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APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
To Fly Free in Space
Explanation: At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured above , was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an “un tether ed space walk ” during Space Shuttle mission 41-B in 1984 . The MMU works by shooting jets of nitrogen and has since been used to help deploy and retrieve satellites. With a mass over 140 kilograms, an MMU is heavy on Earth , but, like everything, is weightless when drifting in orbit. The MMU was replaced with the SAFER backpack propulsion unit.
Best Short Astronomy Videos: APOD editor to speak in New York City on Friday, January 6
| Date | January 1, 2012 |
|---|---|
| Credit | STS-41B , NASA |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |