The news item in Science Brazil’s first homemade satellite will put an extra eye on dwindling Amazon forests says:
Right now, Brazil’s Amazon monitoring program relies on flyovers from the U.S. satellite Landsat, which provides high-definition image data every 16 days. More timely alerts about deforestation come from two satellites codeveloped by Brazil and China, CBERS-4 and CBERS-4A, which together provide images every 3 to 4 days.
Amazonia-1’s cameras, which cover an area of 850 kilometers at 65-meter resolution, will be no sharper than those on the existing satellites. But the new addition to the satellite fleet would shorten the gap between flyovers to generate new images every day or two. That frequency increases the chances of getting clear pictures without cloud cover—a common problem in the rainforest—and gives authorities faster alerts about deforestation.
“A day can make all the difference,” says Cláudio Almeida, who coordinates INPE’s Amazonian monitoring program and oversees its official deforestation reports. With near–real-time monitoring, “enforcement teams can go to the right place at the right time,” he says.
The table below gives some orbital information from Wikipedia. All three are in sun-synchronous obits which means that for a given orbit (for circular orbits a given altitude) the inclination is chosen to precess around the Earth once per year to synchronize observations in some way with the day/night cycle.
- Why can Amazônia-1 observe the Amazon every day or two while Landsat takes 16 days between observations? Is "orbital magic" at play here?
- Why does the quote in Science say every day or two but Wikipedia say "every 4 days"?
satellite altitude inclination period interval Source (km) (deg) (minutes) (days) Landsat-7 705 98.21° 98.83 16 https://en.wikipedia.org/wiki/Landsat_7 Landsat-8 705 98.22° 98.8 -- https://en.wikipedia.org/wiki/Landsat_8 Amazônia-1 756.5 98.51 99.8 "Period of Earth imaging: 4 days" https://en.wikipedia.org/wiki/Amaz%C3%B4nia-1