Impulse Space Inc. today announced that it has closed a $500 million late-stage investment led by 137 Ventures and BANNER VC.

The Series D round brings the company’s outside funding to over $1 billion.

The cost of launching a satellite depends on the altitude at which it’s designed to operate. Sending a payload to low-Earth orbit, or LEO, is significantly cheaper than deploying it in more distant stretches of space. The reason is that reaching higher orbits requires more powerful rockets, which are pricier to build and operate.

Impulse Space is working to lower the cost of high-altitude satellite launches. The company is developing a space vehicle called Helios that can move satellites between different orbits. According to Impulse Space, a customer could launch a satellite into LEO aboard a relatively low-cost rocket and then have Helios ferry the system to a higher altitude.

It’s already possible to raise the orbit of satellites, but the electric propulsion systems used for the task are slow. An altitude change can take six to nine months. That delays space projects and requires the satellite being moved to spend an extended amount of time in regions of space with strong radiation, which can cause malfunctions.

Impulse Space says that Helios is significantly faster than the competition. It can move a satellite from LEO to a geostationary orbit, which corresponds to an altitude of about 22,200 miles, in under a day.

The vehicle is also capable of covering larger distances. Last year, Impulse Space announced its intention to develop a lunar lander that can transport three tons of cargo to the moon. The plan is to launch the system into LEO and then use Helios to move it into a low lunar orbit. The company estimates that the trip will take about a week.

Helios travels through space using an engine called Deneb that is fueled by liquid oxygen and liquid methane. The motor was developed by Impulse Chief Executive Officer Tom Mueller, who founded the company in 2021 after serving as SpaceX Corp.’s chief technology officer of propulsion.

The company also has a second custom engine called Saiph. It powers a space mobility vehicle known as Mira that can be attached to satellites to improve their maneuverability. A weather monitoring satellite, for example, could use Mira to follow a fast-moving atmospheric phenomenon. 

“From Earth orbit to the Moon and beyond, the ability to move quickly, precisely and affordably on orbit is the fundamental capability that will unlock a true space age,” Mueller said. 

Impulse Space has flown two Mila missions to date. Last August, it debuted an upgraded version of the system with enhanced thrusters and solar arrays that can track the sun to increase power generation. Additionally, the company enhanced the onboard software to automate certain tasks that previously had to be performed by engineers on the ground.

The newly closed Series D round will enable Impulse Space to hire more employees and grow its manufacturing capacity. The company plans to launch Helios next year, with trips to the moon set to follow in 2028. Impulse Space says that it has secured customer contracts worth hundreds of millions of dollars.

Image: Impulse Space