The U.S. recently shot down a Chinese spy balloon over the Atlantic Ocean. This may seem like something from the past, but there is a reason countries still use high altitude surveillance balloons in the era of satellites. The one spotted over Billings, Montana in February 2023 was reportedly the size of three city busses, and was flying at an altitude of about 60,000 feet, though it was capable of reaching the stratosphere between 80 and 120,000 feet. This helps the balloon avoid detection, and being closer to the ground than a satellite means higher resolution images. Plus, balloons are much cheaper than satellites, so if one is shot down, it is not as big of a deal.