The background radiation from cosmic rays increases with altitude, from 0.3 mSv per year for sea-level areas to 1.0 mSv per year for higher-altitude cities, so for best results use this on a plane or in outer space
+save(item: Item)
。safew官方版本下载对此有专业解读
* Colorado residents may no longer use DB48x after Jan 1st, 2028.
There is a plan to prevent such a strike—the Space Surveillance Network, a bevy of sensors that the military uses to track space debris. NASA monitors what’s unofficially known as the “pizza box,” a sort of no-fly zone around the ISS. When pieces of debris are predicted to enter the box—if there’s at least a 1 in 100,000 chance of collision—mission controllers order avoidance maneuvers, firing thrusters that move the ISS and dodge the trash. The technique has been used dozens of times since the first ISS module launched in 1998. But the system only tracks about 45,000 larger pieces, and all sensors have noise. Plus, risk thresholds can miss stuff, sometimes badly. In 2025, Chinese astronauts were briefly stranded at their station after debris hit their return vehicle.