HALO
A FIELD GUIDE TO THE LUNAR GATEWAY
Ten chapters on the small international space station designed for a strange, elegant lunar orbit no spacecraft had ever occupied — and on its very recent pause, with real hardware already built and nowhere yet decided to send it. Scroll to begin.
BEGIN — CHAPTER 01 →Not permanently crewed, and not meant to be
The ISS is always occupied, resupplied every few weeks, and reachable by a rescue vehicle within hours. Gateway was designed for the opposite environment: visited by four astronauts for roughly thirty days at a time during Artemis missions, then left to operate autonomously — sometimes for months — far outside Earth's protective magnetosphere.
That meant designing systems that could diagnose their own faults and work around them, with no possibility of a repair crew launching within days the way the ISS has always allowed.
A one-week loop that costs almost no fuel
Gateway's chosen path is a near-rectilinear halo orbit — a highly elongated loop around the Moon that swings within roughly 1,500 km of the lunar surface at its closest and out to about 70,000 km at its farthest, taking about 6.5 days to complete.
It's a close cousin of the same family of orbits governed by the Lagrange-point physics of the Earth-Moon system — stable enough to hold with very little propellant, while keeping constant line of sight to both the lunar south pole and Earth.
Five modules, built by five different agencies
Only the first two elements were ever completed. Select a component to see its planned role.
Four space agencies, one small station
Like the ISS before it, Gateway was structured as an international barter — each partner contributing hardware in exchange for crew time and access, rather than cash.
The most powerful solar-electric spacecraft ever built
The Power and Propulsion Element generates roughly 60 kilowatts from its solar arrays — enough to make it the most powerful solar-electric spacecraft ever flown — and uses that power for high-efficiency ion thrusters, holding Gateway's position in NRHO with a fraction of the propellant a chemical rocket would need.
Built by Maxar (renamed Lanteris Space Systems), PPE also carries Gateway's primary communications and attitude-control systems — everything else on the station depends on it working.
A pressurised cabin built on two continents
The Habitation and Logistics Outpost was to be the first place astronauts actually lived aboard Gateway — its pressurised structure built by Thales Alenia Space in Turin, Italy, then shipped to Northrop Grumman in Arizona for final outfitting with life support, docking ports, and cargo space.
Unlike the ISS, which has hosted continuous crews since 2000, HALO was designed around intermittent occupancy — roughly month-long stays timed to Artemis surface missions, with the station otherwise running unattended.
Outside the magnetosphere, on purpose
Paused, not officially cancelled
On March 24, 2026, NASA paused Gateway "in its current form," redirecting roughly $20 billion toward a faster, surface-first lunar architecture — the same restructuring that pushed Artemis III to an Earth-orbit lander test and made Artemis IV the target for the first crewed landing since Apollo.
By that point, NASA had already committed over $5 billion in prime contracts for PPE and HALO alone, on top of billions more in international hardware contributions — investment that didn't disappear, even if the station's future did become uncertain.
Two nearly-finished modules, no confirmed destination
Figures below reflect the state of the pause as of mid-2026 and are illustrative — several partner decisions remained pending.
An idea that outlasts its own timeline
Whatever becomes of PPE and HALO specifically, the underlying idea — a durable staging point in deep space, built once and reused for years — is very unlikely to disappear from lunar and Mars planning entirely.