How SpaceX will turn its workhorse into a giant space station destroyer
SpaceX plans to equip its Dragon capsule with superchargers to decommission the International Space Station at sea
In just a few years, an upgraded version of SpaceX’s Dragon spacecraft will launch on a unique mission: to safely destroy the International Space Station (ISS).
The first module of the ISS reached orbit in 1998, and crewed spacecraft have been operating continuously since 2000. But even the largest and most expensive piece of orbital infrastructure humanity has ever built can’t last forever. NASA has determined that the aging ISS is too large and unwieldy to be brought back to Earth intact or launched into a higher, longer-lasting “graveyard” orbit. So the ISS’s end-of-life plan instead calls for a carefully orchestrated, fiery entry into the atmosphere, followed by dumping the debris in an uninhabited area of ocean.
NASA announced in June that SpaceX would design and build a specialized deorbit vehicle based on its Dragon spacecraft to provide a means of destructing the space station, currently scheduled for early 2031. But during a July 17 press conference, NASA and the company released additional details that shed light on the extent of the modifications SpaceX will make to accomplish this challenging mission. The company is considering flying a standard, used cargo Dragon capsule as part of the vehicle, which will be connected to a brand new supercharged trunk section that will pack rocket engines and carry additional propellant to perform the complex, high-risk maneuver.
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“They’re calling this a bigger trunk, but it’s nothing like the little carbon fiber pieces that are used for trunks today. This is a much more advanced and complex spacecraft,” says Jonathan McDowell, an astrophysicist and spaceflight expert at Harvard University and the Smithsonian Center for Astrophysics. “This is all certainly old technology, but they’re putting it together in a very new way.”
A typical SpaceX cargo Dragon that visits the ISS is powered by 16 Draco engines; the deorbiter will carry 30 more Draco engines in its trunk, with 22 to 26 firing at once, giving the spacecraft enough weight to maneuver around the vast station. Draco engines have been flying in space since 2010, but the new configuration has never been used before and will need to be thoroughly tested, McDowell says. (The company also makes SuperDraco engines, which produce about 200 times more thrust, but are used only in the launch abort system of the Crew Dragon vehicle.)
SpaceX’s plan calls for nearly tripling the number of engines on a typical Dragon and for the deorbiter to launch with about 16,000 kilograms (about 35,000 pounds) of propellant — six times as much as a standard Dragon, Sarah Walker, SpaceX’s Dragon mission management director, said at a press conference.
Add all that up and the deorbital rocket would be too heavy to be launched by SpaceX’s flagship Falcon 9 rocket or any other launch vehicle in its class. NASA currently only hires SpaceX to build the deorbital rocket, not launch or operate it, so it would have to rely on a heavy launch vehicle instead. McDowell said the company’s Falcon Heavy is the obvious candidate for the mission, noting that United Launch Alliance’s Vulcan, which first launched in January, or Blue Origin’s New Glenn, scheduled for launch in September, might also be powerful enough to handle a deorbital rocket this heavy.
NASA has provided more details about its choice to hire SpaceX for the job. The agency received three proposals in total, but rejected one that did not meet essential requirements. McDowell said the two proposals came from unsurprising sources: SpaceX, which operates both cargo and crew missions to the space station, and Northrop Grumman, which has conducted 20 resupply flights to the space station and plans to launch another one next month. But NASA’s evaluation found that SpaceX’s proposal was both lower cost and more capable, according to a report by Ken Bowersox, deputy administrator for NASA’s Space Operations Mission Directorate.
Despite the emphasis on integrating reliable existing technologies into the deorbiter, the fact remains that humanity has never disposed of a spacecraft as large as the ISS, which is roughly the length of a football field, has more interior space than a six-bedroom house, and weighs about 460 tonnes. Its predecessor in controlled deorbit of a space habitat, the Russian Mir space station, was much more compact and weighed less than a third as much.
As the final, fateful moment approaches, the ISS and the deorbiter will be at the mercy of Earth’s thick atmosphere, shaking and burning up the iconic facility. If the deorbiter isn’t strong enough to maintain a smooth orbit, the plummeting station could tumble through the air, breaking apart and scattering dangerous debris over populated areas of the planet rather than falling safely into the ocean. This will be SpaceX and Dragon’s riskiest mission yet after more than a decade of visits to the orbital laboratory.
“It’s been an incredible full-circle experience, from being the first commercial vehicle to approach and connect with the space station to now being ready to hand the baton over to the next platform to follow,” Walker said at a news conference.
