SpaceX launched its ninth “Transporter” mission on Saturday from California, carrying dozens of small- and medium-sized satellites into low-Earth orbit.

The upside of these launches for customers is that they can rely on regular, low-cost access to space aboard the reliable Falcon 9 rocket. The downside is that the satellites are all released into a basic orbit, and if they want to reach a different altitude or inclination, they have to bring their own propulsion along for the ride.

This has led to the advent of “last mile” services from various companies offering small add-on spacecraft capable of providing in-space propulsion. One of the most intriguing of these is Impulse Space, a company founded two years ago by rocket scientist Tom Mueller, who was a founding employee at SpaceX before leaving in 2020.