Dec 30, 2022

Power Games

The Little Engine That Could


Mike Cassidy is an astropreneur whose small electric thrusters move big things in space.


By Robert C. Jacobson


Correcting the course of an orbiting satellite is at once relatively simple and maddeningly complex. The simple part: Given weightlessness and the lack of friction, a force equal to the weight of a paperclip can push a small satellite back to its proper orbit. The complex part: developing a thruster that is lightweight enough, powerful enough, and, precise enough to accomplish this. It’s a problem so vexing that the makers of the roughly 4,500 small satellites currently aloft didn’t bother trying. When those satellites drift off course, they’re toast.

But solutions to this problem and others like it are being developed by a diverse group of entrepreneurs—call them astropreneurs —who come from a wide variety of backgrounds. Mike Cassidy is one of them. With degrees from MIT, Harvard, and the Berklee College of Music, Hughes Aircraft experience, three decades in tech, and five startups behind him, Cassidy is in many ways both a surprising and expected candidate to solve the satellite propulsion problem.

In 2016, Cassidy had founded Apollo Fusion to create clean, plentiful energy through nuclear fusion: the same process that powers the sun. Yet after several years of rapid improvements, Cassidy saw that progress was slowing and he recognized that the technology his startup was developing could be used to propel spacecraft. He pivoted his company’s focus to design a Coke-can-sized solar-powered thruster for small satellites. Last June, Cassidy sold Apollo Fusion to Astra for a cool $50 million. Two months later, Astra successfully deployed Apollo’s electric propulsion thruster on a satellite in a proof of concept demonstration.

“It’s not an overstatement to say that this fundamentally changes the smallsat market,” Cassidy told Space Flight, a Seattle-based launch services company, after the test. “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 earning an undergraduate degree from MIT in 1985, and a master’s degree the following year from there as well, Cassidy worked on communication satellites and rockets at Hughes Aircraft Company. He developed software for the Sunraycer, General Motors’ solar-powered car for which Hughes supplied a power system. Cassidy’s software was able to “simulate racing conditions and predict vehicle performance.” The vehicle won the ​​1987 Solar Challenge race in Australia and is on permanent display at the Smithsonian Museum of American History.

Despite this success, Cassidy says he felt “let down” at the glacial pace of innovation within the aerospace industry. At the time, microcomputing was a growing tech sector and he seized the opportunity to co-found his first business, Stylus Innovation, with Krisztina “Z” Holly and John Barrus, two classmates from MIT. (Cassidy also earned an MBA from Harvard in 1991.)


The trio invented technology described by a Lemuelson-MIT publication as “a system that enabled a user to scan bar codes to order such items as groceries, before the Web became popular.” They also created complex telephone systems: think creation of voicemail, automatic call answering, faxes—years ahead of similar web-enabled systems. Their company was acquired for $13 million by Artisoft in 1996.

Cassidy then hit pause. He enrolled at Berklee College of Music in 1997 seeking to become a producer. He fondly recalls a studio production class where he had the opportunity to learn every role in the making of a pop album—useful practice for founders who wear many hats. “One day you're the producer, and you say things like, gosh that song stinks or that song is off the album. Then the next week you're the low man on the totem pole getting people coffee, wrapping up wire cables, so you learn all the phases.”


He was also enamored by jazz improvisation where musicians create compositions and interact with each other in real time. He believes that there might be “some correlation” between jazz and starting a company. “Improvisation is a lot of what you do as an entrepreneur. You start with an idea; you start with the team. It's going to go great, and then problem number one out of the 10,000 problems you face hits you. We're going to have to improvise. We have to solve this, we have to fix this problem, and we have to move quickly.”


Despite his love of music, Cassidy’s experience with Stylus Innovation had hooked him on being an entrepreneur. He started a search engine called Direct Hit which he sold for $532.5 million to Ask Jeeves in 2000, just 500 days after launch. Cassidy then founded two more tech companies: Xfire, an instant messaging platform for the gaming community, which he sold to Viacom for $110 million in 2006, and Ruba, a visual travel guide, which he sold to Google for an undisclosed amount in 2010.


The sale of Ruba landed Cassidy at Google, where he served as a technical lead on the company’s main search engine. He explains that he “grew restless after one and half years, but instead of leaving Google, [he] got excited about GoogleX and became the Project Leader for Project Loon.”

Project Loon sent balloons 60,000 feet above Earth and used them to beam internet access to unconnected parts of the planet. “There are a billion people in Africa and only 100 million of them have the internet,” he says. “There are 1.3 billion people in India and only a couple hundred million have the internet.”


Cassidy describes his four and a half years at Project Loon as representing “a kind of a return to my aerospace roots.” Some of its accomplishments include laser communications between balloons, the use of artificial intelligence to pilot them, and a duration record of 312 days for a balloon being aloft. While Alphabet (formerly Google) wound down Project Loon in 2021, technology from the endeavor continues to provide Internet connectivity to Kenya, the Republic of the Congo, and the Democratic Republic of the Congo.



Perhaps spurred by GoogleX’s moonshot philosophy, Cassidy founded Apollo Fusion to imitate the way stars produce energy. Fusion, which requires a great deal of energy to fuse hydrogen atoms at extremely high temperatures under enormously great pressure in order to create energy, is a potentially clean source for electric power. No greenhouse gases and no radioactive waste.


But much like other people attracted to the promise of fusion, Cassidy ran into difficulties producing more energy from the process than the process itself required. “We didn't reach breakeven from an energy standpoint. We weren't getting more energy out than we're putting in,” he says. He explains that his team was improving an order of magnitude of 10x every quarter but as time went on the rate of progress slowed to 10-percent a quarter.

Lacking funds to continue pursuing energy breakeven, the Apollo team set their sights on a different challenge. Cassidy explains that “the plasma physics associated with nuclear fusion is actually very similar to the plasma physics associated with the type of Hall effect” which can be used as electric propulsion for spacecraft.


In very simple terms, the Hall effect describes the way a magnetic field arises from voltage differences between an electric current and a conductor. The resulting magnetic field can be used to supply electricity to an attached device, like a small thruster on a satellite.


“The nice thing about electric propulsion is that you can use big solar panels in space and you can take the energy from the sun to power your little electric propulsion engine,” Cassidy says. Electric propulsion also held the promise of being lighter and more compact than chemical propulsion alternatives, a critical consideration when sending mass into space. Apollo Fusion soon developed two electric propulsion engines, one requiring 400 watts of power and a larger one requiring 1,400 watts.


“Our coke [can] sized thruster produces the amount of thrust approximately equal to the weight of a paperclip. The weight of a paperclip is the only amount of force coming out of this little thruster,” explains Cassidy. “But the thing is in space,  there's nothing resisting it. You can accelerate at .01 meters per second squared for 100,000 seconds —about 1 day, and you will be going quite fast at the end—1,000 meters per second or 2,000 miles per hour.”

Apollo Fusion’s engines meet an urgent need of the booming small satellite industry, which generated $271 billion in 2020. More than 1,100 of these satellites—about 40-percent of all satellites in operation today—were launched in that year alone. However, these small satellites were designed without thrusters because they were generally too small to make use of chemical propulsion.


With electric propulsion, more precise satellite delivery is possible. “Many of the communication satellites get dropped off in low Earth orbit about 500 kilometers up, “ Cassidy says. But “they want to be in a final orbit maybe at 800 kilometers or 1000 kilometers, so you can use this little engine, this little electric propulsion engine and you can slowly—may take a month or two—boost up to your final orbit.”



Investors poured $7.6 billion into space companies in 2020, a TK-increase  from TK-years earlier. One early beneficiary of this activity has been Astra, an Alameda, California based rocket company, which in June 2021 acquired Cassidy’s Apollo Fusion. Astra then received an infusion of $500 million as part of a special-purpose acquisition company the following month. (For more on Astra, see “They Build Rockets Here,” page TK.) 


Last November, Astra filed an application with the Federal Communications Commission to build a constellation of 13,620 satellites and offer global Internet connectivity. It’s an audacious goal given that there are only 4,550 or so satellites operating today, and it comes with a public benefit that appeals to Cassidy. “It's very much like Loon,” he says, but instead of balloons they use satellites to bring the internet all around the world. We still have the same problem that Loon didn't finish solving.”

Cassidy is keen to  imagine the applications that would come from bringing the Internet to billions of people. “It's very inspiring to think about the second-order effects. As a team, we try to focus on the basic things that it can bring, for example, weather reports. There are many places in India or Africa or other places where they don't have weather reports.”


While joining Astra represents an opportunity to tackle some unfinished business, Cassidy remains intrigued by the possibility of developing fusion energy. “If you can do it,  it's amazing!” he says excitedly. “Two trillion dollars a year just generating electricity. And we could solve global warming, too!” Starry-eyed talk, sure, but the stars are where Cassidy finds inspiration for useful technologies here on Earth— and beyond.


Special thank you to Blaise Zerega for his help and support.


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