The number of satellites — both working and defunct — floating in space pose the risk for hazardous collisions, particularly in low Earth orbit where the majority of satellites are placed for applications such as Earth monitoring and internet constellations.

To potentially prevent the risk of orbital collisions, a team of researchers from TNO High Tech Industry are proposing that satellites be outfitted with laser-activated license plates.

The approach, according to the researchers, could allow for the identification of satellites from the ground via laser technology. For instance, the technology would still be able to track satellites even when they run out of fuel or power, thereby potentially reducing the opportunity for collisions.

Working much like a traditional vehicle license plate system, the proposed Satellite License Plate (SLP) system is expected to function as a unique satellite identifier, using small cubic mirrors with light filters that uniquely reflect laser light.

The team further explained that the SLP system’s spectrally coded retroreflecting tags are mounted on satellites where they reflect light in precise spectral patterns that can be decoded for the purpose of identification.

Optical ground stations can reportedly fire a laser at the mirror tags, transmitting laser beams to the target spacecraft at different wavelengths, while the light reflected can reveal the identity of the satellite.

An article detailing the SLP system, “Satellite License Plate: passive and compact optical spectrally-based identification method for satellites,” appears in the journal Communications Engineering.