How Satellites and Telescopes are Tracking the Effects of Global Change, Down to the Millimeter Read
NASA and other research agencies bring are bringing new tools to the science of geodesy.
By Alexandra Witze
Air & Space Magazine
In the Davis Mountains of far west Texas, at the University of Texas McDonald Observatory, astronomers spend their nights peering at the stars through some of the world’s most powerful telescopes. Soon they’ll be adding a more down-to-Earth job. Within sight of the giant domes, NASA is installing a sprawling network of equipment to help researchers study planetary change.
Last July, engineers achieved first light on a towering radio antenna, 12 meters across, that watches for signals flashing from cosmic beacons called quasars located in the distant universe. Nearby, scientists have set up new global-positioning-system stations—tripods topped with bulbous heads that communicate with GPS satellites to determine their precise location on Earth’s surface. On a neighboring mountain, technicians plan to build a powerful laser system that can zap a beam of light up to a satellite, then clock how quickly it reflects back to Earth. Together, all this high-tech equipment will allow scientists to pinpoint individual spots of ground at McDonald Observatory to within millimeters.
Similar activities are going on all over the world. NASA is helping to upgrade Earth-measuring observatories from Tahiti to South Africa. By linking the McDonald measurements with the others, researchers aim to better understand how Earth’s shape, rotation, and gravity change over time.
Called geodesy, this field of science underlies almost every aspect of modern life, whether it’s using Google Maps to find the nearest coffee shop or determining how sea level is rising as the planet warms. “You would never think that navigating your car is dependent on our measurements of distant quasars,” says Stephen Merkowitz, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who manages the agency’s Space Geodesy Project. “But it is.”
https://www.airspacemag.com/airspacemag/how-measure-planet-180972957/
