The US Space Force plans to use lasers on new GPS satellites, launching in 2025, to find Earth’s exact centre more accurately, reports Space.Com.
Earth’s Centre and Geodetic Measurements: As we know, Earth’s centre, also known as the geocentre, is the point at the very core of our planet. It is located about 6,371 kilometres (3,959 miles) beneath the surface, roughly equidistant from all points on the Earth’s surface. This geocentre is the reference point for many geodetic measurements and satellite orbits, helping scientists understand Earth’s shape, gravity and movements more precisely.
Geodetic measurements refer to the methods and techniques used to determine the exact positions and shapes of points on Earth’s surface. This field, known as geodesy, involves measuring distances, angles and elevations to create accurate maps and models of Earth. These measurements help in understanding Earth’s shape, size, gravitational field and how it changes over time due to such factors as tectonic movements and sea-level changes.
NASA Enhances GPS Accuracy with Lasers: NASA’s Space Geodesy Program will place Laser Retroreflector Arrays (LRAs) on two GPS III satellites, named SV9 and SV10, to improve their space sensor network. The lasers use a method called Satellite Laser Ranging (SLR) to make very precise measurements that are accurate to less than a centimetre. This helps researchers pinpoint Earth’s centre more accurately, according to a statement from the US Space Force.
Accurate positioning is crucial for determining Earth’s centre of mass, which can shift slightly after such events as tsunamis and earthquakes. Data from the LRAs will help researchers more accurately measure changes happening to Earth.
Laser ranging uses brief pulses of laser light to measure the distance between objects. Pulses of laser light from a ground station are aimed at a satellite with LRAs. These reflect the light beams back to the ground station. The time it takes for the laser light to travel to the satellite and back to the ground can be used to measure the distance between them.
The light is reflected by three mirrors arranged at right angles, forming the inside corner of a cube. The LRAs are made up of 48 mirrored corner cubes. These ensure that the light beam is reflected back at the same angle it entered. According to the statement, NASA and the Naval Center for Space Technology at the Naval Research Laboratory built the LRAs, and they will be operated by the US Space Force.
On May 6, two LRAs were sent to Lockheed Martin to be added to the GPS III satellites before their launch. This mission is a joint effort by the Space Force, the National Geospatial-Intelligence Agency (NGA) and NASA.
US Space Force Col. Andrew Menschner, commander at Space Operations Command, says they managed to add new features to the GPS system years earlier than planned, while making sure that the billions of people who depend on their signals every day were not affected. He also said they believed LRAs would become standard on future GPS satellites and SV9 and SV10 would have the feature before their launch.
Menschner further said that putting two new reflectors on orbit with GPS III next year would show how quickly they could upgrade their capabilities. This achievement was a great testament to the team’s exceptional talent, dedication to the mission and collaboration, he concluded.
