The Space Force is launching lasers into orbit
The Space Force aims to better pinpoint the location of Earth’s true centre using lasers on GPS satellites, slated to launch in 2025. A set of Laser Retroreector Arrays, or LRAS, will be installed onto two GPS III satellites, SV9 and SV10, as part of NASA’S Space Geodesy Program. The lasers are designed to make precise sub-centimetre measurements using a technique called Satellite Laser Ranging, which will allow researchers to more accurately determine Earth’s centre.
On 6 May 2024, the LRAS were delivered to Lockheed Martin to be integrated with the satellites ahead of launch. The mission is a partnership between the Space Force, the National Geospatial-intelligence Agency and NASA. “We were able to add new capabilities to the GPS constellation years ahead of schedule while ensuring the billions of people who rely on our signals daily would be unaected,” said Space Force Colonel Andrew Menschner. “We expect LRAS to be standard on future GPS vehicles and are pleased that SV9 and SV10 will have the capability prior to launch.”
Laser ranging relies on small bursts of laser light to detect distances between objects. Pulses of laser light from a ground station are directed towards an orbiting satellite equipped with the LRAS, which then reect the light beams back to their original source. With this data, the time it takes for the laser light to travel from the ground to the satellite and back again can be used to calculate the distance between the satellite and the ground. The light is reected using three mirrors positioned at right angles, forming the inside corner of a cube. The LRAS consist of an array of 48 of the mirrored corner cubes, ensuring that the beam of light is reected back out at the same angle it came in at.
The LRAS were built by NASA and the Naval Research Laboratory’s Naval Center for Space Technology and will be operated by the US Space Force. Having accurate positioning information is essential to nd the centre of the mass of Earth, which can undergo small changes following events like tsunamis and earthquakes. Therefore, the data collected by the LRAS will allow researchers to more accurately measure how the world is changing. “GPS III putting two new reectors in orbit next year shows how quickly we are able to upgrade capabilities,” Menschner said. “This success is an incredible tribute to the outstanding talent, mission focus and partnering across the entire team.”