1st untethered spacewalk is taken, February 7, 1984
The unit featured redundancy to protect against failure of individual systems. It was designed to fit over the life-support system backpack of the Space Shuttle extravehicular mobility unit and to adapt to astronauts with different arm lengths (see NASA photo below of McCandless using the MMU).
After the Space Shuttle Challenger disaster in 1986, the MMU was deemed too risky for further use. NASA determined many of the activities planned for the MMU could be done effectively with manipulator arms or traditional tethered EVAs. NASA also discontinued using the Space Shuttle for commercial satellite contracts, and the military discontinued its use, eliminating the MMU’s main potential use for rescuing wandering or damaged satellites.
Although the MMU was expected to be of help in constructing the International Space Station, NASA developed different tethered spacewalk approaches by that time. A smaller MMU successor, the simplified aid for EVA rescue (SAFER) unit, was first flown in 1994. It is intended for emergency use only.
- 1st spacewalk takes place, March 18, 1965
- International Space Station Unity module is launched, December 4, 1998
- Space Shuttle Challenger explodes, January 28, 1986
- NASA: Revealing the unknown to benefit all humankind
For more moments in tech history, see this blog. EDN strives to be historically accurate with these postings. Should you see an error, please notify us.
Editor's note: This article was originally posted on February 7, 2013 and edited on February 7, 2018.