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On its 10th anniversary, here are 5 key facts about India’s first space probe Chandrayaan

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ISRO probe Chandrayaan was aimed at mapping the entire surface of the moon.

Exactly a decade ago, on this day, a Polar Satellite Launch Vehicle (PSLV) rocket in its XL configuration carried India’s first space probe — Chandrayaan — beyond the Earth’s orbit.

Five years in the making, Indian Space Research Organisation (ISRO)’s probe was aimed at mapping out the entire surface of the moon, including the far side which is not visible from Earth. The auto-rickshaw sized orbiter, further, performed mineralogical mapping of the lunar surface.

On the tenth anniversary of the launch, here are five key facts to know about India’s prestige project.

Chandrayaan carried payloads from other countries, organisations

The orbiter carried five Indian instruments and six foreign ones. Four of the international ones were mineral mappers — two were built by European Space Agency (ESA), and the other two were a NASA JPL-Brown University collaboration and an ISRO-ESA-Rutherford Appleton laboratory, UK, partnership.

The remaining two payloads were a lunar atmospheric radiation monitor from Bulgarian Academy of Sciences and a lunar water detector built by NASA with help from ISRO.

The Indian flag

While the main craft was an orbiter going around the moon, Chandrayaan also had an impactor called the Moon Impact Probe (MIP). Its purpose was to separate from the orbiter and crash on the moon, taking pictures along the way and studying the lunar atmosphere. On 14 November 2008, it ejected from the orbiter and flew down in 31 minutes, carrying with it an image of the Indian flag. The crash made India the fourth country to place its flag on the moon after the Soviet Union, US and Japan.

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Discovery of water

The MIP, upon crashing on the lunar surface, displaced soil and exposed the inner layers of the surface for study. On 24 September, 2009, NASA announced that their instrument on board Chandrayaan had detected water. The next day, ISRO announced that their payload aboard the MIP, called Chandra’s Altitudinal Composition Explorer (CHACE) had detected it three months earlier, and they had just been waiting for confirmation from NASA. As MIP was in free fall towards the surface, it recorded more evidence of water.

Confirmation of ‘fully liquid’ theory

The well-accepted theory for the formation of the moon today is the ‘giant-impact hypothesis’. It states that a body the size of Mars, called Theia, collided with early Earth when it was just forming. The collision vapourised the body entirely and Earth partly, leading to a mixture of cores. Excess material from this fused body then spilled out, starting to orbit the Earth and coalescing into a ball. This ball was fully liquid rock at one point, before cooling and solidifying to form the moon. NASA’s Moon Mineralogy Mapper aboard Chandrayaan analysed the surface and confirmed this theory in 2009.

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Disappearance and reappearance 

Chandrayaan was expected to last two years but the mission lasted only 10 months. On 28 August, 2009, after 312 days in orbit, communication with the spacecraft was lost. The loss of contact could not be explained with certainty, with ISRO scientists guessing that the most likely reason would be the frying of the orbiter’s power supply by excess radiation around the moon. The mission was declared over and successful with 95% of its objectives met. The orbiter was expected to spiral into the moon and crash in 1,000 days.

However, seven years later, in 2016, NASA’s ground based radar fired pulses of microwaves into the lunar orbit, studying it for three months. They were able to ascertain that Chandrayaan is still in orbit and continues to be, although the craft cannot be revived.

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