3 ms·

More information on satellite calibration markers for those curious like me: https://www.livescience.com/17052-mysterious-symbols-china-desert-spy-satellite-ta

• londons_explore 6y ago
  The US marker makes sense - it allows checking all alignment angles, focus, scale, and various spacial frequency response parameters to be measured. All in perhaps the simplest possible shape. The Chinese one on the other hand, isn't so useful for any of that. All the lines are the same thickness, and there are no smaller features for fine calibration or measurements. For just calibration, it's far bigger and more complex than necessary.