How NASA and SpaceX Will Take Down the Space Station When It’s Out of Service

CAPE CANAVERAL, Fla. (AP) — SpaceX will use a powerful, souped-up capsule to push the International Space Station out of orbit once the sprawling laboratory’s time runs out.

NASA and Elon Musk’s company outlined a plan Wednesday to burn up the space station upon re-entry and dump what’s left into the ocean, ideally in early 2031 when it reaches the 32-year milestone. The space agency rejected other options, such as taking the station apart and taking everything home or giving the keys to someone else.

NASA gave SpaceX a $843 million contract to shoot down the space station, the largest structure ever built on the planet.

Below is an overview of the work we will do and the challenges we face:

Why should we abolish the space station?

The space station is already showing signs of age. Russia and the United States launched the first segments in late 1998, and astronauts moved in two years later. Europe and Japan added their own segments, and Canada provided robotic arms. By the time NASA’s shuttles retired in 2011, the station had grown to the size of a football field, weighing nearly 1 million pounds (430,000 kilograms). NASA estimates the station will last until at least the 2030s. The goal is for private companies to launch their own space stations by then, with NASA as one of several customers. That strategy — which already applies to the station’s cargo and crew deliveries — will free NASA to focus on trips to the moon and Mars. NASA could also decide to extend the station’s lifespan, if there are no commercial outposts yet. The goal is to have an overlap so that scientific research is not interrupted.

Why not bring it back to Earth?

NASA considered dismantling the space station and bringing the pieces back to Earth, or having private companies salvage the parts for their own planned outposts. But the station was never intended to be disassembled in orbit, NASA said, and such an effort would be expensive and risky for the astronauts doing the disassembly. Plus, there are no spacecraft as large as NASA’s old shuttles to bring it all down. Another option would have been to launch the empty station into a higher, more stable orbit. But that too was ruled out because of logistical challenges and the increased risk of space debris.

How will it be taken down?

Visiting spacecraft periodically boost the space station upward, keeping it in orbit at about 260 miles (420 kilometers). Otherwise, it would gradually drop lower and lower until it uncontrollably plummeted out of orbit. NASA wants to ensure a safe return over a remote part of the South Pacific or possibly the Indian Ocean, so that means launching a spacecraft that will dock with the station and send it to a watery grave. NASA expects denser pieces, ranging in size from a microwave to a sedan, to survive in a narrow debris field 1,200 miles (2,000 kilometers) long. NASA and its partners considered using three Russian supply ships for the job, but a more robust craft was needed. The call went out to industry, and in June SpaceX won the contract for a deorbit vehicle.

What will the spacecraft look like when it leaves Earth’s orbit?

SpaceX plans to use a regular Dragon capsule, the kind that carries supplies and astronauts to the space station, but with a much larger trunk that holds a record 46 engines and more than 35,000 pounds (16,000 kilograms) of fuel. SpaceX’s Sarah Walker said the challenge will be to create a spacecraft powerful enough to guide the space station while also withstanding the pull and forces of increased atmospheric drag during the final descent. According to NASA, this spacecraft would require a particularly powerful rocket to reach orbit. The capsule would launch 1 1/2 years before the station’s scheduled demise. Astronauts would remain aboard as it is gradually lowered. Six months before the station’s destruction, the crew would leave the ship and return home. Once the station is about 137 miles (220 kilometers) away, the Dragon would bring it down four days later.

Has this been done before?

NASA’s first space station, Skylab, crashed in 1979, showering debris on Australia and the surrounding Pacific Ocean. The space agency had hoped that one of the early space shuttle crews would be able to attach a rocket to control Skylab’s descent or improve its trajectory. But the shuttle wasn’t ready then, with its first flight not until 1981. Ground controllers managed to slowly lower Skylab, aiming for the Indian Ocean. But some pieces also landed in Western Australia. Russia has more experience with incoming space stations. Mir operated for 15 years before being guided to a fiery reentry over the Pacific Ocean in 2001. Several Salyut stations failed before that.

Will anything be saved?

NASA wants to bring back some small items from the space station for museum displays, such as the ship’s bell and logs, patch panels and other memorabilia. Those could come down in SpaceX supply ships in the last year or two. “Unfortunately, we can’t bring back really, really big stuff,” said NASA’s Ken Bowersox. “The emotional part of me would like to try to salvage some,” but the most practical approach is to bring everything down in one devastating blow, he said.

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