WASHINGTON — NASA’s deputy administrator says there is nearly unanimous support for its low Earth orbit microgravity strategy that endorses keeping humans in orbit continuously during the transition to commercial space stations.
NASA released Dec. 16 a final version of LEO Microgravity Strategy that backed a concept called “continuous heartbeat” by the agency, which calls for maintaining humans in LEO continuously as NASA shifts from the International Space Station to commercial stations.
NASA had been weighing continuous heartbeat against an alternative called “continuous capability” that retained the ability to send humans to LEO but opened the door to having gaps in crewed presence in orbit. NASA Deputy Administrator Pam Melroy, speaking at the International Astronautical Congress (IAC) in October, suggested NASA had not decided between the two at the time: “While we originally hoped that this would just emerge from this process, we’re still having conversations about that.”
In a recent interview, Melroy said she made those remarks at IAC to stimulate additional discussion. “I did that on purpose because we needed people to come back and tell us what they thought,” she said. “If you were sitting on the sidelines with an opinion, it flushed everybody out.”
By the time she spoke at IAC, nearly two months after the release of a draft of the strategy, the agency already had what she described as an “internal convergence” around the continuous heartbeat approach. That was driven by several factors, including the need for long-duration flights to gain experience for future Mars missions as well as supporting the business cases of commercial transportation providers that need a regular cadence of missions.
“But then we asked, we stirred it up a little bit at IAC, just to see if everybody would step forward and say what they thought,” she said. International partners as well as other government agencies came out unanimously in favor of continuous heartbeat, while industry was “nearly unanimous” in support of it as well.
She didn’t identify which companies supported the continuous capability alternative, but said she believed companies were worried that NASA wasn’t moving fast enough to transition from the ISS to commercial stations, which might deter investors in those commercial ventures. She said there were also concerns about the challenges in developing stations that could support humans continuously, with some seeking a more evolutionary approach starting with shorter missions.
With the strategy now published, the next step for the agency is to use it to support development of the request for proposals (RFP) for phase two of the Commercial LEO Development (CLD) program. In that phase, NASA will select companies to certify their stations for NASA astronauts and to purchase services on those stations. Under a proposed schedule discussed with industry in December, NASA expects to release a draft RFP in June and a final version in the fall, with awards in mid-2026.
“Given how long it takes to develop these things, we need to get them on contract,” Melroy said of commercial station companies. “The full decomposition to capabilities, needs and requirements is going to be a bit of a slog early next year to get there, but I think they can do it.”
She acknowledged, though, that it will be a challenge to get at least one commercial station operating by 2030, the current schedule for deorbiting the ISS. “It’s tight,” she said of that schedule, noting that, historically, it’s taken at least five years to develop any new human spaceflight capability. Budget caps, she added, have also restricted the ability for NASA to fund the CLD program as well as the U.S. Deorbit Vehicle for the ISS alongside station operations.
Besides clarifying the support for continuous heartbeat, Melroy said the feedback NASA got on the draft version of the strategy helped refine the science objectives. “They’re doing really well on ISS, and I think they want to make sure that they’re going to continue to make progress,” she said of researchers currently using the ISS. That included the addition of a goal to support “rapid” science in LEO through capabilities that would allow crews to conduct iterative research.
The LEO Microgravity Strategy used the same approach as NASA’s Moon to Mars Architecture, which has gone through two updates since its rollout in April 2023. The same approach, she suggested, could be used elsewhere in the agency. “We have some problems that could benefit from a strategic exercise” like that, she said.
Aligning multiple such strategies is part of an agency initiative called NASA 2040 that will look at how those approaches work together at the level of mission directorates and field centers. “That would be great if you could see all those interlocking points,” she said. “I think it will really help the agency work together better and be more efficient in making some of the decisions that we make.”
Those plans will be for others, though, as Melroy is leaving NASA at the end of the Biden administration later this month. “I’m not taking on another strategy.”
