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Science & Tech

Megha Tropiques Satellite

To lower the orbit and reduce space debris, ISRO attempted a controlled re-entry of the Megha Tropiques-1 satellite with leftover fuel.

Satellite Megha Tropiques

  • The Indian and French space agencies collaborated to develop the weather satellite Megha Tropiques-1.
  • The space agency launched it aboard a PSLV in 2011.
  • And, although the planned mission life of the satellite was only three years, it continued providing data on water cycle and energy exchanges in the tropics for nearly a decade.

How did the satellite come down?

  • With more than 120kgs of fuel remaining in the satellite after it was decommissioned.
  • ISRO determined that there was sufficient fuel for a controlled re-entry.
  • When the satellites re-enter the atmosphere, friction causes temperatures to rise to thousands of degrees Celsius.
  • Without a heat shield, 99% of a satellite is destroyed during re-entry, whether controlled or uncontrolled.

The significance of the change

  • Despite the fact that the satellite was not designed to do so, this was the first time ISRO attempted such a manoeuvre to clear out space debris.
  • Typically, satellites are left in orbit, and due to the earth’s gravitational pull, they fall to the atmosphere over time.

Why did the International Space Station attempt a controlled re-entry?

  • ISRO attempted control re-entry to demonstrate and comprehend the process.
  • With multiple spacefaring nations and private entities launching satellites, keeping space clean is critical.
  • Thousands of objects, including old satellites, parts, and rocket stages, are floating around in low earth orbit.
  • Because of the high speeds, even small debris can destroy active satellites.
  • Kessler syndrome is a terrifying scenario in which space debris collisions generate even more debris.

What usually happens to satellites?

  • A controlled re-entry, such as the one attempted by Isro earlier this week, is only possible for satellites in low-Earth orbit, which is about 1,000 kilometres above the earth’s surface.
  • These manoeuvres, however, are rarely attempted because fuel reserves must be kept in the satellite after the mission is completed.
  • This is also impossible for satellites in geostationary or geosynchronous orbit, where the time it takes the satellite to orbit the Earth matches the rotation of the Earth.
  • These satellites orbit at nearly 36,000 km altitude.
  • A massive fuel reserve would be required to attempt to bring a satellite down from such an orbit. This will simply make the satellite heavier and more expensive to launch.
Source: https://indianexpress.com/article/explained/explained-sci-tech/isro-brings-down-weather-satellite-controlled-re-entry-8489195/
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