A rather special linear-action switch connected the Beagle 2 Lander
internal electrical bus system to its battery pack when it touched down
on Mars last month. The device is motorised, so much depended on the
reliability of the tiny geared motor, which forms an integral part of the
assembly
At the heart of the Beagle 2 Lander - a British-designed, automated
laboratory module that will collect samples from the Martian surface and
analyse them - is a rather important switch that connects the main
battery to the Beagle 2's internal electrical bus. Manufactured by Leeds
based Isotek Electronics, this linear-action device is operated by a 10mm
diameter geared motor supplied by maxon motor. Like other components on
the craft, the switch needed to survive significant levels of vibration
during launch, as well as the effects of a high-impact landing. As a
result, the assembly underwent a regime of tests at the Rutherford
Laboratories, including shock testing to 400g and environmental testing
between +55°C and -125°C.
Compact size and, more importantly, low weight are also requirements of
Beagle components (the whole machine has a landed mass of less than
30kg). The Isotek switch, complete with Maxon motor and gearhead weighs
less than 35g. Isotek's chief mechanical engineer, Greg Firth takes up
the story.
Size, weight and performance are all very important, but reliability is
essential. We simply couldn't afford to have anything go wrong when the
equipment is 78 million kilometres away. maxon produced a component that
was tailor-made for our application. We didn't want an off-the-shelf
product, so we worked closely with the company's engineers to develop the
gearhead and meet the required specifications for the Mars landing.
maxon motors are used elsewhere on the Beagle 2 Lander. The solar array
deployment (the solar 'wings' that power the craft) and the robotic arm,
which supports the panoramic cameras and other instruments, are both
powered by maxon units. Possibly the most important, however, are the
'Mole', code-named PLUTO (planetary under-surface tool) and the Corer.
These capture samples from the surface and subsurface layers and transfer
them via the arm into the Lander's laboratory. By analysing the samples
and looking for fossilised evidence, scientists may finally be able to
provide irrefutable evidence of whether life exists, or ever existed, on
the red planet.
For more information about the Beagle 2 Lander visit www.beagle2.com
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