The retired Earth-watching satellite Landsat 5 may have quit taking pictures of the planet, but it's apparently not finished posing in them.
Landsat 5 photobombed its youngest cousin, Landsat 8, as the two satellites flew past each other over northwestern Brazil back in November.
Mike Gartley, a research scientist at the Rochester Institute of Technology, recently spotted the cameo during his hunt for "resident space objects" in Landsat images, according to NASA. [Earth Pictures From Space: Landsat Satellite Legacy]
"Believe it or not, there are anywhere from 1 to 4 such underflights of space objects that are passing through the field of view of Landsat 8 on any given day," Gartley told NASA's Earth Observatory. The most common interlopers are old rocket bodies and Russian satellites, Gartley said, though he has also spotted the International Space Station at least three times since last May.
The United States keeps tabs on all the space junk and satellites circling the planet through the Space Surveillance Network, a U.S. Air Force program that uses telescopes, radars and computer models to catalogue these objects in order to identify potential collisions. Gartley uses this data to determine when an object will pass through Landsat 8's view, according to the Earth Observatory.
Landsat 5 — which looks like a pixelated streak in the photo taken over Brazil on Nov. 22, 2013 — was officially retired last year and its photobombing days are nearing their end. As part of its decommissioning process, the spacecraft was maneuvered down to a graveyard orbit in January 2013 and it's being slowly pulled back to Earth.
Landsat 5 was the most prolific satellite in the Landsat program, a joint project of NASA and the U.S. Geological Survey. The spacecraft launched in 1984 and long outlived its three-year mission; its 29-year globe-circling campaign earned it a Guinness World Record for the longest-running Earth-observing satellite.
Over the course of its lifetime, Landsat 5 witnessed the aftermath of the Chernobyl disaster and the Sept. 11 terrorist attacks. Its photos have helped scientists track urban sprawl and the effects of climate change, from ice loss to desertification.
Landsat 8 is continuing that work, beaming 400 photos back to Earth per day. It launched into orbit on Feb. 11. 2013, and reached its final altitude of 438 miles (705 kilometers) in April.