| Title | A Fiery End? How the ISS Will End its Life in Orbit | |
| Date | Sunday May 07, @09:33AM | |
| Author | janrinok | |
| Topic | ||
| from the are-those-African-or-European-elephants? dept. | ||
[...] Drift into the wrong part of the Pacific Ocean in eight years, and you might be in for a shock. Tearing through the sky will be some 400 tonnes (880,000lbs) of metal, set aglow by its re-entry through the atmosphere. This raging inferno will crash into the ocean, across an area maybe thousands of kilometres in length, signalling the end of one of humanity's greatest projects – the International Space Station (ISS).
The ISS has been orbiting the Earth since construction on it began in 1998. It has hosted more than 250 visitors from 20 countries since its first crew arrived in November 2000. "The space station has been a huge success," says Josef Aschbacher, the head of the European Space Agency (Esa), one of the more than a dozen partners in the programme. It has been a boon for international collaboration, not least between the US and Russia, who partnered shortly after the fall of the Soviet Union. "It is really one of the big international victories," says Thomas Zurbuchen, Nasa's former head of science.
But much of its hardware is decades old, which could eventually see the station become dangerous or even uncontrollable in orbit – a fate that befell the Soviet Union's Salyut 7 space station in 1985, requiring two cosmonauts to revive the tumbling station. "We really don't want to go through that again," says Cathy Lewis, a space historian from the National Air and Space Museum in the US.
To prevent such a catastrophe in space from happening once more, the space station will be deorbited in 2031, bringing it through the atmosphere to safely splash down in the Pacific Ocean. This will be the largest re-entry in history and, in March, Nasa asked Congress for funding to start development of a "space tug" that might be needed to perform the task – a spacecraft that can push the station back into the atmosphere. Kathy Leuders, head of Nasa's human spaceflight programme, later revealed it was estimated the tug vehicle would cost just shy of $1bn (£800m).
Working out how exactly to deorbit the station is a mammoth undertaking. Many large objects have burned up in the Earth's atmosphere, most notably Russia's Mir space station in 2001 and Nasa's Skylab space station in 1979. The ISS represents a whole new problem, however, being more than three times the size of Mir. "It is a significant challenge," says Jonathan McDowell, an astronomer at the Harvard–Smithsonian Center for Astrophysics in the US. "A 400-tonne object falling out of the sky is not great."
Beginning as the single Russian-built Zarya module in 1998, the station today is enormous, boasting 16 modules, vast solar panels mounted on a metallic truss, and radiators to expel heat. At 109m (356ft) in length it is the size of a football field, the largest human structure ever assembled in space. "It's like the pyramids of Giza," says Laura Forczyk, a space analyst at the US consulting firm Astralytical. A rotating crew of seven inhabit the station today.
[...] Events will begin in 2026, when the orbit of the ISS will be allowed to naturally decay under atmospheric drag, dropping from 400km (250 miles) to about 320km (200 miles) in mid-2030. At this point a final crew will be sent to the station, likely ensuring any remaining equipment or items of historical significance that have yet to be removed are done so, also reducing the weight of the station. "That is still in discussion," says Aschbacher.
Once the final crew has left, the station's altitude will drop further to 280km (175 miles), deemed the point of no return – where the station could no longer be boosted back above the drag caused by our planet's thickening atmosphere – a process that will take several months. Here, Russian Progress spacecraft are earmarked to then give the station a final push back into the planet's atmosphere.
[...] Whatever spacecraft is used, after this final push, the station will reach an altitude of 120km (75 miles), where it will hit the Earth's thicker atmosphere at some 29,000km/h (18,000 mph), beginning re-entry in earnest. First, the solar panels will be torn from the structure. "The headwind will be so much," says McDowell. Based on studies of the Mir re-entry, this might be expected to occur at an altitude of about 100km (62 miles) and take just minutes before they are all ripped away. Then at around 80km (50 miles) above the Earth's surface, the modules themselves start to be ripped apart from each other before they are set ablaze by the re-entry temperatures of thousands of degrees, causing them to melt and disintegrate. Several sonic booms will be heard as the wreckage streaks across the sky.
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printed from SoylentNews, A Fiery End? How the ISS Will End its Life in Orbit on 2023-05-23 21:55:59