Portal Systems Is Planning To Use Sunlight To Move Spacecraft - Here's How

Mobility in space continually cements itself as important in this modern era of space exploration, with satellites like Starlink, Amazon's upcoming Project Kuiper, the International Space Station, and more in orbit. Moving spacecraft and maintaining things in the various orbits around Earth is an increasingly complex and busy field. Now, a young startup called Portal Systems looks to disrupt that industry by offering an alternative power source: sunlight.

Portal Systems was founded in 2021 by Jeff Thornburg, an Air Force vet who's worked for Amazon, SpaceX, and NASA. It boasts that its spacecraft, called Supernova, will be highly maneuverable, able to deliver payloads, and rapidly respond to changing needs. It also will be able to perform maintenance and remove debris. Driving all of this is a solar propulsion system.

Supernova will use mirrors to concentrate sunlight onto a thermal battery. That thermal energy can then be harnessed by a proprietary 3D-printed integrated heat exchanger and thruster (Portal Systems calls it a HEX thruster). Ammonia then passes through the HEX thruster, expanding from the absorbed heat, and being used to maneuver the satellite. Portal Systems believes this process will make Supernova an innovative game changer in inter-orbit mobility. There are plans for a 2026 launch, and while this isn't the first time sunlight has been considered as a power source for spacecraft, not everyone agrees that this is the future for space.

Portal Systems sees itself as meeting three distinct needs in space. First, it will work with commercial operators for orbital maintenance and servicing. Second, it will further scientific endeavors through delivering payloads and repositioning craft in orbit. Third, it will contribute to national security efforts by monitoring orbits for potential threats and responding to them quickly. This might become increasingly important in the future since, even though Russia's rocket engine development is struggling, the country has plans to create its own international space station and separate itself from space collaboration.

Portal Systems believes its technology and business plan puts it in an ideal place to accomplish these goals. It has an 8,000 square foot research and development site in Washington state. It has $20 million in venture capital funding to support its mission. It's partnered with leaders in the industry including the United States Space Command, the Aerospace Industry Association, the United States Space Force, and more. It also has plans to complete a 50,000 square foot manufacturing by the end of 2026, enabling Portal Systems to produce one spacecraft per month. That's quite the lofty goal. 

Portal's new HEX thruster is potentially better than traditional spacecraft engines because it uses solar heat instead of combustion to create powerful, efficient thrust. Thus, it can move between orbits quicker than chemical or electric systems. By heating a simple, storable propellant inside a 3D-printed heat exchanger, it can undertake long missions without running out of fuel. 

Thornburg believes this technology is the future for space. Some agree, citing this move by Portal Systems offers a variety of benefits including better deep space exploration due to ongoing propulsion energy from the sun, easier transportability of craft to far locations like the moon or Mars, and lower risk of in-space collisions due to the high maneuverability goals of Supernova.

Others aren't so sure. Solar thermal propulsion would just be another type of propulsion system used in space, and not necessarily something that disrupts the way the industry functions. There is also the problem of this deviating from the standard. Space exploration is an extremely expensive endeavor. If something goes wrong, the company can lose massive amounts of money. Though some loss is just considered part of the risk, like Starlink satellites falling from the sky before making it to orbit, this type of propulsion might still worry those that are more risk-averse.

Portal Systems certainly has a lot to prove. Though the company is young, its rapid timeline for an operational satellite puts the spotlight on it. Come 2026, we'll see if this solar thermal propulsion system can do everything it's claimed it will be able to. If so, the next era of space mobility will be an exciting one.