New technology will help satellites avoid collisions in space

Space is becoming more crowded every day, with over 11,000 active satellites and nearly 40,000 pieces of debris in low Earth orbit. But Los Alamos National Laboratory has just demonstrated a new, patented technology called Extremely Low Resource Optical Identifier, or ELROI, that gives the space research community an innovative way to track satellites and avoid costly collisions.

“With all these objects flying around at more than 17,000 miles per hour, it is vital to avoid collisions,” said David Palmer, scientist at Los Alamos and lead on the ELROI project. “When two space objects collide, they can release thousands of fragments, each of which might hit other objects, causing a chain reaction that can fill orbital space with debris and destroy the satellite systems we rely on.”

There are many organizations that track things in space. For example, the U.S. Space Force operates a system of telescopes and radars to watch the skies, along with many commercial companies and other international organizations. When they see two satellites in danger of crashing, they contact the satellite operators to warn them. But this only works if the observers know the satellites’ owners.

To a telescope or radar, a satellite is just a dot of light or a blip on the screen.  There is no general way to know which satellite it is just by looking. Instead, they have to use a variety of methods to make an initial identification — easy to do if a rocket drops off a single satellite, but more difficult when some rocket launches release more than a hundred satellites at time. When a hundred or more satellites are sent into orbit on a single launch, spending weeks figuring out which is which cuts into the limited lifetime when the satellite could be doing something useful. And after a satellite is identified, it must be repeatedly re-observed and matched to its previous track to maintain the identification, often on a weekly basis. If too long passes between observations and it drifts out the expected orbital location, it may be misidentified, unrecognized or lost.

ELROI can help solve these problems. The device is a small light that can be attached to anything that goes into space, which then blinks out a “license plate number” code that uniquely identifies satellites. The low-power device only emits as much light as the power-on LED on an at-home electronic device, but it uses a series of novel algorithms that let it be detected and read out from a thousand kilometers away with a small telescope.

The power can be supplied by a few square centimeters of solar cell and sustained by a rechargeable battery a few millimeters thick; this allows the entire device to be the size of a thick postage stamp. The satellite operator can simply attach it to the outside of the satellite and, once in orbit, it operates without any further effort.

“ELROI is cheap, tiny, self-sufficient and easy to attach to anything that goes into space,” Palmer said.

The system was tested on two launches in 2024, and in both cases, ELROI successfully identified the satellite before the operator knew which one it was.  

“For the second launch there were eight objects in space, but nobody knew which was which. I looked at all eight as they passed over our telescope, and within 48 hours, I had the data that identified the ELROI-carrying satellite,” Palmer said.

LA-UR-25-21529