りら がリツイート
Looking at Starlink 🛰from above
Maxar was looking at a Chinese military airbase from space, as one does, and a Starlink satellite zipped by at 17,500 MPH in a lower orbit, photobombing in technicolor.
Given Starlink's speed, Maxar's integration of different sensors led to a lagging rainbow of colors. The push broom sensors in the imaging satellite use its steady motion to integrate a rectangular image from a linear sensor sweeping forward like a push broom. So, a fast moving rectangle will distort into a quadrilateral polygon. And with multiple lines of sensors for different colors, high altitude objects (planes, balloons, satellites) also cause misalignment from parallax shifts (unrelated to their lateral movement). This creates an easily-detectable image artifact that can now serve as a search feature. Planet used this "bug" to search its daily planetary imaging database to find all of the high-altitude Chinese spy balloons and trace them back in time to their launch site in China.
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