Beagle, We Have Separation

Mid-morning on December 19, the sucessful separation of the Mars Beagle 2 lander was officially confirmed by the European Space Agency (ESA).

Image of Beagle moving away from Express at separation Credit: ESA

Although the mission is far from over, relief was expressed by ESA scientists when formal confirmation was indicated by a bright red light in mission control at Darmstadt, Germany; the red light showed that telemetry values were broadcasting above baseline, an anomaly if Beagle was attached to its orbiter, but positive confirmation without the Beagle 2.

David Southworth, ESA scientist showed confidence that the "mother and baby are both doing well, and the progress of the family is being monitored closely. I’m very proud to say Beagle is separated. It has been a very tense morning and a professional team should be congratulated. This is a big step to get to Mars, even though it is really only a beginning. The scientists and everyone else involved deserve our congratulations."

The lander is headed straight for its expected site. Beagle 2 will have to enter the martian atmosphere, deploy its parachutes and airbags. The orbiter, Mars Express, will enter its orbital insertion point. Without a course correction, the orbiter is headed for a collision course presently, so its trajectory must be adjusted for an ensuing safe orbit. From this point onwards, there is retargeting and capture. The success of the Beagle release puts the mission into its six-day timeline for Christmas morning.

Prof. Colin Pillinger, Beagle project scientist said from the National Geographic Society in London: "I think of today’s events, we were about to play a two-legged match and both of them were far from Earth. We are 1-0 in this match, and the second match begins on Christmas morning. I am not offering anyone the day off on Christmas, so I am the Scrooge on that day. We will be watching on that early morning."

The next events will be the important course correction to get the orbiter into safe injection. The maneuver will be prepared today and executed early tomorrow.

After a joint journey of 250 million miles (400 million km), the British-built Beagle 2 spacecraft and the European Space Agency’s Mars Express orbiter has parted and gone their separate ways. Three webcasting events are available (morning and mid-morning and lunch local time, Real Media) from the European Space Agency along with the release of the first separation image.

Artist’s conception of Beagle moving away from Express at separation Credit: ESA

Mars Express, the European Space Agency’s first probe to Mars, has carried the lander to the point where its final stages until Christmas can now begin.

At 8.31 GMT, software on Mars Express sent the command for the Beagle 2 lander to separate from the orbiter. This fired a pyrotechnic device that slowly released a loaded spring and gently pushed Beagle 2 away from the mother spacecraft at around 1 ft/s (0.3 m/s).

If all goes according to plan, the release mechanism will also cause Beagle 2 to rotate like a spinning top, stabilizing its motion during the final stage of its flight towards Mars.

Since Beagle 2 does not have a propulsion system of its own, it must be carefully targeted at its destination. With Mars Express acting as a champion darts player aiming at a bullseye, Beagle 2 should be placed on a collision course with the planet, following a precise ballistic path that will enable it to hit a specific point at the top of the Martian atmosphere in six days’ time.

Mars Express above the thin Martian upper atmosphere after lander begins its descent at 12,000 miles per hour Credit: ESA

Initial confirmation that the separation maneuver has been successful had to wait until 10.40 GMT, when the European Space Operations Centre (ESOC) in Darmstadt, Germany, could receive X-band telemetry data from Mars Express.

In addition, it is hoped that the orbiter’s onboard Visual Monitoring Camera (VMC) will provide pictures showing the lander moving slowly away. The images are expected to be available within hours of the separation event.

However, after six months in space, during which the spacecraft were buffeted by solar storms, the maneuver was not without risk. Although it has been tested many times on Earth, there was always the outside possibility that something may go wrong during the all-important separation.

Mars Beagle 2 spacecraft.
Credit: ESA

After its separation successful separation, Beagle 2 must rely on its own battery, which cannot last beyond 6 days, until its solar arrays are fully deployed on the surface. This means that Mars Express had to release Beagle 2 at the last possible moment in order to ensure that the lander had enough power for the rest of its journey to the rust-red Martian plains.

This will be the first time that an orbiter has delivered a lander without its own propulsion onto a planet and then attempted orbit insertion immediately afterwards.

Meanwhile, Mars Express will follow Beagle 2 for a while until, three days before arrival at Mars, ground controllers will have to fire its thrusters and make it veer away to avoid crashing onto the planet.

Early on 25 December, Beagle 2 should plunge into the atmosphere before parachuting to its planned landing site, a broad basin close to the Martian equator, known as Isidis Planitia. Later that day, Mars Express should enter orbit around Mars.

Following a carefully targeted ballistic trajectory, the 68.8 kg probe will remain switched off for most of the 5 million kilometer coast phase to Mars.

Then, a few hours before entering the Martian atmosphere, an onboard timer will turn on the power and boot up Beagle’s computer. Beagle 2 must rely on its own battery until its solar arrays are fully deployed on the surface. Beagle 2 has no propulsion system of its own so it is carried to Mars by the Mars Express spacecraft which will go into orbit around the planet for remote sensing purposes.

The Beagle 2 Spin-Up & Ejection Mechanism (SUEM) was designed and developed by INSYS Ltd. of Ampthill, Bedford, UK. The SUEM has two elements: the first, the launch clamp mechanism, will provide a secure mounting system to withstand loads applied during ground handling and lift-off. During the launch phase, three matched cup and cones transfer the launch loads from the probe to the orbiter. Each cup and cone is preloaded by the use of a "Frangibolt(r)" which uses a memory metal collar, which when heated expands and fractures each bolt. Release of the Frangibolts(r) was initiated a few days after launch, shortly after insertion of Mars Express into its transfer trajectory between Earth and Mars. The second element, the ejection mechanism, releases the probe for its descent to Mars. This is accomplished by means of a pyrotechnic protractor that releases a ball cage locking device. This allows a spring within the SUEM to push the probe from Mars Express. A helical guide groove induces a linear velocity of 0.3 m/s (1 ft/s) and an angular velocity of 12 rpm into the probe.

Related Web Pages

Where is the Mars Express Now?
Where is Spirit Now?
Athena Science: Cornell University
Mars Image Rendering:
Nozomi, Planet-B
Five Year Retrospective: Mars Pathfinder