Humans have ventured into space over the last 50 years, and all manner of junk has been left behind. From tiny bolts to whole space stations, people have discarded lots of stuff up there. Much of it eventually dies a fiery death as it falls through Earth's atmosphere, but some larger debris poses risks for astronauts and spacecraft that could collide with it. Here are some of the quirkier items left in space:

1. Spatula

While spreading some goo as a test of heat-shield repair materials, spacewalking astronaut Piers Sellers accidentally lost a spatula he had been using. The mishap took place during the space shuttle Discovery's 2006 STS-121 flight to the International Space Station, on a mission to test new safety techniques after the 2003 Columbia disaster. "That was my favorite spatch," Sellers reportedly said. "Don’t tell the other spatulas."

2. Tool bag

Astronaut Heide Stefanyshyn-Piper lost her grip on a tool bag while doing a spacewalk in November 2008 to try to repair a jammed gear on a space-station solar panel. The 30-pound bag, filled with grease guns, a scraper tool and a couple of bags for debris, cost about $100,000. Amateur astronomers spotted subsequently spotted the bag in orbit, and North Americans can check to see if the tool bag is in their slice of the sky with Spaceweather.com's satellite tracker. Watch the bag float away below. http://www.spaceweather.com/flybys/?PHPSESSID=v5r9ilmkqgek0vcqoq2svcenr2

3. Glove

Starting out the long trend of astronauts losing stuff in space, the very first American spacewalker, Ed White, let go of a glove during his first extra-vehicular activity on the 1965 Gemini 4 flight. The glove stayed in orbit for about a month before burning up in Earth's atmosphere.

4. Tank of ammonia

This one was lost on purpose. In July 2007, NASA instructed astronauts to throw an unneeded 1,400-pound tank full of ammonia overboard. The device used to be part of the space station's cooling system, but when the A/C was upgraded, it became obsolete. Deeming that it would take up too much cargo room to carry it back to Earth, mission managers decided to have it trashed. More than a year later, the tank burned up over the South Pacific Ocean as it hit the atmosphere.

5. Gene Roddenberry's ashes

A portion of the ashes of Gene Roddenberry, creator of the Star Trek series, were delivered to space in 1992 by the space shuttle Columbia on its STS-52 mission. The lipstick-sized capsule containing his ashes orbited the Earth before eventually disintegrating in the atmosphere. The rest of Roddenberry's ashes, along with those of his wife Majel who died in December 2008, will be shipped into space along with digitized fan letters in 2010.

6. Pee

Over the years, most of the urine produced by astronauts has been simply dumped overboard. Once pee hits the cold vacuum of space, it quickly freezes into tiny crystals which then float around as debris. (Astronauts have described watching urine being released into space as one of the most beautiful sights in orbit). Recently, however, a new pee-recycling system was brought up to the International Space Station to turn urine into drinking water, cutting down on the pee debris.

7. Pliers

While repairing a damaged solar array during a November 2007 spacewalk, astronaut Scott Parazynski accidentally lost a set of needle-nose pliers, which were spotted floating away below the station.

8. Camera

Astronaut Suni Williams was tussling with a stuck solar array on the space station in June 2007 when her camera came untethered and drifted away. Rather than astronaut error, this incident may have been caused when the button holding down the camera broke. Watch video of the mishap below.

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Image: Illustration of amount and spread of space junk around Earth based on real data/ESA