A Clue To Columbia Disaster
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A research team led by Prof. Sandip Kumar Chakrabarti, an astrophysicist from the S. N. Bose Centre for Basic Sciences (SNBCBS), Kolkata and Centre for Space Physics (CSP) also in Kolkata has provided a clue to Columbia space shuttle disaster.
According to Chakrabarti, a cloud-to-cloud thunderbolt could have struck the left side of the space shuttle triggering a chain of events that ultimately led to the destruction of the shuttle over Texas, United States. But, how he got to this conclusion is an exciting story. “At CSP, in the evening of February 1, we tuned a twelve metre high antenna which listens to long radio waves having a very low frequency (VLF),” says Chakrabarti. “It was precisely 7:26 p.m when the antenna began recording radio signals.” On that day, the antenna was listening to radio waves having a frequency of 18.2 KHz that was the range of two VLF generating stations in San Diego and San Francisco, United States. Any disturbance in the weather affects the man made radio waves, which is measured by the antenna at CSP.
. Back home late that night, Chakrabarti witnessed the tragic end of the space shuttle on television. “It was 9 a. m. at the Kennedy Space Centre, Florida when the shuttle disintegrated over Texas,” he says. “The freely falling debris of the space shuttle reminded me of the meteor shower which also emits very low frequency radio waves while burning and darting through the earth’s atmosphere.” What is more, radio waves generated in this way travel at the speed of light and for a long distance as much as 20,000 km on earth almost without losing its intensity.
Next day, driven by this insight, Chakrabarti alerted his teammates and rushed to CSP. The team checked out the signals recorded by the antenna. “We got more than we anticipated,” Chakrabarti says. “Actually, the antenna recorded intriguing signals immediadtely after it was switched on at 7:26 p.m.” The antenna also recorded signals at 7:30 p.m, which coincided with the time of disaster.
But, Chakrabarti and his teammates were more interested in the signals recorded at 7:26 p.m. These signals showed noticeable disturbance in the weather when the Columbia was making its descent. It was not the signals genarated at the time when the shuttle’s debris were falling freely and emitting VLF radio waves.
As it was morning in the United States, sun’s ultraviolet rays had formed the lowest layer of the ionosphere. It is well known that the lowest layer of the ionosphere absorbs radio waves halting their propagation for a long distance. “Despite this fact, the radio signals reached the antenna at CSP,” says Chakrabarti. “So, we were curious to know how the signals traveled to CSP all the way from United States.”
Only, any abnormality in the weather could have strengthened and ferried the signals to CSP’s antenna. “So, we looked for any abnormalities in the weather when the space plane was on its way to land at Kennedy Space Centre, Florida.”
The team’s search was rewarded as the National Aeronautics and Space Agency (NASA) released a few photographs snapped by an amateur astronomer. With it, came the clue to the disaster. Those photographs clearly showed that a thunderbolt struck the craft as it was flying over California sky. “In California, it was 5:53 a.m when the bolt struck,” says Chakrabarti. “At the same time, sensors of the doomed craft first indicated that something went wrong.”
The cloud-to-cloud thunderbolt formed a lightning channel between the two clouds. “With enormous energy and temparature, the channel might have touched the left side of the craft causing irreversible damage.” The energy in that channel was enough to keep an ordinary room air conditioner running for nearly two weeks and temparature rose to twenty five thousand degrees Celsius, which could easily vapourize any earthly metal. “Immediately after the bolt struck, sensors on the left side of the craft started to detect an abnormal rise in temparature.”
According to a timeline released by NASA, when the craft was over Arizona and New Mexico, two sensors on the left wing’s upper and lower skin failed off. Two minutes before the disaster, on board computers detected that the shuttle began to fly off course due to increased drag on the left wing. “To overcome the drag,, the craft desperately turned on its recovery system.”
Columbia automatically fired two of its nose steering jets for 1.5 seconds to counteract the drag on the left wing. “In the meantime, superhot plasma (combination of ions and electrons formed due to craft’s friction with the atmosphere) seeped into the crew area of the craft”, says Chakrabarti. “Around 9 a.m, Kennedy Space Centre, Florida completely lost communication with the Columbia which was then seen breaking into pieces over Texas.”
NASA experts has ruled any possibility of accident caused by the knocked out tiles that protect the craft against the heat produced due to friction between the craft and earth’s atmosphere, he says. “What is more, NASA has also ruled the possibility that the landing gear was lowered a few seconds before the scheduled time.”
Ned Lewis, a radio astronomer from California who also monitored the very low frequency radio waves generated during the time of thunderbolt has supported the data of CSP. “It enhances the chances of thunderbolt being the culprit to cause the Columbia’s demise,” says Chakrabarti who has sent his findings to NASA.
This story has been originally published in the science and technology page of ‘The Statesman’.
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