McAlister: Space Station Gap Would Be “Not Great, But Not Irrecoverable”

As the International Space Station celebrates its 25th anniversary, the Director of NASA’s Commercial Space Division said today that the agency is working closely with partners to avoid a space station gap. If it does happen, though, the situation is “not irrecoverable” because NASA can use U.S. spacecraft that ferry crews to Earth orbit as mini-space stations until commercial successors are available.

Today marks the 25th anniversary of the launch of the first ISS module, Zarya (Dawn), on November 20, 1998. Built by Russia, Zarya was paid for by NASA so counts as a U.S. module. That was just the beginning of a more than decade-long effort to complete construction of the 420 Metric Ton laboratory with modules and other hardware from the United States, Russia, Canada, Japan, and 11 countries working under the auspices of the European Space Agency.

International crews rotating on roughly 4-6 month tours of duty have permanently occupied ISS for 23 of those years. These days it is staffed by international crews of seven. Expedition 70 is now aboard: NASA’s Jasmin Moghbeli and Loral O’Hara, JAXA’s Satoshi Furukawa, ESA’s Andreas Mogensen, and Roscosmos’s Oleg Kononenko, Nikolai Chub and Konstantin Borisov.

But ISS is old and getting older by the day.

Air leaks in one section of the Russian segment — a tunnel that connects to a docking port — have proven impossible to remedy over the past several years. The leak rate is small enough that NASA and its Russian counterpart, Roscosmos, aren’t worried even though it’s increased lately.

Robyn Gatens, NASA’s ISS Program Director, told the NASA Advisory Council’s Human Exploration and Operations Committee (NAC-HEO) this morning that the leak rate is up to one pound per day. That’s “manageable” and “well below our spec leak rate, but a little higher than the historical leak rate.” They keep that section closed off from the rest of the ISS as much as possible.

Asked if she’s worried about a catastrophic event, Gatens said no, the worst that would happen is the docking port would become unusable.

“The worst case scenario here is the loss of that port for the space station, but not a catastrophic, existential concern for the International Space Station itself and no other areas of the Russian segment or the International Space Station has seen these kinds of cracks and leaks.” — Robyn Gatens

The bigger point is that the ISS has been in space exposed to radiation and micrometeoroid hits for many years and won’t last forever. The United States, Europe, Japan and Canada are committed to operating ISS through 2030 and while Russia has only committed to 2028 so far, NASA is confident it, too, will extend to 2030.

NASA’s plan is for one or more commercial space stations to be in orbit before that so it can continue doing research in microgravity, but as a customer rather than an owner/operator.

The agency is working with three companies (a fourth recently withdrew) to build commercial space stations. Teams led by Axiom Space, Blue Origin and Nanoracks (part of Voyager Space) are working on designs, but time is growing short. NASA wants some overlap between ISS and whatever follows it, so at least one of them needs to be in place in 5-6 years.

The impetus for follow-on Earth-orbiting space stations is not just scientific. Yes, NASA wants to continue microgravity research to enable long-duration human trips to Mars and is convinced there’s a substantial market for commercial research, too, but U.S. leadership in space is also part of the calculus. Allowing China to be the only country with a permanently-occupied space station in Earth orbit after 2030 is unfathomable for many stakeholders.

McAlister’s division of NASA’s Space Operations Mission Directorate is in  charge of the Commercial LEO Destination (CLD) program to facilitate companies building new space stations in low Earth orbit (LEO). At the NAC-HEO meeting he acknowledged the clock is ticking, but was very upbeat despite looming budget challenges as NASA braces for Congress to provide less funding than requested for FY2024.

Stressing that CLD is safety-driven, not schedule-driven, McAlister said he’s not worried about a gap between when ISS ends and a successor is on-orbit.  Ideally there will be a two-year overlap, but if that’s not possible, it’s still OK.

“If all the mitigations fail we would have a temporary  gap in LEO presence. That would be bad and I don’t want one but if CLDs were not ready … personally I don’t think that would be the end of the world. … A gap might not be great, but not irrecoverable.” — Phil McAlister

SpaceX’s Crew Dragon that ferries crews to the ISS and Boeing’s Starliner expected to enter service next year could be leveraged to serve as mini-space stations, he said, and three other companies are developing spacecraft that could expand the options before 2030:  SpaceX’s Starship, Sierra Space’s Dream Chaser, and Blue Origin’s Space Vehicle.

If there is a gap, it wouldn’t be the first time.  The United States had a busy 14 years from 1961-1975 launching Mercury, Gemini and Apollo spacecraft and the Skylab space station, but for the next six years no Americans flew in space while the space shuttle awaited its first flight in 1981. During that time the Soviet Union made great strides in its human spaceflight program, introducing their second-generation space station, Salyut 6, with two docking ports allowing resupply missions that meant crews could remain aboard for long periods of time and hand off operations from one crew to another.

After the U.S. space shuttle was terminated in 2011, the United States could not launch anyone into space for nine years until SpaceX’s Crew Dragon made its first flight in 2020. NASA had to pay Russia to take crews to and from ISS.

Space aficionados want to avoid another gap, but as in the first two cases it will boil down to a combination of overcoming technical challenges and getting adequate resources. The Space Operations budget request that includes CLD is under strain not only because of expected congressional cutbacks, but it must absorb the $1 billion cost to develop a Deorbit Vehicle to send the ISS into the Pacific Ocean at the end of its lifetime.

Added to that is whether the companies interested in building commercial space stations are convinced there will be a market for those services beyond NASA. Gatens acknowledged that although more than 20 companies are conducting research on the ISS through the Center for the Advancement of Science in Space (CASIS), they do not have to pay for launch or crew time.  “There’s quite a bit of commercial demand. The trick is, if they have to pay full ride, what happens to that demand.”

Gatens said NASA is still in the “sausage-making” phase of developing the transition plan from ISS to whatever comes next. It’s a very complex process starting with what are NASA’s own needs and goals.

“It’s really all about continuity in low Earth orbit. We want sustained human presence, we don’t want to break our 23 year streak .. and we want to transition to commercial space stations with NASA as one of many customers,” she said. In addition “we want to continue partnering with our non-U.S. government space agencies, not just our current ISS international partners but other international space agencies, … to continue to support and expand the LEO economy, … to use these platforms to enable exploration beyond low Earth orbit. And, of course, we want to continue to use these platforms to return benefits for humanity.”

She seemed more determined than McAlister to avoid a gap and stressed that means flexibility in timing. “We need to have two big things” to retire ISS in 2030: a commercial successor and a Deorbit Vehicle.

They’ve looked at boosting ISS higher into a stable orbit, but that would require 100 times the amount of propellant compared to deborbit. The ISS was not designed to be taken apart, but even if it was without the space shuttle there is no way to bring modules back to Earth. NASA issued a Request for Information several years ago to see if any company might want to take it over, but there was little interest especially since the United States does not own all of it.  That makes deorbit the best choice, she explained.

NASA is working to determine what parts of the ISS might be transferred to another space station if it’s in the same orbit, or preserved and returned to Earth for display in the Smithsonian.