The calibration process for the new satellite's night-band instrument started with pointing it at the Moon every month, since a stable Moon signal would reveal instrument problems, but the Moon alone had too much variability. The team turned to the Saharan Desert and nearby regions like the Sinai, Jordan, and Israel as a stable, cloud-free, dark reference surface. Tracking that desert data, they saw sudden brightness peaks over major cities that didn't match known patterns of gradual light growth, and initially suspected the instrument itself was broken.
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The instrument being calibrated detects a high-gain stage for very small signals, distinct from a low-gain stage, and the team first suspected the high-gain stage was malfunctioning.
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Published research at the time indicated city lights increase gradually year to year, not suddenly season to season, which made the desert data look anomalous.
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2:38and they were recruiting people fresh out of college like me saying, "Hey, calibrate this thing, which is is the data coming out of this new instrument correct? is the integrity everything about this instrument working and I was an I was I trained in as an engineer then I switch over to science so I was always kind of working around the integrity of the data yeah >> working with the instrument teams working with the science teams and trying to be a bridge and they asked me is the instrument the visible infrared imaging radiometer sweep figure it out they gave me two years so First thing
3:19you do is you ask the spacecraft team to look at the moon cuz the moon is very steady. So if they if you look at the moon every month and the moon starts looking dark, you got a problem with Uranus. >> Fair enough. Yeah. >> So we started doing that moon >> and this is literally you just point the thing at the moon. Okay. >> Right. Very stable. Problem is there's a lot of variability even though it's stable. So we needed more data. So what is the next most boring stable place on earth? Just look at any desert where there's not been any kind of source of civilization. So we picked the Saharan
3:59desert and so this picture you showed a section of the Sinai desert next to Cairo up there's you know all these places Jordan Israel and we're we're
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