reaching for the stars

PUBLISHED : Friday, 18 August, 2006, 12:00am
UPDATED : Friday, 18 August, 2006, 12:00am

He's famed in Hong Kong for helping design its contribution to space discovery - tools for the Mir space station and European Mars missions. Ng Tze-chuen recalls in our weekly series the highs and lows of 30 years working with celebrated scientists, battling bureaucracy ... and being tailed by spies

As in life, a space mission is always about give and take, making compromises and hard choices. In our case, the more sophisticated equipment to take on board Beagle 2, the more likely it would be to achieve our scientific objective of finding [past] life on Mars. Yet, given a restrictive payload, we had to give up important tools.

The British-led Beagle 2 lander was, in a way, an opportunistic mission. At least this was how some people on a commission of inquiry into its loss described it. The European Space Agency initially only planned for an orbiter, Mars Express, to circle and survey Mars.

Colin Pillinger, the British planetary scientist, and his colleague Mark Sims saw an opportunity and seized it. Professor Pillinger used all his prestige, professional connections and technical ingenuity to convince the agency to allocate the spare payload necessary to take on board Beagle 2. He convincingly argued that a landing probe must be an integral part of Mars Express, Europe's first mission to the planet.

However, this also meant that Beagle 2's weight and size were restricted from the start. The 60kg, clam-shaped lander - the lightest ever attempted - had the highest instrument-to-payload ratio. For the size of a truck wheel, it was remarkable how so many gizmos were jammed into it. From my perspective, they were perhaps putting too many things into too little space.

The selection of equipment for Beagle 2 was not a purely scientific process. Since every gram counted, the British, Germans, Russians and we Hongkongers all wanted a bigger slice. There is always politics, even in space!

Shaun Whitehead, the chief scientist in charge of the Beagle's sole robotic arm, cancelled the Hong Kong-made rind grinder Professor Pillinger himself had ordered. We suspected the Germans had been exerting pressure because too many tools were being assigned to Hong Kong.

'I will give you 60 grams extra to modify the corer to become a rind grinder as well,' Dr Whitehead said. In the end, we redesigned the front portion of the drill bits to include the rind-grinding function. There had never been a single, multi-functional planetary tool that could grip a rock sample, drill into it and grind its surface at the same time.

Unlike Nasa's Mars rovers, Beagle 2 was immobile. Therefore its robotic arm had to compensate by providing limited mobility. It held all of Beagle 2's scientific instruments in a cluster at the end, including our rock-corers-cum-drills.

It had a camera to beam back images to the orbiter and Earth command; a spectroscopy 'oven' to 'cook' and analyse rock and soil samples; a Russian-German mole to retrieve subsoil samples; a high-power microscope, and two spectrometers to identify individual chemical compounds, the purpose being to find elements that might react with liquid water, resulting in the kind of chemical reactions that could sustain life.

The camera was designed to present a panoramic view of surrounding Martian terrains.

The mole was a tethered device designed to reach underneath rocks and soil. It was thought there was a greater chance of finding microbes or their past chemical residues in places that had not been exposed to lethal doses of ultraviolet light on the Martian surface.

Meanwhile, the Hong Kong-made device would perform the first planetary-rock coring in our solar system. Because Beagle 2 was already weight-restricted, our device faced the same problem. It could weigh no more than 370 grams, about the size of a cigarette box, and consume 2 watts of energy yet had to function as a rock-coring device and a grinder simultaneously. As a backup, we also made a tiny device that functioned essentially like a spoon to scoop up surface samples.

Beagle 2 was effectively a self-contained, fully automated and computerised laboratory with a robotic arm designed to function at Martian gravity that is only 0.38 that of Earth. The arm could not be raised under Earth's gravity.

Extreme Martian temperature fluctuation of plus and minus 100 degrees Celsius between day and night could have a disastrous effect on Beagle's circuit boards and the robotic arm's soldered joints, and could wreak havoc on Beagle 2's motors; dust storms could jam its tiny precision components; and rocks lying within the robotic arm's range could be too hard for coring and drilling. So many things could go wrong even if Beagle 2 succeeded in landing safely.

Next week: Countdown to launch




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