Swift telescope to crash on Earth this month - What to expect, and does it pose a danger?

After a robotic arm failed to save the Neil Gehrels Swift Observatory, the spacecraft is set to crash some time this month. It will make an uncontrolled reentry into Earth's atmosphere. The telescope was launched in November 2004 and 22 years later, is set to tumble down, marking an end to it mission. Earlier this year, NASA tried to save it by launching a private mission to elevate its orbit. But the rescue machine could not catch up to it in time. Swift had fallen to an altitude from where it was impossible to save it.

Over two decades, Swift studied gamma-ray bursts, the most powerful explosions in the universe. But recently, the telescope's low Earth orbit began to rapidly decay. Solar storms made the situation worse, and caused it to drag. This meant that it would inevitably crash. This was expected to happen by early 2027. From 600 km above Earth's surface, it dropped to around 360 km. Most of this drag and drop happened in the last two years.

Also Read: Swift telescope set to crash on Earth as NASA declares saviour mission LINK has failed

Saviour mission LINK

NASA could simply let it go, or save it. It decided to take a step towards keeping it functioning in space. It awarded a contract to Katalyst Space for it. The company successfully "designed, built, tested, and integrated a robotic spacecraft" to rescue Swift. In June, the changes of the telescope crashing stood at 50 per cent. The LINK spacecraft, with its three robotic arms, launched on July 3. It was supposed to carry the telescope to a higher and more stable orbit.

Also Read: NASA launches LINK to catch 22-year-old Swift observatory in space - Details

But weeks later, it went into an uncontrollable spin. NASA and Katalyst tried to save the mission, but nothing could be done. The 1,500-kilogram observatory had fallen to 300 kilometres and could no longer escape the effects of the increased drag. In August, NASA and Katalyst announced that the mission had failed. "Following continued monitoring and assessment of the LINK spacecraft, Katalyst Space and NASA together have concluded that ​due to ongoing attitude control issues, the mission will not include the capture ​and boost of NASA’s Neil Gehrels Swift Observatory," they said in a joint statement.

Does Swift's fall post danger to humans?

Experts expect the observatory to disintegrate in the atmosphere, with only a few fragments crashing. Even these are expected to fall in the ocean. According to Dean Sladen, a quality manager and aerospace engineer at the UK precision-components supplier Accu Components, said that "Swift's orbit only passes over a band within about 21 degrees of the equator", and most of this region comprises only ocean, although it also crosses populated parts of Africa, South and Southeast Asia and Latin America.

He told Space.com, that its aluminium body, wiring and electronics will melt upon reentry. "Six heavy reaction wheels, the spinning flywheels it used to aim itself, along with tougher telescope parts such as lenses and mirrors" are likely to make it down. While NASA has not released a risk assessment report yet, it is expected to do so in the coming days. "The risk is almost certainly very small, but it would give people a clear, factual picture rather than guesswork," he said.