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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: What would it be like to fly free over the seas and clouds of Earth? The first to experience such an “un tether ed space walk ” were NASA astronauts Bruce McCandless and Robert Stewart during Space Shuttle mission 41-B in 1984. McCandless, pictured above , used a Manned Maneuvering Unit (MMU) to move in and around the cargo bay of the space shuttle. 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 in space. The MMU was replaced in 2001 with the SAFER backpack propulsion unit.
| Date | September 24, 2002 |
|---|---|
| Credit | Credit: STS 41-B Crew, NASA |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |