Question: What do you get when you take a Silicon Valley startup approach to aerospace development?
Answer: Apollo Fusion’s electric propulsion systems heralded as part of a game-changing solution to transport smallsats to LEO, MEO, GEO, or beyond.

Mike Cassidy was never one for taking a traditional approach to business. The once-Berklee College of Music jazz pianist major also has two degrees in aerospace engineering from MIT. After moving to the West coast, Cassidy absorbed an appreciation for Silicon Valley’s rapid innovation and entrepreneurism with stints in Internet search and video gaming. “However, my roots in physics were calling. With my appreciation for how Silicon Valley operates and a booming space industry emerging, I was ready to return full circle to aerospace with my new learnings in tow,” he adds.
One key lesson Cassidy, now CEO and co-founder of Apollo Fusion, took away from his Silicon Valley entrepreneurial experiences and applied to aerospace development was how to assemble an all-star team. Today, Apollo Fusion’s management includes experts from SSL, SpaceX, OneWeb, Planet and others. Collectively, they’ve designed and flown hardware flying on more than 1,900 satellites in orbit today and bring over 100 years worth of Hall thruster experience.
Another key differentiator in the Valley was the rapid pace of research and development. To that end, Apollo Fusion runs four vacuum chambers, conducting tests every day at its facilities. “We do all the design and testing in our innovation labs and then hand-off to a proven traditional aerospace manufacturer to make the flight hardware. We’re in lock-step with them throughout the entire process which ensures we’re rapidly innovating and creating a quality product. From day one, our business plan was to supply constellations of propulsion systems and this fast-turn approach makes that a reality.”

By definition, an electric propulsion (EP) system uses energy collected by solar arrays eliminating many of the needs and limitations of chemical propulsion. EP can reduce the amount of fuel, or propellant, needed compared to chemical propulsion systems, saving millions in launch costs while providing greater mission flexibility. “If you’ve ever built or paid for a spacecraft to launch, you know that every kilogram of mass matters,” adds Cassidy. “Our system is extremely compact and lightweight — about a third the size of chemical systems.”
Apollo Fusion currently offers two versions of its Apollo Constellation Engine (ACE): one that uses 400 watts of power and the other 1,400 watts. The plasma physics the company uses in its propulsion products is similar to the technology they’ve explored for fusion power. “We believe this technology still has potential for a revolutionary fusion power plant to serve safe, clean, and affordable electricity to everyone.”
It’s getting noticed.
The company recently signed deals with York Space Systems, providing its propulsion system for at least 10 low Earth orbit satellites to launch in 2022. The follow-on for this program would have up to 150 satellites in orbit.
Apollo Fusion’s first thruster will fly mid-2020 as the propulsion system aboard Spaceflight’s Sherpa-LTE1, scheduled to launch on SpaceX’s Transporter-2 (Spaceflight’s SXRS-5) mission. “Working with Spaceflight on our first flight together has been a joy,” says Cassidy. “Our teams share a supportive, collaborative, and problem-solving approach — we’re very in sync in our approach.”
The Sherpa-LTE orbital transfer vehicle (OTV) is the industry’s first-ever electric propulsive vehicle, with Apollo’s high specific impulse (Isp), xenon propellant, electric propulsion system on board. The solution provides a low-cost alternative to purchasing full direct-inject launch vehicles and will extend the ability of small launch vehicles currently under development to reach beyond LEO.
“It’s not an overstatement to say that this fundamentally changes the smallsat market,” adds Cassidy. “The combination of Spaceflight’s next-gen Sherpa OTVs combined with Apollo Fusion’s propulsion can now take spacecraft to any orbit — from LEO, MEO, GEO, lunar or beyond. It’s a game-changer for smallsats who used to be confined to the standard rideshare orbits; now they’re free to chart their own destiny.”
After deploying customer spacecraft from the SXRS-5 mission, Sherpa-LTE1 will fire up and travel to different orbital destinations, testing several maneuvers in space. “We’ve already conducted many ground simulations and analyzed thousands upon thousands of data points, but nothing beats the opportunity to study the performance measurements in space. We’re ready.”