“Continuous Heartbeat” Wins the Day in NASA’s LEO Microgravity Strategy

NASA released its new Low Earth Orbit Microgravity Strategy today with goals and objectives for the post-International Space Station era. NASA has long held that the United States must have a continuous presence in LEO, but one area of debate centered on whether that means a “continuous heartbeat” with human beings always present or a “continuous capability” where crews might be aboard a space station or not.  In the end, continuous heartbeat won.

NASA and its ISS partners — Russia, Japan, Canada, and 11 European countries working through ESA — plan to end operations of the ISS in 2030, just six years from now.  They have been wrestling for years as to what should come next.  All of them except Russia are working together on the Artemis program to return humans to the lunar surface, but conducting research in LEO continues to be a priority.

NASA wants to build on the Public-Private Partnership model it’s using for the Commercial Crew transportation systems for ISS and many aspects of Artemis where it doesn’t own spacecraft, but purchases services from commercial companies that build, launch and operate them for NASA and other customers. The agency is working with three companies right now through the Commercial LEO Destination (CLD) program to help them get started — Axiom Space, Blue Origin, and Starlab Space. NASA wants more than one provider, but two challenges are how much funding NASA can provide in this early phase and how big the non-NASA market will be once CLDs are in orbit.

The strategy released today sets out goals and objectives for NASA’s future in LEO broadly. In a statement, NASA Deputy Administrator Pam Melroy summed it up: “Together, we are ensuring that the benefits of exploring space continue to grow – advancing science, innovation, and opportunities for all, while preparing for humanity’s next giant leap of exploring the Moon, Mars and beyond.”

Starting early this year, NASA solicited input from many sources — its own workforce and others in the government, industry, academia, international space agencies and the public — and received more than 1,800 comments, and hosted two workshops.

The result is a framework with 13 goals and 44 objectives covering seven areas:

• commercial low Earth orbit infrastructure
• operations
• science
• research and technology development for exploration
• international cooperation
• workforce development and science, technology, engineering, and mathematics (STEM) engagement, and
• public engagement

Although the CLDs are expected to host a variety of customers in addition to NASA performing research with applications on Earth, a key theme for NASA’s future LEO work is preparing for and supporting human exploration of the Moon and Mars.  With today’s propulsion, trips to Mars will take at least six months to get there and another six months to get back, all in microgravity, plus some period of time on Mars, which has one-third the gravity of Earth. The Moon, with one-sixth Earth’s gravity,  is just a few days away, but astronauts will stay there for increasingly long periods of time.

The ISS has been continuously occupied by international astronauts rotating on roughly 6-month schedules for the past 24 years producing considerable data on how the human body adapts to microgravity. But there’s no ISS data about how the body reacts to partial gravity and only a very few crew members have stayed for more than 6 months.

This report stresses that NASA needs more crew mission durations of 6-months to a year and that means keeping astronauts on the CLD commercial space stations continuously, as they are on ISS. “Flights of 30 days to six months will have limited value.”  The agency also wants multiple CLD providers “to assure regular, routine access to and use” of LEO.

Somewhat ironically, although one of the goals of the strategy is public engagement, NASA and the White House held a “microgravity science summit” today that wasn’t public. One of the companies participating in the CLD program, Redwire, posted about it on X after the fact.

Redwire was honored to be a part of the Microgravity Science Summit at the White House Eisenhower Executive Office Building in Washington, D.C., on Monday, December 16. During the event, Redwire’s Rich Boling and Dr. Molly Mulligan highlighted our space-based PIL-BOX technology… pic.twitter.com/lpZmWwbIDh

— Redwire Space (@RedwireSpace) December 17, 2024

Melroy revealed the internal debate over “continuous heartbeat” versus “continuous capability” at the International Astronautical Congress in Milan, Italy in October, at which time a decision hadn’t been reached on which path to take. As noted above, in the end NASA concluded a continuous heartbeat is “logically required” and added that an “unbroken rhythm of human activity will allow NASA to reduce risk for sending humans to Mars, preserve critical operational skills, maintain a steady transportation cadence, continue advancing science, and sustain engagement with commercial and international partners.”

Mentioning the need to “preserve critical operational skills” may respond to concerns raised by NASA’s Aerospace Safety Advisory Panel (ASAP) on October 31 that NASA wasn’t paying sufficient attention to whether critical skills will be retained within the agency to be able to assess and manage risks in a commercial space station environment. If NASA has a partnership with a commercial provider and it includes international partners like the ISS does, “the panel foresees legal and protocol complications for a commercial partner who integrates risk, which then affects NASA and international partner astronauts and assets.”

Another factor in favor of continuous heartbeat is the impact on the business models for the CLD companies if NASA decided it didn’t need astronauts in LEO all the time. The size of the market for commercial space stations is one of the big question marks facing the CLD program and how many companies can survive. NASA wants a “diversity of providers,” so it needs to help close the business case.