All articles tagged with #plutonium 238
Pioneer 10, launched in 1972, sent its last faint signal in January 2003 from about 12 billion kilometres away as its power from plutonium-238 RTGs faded; the eleven-hour transmission highlighted a graceful end to a 30-year mission, later explained as heat radiation affecting the craft’s trajectory rather than new physics, and the probe remains a silent, drifting artifact with a gold plaque honoring human exploration.
New analysis shows the decades-long Pioneer anomaly—the small sunward drift of Pioneer 10 and 11—was caused by asymmetric thermal radiation from the spacecraft’s plutonium-238 RTGs and electronics, not a breakdown of gravity; detailed archival data and thermal modeling by Turyshev and colleagues demonstrated that the recoil from emitted infrared photons pushed the probes backward, a tiny, decaying force that disappeared as the fuel decayed, leaving general relativity intact while the probes continue to drift outward.
The U.S. Department of Energy's recent shipment of heat source plutonium-238 to its Los Alamos National Laboratory is a significant step towards fueling NASA missions with radioisotope power systems. This shipment, the largest since the domestic restart of plutonium-238 production, brings NASA closer to achieving its target of 1.5 kilograms per year by 2026. Radioisotope power systems enable deep space exploration and the new plutonium will be used to power missions like NASA's Mars 2020, which carries the Perseverance rover equipped with a Multi-Mission Radioisotope Thermoelectric Generator. The partnership between NASA and the Department of Energy ensures the availability of radioisotopes for future missions.