The question Is it possible to see animals from space? has several answers, and they are all based on optical imaging.
In this answer I describe and show images from the
- First count of individual birds from space
- First complete count of an entire species population from space
That worked because the birds were known to be roosting on open ground in a very specific, localized area that offered good imaging contrast.
Now I've just read in Spaceflight Now's article Spacewalkers toss nanosatellites into orbit, hook up bird migration monitor
Clad in pressurized spacesuits, two Russian cosmonauts headed outside the International Space Station on Wednesday and hand-released four tiny CubeSats and installed hardware for a German experiment to track animal migration.
Called Icarus, the project aims to reveal changes in migratory routes, animal connections and other animal behavior. The antenna for Icarus was carried aloft in February, and a computer launched on a Russian Progress mission last year to help process the signals coming from tracking units tagged to animals on Earth.
“Icarus is a global collaboration of research scientists that are interested in life on the globe, and once we put together all the information on mobile animals, then we have a different and new understanding of life on Earth,” said Martin Wikelski, lead scientist on the Icarus project, director of the Max Planck Institute of Ornithology, and professor the University of Konstanz in Germany.
The spacewalkers set up an antenna boom, routed and mated numerous cables and connectors, and installed the Icarus antenna.
So rather than optically imaging the bird migrations as I'd first imagined, Icarus receives signals in Space from tracking transmitters attached to individually tagged birds.
Question: How does this work? Do the trackers each have GPS and transmit their locations to the receiver on the ISS, or does the special antenna and signal processing pick up beacon signals from much simpler tags on the birds, and reconstruct each signal's direction using the antenna as perhaps a phased array?
note: While the title of the article says bird migration, the body of the article only talks about animal migration. Land mammals can support heavier trackers than migrating birds, so they might have on-board GPS.
I suppose the birds could grip the GPS units "by the husk" or two could cary it together using a strand of creeper, held under the dorsal guiding feathers...