NASA has approved a safety waiver for the reentry of its Van Allen Probes, satellites that have been in orbit since 2012. The twin spacecraft, built by Johns Hopkins University Applied Physics Lab, were designed to study Earth's radiation belts and made groundbreaking discoveries, including evidence of a transient third radiation belt during intense solar activity.

Originally expected to reenter in 2034, the satellites are now predicted to begin atmospheric reentry no earlier than 2030 due to increased solar activity that expanded Earth's atmosphere. This atmospheric swelling has increased drag on the spacecraft beyond initial estimates. NASA's two probes operate in elliptical orbits ranging from a few hundred miles to nearly 20,000 miles above Earth, with inclinations limited to 10 degrees from the equator to reduce risk to populated areas.

This waiver comes as NASA has previously exceeded its own safety standards for satellite reentries. The agency has a 1-in-10,000 risk threshold for human injury from falling space debris, yet satellites like the Rossi X-ray Timing Explorer have reentered with higher calculated risks. While NASA has occasionally exceeded these standards, the US government maintains better compliance than some international counterparts, particularly China's Long March 5B rocket program, which has left massive cores to fall uncontrolled from orbit.