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Moon Mission Malfunction

Gp. Capt. Ajey Lele (Retd.) is Senior Fellow at the Institute for Defence Studies and Analyses, New Delhi. Click here for detailed profile.
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  • July 20, 2009

    It is a dream project not only for India’s space research organization (ISRO) but for all Indians. With the successful launch of the Moon Mission, ISRO had put India into the bracket of deep-space achievers. The world took serious note of India’ space programme when in October 2008 ISRO successfully launched its satellite Chandrayan-1 towards the moon. If the 1998 Pokharan nuclear tests had helped India demonstrate its ‘hard power’ status, the success of the moon mission indirectly played a significant role towards establishing the ‘soft power’ credentials of the country.

    But a few days back ISRO’s expertise was challenged when a defect occurred in Chandrayan-1 satellite, which is currently hovering 200 km above the moon’s surface. It was a ‘touch and go’ situation, though as of now things have returned to normalcy. In June 2009 Chandrayan-1 lost a vital sensor called the star sensor, meant for precise pointing of the craft towards the moon. Currently nine equipments onboard this craft are taking various observations of the moon’s surface. For the last eight months data from the surface of the moon is being collected essentially by photographing various areas. For successful conduct of these operations, maintaining the orientation of the spacecraft towards the lunar surface is very critical and that was the job of star sensor.

    As ‘Plan-B’, ISRO scientists have tasked the gyroscope on board to do the functions related to positioning. But it is not fully possible to overcome the error with this equipment alone and hence antenna-pointing mechanism is also being put in place. Now, the issue is how long this stopgap arrangement would work? The satellite’s designed mission life is two years and till now it has completed only eight months. But ISRO states that it has already collected most of the data as planned. Till now the spacecraft has made 3,000 revolutions around the Moon and has sent over 70,000 images of its surface.

    After being inserted into the lunar orbit on November 8, 2008, for more than six months this craft was hovering 100 kilometres above the moon surface. This allowed the spacecraft to have a better view of the moon’s surface. The fault occurred after the satellite’s orbit was raised to 200 km from 100 km, which was done on May 19, 2009. This raising of the orbit is now allowing the satellite to photograph additional areas because of the availability of a wider swath. This increase in altitude also allows additional studies on orbit perturbations and gravitational field variation of the moon. Now, if the life of the mission gets curtailed then these additional inputs may not be available to scientists.

    According to the ISRO chief, more than 90 per cent of Chandrayan-1’s mission objectives have already been achieved. However, since the mission was designed for two years, definitely some data-gaps may still exist. More so, since knowledge about the moon’s surface is so minimal that in spite of collection of a huge amount of data any additional data are always an advantage. This will entirely depend upon for how much more time the ISRO succeeds in keeping the satellite operational. For ISRO, this star sensor glitch is a second setback with its space scheme in recent times. A few months back it had suffered a failure in regard to its W2M satellite launched on a commercial basis for a European agency. This 3.4 tonne satellite was the biggest ever built by ISRO at its Bangalore facility and was meant for telecommunications and broadcasting services to various parts of Europe, North Africa and the Middle East. It was launched on December 20, 2008 but was hit by in-orbit power failure within a month’s time and could not be recovered.

    On the other hand there is also a need for ISRO to cater for various eventualities while designing its crafts. One probable reason for the loss of the star sensor could be the impact of a solar storm. Actually the temperature inside Chandrayaan-1 had temporarily increased during November 2008 itself after a sudden increase in lunar temperature during its lunar orbit. These things clearly indicate that we still know little about the lunar atmosphere. In fact some scientists argue that in yesteryears American astronauts were lucky to have come back safely from the moon without encountering any unfortunate weather/atmospheric phenomenon. American scientists have undertaken the various missions without having a total understanding of the atmosphere on the moon.

    Exactly, forty years ago on July 20, 1969 Neil Armstrong became the first human to land on the moon covering nearly 4 lakh kilometres of distance. India may take more than a decade to emulate this achievement. At times such programmes are being criticized because of the tremendous costs involved and the not so evident benefits that accrue. However, such investments are essential to know more about the Earth’s satellite because with earth’s natural resources diminishing very fast the time has come to look for resources elsewhere and according to scientists the moon could be the best option. It would be of interest to know that in an opinion poll conducted on the eve of the 40th anniversary of the American moon landing, a majority of Americans have backed its space policies and feel that the space programme has brought various benefits to the society to justify its costs.

    With regard to the latest difficulty being faced by ISRO, it needs to be understood that every scientific discovery has its own set of failures. For instance, the Japanese moon mission Kaguya launched in September 2007 had encountered some difficulties and the mission time was reduced by a few moths. It had encountered problems with the performance of a reaction wheel, which was meant for the purpose of changing the angular momentum of the spacecraft.

    ISRO has a very clear-cut roadmap for its deep-space missions to the moon and Mars. On the other hand its commercial activities are also increasing rapidly. It has earned Rs 1,000 crore in revenue in 2007-2008 and expects an exponential growth in future. Setbacks, however small they might be, do impact upon ISRO’s standing. Also, ISRO need to be more careful about such a glitch because it has plans to send a similar craft for its Chandrayan-2 mission. This mission would be placing a Russian probe on the surface of the moon to undertake mineral assessment. As such this mission which was to take off during 2012 would be delayed by a year because Russia requires more time. It is hoped that ISRO would quickly learn the lessons from this star sensor failure and be ready for the next mission.

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