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There's a lot of stuff floating around our planet, including dangerous space junk as well as working satellites. But scientists are floating some creative ideas for cleaning up all the debris.

Australian scientists have proposed zapping the debris with lasers. And last month, the European Space Agency proposed its e.DeOrbit mission, which would capture debris with a net or harpoon. No matter what method gets the nod, clean-up crews are facing a huge challenge. Just check out these European Space Agency images showing all of the objects currently in low-Earth orbit:

"Decades of launches have left Earth surrounded by a halo of space junk: more than 17,000 trackable objects larger than a coffee cup, which threaten working missions with catastrophic collision," according to the agency. "Even a 1 cm nut could hit with the force of a hand grenade."

NASA says there are more than 500,000 pieces of orbital debris the size of a marble or larger. These objects include spent rocket boosters, defunct satellites and even "nuts and bolts left behind by astronauts" -- and they can travel at speeds of up to 17,500 miles per hour.