PHOENIX — With one module under contract and a second soon to be formally awarded, NASA says development of the lunar Gateway, a key element of its Artemis effort to return humans to the moon, is moving ahead as planned.

During a panel discussion Sept. 11 at the American Astronautical Society’s Wernher von Braun Memorial Symposium in Huntsville, Alabama, NASA officials said they were making good progress on the first two elements of the Gateway, which will serve as a staging point for missions to the lunar surface.

“I can tell you both the PPE and the HALO have production movement,” said Dan Hartman, program manager for the Gateway at NASA’s Johnson Space Center, using the acronyms for those two modules. “This is real. We’ve got contracts in place and real hardware is being built.”

The first of those elements is the Power and Propulsion Element (PPE), for which NASA selected Maxar Technologies to develop in May. The module, based on the company’s 1300-series commercial satellite bus, will provide power for the Gateway and electrical propulsion.

The PPE is on schedule for a launch in late 2022, after which it will perform a one-year checkout. He said NASA and Maxar are working through “integration things” caused by using a commercial spacecraft with NASA hardware. “There will be some changes, and we’re starting to work through those,” he said, but didn’t disclose the specific issues being worked on.

Besides providing power and propulsion, the PPE will also serve as a platform for other payloads. Two payloads will be installed on the exterior of the module when launched, he said. Hartman said the agency was considering several unidentified payloads to include on the PPE.

The PPE will have two refueling ports, he said. “The Europeans are very interested in launching a refueler, and so we think we can maintain a PPE with the hydrazine and xenon to keep it up and active for a very long time.”

The other module is the Habitation and Logistics Outpost (HALO), previously known as a utilization module or “mini-hab.” NASA announced in a July procurement filing that it intended to award a sole-source contract to Northrop Grumman to build the module after determining it was the only company that would be able to complete it in time to be used to support a 2024 human lunar landing.

Hartman said the company was already working on HALO. “Northrop Grumman is off building that, developing that module for us,” he said. NASA spokesperson Rachel Kraft said Sept. 17 that, while NASA is still negotiating a contract with Northrop for HALO, the company “was given limited authority to start work on urgent HALO-related requirements consistent with the Federal Acquisition Regulations.”

HALO will be based on the company’s Cygnus spacecraft used for International Space Station cargo missions; the company used that design in earlier work under NASA’s Next Space Technologies for Exploration Partnerships program. Hartman said HALO will have an extra section, or bay, compared to the current three-bay Cygnus used on cargo missions. That stretched version will provide more volume, he said, and also ensure adequate clearance for its docking ports.

“It is really the hub of the Gateway,” he said of HALO, noting its two axial and two radial docking ports, power distribution system and command and control systems. “It will be the brains of the outfit.”

HALO is scheduled for late 2023 launch on a commercial rocket, which has yet to be selected. HALO will then dock autonomously with the PPE, something Hartman said will also be true for later elements of the Gateway.

At launch HALO will serve as a cargo module, carrying a metric ton of cargo needed for the 2024 lunar landing mission and other purposes. That could include the spacesuits astronauts on that landing mission will wear on their moonwalks, if they’re ready in time. “Anything we can get up there that helps the overall upmass to be successful for that 2024 mission, we’re going to try to take advantage of.”

More routine cargo deliveries will be provided by commercial spacecraft under the Gateway Logistics Services program, which will be based on the ISS commercial cargo program. NASA issued a request for proposals for that program Aug. 16, with proposals due Oct. 1, and Hartman said that because of that ongoing procurement he could not discuss the program in further detail.

Future elements to be added to the Gateway, as part of what NASA calls “Phase 2” post-2024, will depend on what capabilities international partners decide to pursue. In an Aug. 28 statement, ISS partners said they supported development of the Gateway and were considering habitation modules, logistics facilities and airlocks.

“All these international partners have work to do with their governments, just like we have work to do with our government,” Hartman said. If their governments agree, he said the agreements would build upon the existing ISS intergovernmental agreement. “There are still a lot of discussions out there in front of us.”