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Comment by docbrown | Hacker News Reader

There have been five (5) successful missions to Hubble—beginning in 1993, then 1997, 1999, 2002, and 2009.[1]

The final mission, STS-125/SM4 (servicing mission 4), was done to prolong the life of the telescope. During the 12-day mission, they installed two (2) new instruments and performed two (2) repairs of failed equipment, and six new batteries in addition to replacing gyroscopes. This expected to extend Hubble’s lifespan by five (5) years from 2009.[2] So we were looking at an expected 2014 EOL date.

The 2009 mission was an interesting event in itself with Hubble’s durability aside. During a talk from Dr. Andrew Fuestel, he mentioned how NASA developed specialized tools for him to repair Hubble mid-orbit—which he said were the scariest times of his life—during his three (3) spacewalks.

[1] https://asd.gsfc.nasa.gov/archive/hubble/missions/sm4.html

[2]http://www.cbsnews.com/network/news/space/home/spacenews/fil...

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Any idea what made it the scariest times?

I mean, obviously going on a spacewalk must be pretty intense. But is there a particular difference in doing it to the Hubble?

Or was it scary because he was repairing a very expensive piece of equipment?

IIRC, there were a few different reasons why it was scary.

One of the first was this mission was the last one, it was a difficult repair—SC4 did the first in-orbit repair—to do at the time, especially outside of the telescope. Because when you leave the safety of the shuttle, you’re traveling at a rate of ~17,000MPH and where the hubble orbits, there is a much higher chance of debris floating around than as if they were lower in the atmosphere. So in laymen terms, you’re attached to a cord that is supplying you with O2 and spinning at 17,000 MPH while trying to avoid rocks and other dangerous floating objects.

One other danger was the O2 levels. He said the suits are heavy, all of your tools are attached to you via cords and you have limited time to be outside. If something where to happen in this situation, not only would you become unconscious within seconds from the lack of O2, you’d pretty much be a forever piece of debris floating around the galaxies as your body will never decompose or fall from orbit.

The latter part was one of his biggest worries. He knew that he’s on limited time, he also had to renter the shuttle slow because it’s similar to divers and decompression. If for some reason he went too fast or there was a leak somewhere, his suit would have instantly filled up and the pressure would have blew him apart inside the suit.

Oh wow. Awesome.

Definitely not a walk in the proverbial park.

Thanks for the details!

Is there a video or (hopefully) transcript of that talk somewhere? It sounds interesting!

This presentation is from a different college speech and a couple years earlier than when I saw him but he seems to be talking the same general information about SC4. — https://www.youtube.com/watch?v=fZh60_CxxJM

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