Using an interceptor ballistic missile without an explosive warhead and targeting a satellite at low earth orbit of less than 300 Km, ensured that space debris caused by India’s March 27 anti-satellite (A-SAT) experiment, named Mission Shakti, may not be as harmful as it is being made out to be. The debris causing ‘serious danger’ to the International Space Station, raised by NASA Administrator Mr Jim Bridenstine, could be bit too alarmist, Indian space scientists feel. Experts, like Prof Roddam Narasimha, say that despite NASA administrator Mr Bridenstine raising concerns that India’s test had increased the risk to the ISS by 44 percent due to space debris, “there is no such cause for worry”. Bridenstine had based his worries on estimates provided by NASA and the Combined Space Operations Centre (part of US Strategic Command). interestingly, Mr Bridenstine himself said after his town hall talk on April 1, which was live-streamed by NASA TV when he raised these concerns — as quoted by space.com — “The good thing is (about India’s A-SAT mission), it’s low enough in Earth orbit that over time this (the space debris) will all dissipate.” Scientists from India’s Defence Research and Development Organisation (DRDO), which conducted the March 27 2019 test, and Indian Space Research Organisation (ISRO) have confirmed that the low-earth orbit space debris caused by the test would dissipate within eight days. The debris, they said , will fall to earth, but will burn in the planet’s atmosphere. Compared to that, the 2,000-odd pieces of space debris (several hundreds bigger that a golf ball) caused by the Chinese A-SAT test, conducted on January 11, 2007, are still orbiting the earth as that experiment was conducted at an altitude more than twice that of the Indian A-SAT test — 865 Km above earth. Prof Roddam Narasimha, Indian aerospace scientist and fluid dynamicist who was Director of the Bengaluru-based National Aerospace Laboratories, downplayed the threat to the ISS, saying: “The altitude at which India conducted the test was below that of the ISS. Yes, there will be debris, and space debris should not be caused, but compared to what other countries (USA, Russia and China) have done this is nothing.” NASA and Combined Space Operations Centre reportedly identified 400 pieces of space from India’s A-SAT test. This included 60 pieces which were larger than 10 cm in diameter, and 24 of which were travelling through the orbit of the ISS, which led them to raise the risk rate to ISS by 44 percent. Prof Narasimha also pointed out that had the DRDO’s ballistic missile — developed under India’s ballistic defence missile programme — carried an explosive warhead, the explosion could have provided a powerful thrust to the space debris, pushing the debris to a higher altitude. However, the March 27 test, according the official release, was a “kinetic kill” test, which means there was no warhead used on the missile. It was the sheer velocity (8 Km/sec) of the missile which successfully targeted the satellite, which caused it to disintegrate without causing an explosion. According to space.com, which reported Bridenstine’s livestreamed town hall talk on April 1, he had said describing the Indian test: “That is a terrible, terrible thing, to create an event that sends debris in an apogee that goes above the International Space Station…And that kind of activity is not compatible with the future of human space-flight that we need to see happen. “We are charged with commercializing low Earth orbit; we are charged with enabling more activities in space than we’ve ever seen before for the purpose of benefiting the human condition, whether it’s pharmaceuticals or printing human organs in 3D to save lives here on Earth, or manufacturing capabilities in space that you’re not able to do in a gravity well…All of those are placed at risk when these kind of events happen — and when one country does it, then other countries feel like they have to do it as well.”
Source: http://www.newindianexpress.com/
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