NASA ISS Deorbit Space Tug Could Cost $1 Billion

NASA laid out some of the details of its FY2024 budget request today. The $27.2 billion request, a 7.1 percent increase over FY2023, supports NASA’s full suite of programs in space and earth science, space technology, aeronautics and human spaceflight including the Artemis program to return astronauts to the Moon and continued operations of the International Space Station. One new program is development of a space tug to deorbit the ISS, which could cost as much as $1 billion.

NASA Chief Financial Officer Margaret Vo Schaus and other NASA officials walked reporters through the request during a teleconference this afternoon.

NASA’s human spaceflight programs to operate space stations in low Earth orbit and send astronauts to the Moon and Mars consume just less than half of the request, $12.5 billion. Science programs are allocated $8.3 billion, space technology $1.4 billion, and aeronautics about $1 billion. The remainder is for agency operations ($3.4 billion), Construction and Environmental Compliance ($454 million), STEM Engagement ($158 million), and the NASA Inspector General’s office ($50 million).  All are increases over FY2023. Funding for agency operations includes NASA’s workforce. President Biden is requesting a 5.2 percent pay increase for federal workers.

Vo Schaus said the request supports 148 NASA missions over the next 5 years.

Those include the first Artemis missions to return astronauts to the Moon: the Artemis II crewed test flight around the Moon at the end of 2024, the first landing with Artemis III in December 2025, and the second landing with Artemis IV three years later in December 2028.

NASA did not explain why the gap between Artemis III and Artemis IV has grown from two years to three. Last year’s budget request showed it launching in 2027 not 2028. Artemis IV is a more complex mission intended to begin an era of long-term sustainable lunar exploration rather than Apollo-type sortie missions. It requires an upgraded version of the Space Launch System rocket and associated ground systems, an upgraded version of SpaceX’s Starship Human Landing System, and a space station called Gateway in lunar orbit. Why NASA now expects that to take an extra year wasn’t discussed during the briefing and NASA did not reply to an emailed question by press time.

The Artemis program captures a lot of headlines, but NASA also is committed to retaining a presence in low Earth orbit after the International Space Station ends. The Space Operations account funds ISS and commercial crew and cargo systems to resupply it as well as efforts to facilitate the commercial sector to build their own space stations to replace ISS through Public-Private Partnerships with NASA as one of many customers.  The “commercial LEO” request for FY2024 is $228 million.

The ISS partners — the United States, Russia, Japan, Canada and Europe — need to safely deorbit the ISS at the end of its lifetime to ensure any pieces that survive reentry do not fall on populated areas. Existing plans rely on Russian Progress cargo spacecraft to lower the space station’s orbit and direct it to an unpopulated area of the Pacific Ocean.

This budget request includes $180 million, however, for NASA to build a separate deorbit system. NASA Associate Administrator for Space Operations Kathy Lueders said during today’s telecon that initial estimates are the total cost will be “a little bit short of $1 billion.” A contractor will be competitively selected.  “Our goal is to go out with” a Request for Proposals and “we’re hoping to get a better price than that but this [request] gives us a healthy start in ’24 for us to get that critical capability on board.”

Lueders said NASA continues to work with Russia on plans to use Progress spacecraft, but “we’re always looking for redundancy” and to “better aid the targeting of the vehicle … especially as we add more modules.”

Though the focus is on deorbiting ISS in 2030 because that’s the date the United States has set for it to be replaced by the new commercial space stations, there’s no guarantee it will last that long. The first modules were launched in 1998 and there is a small but persistent leak from one of the Russian modules.

NASA’s Aerospace Safety Advisory Panel raised the alarm about this in October 2022 and recommended NASA develop “an executable and appropriately budgeted deorbit plan.”

“NASA should define an executable and appropriately budgeted deorbit plan that includes implementation on a timeline to deliver a controlled reentry capability to the ISS as soon as practicable to be put in place for the need of a controlled deorbit in the event of an emergency as well as in place before the retirement of the ISS to ensure that the station is able to be deorbited safely.”  NASA Aerospace Safety Advisory Panel, October 2022

ISS continues to be the one safe haven for space cooperation with Russia despite its invasion of Ukraine. NASA did not suggest the decision to build an independent deorbit capability was due to concerns about the continued viability of that relationship or the capability of Russia’s industrial base to continue producing Progress spacecraft.

Progress is a workhorse of the ISS program, periodically raising the orbit to compensate for atmospheric drag or maneuvering it out of the way of orbital debris.

Coolant leaks in Russia’s Soyuz MS-22 spacecraft in December and Progress MS-21 spacecraft last month were intially attributed to damage from micrometeoroids or another external impact, but some Russian specialists reportedly are now concerned it may be a common manufacturing defect. Soyuz and Progress are very similar in design. Soyuz is for crew, Progress for cargo. If it is a manufacturing defect that could, in fact, raise concerns about the health of the Russian space industrial base.