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View Full Version : Why save the HST?



Greg
2004-Dec-15, 06:55 AM
I don't recall seeing alot of discussion on this topic, but I think it is one worth debating. I will state my point of view and invite others to share their own opinions.
I will first review the particulars of the subject. The HST most experts agree is on its last legs. It is only a gyroscope failure or two from becoming completely inoperable. There is a certain element of random chance regarding how long each gyro will survive, but there is a very high probability that the HST will fail by 2010 without further maintence (and quite possibly sooner than that.) There are other problems as well with some of the other instruments and of course a chance that something unforseen will happen that is worse than what is already predicted. Most would agree that its most valuable asset is its optical mirror which achieves better resolution than current active ground based telescopes.
But the situation on the ground is changing rapidly and for the better. A recent article about the GMT posted by Fraser is an example. It will see first light in 2016 and have 10x the resolution of the HST. And there will be plenty more ground based scopes around the same time which will be equally good.
So this begs the question, is the HST really worth saving? What will be achieved: 5 years of observing time for HST connected scientists to do their research before the ground based telescopes go online to do the same research with even better equipment. The cost: Using a valuable NASA shuttle mission, putting seven brave astronauts at extra risk to the unusual location that the HST orbits, and hundreds of millions of dollars. I would also not underemphasize the risk to the astronauts. It is considered to be so high that NASA has said that it is too risky according to its new standards after the Columbia disaster.
So in my opinion, it is not worth the aforementioned cost to extend the life of an ailing and soon to be inferior telescope so that the HST connected researchers can scoop their colleagues a few years before they have access to the new ground based telescopes. And yes, I am aware that there are a few other instruments on the HST that are of value, but to that I say spend less money launching a smaller, better and newer instrument (aside from the HST primary mirror) into an orbit where astronauts can safely upgrade it.
Please excuse me if you feel I wrote this in an inflammatory fashion. I hope to generate a more lively debate by writing my post this way.

Erimus
2004-Dec-15, 08:08 PM
I will outline the reasons why I think Hubble should get at least a final servicing mission:

1.) To use a cliche, a bird in the cage is worth two in the bush, IMO. The equipment for HST is already complete and paid for; why build another telescope when we can just install it? To launch a new telescope would require years more planning, construction, Congressional approval, and dodging the budget axe before it saw first light, by which time there would probably be better telescopes aloft anyway, therefore rendering the new telescope redundant--even if the total cost was less than or equal to a HST servicing mission.

2.) The risk aside, if the astronauts are willing to volunteer to take that risk--since they are the ones who will be exposed--why should NASA prevent them? Astronauts know their profession is a risky one, but it's a risk they (presumably) enjoy taking. Also, an NAS report suggests that repairing HST with astronauts makes more sense than doing so robotically at far greater monetary cost:

http://www.space.com/news/hubble_report_041208.html

3.) The Hubble Space Telescope is arguably NASA's best PR machine. Colorful pictures of the Horsehead Nebula may not have much scientific value, but they inspire the public, which (presumably) makes them more willing to pay NASA's meal ticket.

4.) There are telescopes on the ground that can beat Hubble's resolution. However, those telescopes use expensive adaptive optics technology, and primarily work in the infrared, rather than in the UV through IR range that HST is capable of. In the visual wavelength HST's sensitivity is unmatched, down to magnitude 31 in the Andromeda Deep-Field image.

5.) Keeping HST aloft will hopefully give us continuous space-based coverage until the real great observatories of the future go up, like SIM, Gaia, JWST, etc.

6.) The HST is capable of far more than than just visual and spectrographic observations. Recently, astronomers have used HST's Fine Guidance Sensor as a kind of improvised Hipparcos, to produce what are currently the most precise astrometric and parallactic measurements until SIM and Gaia go up.. Some recent dividends have been accurate distances to the standard candles Delta Cephei and RR Lyrae, and the first precise astrometrically-determined mass of an exoplanet (Gliese 876). Currently, HST is being used to astrometrically determine the masses of Epsilon Eridani b and the outermost planet of Upsilon Andromedae. These cannot be done from the ground currently, IIRC, at least not with a comparable level of accuracy.

bossman20081
2004-Dec-15, 08:39 PM
There maybe new and better telescopes going up, but why does that mean we just abandon the telescope? The fact is is that Hubble is still a fully operational telescope which could last for a further 10+ years, if we keep upgrading it. I see no reason to just give up on it, indeed, two telescopes are better than one; we could combine the two telescopes images using interfermonetry (sp?) Not to mention that Hubble is one of the many great things NASA is known for, among other things like the STS, Apollo, etc. I see no reason to abandon it.

Now about sending astronauts, I really dont know what to do. The astronauts already know the dangers of any space mission, and Im sure they would line up to do such a mission, but NASA says its too dangerous....

Duane
2004-Dec-15, 10:25 PM
Just to toss in my 2 cents--I also feel the cost of servicing the Hubble is a waste. NASA would be better to put 2 or three smaller scopes into orbit to take over the various roles of Hubble for something like 1/10th the price.

I also think the primary mirror has an unused twin here on Earth. Send that up as well.

Even smaller scopes, like the Canadain MOST satillite, can do alot of science. There are big scopes going up all over the place, and some very ambitious space scopes planned. Hubble was great for it's day--but's its day has ended.

wstevenbrown
2004-Dec-16, 12:18 AM
Some random thoughts:
!) The Webb telescope is not a done deal. The present eye is better than none, and much better than government promises.
2) No launch taking place later than yesterday is a done deal.
3) All ground-based scopes have blind spots both from atmosheric absorption and from bad weather
4) Ground-based scopes cannot observe more than a 160deg cone , even in a clean sky.
5) US could re-task any of 16 (minimum) keyhole satellites.
6) Poll the Astronaut Corps for volunteers. If no viable crew, fugeddaboutit,
7) O'Keefe just resigned. Being stone-paranoid myself, I suspect that even the emasculated shoestring budget was too much for his "superiors", and his level of success even under those conditions was too high. A series of abject failures would have justified outright cancellation of the space program.
8) The safety issue is a straw man. It isn't about safety, any more than ... [insert rant of your choice concerning misplaced national priorities, political scare tactics, etc.].
9) Space-based telescopes do not require adaptive optics systems.
10) Space-based telescopes do not need to be made of thick, hard-to-machine glass or refractory ceramic materials, expensively machined on the ground, then lifted as expensively as possible from the bottom of a gravity well. The gravitational flexing and differential temperature expansions simply do not apply-- they (projects requiring these) are pure political pork; more accurately, pigpoop.

Rx: three fingers of ObAn, with deep breaths. Thanks for your patience. Steve

astromark
2004-Dec-16, 01:10 AM
I think we have to exept the cost is to great. The risk to human life does out waigh the photo opertunity that the Hubble has so amply proven. With the ever advancing technoledgy we are going to see some new gear that will exeed our expectations. As well as that huge thing they have planed for Chile, I have been told that China has a giant skope on the drawing boards. Remembering that at the Mount Keck Obs they are linking the giant eight and a half metre scopes, all four of them. That is being done in the Cannery Islands and again in Chile..and isent there a VLT in South Africa about to be commisioned.
So take a brouder look. Its had its moment in the spotlight, and it served us well. Its time has passed. If there is a twin mirror laying about some where could I Please..... or has it got the same built in error as its mate? How did that happen?

spacepunk
2004-Dec-16, 01:49 AM
So this begs the question, is the HST really worth saving?

...The cost: Using a valuable NASA shuttle mission, putting seven brave astronauts at extra risk to the unusual location that the HST orbits, and hundreds of millions of dollars

A few ingenious low cost, low risk repair plans have been forwarded. Some involve sending pre-programmed robots that have a measure of manipulative control from Earth. But there remains a price tag, which would have to be paid for by either new funding, siphoning off of funds from the ISS, or by selling the entire telescope to an enterprising business consortium that is willing to finance its repair (the downloading of artificial satellites to the private sector is not without precedent).

As for previous maintenance missions performed by the space shuttle and crew, repairing Hubble may have been the main focus of those missions but there were always other objectives achieved. So the full cost of servicing the Hubble was always somewhat less than the entire mission. Has anyone an idea of what these costs were?

Tom2Mars
2004-Dec-16, 02:06 AM
Hubble's been good, but it might be time to think of saying Bye, Bye. I think I'd rather see the billions put towards some observatories on the Moon.

With Astronomernauts.

astromark
2004-Dec-16, 12:06 PM
Astronomernouts.....Mmmm....

Greg
2004-Dec-17, 05:43 AM
When talking about he cost of the telescope you actually must conisder the cost of the program. The whole program costs 250 million per year to run. This figure includes mandated technology upgrades as well as expected servicing mission, each of which it is better to think of as a process rather than a discrete item. Day to day ground support operations for analyzing the data is also part of that figure.
I could not find a breakdown on how much of the 250 million per year is devoted to servicing and upgrades but you can bet it is at least half and probably as much as 2/3 of the HST annual budget.
One thing to think about also regarding this topic is whether or not a manned or robotic mission would be required to safely deorbit the telescope. NASA had all along planned a manned mission to deorbit the telescope before the Columbia disaster. If this can not be done remotely and astronauts have to go there anyway to deorbit it, then why not upgrade it? I think some merit can be gleaned out of using this argument to save it.
In my own opinion, I think a robotic mission to repair it will be more costly than a manned one. I think that it can safely be deorbited robotically so long as this is the only objective of the robotic mission. If in fact it has to be deorbited with a manned mission, then I say install the currently developed componets and a rocket package (to deorbit it) and be done with further development.

spacepunk
2004-Dec-17, 06:45 AM
This debate on trashing or saving Hubble has some similarities with Skylab's and Mir's eventual demise.

So Hubble is abandonned as planned. If and/or when other replacement space telescopes are put in orbit, or on the moon, wouldn't they too be expected to incur maintenance missions from time to time ... and at what cost?! From a financial point of view it is possible that we should keep Hubble hobbling along for a few more years until a near-maintenance free replacement is designed.

Jakenorrish
2004-Dec-17, 01:28 PM
There was a very good and imformative Sky at Night about the VLT (very large telescope) based in Chile on the other day. The Hubble's days will be numbered when this beautifully thought out telescope is up and running. It would cost an extortionate amount of money to service the hubble, and the earth based telescopes have reached and will surpass Hubble's capabilities.

I hope that they send up another space telescope to replace hubble. With the advances in technology over the last 14 years, can you imagine the images that it could produce and the advance in our knowledge? Wow!!

bossman20081
2004-Dec-17, 10:40 PM
I still see no reason why we have to abandon a fully operational telescope, even if better telecopes are made. Every time the largest earth based telescope is built, do we destroy the last one? No, we still use it, and we use it well.

Also, another thing about a new telescope is how long it will take. Between approving, funding, and actually building it, it will take well over a decade. Please tell me why we are even considering something like that when its so in the future. A million things could happen between now and then to completely scrap that project.

antoniseb
2004-Dec-17, 11:25 PM
Originally posted by bossman20081@Dec 17 2004, 10:40 PM
I still see no reason why we have to abandon a fully operational telescope, even if better telecopes are made.
For the cost of trying to preserve this one 2.8 meter telescope for another four years, we could build three 28 meter telescopes with a new generation of detectors, and operate them for forty years. If you can pick one or the other [I know it's not quite that simple], which do you pick?

bossman20081
2004-Dec-18, 08:56 PM
Originally posted by antoniseb+Dec 17 2004, 06:25 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb @ Dec 17 2004, 06:25 PM)</td></tr><tr><td id='QUOTE'> <!--QuoteBegin-bossman20081@Dec 17 2004, 10:40 PM
I still see no reason why we have to abandon a fully operational telescope, even if better telecopes are made.
For the cost of trying to preserve this one 2.8 meter telescope for another four years, we could build three 28 meter telescopes with a new generation of detectors, and operate them for forty years. If you can pick one or the other [I know it&#39;s not quite that simple], which do you pick? [/b][/quote]
Wow, its that much?&#33; I must have missed the estimate. But, would they (the four ones we could build in its place) be ground-based or space based telescopes? (I know it hardly matters because of adaptive optics) How long would it take to build them? This is just plain curiosity, no more arguements from me for now.

Betelgeuse
2004-Dec-19, 05:57 PM
I&#39;m all for saving the HST. We know now that there are always better developing mechanisms of science but the thing is the Hubble Space Telescope is more of a symbol of man&#39;s efforts to discover. In the past 20 years or more the HST has done as much to enlighten people as Darwin&#39;s or Einstein&#39;s theory&#39;s and works therefore, in my opinion it deserves a place enduringly in it&#39;s course or orbit.


Equipped with his five senses, man explores the universe around him and calls the adventure Science.
- Edwin Hubble

Need more convincing? Take a look here (http://hubblesite.org/gallery/).

Regards
Rigel