WASHINGTON — Members of the Senate space subcommittee used a June 6 hearing to once again express opposition to the administration’s proposal to end NASA funding of the International Space Station in 2025.

In the second in a series of hearings on the future of the ISS, witnesses from industry and other organizations said either transitioning the ISS to commercial operators, or shifting to new commercial space stations, may not be feasible by that time, and that even consideration of the proposal may scare away potential station users.

“We understand that commercialization is imminent, and we are fully supporting this process. However, to achieve this goal, enough time must be given both for a smooth transition and for the nation to realize a return on investment,” said Cynthia Bouthot, director of commercial innovation and sponsored programs at the Center for the Advancement of Science in Space (CASIS), which operates the portion of the ISS designated a national laboratory.

Bouthot said setting a 2025 date for ending NASA funding of the ISS, and potential the station as a whole, is starting to concern researchers. “We’ve already had anecdotal evidence of companies that we’re working with to try to get to the station hesitate once that 2025 date was announced,” she said.

On the heels of a Washington Post report where NASA Administrator Jim Bridenstine said the agency was in discussions with several companies about taking over the station, an executive with one major aerospace company expressed skepticism that the ISS itself could be operated profitably.

Jim Chilton, senior vice president for space and launch at Boeing, said at the hearing that it costs NASA about $3.2 billion a year to operate the U.S. segment of the ISS. That includes $1.8 billion in cargo and crew transportation costs, $1.1 billion in operations of the station itself and $300 million for research. By contrast, commercial activities at the station today produce only about $100 million in revenue. “That’s a big gap,” he said.

Bob Mitchell, president of the Bay Area Houston Economic Partnership, was skeptical cost savings that would be created by ending funding of the ISS would provide significant additional resources for NASA’s deep space exploration efforts. “Commercial alternatives would likely cost significantly more to sustain than the ISS, creating an entirely new development program while providing a fraction of the existing capability,” he said.

One of those companies planning commercial space stations is Axiom Space. Michael Suffredini, the president and chief executive of the company and a former NASA ISS program manager, said NASA should approach any transition to commercial space stations carefully. “One concept must remain inviolable: the United States must not relinquish uninterrupted access to LEO for its astronauts,” he said.

He did press NASA, though, to accelerate efforts to bring on commercial modules to the ISS. In 2016, NASA issued a request for information from companies interested in using a docking port on the station. The agency has yet to follow up that request with a competition and is now instead seeking proposals for LEO commercial market studies.

“NASA must allow companies to compete for the right to attach one or more modules to the ISS as soon as possible,” he said. That competition, he said, should take place in parallel with the commercialization studies, and not wait until after the studies are completed at the end of this year.

Senators at the hearing made it clear even before the witnesses testified that they remained opposed to ending NASA funding of the ISS by 2025, particularly since it has the technical ability to operate through at least 2028. “It is my firm belief that it would be irresponsible for the United States government to prematurely end the life of the International Space Station before maximizing American taxpayer investment,” said Sen. Ted Cruz (R-Texas), chairman of the subcommittee.

Cruz had previously criticized the proposal, as had Sen. Bill Nelson (D-Fla.), ranking member of the full Senate Commerce Committee. “Why in the world would you want to take a large, multi-year investment of $100 billion and suddenly deorbit it and let it burn up on reentry?” Nelson asked.

Sen. Ed Markey (D-Mass.), ranking member of the space subcommittee, did not participate in last month’s hearing on the ISS, but appeared in lockstep with his colleagues at this hearing. “We simply cannot pull the plug on the International Space Station without a plan in place for what comes next,” he said.

A conversation “on steroids”

A few hours before the hearing, NASA Administrator Jim Bridenstine met with reporters at NASA Headquarters. One of the topics he addressed was the future of the ISS and any transition to commercial operations of the station, or commercial space stations.

“There are companies that are interested in managing the ISS from a commercial perspective. That exists right now, and that existed before I got to NASA,” he said. The issue, he said, is what circumstances would allow those companies to close their business plans by operating the ISS, or some elements of it.

“No decisions have been made” about the station’s future, he emphasized. “There’s a range of options here. What the president’s budget request did is it has started this conversation, and kind of put it on steroids.”

One big issue for any ISS transition, he said, is to avoid any gap in human activity to low Earth orbit. “We saw what happened with the space shuttles,” he said. “We don’t want that to happen with low Earth orbit.”

The other major issue, he said, is figuring out how much NASA wants to spend on activities in LEO after the end of the ISS, and how much commercial activities can cover the costs of such activities. “There are opportunities here for us to look at options, a range of options, that ultimately enable us to go further, which is the objective,” he said.

Any decision on the future of the ISS, he said, will be done in consultation with the other countries involved on the station, discussions that are already underway. “Nothing will be done outside of the consent and advice of our international partners.”