Fourth Spacewalk to Repair and Upgrade Hubble Space Telescope

After several major successful repairs, according to Mission Control, it appears that yesterday’s work to repair the Advanced Camera for Surveys High Resolution Channel was not successful and this is probably not repairable in orbit during this STS-125 mission.

Today, Sunday, the 17th, Mission Specialists Massimino and Good are now live on NASA TV as well as the online feed available most notably through and

Take advantage of this and the next space walk to see what is almost certainly the last repair mission to one of the great scientific instruments of the last century.

This is the fourth of a scheduled total of five spacewalks to service the Hubble Space Telescope (HST).

Today’s job is to replace some computer processing power and particularly get the HST Imaging Spectrograph working at optimal capacity.

This is one of the several jobs which were never intended to be done in orbit – the HST was designed to have some repairs and changes made when it was initially designed and those have gone relatively easily.

But the extraordinarily long service period for this now ancient but still powerful telescope means that a number of basic changes to the underlying technology are called for – that is, this shuttle mission is also attempting to make repairs on what are essentially sealed systems.

It sometimes takes many hours just to get the existing hardware out of the way so the mission specialists can even reach the equipment they are trying to repair or replace.

So far this has been a great mission and should dramatically increase the capabilities of the HST.

Sitting at home it is difficult to remember that this is not just special effects with actors. Real people are actually out in zero atmosphere more than 300 miles above the Earth’s surface, making delicate adjustments to a massive piece of hardware and doing so while in a confining suit working with bulky stiff gloves making adjustments which were originally done over several weeks in a comfortable laboratory with no particular time limit and plenty of coffee and bathroom breaks.

The biggest concern now among many observers is the worry that something could still go wrong with the shuttle, leaving it stranded in high orbit and unable to reach the safety of the Space Station.

As the mission continues there is less and less time for a second rescue launch to be accomplished if that proves necessary.

These astronauts are heroes in the truest sense – they are voluntarily going into what is actually extreme danger and doing so to advance the knowledge available to the human race.