The two elements that will form the initial Gateway capabilities for NASA’s Artemis campaign are preparing for system installations this year and next as the space agency reviews progress to set a new launch date. The Power and Propulsion Element (PPE) and the Habitation and Logistics Module (HALO) are being built on different continents to ultimately be launched together as the Gateway’s co-manifested vehicle (CMV).
NASA announced that the previously planned September 2025 launch of the CMV would be postponed; A new estimate is still being worked on, but the Conservative baseline commitment to Congress estimated that this could not be until December 2027. Meanwhile, Maxar is ready to begin installing PPE hardware, and HALO is now expected to arrive in Northrop Grumman’s Gilbert, Arizona. facilities by the end of the year.
First elements to complete structural assembly, and begin system integration
The Gateway will be a lunar space station that serves as a staging post for Artemis crews on their way to the moon’s surface. Orion crews will rendezvous and dock at Gateway in its dedicated Near Rectilinear Halo Orbit (NRHO) before transferring to a SpaceX or Blue Origin lunar landing spacecraft already at Gateway to head to the moon’s south pole.
The space station will be used differently than the International Space Station (ISS) in low Earth orbit. The ISS has been permanently manned since the beginning of this century, but Gateway is intended for crew care only and will remain unmanned for much of its life in space.
The PPE and HALO elements will be launched together on a Falcon Heavy rocket to begin Gateway operations, but the big question for several years is when that launch will occur.
An update recently provided by NASA notes that the PPE element structure was ready for installation of propulsion system components. Two pairs of propellant tanks have been delivered to main contractor Maxar and are in final preparations for installation. Installation of a pair of dual propellant tanks and a pair of Xenon Composite Overwrapped Pressure Vessels (COPV) is scheduled to begin this month.
The Xenon tanks will power the PPE’s solar electric propulsion systems (SEP). The development of high-performance SEP thrusters has been an important part of PPE.
Aerojet Rocketdyne’s Advanced Electric Propulsion System (AEPS) thrusters are now undergoing environmental qualification testing. NASA said vibration testing has been completed and will be followed by qualification shock and thermal vacuum testing. The environmental qualification test campaign for the bow thruster is expected to be completed by the end of the year.
An image of all planned Gateway elements. (Credit: NASA)
Plans are to deliver the first of three flight engines to Maxar early next year for later installation on the spacecraft.
Three AEPS thrusters and four Busek BHT-6000 thrusters will provide solar-electric propulsion for PPE. NASA says the qualification test campaign for those thrusters is underway and the four flight units are expected to be delivered to Maxar early next year.
The space agency says the standalone critical design review (CDR) of PPE was conducted in March.
The other element of the co-manifested vehicle is the HALO module. Originally designed as a standalone spacecraft that would be launched to intercept the moon and then rendezvous and dock with PPE in Gateway orbit, NASA decided in early 2020 to essentially dock the vehicles on the ground first and put them together to launch.
The HALO design has been modified to remove the self-contained spacecraft elements and retain the habitation modules. NASA says the HALO CDR was completed in June 2023.
The module structure is currently located at a Thales Alenia Space facility in Turin, Italy, where welding was completed in fall 2023. The structure is now undergoing structural stress testing ahead of a planned shipment from Italy to prime contractor Northrop Grumman’s factory in Gilbert, Arizona, sometime in the second half of this year.
Once the module structure is completed, the integration of fluid piping and wiring and the installation of subsystems begins.
NASA is working to determine a target launch date, conservative base estimates are for launch in December 2027
The two elements will fly together and the critical design review for the integrated spacecraft is now also scheduled for the second half of 2024. A fully expendable Falcon Heavy launch vehicle will carry the CMV into a highly elliptical orbit of 200 by 33,700 km.
The PPE will then begin a SEP-powered transfer from that insertion orbit to the moon. The spiral to NRHO is expected to take just over a year.
A presentation slide on the transfer path that the Gateway CMV will follow from its insertion into orbit to its final near-rectilinear halo orbit. (Credit: NASA)
The target launch date for the CMV is currently undefined. When NASA announced delays to the Artemis II and Artemis III launch dates in January, the space agency also announced that the previous target for the Gateway launch of October 2025 was being revised. Government Accounting Office (GAO) reports note delays in the PPE and HALO schedules, so a delay was not unexpected; However, no new target date has been specified.
A conservative estimate was provided as part of the Key Decision Point-C (KDP-C) program lifecycle evaluation. That review was completed in 2023 and the agency’s baseline commitments were disclosed with the FY 2025 budget request documents. “Gateway Initial Capability was approved with a base development cost of $3,562 million and a baseline milestone of Launch Readiness Date (LRD) in December 2027, with a joint trust
level of 70 percent,” according to the congressional document published on March 11.
NASA cited a disclaimer in announcing these cost and schedule baselines, specifically the projected dates, saying in the budget document:[Joint confidence level assessments] are used to track program performance. NASA continues to manage a more aggressive schedule.”
Historically, groundbreaking projects and programs, especially in the field of human spaceflight, have tended to delay their schedules.
The Gateway will support the Moon to Mars programs, starting with the Artemis IV mission, which is currently scheduled for no earlier than September 2028. Artemis IV is planned as both a Gateway assembly mission and a lunar landing mission. NASA’s Space Launch System rocket will launch Orion with the International Habitation Module (I-Hab).
According to the European Space Agency (ESA), welding of the I-Hab module structure should begin early in the last quarter of 2024, with completion scheduled for October 2025. Welding of the Lunar View module, formerly known as the European System Providing Refueling The Infrastructure and Telecommunications (ESPRIT) Refueling Module (ERM) is expected to launch in the same timeframe of October 2025; that module will be launched to the Gateway on the Artemis V mission currently scheduled no earlier than March 2030.
(Main image: The Gateway-manifested vehicle is depicted heading toward the moon in this artistic image. Credit: NASA)