of the two planets made for the shortest possible route, a condition that occurs once every twenty-six months. The intrepid spacecraft started its six-month journey from the Baikonur launch pad in Kazakhstan onboard a Russian Soyuz/Fregat launcher. Mars Express began the six-month interplanetary cruise at a velocity of 10 800 km/h relative to Earth. Five days before arrival in December 2003, Mars Express will eject the Beagle 2 lander, which will make its own way to the correct landing site on the surface. The orbiter will then manoeuvre into a highly elliptical capture orbit, from which it can move into its operational near-polar orbit.
communications test Mars Express
The MELACOM system is designed to communicate with Beagle 2, passing the lander's data to Mars Express's main antenna for relaying to Earth. The MELACOM test was done in collaboration between sites at Stanford (USA), New Norcia (Australia) and ESA's Space Operations Centre (ESOC) in Darmstadt, Germany. The 34-metre dish at Stanford pretended to be Beagle 2, using its greater size to overcome the large distance between Earth and the spacecraft.
The test consisted of two sessions, a first one in which the Stanford's signal was sent to Mars Express's MELACOM, and a second one in which MELACOM sent a signal back to Stanford. Con McCarthy, ESA's Beagle 2 manager, who supervised the operation, said: "We were on a hilltop, outside San Francisco. It was 4:10 UT and Mars was clearly visible in the sky. The Stanford dish tracked Mars Express slowly, transmitting to it for 40 minutes." Then the spacecraft re-oriented itself to point its main antenna to Earth to confirm it had received the signal. The confirmation was received by ESA's New Norcia ground station and relayed to ESOC. Following this, at 6:10 UT, it was the Stanford dish's turn to listen, as Mars Express had been programmed to turn MELACOM back towards Earth and begin transmitting. A faint but clear signal was heard proving MELACOM was ready to talk to Beagle 2.
A way to overcome the under-performance of the spacecraft's power systems has been found. This was due to some intensive and creative thinking by ESA engineers and the team from Astrium Toulouse, led by Mars Express Project Manager Rudi Schmidt. Although only up to 70% of the spacecraft's expected power is available, all of its instruments can be switched on without any restrictions for 85% of the time. The remaining 15% of the time, some compromises need to be made, including optimising the power dissipation within the spacecraft subsystems. Most importantly, power will be saved by tilting the spacecraft to gain heating from the Sun. On its bottom surface the spacecraft has a silvered ring that attached the spacecraft to its rocket during launch. It has been found that if sunlight falls on the ring, it will conduct some heat inside Mars Express, allowing some of the heaters to be turned off thus saving electricity. The instruments can then use this extra power.
"In the current situation, I am confident that we can achieve all mission goals." says Schmidt.
The Mars Express team is now preparing for a series of Mars orbit insertion and Beagle 2 landing simulations to take place at ESOC during October and November.
Meanwhile, Mars Express is safely continuing its journey to Mars, getting closer every day to the time of arrival, due in late December this year.
No affiliations
No associations
LandOfFree
Successful communications test for ESA's Mars Express does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Successful communications test for ESA's Mars Express, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Successful communications test for ESA's Mars Express will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1036001