Hubble II instead of repair mission 4

[MeteorWayne]

Thanx for the insight RS_R!

 

[wtrix]

As I'm relatively new here, I believe that I owe some concluding explanation. I'm not an unconditional NASA supporter or NASA basher. Just a curious person. I had a question in my mind and I couldn't find the answer. So thank You for your insight, RS_Russell . That explains the cause and decisionmaking process pretty much.

 

[dragon04]

This question has probably been asked before, but if so, I've never come across it. While I am sure there are very good reasons for four Repair Missions, but what reasons made/make it prohibitive to simply snag Hubble, put it in the Orbiter Payload Bay, bring it back to Earth, repair/upgrade it, and then put it back in orbit on the next Shuttle Mission?

I've tried to figure this out. The only possible reasons I could come up with on my own were that NASA felt it too big a risk to lose the instrument in a catastrophic launch/re-entry failure, that scientists just couldn't do without 3 month lapses in Hubble Time, or NASA felt it imperative to keep their EVA skills honed.

I can't imagine that potential physical damage to Hubble during a "normal" re-entry/launch evolution was a big concern because Discovery took it to space to begin with. The most "common-sense" thing to me personally would have been to bring it back to Earth, repair it and re-orbit it.

Guess that's why I don't make the big bucks.

 

[wtrix]

Maybe they still shall have opted for replacement: http://www.space.com/missionlaunches/09 ... l-fix.html

 

[wtrix]

This question has probably been asked before, but if so, I've never come across it. While I am sure there are very good reasons for four Repair Missions, but what reasons made/make it prohibitive to simply snag Hubble, put it in the Orbiter Payload Bay, bring it back to Earth, repair/upgrade it, and then put it back in orbit on the next Shuttle Mission?

I've tried to figure this out. The only possible reasons I could come up with on my own were that NASA felt it too big a risk to lose the instrument in a catastrophic launch/re-entry failure, that scientists just couldn't do without 3 month lapses in Hubble Time, or NASA felt it imperative to keep their EVA skills honed.

I can't imagine that potential physical damage to Hubble during a "normal" re-entry/launch evolution was a big concern because Discovery took it to space to begin with. The most "common-sense" thing to me personally would have been to bring it back to Earth, repair it and re-orbit it.

Guess that's why I don't make the big bucks.

Instead of one Shuttle missions you propose two? Shuttle missions are limited now and thus this can't be done.

 

[MeteorWayne]

Maybe they still shall have opted for replacement: http://www.space.com/missionlaunches/09 ... l-fix.html

Well...
"Because of mission time constraints, Hubble engineers chose to focus the repair on the wide-field channel because 95 percent of the camera's science observations are performed by that channel alone, Byerly said."

So 95% ain't so bad

 

[silylene]

Maybe they still shall have opted for replacement: http://www.space.com/missionlaunches/09 ... l-fix.html

Well...
"Because of mission time constraints, Hubble engineers chose to focus the repair on the wide-field channel because 95 percent of the camera's science observations are performed by that channel alone, Byerly said."

So 95% ain't so bad

95% isn't bad, the mission was quite a success.

Still, I was really hoping that the high resolution channel got fixed. I was perhaps more interested in the science from this channel than the wide field channel. I am very interested in planetary detection and imaging, and also in exploring the innard of galaxies and dense clusters and mapping the rapid motions of inner stars around black holes. Here is about the part that wasn't fixed:

http://www.gsfc.nasa.gov/gsfc/spacesci/hst3b/ACS.pdf_1.pdf
High Resolution Channel: Capturing the Details
The High Resolution Channel will take extremely
detailed pictures of the inner regions of galaxies, and
search neighboring stars for planets and planets-to-be.
This channel uses a one-million-pixel CCD, and a
coronagraph to suppress light from bright objects,
enabling astronomers to view nearby faint objects.
Scientists will use this capability to examine the galactic
neighborhoods around bright quasars.
The High Resolution Channel will also polarize
and disperse light. These functions will allow Hubble
users to study light in the centers of galaxies with massive
black holes, as well as ordinary galaxies, star
clusters, and gaseous nebulae.

 

[MeteorWayne]

I understand your disappointment, and I agree, but there are now other spacecraft in space and in planning that are specifically designed for that purpose.

 

[RS_Russell]

This question has probably been asked before, but if so, I've never come across it. While I am sure there are very good reasons for four Repair Missions, but what reasons made/make it prohibitive to simply snag Hubble, put it in the Orbiter Payload Bay, bring it back to Earth, repair/upgrade it, and then put it back in orbit on the next Shuttle Mission?

I've tried to figure this out. The only possible reasons I could come up with on my own were that NASA felt it too big a risk to lose the instrument in a catastrophic launch/re-entry failure, that scientists just couldn't do without 3 month lapses in Hubble Time, or NASA felt it imperative to keep their EVA skills honed.

I can't imagine that potential physical damage to Hubble during a "normal" re-entry/launch evolution was a big concern because Discovery took it to space to begin with. The most "common-sense" thing to me personally would have been to bring it back to Earth, repair it and re-orbit it.

Guess that's why I don't make the big bucks.

Actually, there was at one point a tentatively scheduled mission (STS-144) that would have at some point retrieved Hubble at the end of its life. The notion being that it could have been displayed in the Smithsonian.

To return it for servicing was likely not considered, as Hubble was designed to be repaired and PMs done on orbit. Also, some of the constraining systems used on the mirror, once released, may not be reachable to re-attach. The mirrors or other instruments might suffer damage on the return. Not an issue for the Smithsonian but a big one if you are going to fly the instrument again. In a sense HST is the classic idea of a "man-tended" facility. This was a key idea from the late 60s, early 70s, when they were looking at MOL and other intitial space station ideas. The early station designs also included "free-flyers," like telescopes or robotic labs that would be serviced by either the station or some type of re-useab le craft.

However, post-Columbia any notion of a retrieval is, well, strictly notional , especially with the assumed closure mission coming up in 2010.

RSR

 

[CalliArcale]

Yeah, post-Columbia, an HST-retrieval mission is pretty much dead. Partly because it was meant to use Columbia for the purpose, but mostly because NASA is quite a bit more risk-averse when it comes to Shuttle, and carrying home something as massive as Hubble is risky. No Shuttle has ever landed that heavy. I'm confident it could've been done, but I'm not responsible for people dying if it goes wrong. If I were, I'd likely be a bit more cautious as well.

 

[dragon04]

Those are all good answers to my question. Thanks all.

 

[vulture4]

Once NASA starts down a path it can't easily change course. Early in the Shuttle program it was assumed Shuttle operational costs would be much lower than they are today. Had this been the case, the strategy of human servicing would have been superior to launching a replacement. Once the program was underway the commitment had been made, and at the time the EELVs were not yet available. However several scopes since then, including the "successor" more or less to the HST (i.e. the Webb) were planned for ELV launch without servicing.

Had the Webb been planned to be a reasonable evolution from the HST, it could have had a monolithic mirror of about 3.5-4 meters and been launched on a Delta. With no need for man-rating and design for servicing it would probably have actually been cheaper than servicing the HST, and probably a replacement could have been launched every 5-10 years. If one of them laste past its expected lifetime, two Hubbles in orbit would have gathered twice as much data.

Unfortunately the Webb is radically different, the first telescope with a mirror that must be deployed in space, originally planned to have a mirror of an incredible 8 meters. How this was chosen I don't know, I have heard it was an impulsive decision by Golden, though it later had to be reduced somewhat. The development program was correspondingly so long that Hubble would have failed long before. Having already been funded to build the Webb, NASA would probably have had to admit it made a mistake if it then asked for another new telescope start at that point, and very few people at NASA ever admit they made a mistake. On the other hand, the servicing missions were already on the schedule and could be more easily defended regardless of its cost. Go figure.