Heute gab es mal endlich etwas ausführlichere Informationen zu den möglicherweise noch bestehenden Kommunikationsmöglichkeiten. Den nicht Beagle-relevanten Text (Gratulation an die NASA) habe ich geschnitten.
Congratulations to NASA. Beagle 2 Team Still Hopes To Repeat Mars Landing Success.
04-Jan-04 11:23 GMT
Adding his congratulations, Mark Sims said, "I'd like to reiterate the international cooperation we've been getting in terms of looking for Beagle. In particular, the JPL team which has been working very strange hours supporting the Odyssey passes, Lockheed Martin, who've been running the Odyssey spacecraft, Jodrell Bank, Westerborg, the British Astronomical Association and Malin Space Science Systems. Mike Malin is looking at imaging the landing site potentially from tomorrow."
Meanwhile, the search for Beagle 2 goes on.
"We haven't in any shape or form given up on Beagle 2," said Professor Pillinger.
"We have realised that Mars Express is not in the orbit we originally expected, so our communication strategy is now different from the one that we explained at the beginning of last week."
Describing the ongoing work at the Lander Operations Control Centre, Mark Sims explained that teams from the University of Leicester, SciSys and Astrium are continuing their efforts to identify possible failure modes that can be addressed.
"We're still concentrating on both the communications and timing/software issues, and working our way through the logic and fault tree on the basis that Beagle 2 is on the surface of Mars and for some reason is failing to talk to us," said Dr. Sims.
"There are six or seven scenarios that we're still working through and we still can't eliminate any of those."
However, possible failure scenarios involving a reset of the clock hardware and a problem with a tilted antenna seem to have been ruled out. Today's successful transmission of signals from the Spirit rover via Mars Odyssey also indicates that the radio on board NASA's orbiter is working properly.
Meanwhile, an attempt to send blind commands to Beagle 2 via Mars Odyssey on 31st December also resulted in no obvious response from the lander.
There has also been no response from the Beagle 2 transceiver during 11 programmed passes. Unfortunately, the last four contact opportunities pre-programmed into Beagle 2's computer no longer coincide with Mars Express on its current orbit, so the team is now relying on the spacecraft switching to various back-up communication modes.
The mission team is now waiting for their little lander to switch to one of its backup communication modes. Beagle 2 could already be operating in 'communication search mode 1', during which it listens for 80 minutes during both the Martian day and night in an effort to establish contact with an available orbiter at Mars Odyssey overflight times.
If no link is established by this method, 'communication search mode 2' should eventually be activated. The earliest date by which this mode could become operational was 3rd January. In this mode, the receiver is on for 59 minutes out of every hour throughout the Martian day, and the spacecraft sends a carrier signal five times in each daylight hour. During the Martian night, Beagle 2's receiver will be on for one minute out of every five, but there is no carrier signal.
Although Mars Odyssey will continue to search for the lander, Mars Express will soon become the prime communication link with Beagle 2. After reaching its operational polar orbit today, ESA's orbiter should pass over the Beagle 2 landing site regularly from 7th January onwards. Various modes of communication can be attempted during passes by Mars Express, although the team anticipates starting on 7th and 8th January with the standard 'hail and command' which has been used with Mars Odyssey.
The first four passes with Mars Express (7th, 8th, 9th and 10th January) are almost directly over the landing site and only 5 to 8 minutes long, so they are not ideal for communication, whereas the opportunities on 12th and 14th January are potentially much longer.
