How does Beagle 2 communicate with Earth?

There are three routes of communication with Beagle 2:

(1) Mars Express - which is currently manoeuvring into an orbit around Mars. During each orbit, Mars Express will spend some time turned towards the planet for instrument observations and some time turned towards Earth for communications with ground stations. The special UHF antenna will receive data from the Beagle 2 lander on the surface each time the spacecraft passes overhead.

Data collected by Beagle 2 and the orbiter instruments will be transmitted to an ESA ground station at New Norcia near Perth, Australia at a rate of up to 230 kbps. Between 0.5 and 5 Gbits of scientific data will be downlinked from the spacecraft to Earth every day.

From Perth they will be sent on to the European Space Operations Centre (ESOC) in Darmstadt, Germany, which will add spacecraft attitude and orbital data, and then retransmit the data to the instrument Principal Investigators (PI) for further processing and analysis.

(2) Odyssey - whilst Mars Express is moving into the correct orbit, it will hopefully be possible to contact Beagle 2 via NASA's Odyssey, already in an orbit around Mars. Information will be relayed back via NASA's Deep Space Network to the Jet Propulsion Lab in California and then passed onto the Beagle 2 team.

(3) Jodrell Bank - it may also be possible to pick up a signal from Beagle 2 from the telepscope at the Jodrell Bank Observatory, near Manchester, UK.

    When will the first communication be?

Because Mars Express will be preoccupied moving into an appropriate orbit around Mars on Christmas day, the first communication opportunity will be via Odyssey and may include an image from the surface. At about 5.30 GMT (tbc) Odyssey will fly directly over the landing site and will be in range of making contact with Beagle 2 for 10 mins to transfer data, including compressed image data if Beagle 2 has successfully taken a picture.

Assuming Beagle 2 and Odyssey make contact, the information cannot be passed instantaneously back to Earth as the antenna needs to be redirected to Earth. It is anticipated that Odyssey could be beaming back information around 6.30-7.00am GMT.

There is no guarantee that we will be able to communicate at this first time as Beagle may not have fully opened by the time Odyssey appears over the horizon. It may not be until the next day that Odyssey can reach Beagle 2. Shortly after the Odyssey pass, Beagle 2 will be shut down for the martian night time. There is another chance to contact Odyssey on Christmas day (on Earth) but Beagle 2 will not be switched on during its night (to conserve power), even if it was not able to make contact earlier.

At about 10pm GMT on Christmas day (after sunrise on Mars), Beagle 2, having woken from its cold martian sleep, and the massive Jodrell Bank telescope will be staring at each other across space. Beagle 2's transmitter will be set to "carrier" mode (a continuous unmodulated signal) and Jodrell should be able to detect that the lander is still alive. The telescope will not be able to send any reply, but should be able to work out a provisional location for Beagle 2 to allow the Odyssey antenna to be directed at Beagle 2 more accurately on its next pass.

    How much power does Beagle 2 have?

Beagle 2's battery supplies enough power to run a 60W lightbulb for about 2.5 hours. Before it runs down, the battery will be replenished using solar energy collected by the 4 solar panels.

    How big is Beagle 2?

The Beagle 2 probe (during the cruise phase, from Mars Express to Mars) is small: the maximum depth at its middle is 532mm (21 inches) and the minimum at its edges is 304mm (12 inches). At its widest point it is 924mm (36 inches) in diameter and 372mm (15 inches) at the narrowest.

Once Beagle 2 disposes of its outer shell and heat shields and only the lander remains, it is about 660mm (26 inches) - the size of an average bicycle wheel - in diameter and 119mm (5 inches) deep at the centre. With its solar panels unfurled, Beagle expands to about 1900mm across (75 inches).

    How much does Beagle 2 weigh?

The packed probe on Earth weighs 68.84kg (about 10.5 stone). The lander inside (i.e. minus the heat shields, parachutes, airbags etc) weighs 33.2kg (about 5 stone 3lbs). Of this, 9kg (about 1 stone 5lbs) is taken up by the science package.

    How will you get the samples back?

Beagle 2 will not return home. It carries out all its analysis of rocks, soil and the atmosphere in-situ on Mars, controlled remotely from Earth.

    What frequency is Beagle 2 transmitting at?

The return (telemetry) link from Beagle 2 to Odyssey and Mars Express is 401.56 MHz. The forward (command) link from Mars Express and Odyssey is 437.1 MHz. Both are UHF.

    What is "canister" mode?

Canister mode is a super-sensitive search mode. This particular search mode was built into the Mars Express communication system to detect signal "beacons" from other craft at a future date. Beagle 2 does not have such a beacon due to mass constraints, however the search mode may be able to pick up other very faint signals generated at low power levels.

The data processing required to interpret the results of a canister mode search is complicated and takes many hours. Therefore the results will not be available straight away.