GAO Questions Gateway’s Mass, Schedule

The Government Accountability Office wants NASA to document and communicate a mass management plan for the Gateway lunar space station before the next program review in September. The first two Gateway segments are scheduled to launch together in 2027, but their combined mass exceeds allowed limits. GAO also illuminates concerns about the schedule and whether Gateway’s Power and Propulsion Element will be capable of controlling the small space station when more massive vehicles are docked.

As part of the Artemis program to return astronauts to the lunar surface, NASA and four international partners are building the Gateway space station that will orbit the Moon. Astronauts will launch to the Moon on NASA Space Launch System rockets aboard NASA Orion spacecraft and dock to the Gateway. Some will remain there to conduct science experiments while others board commercially-provided Human Landing Systems to go down to the surface and back.

Two Human Landing Systems, Starship HLS and Blue Moon, are being built through Public-Private Partnerships with Elon Musk’s SpaceX and Jeff Bezos’s Blue Origin respectively. The companies own the landers. NASA will purchase lunar landing services from them.

The baseline cost of the Gateway for NASA is $5.3 billion.

In addition, Japan, Canada and the European Space Agency, all partners in the Earth-orbiting International Space Station, plus the United Arab Emirates are contributing modules or other hardware. The Gateway is small compared to the ISS. When fully assembled, it will be about one-fifth the size of ISS by volume and one-sixth by mass. The total mass will be 63 Metric Tons (MT) with a habitable volume of 125 cubic meters. Unlike the ISS, it will not be permanently occupied. As its name implies, it’s a gateway — a transition point between Earth and the lunar surface.

The Gateway won’t be there for the first human return to the lunar surface, Artemis III, scheduled for September 2026. In that case Orion and SpaceX’s Starship HLS will dock with each other directly in lunar orbit.

Beginning with Artemis IV two years later, astronauts will use the Gateway as the transition point.

Initially the Gateway will be comprised of only two segments — the Habitation and Logistics Outpost (HALO) and the Power and Propulsion Element (PPE) — and they’re the focus of GAO’s report. Maxar is the prime contractor for PPE and Northrop Grumman for HALO.

Originally NASA planned to launch them separately, but later decided it would be better to integrate them together on the ground before launch than after they’re in space.  Northrop Grumman is responsible for integrating them. They’ll launch on a SpaceX Falcon Heavy on a trajectory where they slowly spiral out to a special 6.5-day lunar orbit called a Near-Rectilinear Halo Orbit or NRHO. That journey will take about a year.

To be there in time for the September 2028 Artemis IV mission, that means they need to launch by September 2027, but the current launch date is December 2027. GAO reports that NASA will hold a program review next month to assess the schedule and cost and set an “accelerated date to drive contractor performance and create schedule margin.”

GAO points how complex the Artemis IV mission as a whole will be.  The second human lunar landing since Apollo and the beginning of Gateway operations, it involves not only the first docking of both an Orion and a Starship HLS to Gateway, but delivery and integration of the next Gateway module (I-Hab) and the first Deep Space Logistics (DSL) cargo delivery. In addition, it will be the first launch of the upgraded Block IB version of the Space Launch System rocket.

In this report, however, “NASA Should Document and Communicate Plans to Address Gateway’s Mass Risk,” the emphasis is finding a way to deal with Gateway’s mass growth.  At the moment, the combined mass of HALO and PPE — the “Comanifested Vehicle” or CMV — is 1,312 kilograms (2,892 pounds) too high.

GAO identifies several methods of addressing the problem, but the main point is that NASA needs to come up with a plan and communicate it at next month’s meeting.

Another issue GAO illuminates is that PPE may not be sufficient to control the Gateway when additional vehicles, like Human Landing Systems, are docked there.

Orion spacecraft transporting crews to and from Earth, SpaceX’s Starship HLS and Blue Origin’s Blue Moon HLS ferrying them down to and back from the surface, and logistics vehicles delivering supplies and removing trash, all will dock with Gateway periodically. The PPE needs to control the orientation of the Gateway when they’re attached — the “integrated stack.”  That could be a problem with vehicles like SpaceX’s Starship HLS whose mass is “18 times greater than the value NASA used to develop the PPE’s controllability parameters.”

NASA is looking at two options: using the propulsion systems on the visiting vehicles to help control the stack, or changing the control algorithms for the PPE. If neither of those works, “NASA plans to either change the PPE’s requirements or add requirements for visiting vehicles.”  GAO’s concern is that making those types of changes at this point in the program could add cost and delay the schedule.

GAO’s key point appears to be that the clock is ticking and NASA needs to resolve these issues, especially mass, immediately because they can affect cost and schedule. NASA will update the Joint Cost and Schedule Confidence Level (JCL) analysis at next month’s “critical design-informed synchronization review.”  The last JCL review was in May 2023 and since then GAO found that some risks have been mitigated and “other risks have grown worse and new ones have emerged.”

The 54-page report raises many issues about Gateway, but GAO makes just one recommendation: “NASA should ensure that the Gateway program documents and communicates an overall mass management plan before its next program-level review.”

In its response (published as an appendix), NASA concurred.