关于这张图
Engineers at NASA's Jet Propulsion Laboratory in Southern California test an engineering model of a high-frequency (HF) radar antenna that makes up part of NASA's Europa Clipper radar instrument on Dec. 17, 2019. The antenna is a 59-foot-long (18-meter-long) narrow copper tube held straight by several cables and a cross bar on the tower at right. In space, the copper tube will stick out straight on its own, but in Earth's gravity, the antenna requires supports to keep it straight for testing. The mobile tower at left holds a model of the VHF (very high-frequency) antenna so that engineers coul…
