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November 11, 1998


ISRO prepares for comet threat to satellites

Email this story to a friend. The Indian Space Research Organisation is preparing to ward off the potential disaster of the century - the approaching Tempel-Tuttle Comet.

The space agency is taking a series of precautionary measures to minimise the impact of 'meteoroids' even as stock exchanges, banks, and the service sectors that use satellites have sounded an alert to their customers.

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To minimise the impact of meteoroid and comet debris that may cause physical damage to the 500-odd artificial satellites, ISRO is taking various steps including reorientation of solar panels of the satellites that will project a minimum surface area to the approaching debris.

The comet 55p/Temple-Tuttle is likely to enter the Earth's atmosphere between November 14 and 20 and is likely to be nearest to Earth on November 17-18.

Satellites of ISRO, Intelsat, Panamsat and Asiasat in the geostationary orbits around 36,000 kilometres from Earth run the risk of being hit by particles of comet and a Leonid meteoroid shower.

An ISRO spokesperson in Bombay said that it is predicted that the meteoroid storm would be at its peak around 2.10 am India time on November 18 and it may strike at the rate of 71 kilometres per second.

During the peak of the storm, zenithal hourly rate, the ZHR, may reach about 150,000 particles per hour.

Meanwhile, the National Stock Exchange and the Bombay Stock Exchange that are hooked to ISRO's INSAT-2B and INSAT-2C, have alerted their members to square off their long-term positions to avoid panic.

Sources said that other stock exchanges with a satellite link have also taken similar precautionary measures. Banks and other service sectors using satellites have also taken steps to avert panic.

ISRO said that it would take every possible step to protect its INSAT series of satellites: INSAT-1D, INSAT-2A, INSAT-2B, INSAT-2C, and INSAT-2D and the four Indian remote sensing satellites IRS-1B, IRS-1C, IRS-1D and IRS-P3 besides the scientific satellite SROSS-C2.

Former director of Nehru Planetarium Dr V S Venkatavaradhan has said that the Tempel-Tuttle comes after every 33 years and its orbit edges the Earth's atmospheric layer.

However, the last time when it came close to Earth in 1965 there was hardly any danger because very few artificial satellites were up there then.

A senior scientist from Nehru Planetarium Dr Bharat Adur said Leonid meteoroids are associated with the Temple-Tuttle Comet as it passes from the Leo Constellation.

He said that the US space agency, the National Association for Space Administration, is taking measures to combat the situation that has posed a very serious threat to artificial satellites - the worst threat of this century.

Also it has posed a challenge to space scientists and researchers across the globe.

The main risk from the meteoroid storm could be physical, mechanical and electrical damages to the satellite resulting in direct mechanical catering, plasma or electrostatic charges, Dr Adur explained. He said that the satellites, however, could be drifted away from the danger zone and it would also be advisable to shut it down to minimise the damage.

Dr Venkatavaradhan remarked in a lighter vein that there is a myth attached to comets and meteoroid showers. Quasi-astrological studies say that recession prevails when a comet comes while historical manuscripts says that the comets bring along with it famine and drought, but there are no scientific proofs to such claims.

An ISRO release from its headquarters at Bangalore said that it would closely monitor the health of its satellites from spacecraft control centres of ISTRAC at Bangalore for the IRS and SROSS satellites and the Master Control facility at Hassan for INSAT satellites. ISRO hopes to detect any electrical anomalies during the period. The designers of various satellite subsystems would be present at these spacecraft control centres to guide any corrective operations, if necessary, it said.

The solar panels of the satellites would be oriented in such a way that they present minimum surface area to the approaching meteoroids debris. Some of the operations like that of panchromatic camera steering on board IRS-1C and IRS-1D would be avoided during the shower.

Operations of high-voltage instruments would also be suspended, and only essential equipment would be kept on during the period.

Meanwhile, various research institutes and other organisations like the Nehru Planetarium, Amateur Astronomers Association and Pune-based Jyotirvidya Parisanstha are also preparing to observe the event of the century.

The NSE would be in constant touch with the ISRO Network Operations Control Centre for any last-minute announcements with regard to the switching off of satellite services to NSE-VSAT network in case it occurs and the same would be communicated to the members immediately.

In view of the situation, ISRO/NOCC and Department of Telecommunications may switch off certain satellite services at a short notice or even without notice during any part of the day including the trading hours from November 13 to 20.

In case such as event occurs, the exchange may not be in a position to inform its trading members in advance about the disruption in services. In this regard, the exchange has broadcast an alert to its members in advance so that they can exercise adequate precaution in their dealings on the exchange and in leaving open positions during the relevant trading session.


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