HST SM4: STIS Repair, The Quest for Renewed Exploration

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HST SM4: STIS Repair, The Quest for Renewed Exploration
09.10.08
 
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Malcolm Niedner, Deputy Senior HST Project Scientist: In August of 2004, there was a 5-volt power supply that drives the mechanisms on STIS, and it failed. When that happened, it basically meant that STIS could not do science anymore.

David Leckrone, HST Chief Scientist: STIS was our first black hole hunter. It confirmed for the first time the existence of a super massive black hole in the center of a galaxy. And it went on to make the first detection and chemical analysis of the atmosphere of a planet around another star. We want to want to keep on doing that kind of work.

Malcolm Niedner, Deputy Senior HST Project Scientist: STIS is what’s called a spectrograph. What it does is spreads the light out into its different wavelengths. That’s really important if we want to learn about how fast an object is moving, what it’s made of, what the pressure and temperature, it’s getting a the physics of what’s going on up there in the universe.

David Leckrone, HST Chief Scientist: You might well ask if we are going to fly the Cosmic Origins Spectrograph, that is the most sensitive spectrograph we’ve ever put in Hubble, why do we need to bother to repair the Space Telescope Imaging Spectrograph? Space Telescope Imaging Spectrograph can do a number of things that COS can’t do, and conversely. The Cosmic Origins Spectrograph is very fast and very efficient and the Space Telescope Imaging Spectrograph provides finer resolution, and a smoother cut as it were through the light from a star or galaxy and you have a much more complete set of tools to use for a variety of purposes.

Michael Weiss, HST Deputy Program Manager: There’s huge motivation to recover STIS. So, our engineers embarked on one of these rapid development programs. The STIS Failure was very easily characterized. We knew exactly what happened; we knew exactly what card; we knew exactly what component. And, the challenge became: Can we get to it?

Michael Good, EVA Astronaut, HST SM4: This particular activity we are going to do to try to fix STIS wasn’t meant to be done in space. It was meant to be done here on Earth in a cleanroom.

Michael Massimino, EVA Astronaut, HST SM4: Now, since no one ever expected to happen when they sealed up this instrument, they sealed it up so it was nice and secure. In fact there is a hundred and ten of these very small screws that we need to remove from the instrument in order to gain access to the board we need to replace.

Michael Good, EVA Astronaut, HST SM4: And these screws are not, what we call, “captive”. In other words, as you take the screw out, it’s loose; there’s nothing holding it to the board. The engineers here at Goddard have been very creative in designing a cover plate that can be put on over top. That as we take the screws out they’ll be captured by this Plexiglas cover.

Michael Weiss, HST Deputy Program Manager: We designed what is called the Fastener Capture Plate. It attaches on to the instrument. It’s got holes that the astronauts can access their tool into. They’re small enough for the tool bit but, not large enough so that the fastener can come out.

Michael Massimino, EVA Astronaut, HST SM4: My job is going to be to drive each one of these screws, remove that plate, get inside of it then remove the board. Much like you would remove a board in a computer in your house, except we’re in these fancy clothes, big fancy space suit and we’re using fancy tools to do it. We want to make sure we do it right.

Michael Weiss, HST Deputy Program Manager: If we are going to go do exploration and continue with on orbit assembly and test of spacecraft, we got to learn how to do that. We’ve got to learn how to pull boards out and put boards in. And so here we are, Hubble once again is the pathfinder.

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