NASA Watches Earth’s Weight, Finds Center of Mass
Seasonal changes redistribute enough water around Earth to shift the planet’s center of mass back and forth by fractions of an inch relative to its geometric center. NASA scientists are on the case, tracking the oscillations because Earth’s center of mass is a crucial reference point for satellite navigation and elevation measurements. A team, led […]
LAGEOS: An Earth Science Mission Built for Enduring Precision
On May 4, 1976, a spacecraft resembling a disco ball entered orbit almost 3,700 miles (6,000 kilometers) above Earth. This shiny, two‑foot‑wide (60‑centimeter) sphere called the Laser Geodynamics Satellite, or LAGEOS, is covered with 426 retroreflectors—small mirrored prisms designed to bounce laser light directly back to where it came from. Beneath its aluminum exterior sits […]