Meet Halo, The first module of NASA’s Gateway Lunar space station

The Apollo lunar missions worked by using a spacecraft in two parts. The Command and Service Module (CSM) and the Lunar Module (LM) traveled together from the launch pad at Cape Kennedy to lunar orbit a quarter of a million miles from here. Once there, the Lunar Module separated and descended to the Moon’s surface.

While Neil Armstrong and Buzz Aldrin were putting the first boot prints in the lunar regolith, Michael Collins was holed up in the CMS, waiting to rendezvous with the away team and return home. It’s been over 50 years since then, but when humanity returns to the Moon with the Artemis program, astronauts orbiting in lunar orbit will have somewhere a little nicer to hang their helmets.

The HALO module will serve as the heart of the upcoming Gateway lunar space station, and it’s almost ready for showtime.

What is Gateway, NASA’s Lunar Space Station?

Like the International Space Station, Gateway will provide a pressurized and livable environment for astronauts to work in space. Unlike the ISS, Gateway will orbit much farther away and provide regular access to the lunar surface. It’s a space-based architectural project nearly on par with the interstellar crafts of The Ark (streaming now on Peacock).

The Gateway station will be built in stages, but it begins with HALO and its traveling partner, the Power and Propulsion Element (PPE). Both modules will be joined together into one integrated spacecraft at NASA’s Kennedy Space Center and strapped to the top of a Falcon Heavy rocket. Once off Earth, HALO and PPE will take about a year to settle into a near-rectilinear halo orbit around the Moon.

Rather than having a mostly circular orbit like a planet, Gateway will have an oblong orbit like a comet. Most of the time the station and its crew will hang out in deep space, as much as 43,500 miles from the Moon, but once a week it will swing in for its closest approach, just 1,000 miles above the lunar surface. This peculiar orbit marries the benefits of a wide orbit (lower fuel requirements) with the benefits of a low orbit (access to the surface).

Gateway is intended as an orbiting research facility, a staging ground for lunar surface activities, and a stepping stone toward crewed missions to Mars.

What is Gateway’s HALO module?

Short for Habitation and Logistics Outpost, HALO is the first habitation module for the Gateway station. The module, which was manufactured by Thales Alenia Space in Italy, recently completed the first leg of its journey to the Moon. On April 1, 2025, following a quick flight across the Atlantic and across most of North America, HALO arrived at Northrop Grumman’s integration and test facility in Arizona.

The module provides space for astronauts to live, work, do space-based research, and prepare for surface activities on the Moon. It also provides docking ports for visiting spacecraft, resupply missions, and lunar landers.

While in Arizona, the HALO team will install propellant and electrical lines, attach radiators for thermal control, and mount racks to house life support hardware, flight computers, avionics systems, and other crucial spaceflight equipment. Once finished, HALO will also feature an Internal Dosimeter Array (IDA), the Heliophysics Environmental Radiation Measurement Experiment Suite (HERMES) and European Radiation Sensors Array (ERSA) to measure and study the effects of cosmic radiation in a unique lunar environment.

Meanwhile, the aforementioned Power and Propulsion Element (PPE) is being assembled at Maxar Space Systems in California.

The PPE is a vast solar electric plant of the same type used on NASA’s asteroid-punching DART mission. Two sprawling solar arrays, each about the size of a football field’s endzone, collect sunlight and convert it to electricity. The system generates 60kW of power, enough to keep all of Gateway’s subsystems fed, in addition to powering the station’s solar eclectic propulsion system. Electricity generated by the PPE is used to ionize xenon gas, then those ionized atoms are fired away from the craft to generate thrust and keep the station in orbit. Onboard batteries provided by JAXA will keep the station in power during eclipse periods when the solar panels won’t get enough sunlight.

Both modules will be connected together at Kennedy Space Center in Florida and launched as a single integrated spacecraft no earlier than September 2028, as a part of Artemis IV.

Later missions will integrate additional modules, including the ESA’s Lunar I-Hab. Taken together, astronauts will be able to live and work around the Moon for about 30 days, splitting time between orbital operations in deep space and surface operations at the lunar South Pole.