The U.S. Space Force found a balloon that had been lost for a quarter century. The object is S73-7, the Infra-Red Calibration Balloon, cataloged as object 7244. It launched in 1974 as a piggyback on a KH-9 Hexagon spy satellite and was supposed to inflate into a 26-inch calibration target for ground sensors. It did not fully inflate. It became junk. It dropped out of tracking, flickered back in the early 1990s, then vanished again. New two-line elements started appearing on April 25, 2024. Harvard-Smithsonian astrophysicist Jonathan McDowell flagged it on April 29: “Congrats to whichever @18thSDS analyst made the identification.”
The 18th Space Defense Squadron catalogs man-made objects in orbit. There are tens of thousands of them, most of them dead. S73-7 is small, not very metallic, and has a miserable radar cross-section. McDowell noted it might even be a dispenser or a misfiled fragment. Its altitude had dropped only about nine miles from the original near-500-mile orbit, so re-entry is not imminent. Finding it matters because collision avoidance only works if you know what the rocks are.
The AEGIS Alliance covered the other half of the space-communications problem when NASA’s Psyche spacecraft lasered a message home from 140 million miles. For how you eat once you get there, see the Wageningen intercropping tests in fake Martian dirt. このビートの多くは、 科学研究. McDowell’s note is here.
