JUST IN: Experimental Satellites Orbit Without Propulsion System

Red-Eye Satellite

A constellation of small satellites recently demonstrated the ability to move around space without the benefit of a propulsion system.

Millennium Space Systems, a subsidiary of Boeing that specializes in small satellites, showcased a host of capabilities on orbit with Red-Eye — a constellation comprising three 70-kilogram satellites. The spacecraft were built for the Defense Advanced Research Projects Agency to advance space-based small satellite technology needed for warfighters — including on-board data processing, avionics, crosslink communications and more, said Doug Hulse, the company's Red-Eye program manager.

Because the satellites were launched off the international space station, they were not given propulsion systems due to safety concerns, Hulse said. However, the company discovered that the spacecraft could be controlled using aerodynamic drag by adjusting the satellite’s solar arrays to move it through the small amount of atmosphere in low-Earth orbit, he told reporters July 20 during a media roundtable.

Aerodynamic drag is the force an object faces when moving through the atmosphere and normally causes satellites to deorbit slowly over time. Even with the low air density of low-Earth orbit, the air resistance from the atmosphere is strong enough to manipulate a small satellite’s position, Hulse said.

“With no propulsion at all and just by modulating our drag profile … they were able to drive them apart, pull them closer together, and really just control that spacing,” he said.

For example, if two Red-Eye satellites needed to move closer together to perform a crosslink data transfer, an operator from the ground could reposition the satellites’ solar arrays in a way so the aerodynamic drag closes the distance between them. Millennium also created a ground-based automation system that allows the constellation to self-control its orbital spacing, Hulse said.

Millennium’s program with DARPA began at the end of 2015. The company launched its first satellite shortly after it was delivered in 2019 and concluded the contract in December 2021, according to a company press release. 

Of the different capabilities Red-Eye demonstrated while in orbit, the most significant were real-time onboard processing of sensor data at the edge and various avionic technologies, Hulse said. The company has already leveraged some of the advancements made during the demonstrations and incorporated them into their other small satellites, he added.

Overall, the constellation showed that the technology for small satellites is available for national security missions, Millennium Space Systems CEO Jason Kim said during the roundtable. 

“There are a lot of unique benefits of a hybrid architecture of large, monolithic satellites that perform the high-performance missions that they need to, and then the augmentation of that with small satellite constellations,” he said. 

The Defense Department has shown its intent to use smaller-sized satellites to perform missions. Earlier this week, the Space Development Agency awarded two prototype agreements to teams led by L3Harris and Northrop Grumman for the establishment of its tranche 1 tracking layer of small satellites, according to a department press release. The tracking layer will provide detection, warning, tracking and identification of missile threats, including hypersonic missile systems.

Topics: Space