Portal Space Systems, a pioneering startup, has introduced a novel approach to satellite mobility, focusing on using solar-powered spacecraft to heat propellant and generate thrust. This method promises to enhance the maneuverability of satellites in orbit.

Traditionally, satellite propulsion has been relegated to a secondary role, primarily used for maintaining position and conducting minor maneuvers once the vehicle reaches its intended orbit. However, Jeff Thornburg, the founder of Portal Space Systems, revealed that their focus will be on changing this dynamic by employing thermosolar propulsion. “Propulsion has been traditionally designed to keep satellites in a position, not to maneuver them,” Thornburg explained in an interview. He emphasized the challenges faced by commercial and military clients in managing the limited delta-v — a measure of a spacecraft’s capacity to change its speed — available before the end of their asset’s lifespan.

Delta-v, or “change in velocity,” is crucial for orbital maneuvers and is a key metric in astrodynamics. It represents the impulse per unit mass of the spacecraft. For example, a spacecraft with a delta-v capacity of 500 meters per second (1,120 mph), starting from zero, would reach that speed after consuming all its propellant. This concept is fundamental in the space industry, akin to a currency in the Solar System. It takes a significant amount of delta-v, nearly 10,000 m/s, to move from Earth’s surface to Low Earth Orbit (LEO), necessitating powerful rockets. Once in LEO, the delta-v costs to move further, such as to the Moon’s surface, are lower but still substantial.

Most satellites are launched with only about 500 m/s of delta-v, enough to adjust their orbits and perform basic maneuvers. However, this is insufficient for substantial orbital changes. Here, Portal Space sees an opportunity. The company is developing a spacecraft based on the concept of solar thermal propulsion, which uses solar energy to heat the propellant, generating the necessary thrust. These engines, studied for decades but never practically implemented, could revolutionize how satellites maneuver in space.

Thornburg mentioned that the chosen propellant could be stored in orbit and is non-toxic, unlike hydrazine, possibly resembling ammonia. Since founding Portal Space in November 2021, Thornburg and his team have been tackling the technical challenges associated with their Supernova satellite infrastructure. These spacecraft are expected to achieve remarkable mobility, with a delta-v capacity of 6,000 m/s, sufficient to transition between high Earth orbits and cislunar orbits.

This development could significantly impact the satellite industry by providing more dynamic and efficient ways to manage satellites, potentially extending their operational life and enhancing their capabilities in orbit.