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The News:
European Space Agency’s Lunar mission ends with a planned crash. This is the Europe’s first ever probe to the Moon and its primary mission is to test a new, efficient ion propulsion system. Scientists hope to use this technology on future interplanetary missions. The probe also sent a veritable trove of data about Moon, it is reported.
The Innovation they tried and the Bonus they got:
“That’s it — we are in the Lake of Excellence,” said spacecraft operations Chief Octavio Camino as applause broke out in the European Space Agency’s mission control centre in Darmstadt, Germany, “We have landed.” The excitement is palpable every where, not only in ESA, as the mission did cost ESA only Euro 110 million, peanuts in terms space exploration projects’ costs, using a meager 80kg of xenon fuel to travel from earth to moon!
This novel lunar probe called SMART-1 was launched into Earth’s orbit by an Ariane-5 booster rocket from Kourou, French Guiana, on September 2003.
The novelty of the probe is its ion thruster engine, which uses electricity from the craft’s solar panels to power the electric guns used to charge the xenon gas. This produces stream of charged particles called ions, which are expelled from the rear of the space craft. This bluish glowing exhaust generates only a tiny thrust that is likened to be enough to lift an A$ sized paper! So, what? It used only 80kg of xenon fuel! This tiny engine is used to thrust the probe slowly to raise its orbit around earth over 14 months until the moon’s gravity grabbed it.
SMART 1 traveled some 100 million km as the probe need to circle and circle the earth before escaping its gravitational tug. Actually, it did about a dozen loops around earth before getting into a lunar orbit. This involved a very complex set of maneuvers and non-stop firing of its engine. The engine is said have been functioned excellently needing 14 months to reach moon for what an almost straight line trajectory of Apollo missions took three days to cover 347000 to 400000 kms.
This engine is used not for the first time, it has earlier been used in the NASA’s Deep Space Craft whose mission is a rendezvous with an asteroid and an comet. Deep Space used a straight line trajectory. SMART 1’s engine is only one metre across and weighed no more than 350 kilos.
As the main aim of the craft is to test the engine and its technology, they say they got the extra bonus of scientific data about moon form extreme close-ups. The craft’s X-ray and
Infrared spectrometers have relayed valuable information that would help enhance scientists’ knowledge about the moon’s geology, its surface evolution and also to test the theories of the evolution of the moon itself. The light weight of craft helped lowering its orbit so much, thanks to the lack of atmosphere on the moon, that the scientists could afford a better look at the surface. Actually, its lunar orbit was shrunk as much as to finish in five to six hours compared to 14 hours or so required for other crafts.
Finally, the craft ended its three year mission with a planned crash on to the lunar surface at what is called the “Lake of Excellence” at an astonishing 7200 kmph speed. It approached the surface so tangentially that the spatially extended fire works raked up dust more than expected that the astronomers down on earth could see a bright momentary glow on lunar surface. You can even see the video of the broght glow on internet.
So, low was its orbit that on September 2, the mission controllers in Darmstadt, Germany had to raise the craft’s orbit by 600 metres to avoid hitting a crater rim on final approach. Had that been not done quickly, the craft would have crashed too soon with one orbit less, making the impact difficult or impossible to observe from earth. Also, the maneuver
gave controllers some tense moments as it needed to be finished in an hour. The miniaturised camera had sent back close-up images even just minutes before the impact.
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