Impulse Space is developing a “kick stage” it calls Helios, which can provide up to 9 km/s of delta-V to a payload, rapidly boosting it from low-Earth orbit to geostationary orbit about 36,000 km above the Earth’s surface. Essentially, this allows the company to transform a medium-lift rocket, such as SpaceX’s Falcon 9 vehicle, and give it the performance of a larger and more powerful rocket.
Helios still under development
Under Lane 1, Impulse Space will contract with the Space Force to provide end-to-end service, procuring a launch vehicle and then stacking the Helios stage and designated satellite into the payload fairing of the rocket. Helios is compatible with a range of rockets, from the Falcon 9 to boosters built by United Launch Alliance, Rocket Lab, Relativity Space, and more.
To be eligible to bid on Lane 1 contracts, Impulse Space must first successfully demonstrate Helios in flight. Following a post-flight review by the US Space Force, Impulse can seek to win task orders. Launches could follow 18 to 24 months later.
According to Romo, the development of Helios continues to progress well. The company recently shipped a “run tank” to its test stand at the Mojave Air & Space Port in Mojave, California. A run tank is designed to be loaded with propellant many times and put through a series of rigorous tests to ensure its ability to hold pressure and perform in flight. A flight tank is typically lighter, as it will not be subjected to the wear and tear of multiple uses in flight.
Romo also said the “Deneb” engine that powers the Helios vehicle is doing well in testing. Powered by liquid oxygen and methane, Deneb has a thrust of 15,000 pounds. The company is targeting a 2027 debut of Helios in flight, launching on a Falcon 9 rocket.
Impulse Space and Relativity Space are the newest companies to be on-ramped to Lane 1 of the national security launch program. Rocket Lab, with its Neutron rocket, and Stoke Space, with the Nova vehicle, were added in March 2025. SpaceX, United Launch Alliance, and Blue Origin were the original awardees in 2024.
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