Impulse Space

Mira is a small orbital maneuvering vehicle that carries up to 300 kilograms and gives it between 550 and 850 metres per second of delta-v from eight thrusters burning nitrous oxide and ethane. Helios is the larger idea: one restartable methalox engine producing 67 kilonewtons, sitting on as much as fourteen tonnes of propellant, sized to move a four-tonne satellite from low orbit to geostationary in under a day. Electric tugs take months to make the same trip. That difference is what Impulse charges for.

Tom Mueller was SpaceX's first employee and designed the Merlin, Draco and SuperDraco engines. He started Impulse on the view that launch had already been solved and made cheap while everything after separation had not, so the next bottleneck is moving things around once they are up there. Enough of the industry agrees that Vast buys its station thrusters from Impulse, and Starfish Space flew an autonomous rendezvous against a Mira in late 2025.

Mira has flown three times. Helios has not flown at all, and its first flight has moved from early 2026 to mid-2026 to, in some reporting, 2027. Its published payload capacity has moved in an unusual direction too: over five tonnes in the January 2024 specification, four tonnes in later coverage, and no number at all on the current product page. Underneath sits a physics problem, because a stage loaded with fourteen tonnes of cryogenic methane and oxygen before launch loses propellant to boiloff the longer it loiters. Every Impulse vehicle so far has ridden a Falcon 9 with no alternative qualified, which makes SpaceX at once the company's only road to orbit and, if Starship reaches cadence and inserts payloads directly, the most credible threat to the whole business.