SpaceX’s spacecraft that will deorbit the International Space Station is a Dragon on steroids

SpaceX revealed Wednesday that the $843 million spacecraft it is designing to land at the International Space Station by the end of the decade will be a super-powerful version of the Dragon capsule used to carry astronauts and cargo into orbit today.

NASA awarded SpaceX a massive contract to develop the U.S. Landing Vehicle (USDV) last month. It won the contract — over Northrop Grumman, the only other bidder — in part because the design relies on a lot of flight-proven hardware, NASA said. Source Selection Statement Published on Tuesday.

NASA is looking for proposals that maximize the use of flight heritage because reliability will be key, Dana Weigel, NASA’s International Space Station program manager, said during a news conference Wednesday. But even with the major integration of Dragon’s engineering, about half of the American spacecraft will be entirely new, and 100 percent of the deorbiting functionality will be new to the spacecraft, she said.

The spacecraft is intended to perform a series of critical burns during the station’s final week, but NASA plans to launch the spacecraft about 18 months before those burns occur. It will dock with the forward port of the ISS, where it will remain while the ISS slowly “drifts” toward Earth, Weigl said. The agency will leave the crew on board for as long as possible to keep the station on track, but they will eventually leave for the final time about six months before reentry.

The American spacecraft will enter its role when the station reaches an altitude of about 220 kilometers above the Earth’s surface. The spacecraft will perform a series of burns to prepare the station for a precise deorbit trajectory over about four days before performing a final burn for re-entry into the atmosphere. The parts of the station that do not burn up in Earth’s atmosphere will splash down in an uninhabited part of the ocean that has yet to be determined. This is the same disposal method the station has used for other large spacecraft, such as Northrop Grumman’s Cygnus spacecraft or Japan’s HTV cargo capsule.

The mission is complex, and SpaceX will have to develop a vehicle powerful enough to guide the station through increasing amounts of atmospheric drag. “The thing that I think is the most complex and challenging is that this vehicle is capable of carrying a larger payload than Dragon,” said Sarah Walker, SpaceX’s Dragon mission director. [final] “The burn must be powerful enough to fly the entire space station, while resisting the torque and forces caused by increased atmospheric drag on the space station to ensure it eventually ends up at its intended location.”

SpaceX’s final design is for a spacecraft that will carry six times the amount of usable fuel and generate three to four times more power and storage than the Dragon capsules. The end result, at least according to the design SpaceX released earlier Wednesday, is what looks like a traditional Dragon with a giant hose attached to the end.

The box will hold all the extra fuel, power generation and electronics needed to complete the mission, Walker said. That includes 30 additional Draco thrusters, in addition to the 16 already in the standard capsule configuration. The goal of the massive final burn is to help ensure that the debris footprint is small — and there will likely be some debris, ranging in size from microwave ovens to small sedans.

NASA officials said the agency, along with other station partners — Roscosmos, the European Space Agency, the Japan Aerospace Exploration Agency and the Canadian Space Agency — agreed to request a private sector vehicle to deorbit it after realizing that Roscosmos’ capabilities were not up to the scale of the station. NASA issued a request for proposals last fall.

The award comes now, Weigel added, because developing spacecraft of this complexity could take years.

But the contract is different from other big wins SpaceX has won for NASA. Unlike the station crew and cargo contracts, where NASA simply buys services for the vehicles SpaceX owns and operates, the lander contract flips that on its head: SpaceX will design and deliver the vehicle to NASA, but the space agency will be responsible for providing the launch, operating the spacecraft and returning the International Space Station to Earth.

The agency will begin the process of purchasing rockets about three years before launch in a separate request. If the International Space Station ceases operations in 2030, the station will land on Earth sometime the following year.

Agency officials said they are keen to ensure overlap with commercial space station providers in low Earth orbit, though they acknowledge that any number of variables could hinder a smooth transition. That includes the development schedules of the handful of commercial companies that have stations in development, such as Axiom Space, Voyager Space’s Starlab or Blue Origin and Sierra Space’s Orbital Reef project. NASA currently has a permit to operate the station through 2030; after that date, it will need to get government approval and work with other partner space agencies, said Ken Bowersox, NASA’s associate administrator.