Live In Orbit: Crew Installs Crucial Control Unit

NASA astronaut are replacing a critical Hubble Space Telescope control unit that failed within two weeks of the planned launch of Atlantis last October, triggering a seven-month delay in the ongoing mission to service the observatory.

Anchored to the end of the shuttle's 50-foot robot arm, spacewalker Drew Feustel is installing a newly refurbished Science Instrument Control and Data Handling unit into the 19-year-old observatory.

The new unit replaces one that malfunctioned last September, leaving Hubble one failure away from a scientific shutdown. NASA consequently delayed the ongoing Hubble Space Telescope servicing mission until a replacement could be tested and delivered to Kennedy Space Center for launch on Atlantis.

Feustel and Grunsfeld removed the old unit from the telescope bay that housed it. It since has been stowed in a shuttle cargo bay carrier for a return to Earth.

An aliveness test of the refurbished unit was successful.

Here's NASA line art that shows what the unit looks like: Science Instrument Controller.

Click here for a primer on Hubble systems: HST SYSTEMS It shows how the Science Instrument Control & Data Handling unit fits in with other Hubble systems. See section 5.5.

The astronauts have one more major task to complete today: Installing a docking mechanism that ultimately will be used in the disposal of the 12.5-ton observatory at the end of its useful life.

The mechanism will enable a robotic spacecraft to latch onto the observatory and guide it on a controlled atmospheric reentry during which any surviving wreckage would fall into remote areas of the Pacific Ocean.