“All kinds of stuff has been launched over the years. Normally it falls to Earth but some accumulates,” says Jonathan McDowell, an astronomer at Harvard-Smithsonian Center for Astrophysics.
These objects – predominantly balloons – are used to monitor the weather, conduct scientific research that can’t be done on the ground or to check things on Earth that can’t be seen by a satellite.
“The simple fact is they’re cheaper to fly than a satellite, you can put up many more … and resolution can be better because they’re closer to Earth,” says Brad Tucker, an astrophysicist and an astronomer at the Australian National University.
These balloons are launched by governments all over the world, as well as by scientific research groups and private companies.