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Although the International Space Station is scheduled to be replaced in the 2030s, it will be a long time before the space laboratory officially reaches the end of its life, NASA says.
SpaceX’s newly deployed reentry vehicle won’t push the International Space Station (ISS) into Earth’s atmosphere for 12 to 18 months after the complex “drifts” from its normal orbit. “We’re keeping the crew on board as long as possible so they’re available to help maintain the station and keep it healthy,” NASA’s ISS program manager Dana Weigel told reporters today (July 17) in a livestreamed briefing on the reentry plan.
“Our plan is for [the astronauts] to leave about six months before final re-entry into the atmosphere, as the ISS will be about 220 kilometers high [136 miles],” Weigel said, explaining that this is the lowest altitude human vehicles are typically allowed to fly. For comparison, the typical ISS orbit is 250 miles (400 km) above Earth.
NASA selected the deorbit vehicle last month, saying it will award SpaceX up to $843 million for development (that figure doesn’t include launch costs). The selection comes after NASA asked the aerospace community for proposals in March 2023, and again in September 2023, for a “space tug,” or “U.S. deorbit vehicle (USDV),” concept that could bring down U.S. segments of the ISS.
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SpaceX’s deorbit vehicle will be based on the company’s Dragon spacecraft design, which has sent cargo variants to the ISS since 2012 and launched crew members to the lab since 2020. Notable will be an “enhanced trunk section” that will carry additional fuel tanks, along with engines, avionics, power generation and other items customized for the complex mission, Sarah Walker, SpaceX’s director of Dragon mission management, said in the same briefing.
“One of the benefits of leveraging Dragon’s rich flight history is that we can continue to use NASA-certified hardware for a number of key systems, such as the docking system,” she said. “While the assembly-level design is uniquely developed for this mission,” she added, “we intentionally use building blocks of components that NASA is familiar with and that SpaceX has extensive experience building and operating.”
SpaceX is the dominant player in ISS operations. The company, founded by billionaire Elon Musk, benefits from vertical integration (it owns much of the supply chain required for space launches) in a way that its competitors don’t. In addition to launching both crew and cargo to the ISS, SpaceX is funded by NASA for a Starship contract to land astronauts on the moon. (The Starship contract is behind schedule and is one reason the first human moon landing in more than 50 years has been delayed by a year to 2025, at least, because NASA wants a “significant number” of successful Starship launches before putting astronauts aboard.)
SpaceX also launches lucrative satellite missions into space, funded by the military and the U.S. government. SpaceX also launches its own Starlink broadband satellites several times a month aboard SpaceX’s Falcon 9 rocket, one of the most reliable launch vehicles in the world. (Falcon 9 is currently grounded after a rare launch failure, but SpaceX is hoping the Federal Aviation Administration will allow it to launch again while the mandatory investigation into the accident continues.)
Related: SpaceX Falcon 9 rocket failure forces NASA to reevaluate launch schedule for astronauts on ISS
SpaceX’s approach to the ISS deorbit vehicle was praised in the official source selection document posted Tuesday (July 16) on the government procurement website SAM.gov. “SpaceX’s approach significantly increases the likelihood of producing a highly reliable USDV, minimizes new development and testing, and reduces the risk to the government of late delivery of the USDV and significantly increases the likelihood of successful contract performance,” the document said.
Northrop Grumman (NG), a major SpaceX competitor that is currently launching cargo missions to the ISS, had a higher total cost for the project. The document added that it was “particularly concerning” that NG’s space tug idea might not work at certain “solar beta” angles. (These angles are between the ISS’s orbit in space and an imaginary line connecting the sun and Earth, according to NASA.)
“This weakness forces NASA to choose between a potentially lengthy and costly redesign of the NG system, which would give NASA greater flexibility in planning ISS deorbit operations, or launching a USDV that would limit NASA’s planned deorbit planning,” the source selection document said.
Currently, most of the ISS consortium has committed to operations through 2030, while Russia says it will stay until at least 2028. Russia is leaving the consortium in the wake of the internationally condemned war in Ukraine, an exit that was initiated without provocation in 2022. While most of the world pulled contracts from Russian launch operations, it has focused on China and North Korea, which are frequently cited in congressional testimony as posing security risks to the US.
NASA officials have stressed that the ISS’s end date depends on when new commercial replacement stations, funded by the agency, will be ready. “We want [the commercial stations] “To support them, and when they’re ready to go, the ISS will get out of the way,” Steve Stich, the manager of the commercial crew program at NASA’s Johnson Space Center (JSC) in Houston, said at a briefing earlier this year.
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And there are financial and policy reasons to keep experiments on the U.S. side going as long as possible, at least as far as lawmakers are concerned. Tiangong, a Chinese space station, could take a big slice of the lucrative low-Earth orbit market if the U.S. lets the ISS go early, Congress warned earlier this year. NASA is barred from entering into bilateral agreements or coordination with China under a 2011 congressional directive known as the Wolf Amendment.
Several companies are currently building commercial outposts. Axiom Space plans to place modules on the ISS before undocking them in a free-flying set known as Axiom Station.
Other independent stations are also in the works. Orbital Reef includes Amazon, Boeing, Blue Origin and Sierra Space; the Voyager Space-led Starlab complex has participation from Lockheed Martin and Northrop Grumman; and Vast Space expects to launch the first Haven-1 module into space in 2025.