Hubble Mistake **2** - Action still Needed

Euler · 2005-01-07 15:26:08

In order to give a thorough argument on the merit of saving Hubble I decided to do further research into adaptive optics (to increase my knowledge on the subject as its been a while since I looked at them). I wish people would give up to date information on science related web sites - one says that the biggest adaptive optics telescope is just under 5 meters in diameter, another states that one is 8 meters... the list goes on and on.
Maybe my google search phrase "adaptive optics ain't worth sh...." does not help
Does anyone have any uptodate info on adaptive optics or links to sites that does.

http://en.wikipedia.org/wiki/List_of_la … copes]list of large refracting telescopes

All major research telescopes have started using adaptive optics, beginning with Keck I in 1993. The 2 Keck telescopes and the 4 VLT telescopes can act as interferometers. That gives the Keck interferometer an 85 meter baseline and 150m^2 of light gathering power, while the VLT interferometer has a 200m baseline and 210m^2 of light gathering power. VLTI has an optical resolution of .001 arcseconds. http://www.eso.org/outreach/ut1fl/]VLT official site

Hubble has 2.4 meter mirror for 4.3 m^2 of light gathering power and a resolution of .1 arcseconds.

GCNRevenger · 2005-01-07 19:39:50

Adaptive optics are still in their infancy really, now that computers have become more powerful and the "laser star" method has been cooked up. Even hubble-hugger apraisals of the technology estimate that ground based telescopes will reach optical parity with Hubble by aproximatly 2015. Infrared imaging, which is easier then optical with AO, is already aproximatly equal or superior to HST. Ground based telescopes would operate in much more "noisy" environment being under an atmosphere, but I bet that the much larger practical aperature will help offset this problem.

But lets say for a minute that a space telescope is called for. Perhaps for larger field of view or to detect extremely weak objects. UV imaging is deemed important enough to be worth money. Whatever reason... I think this sums it up nicely:

http://www.thespacereview.com/article/2 … icle/257/1

A telling quote: "“Everybody says, ‘We want to save the Hubble.’ Well, let’s go save the Hubble...”" by O'Keefe

O'Keefe has commissioned the robot repair mission under the duress of public relations pressure and not because it is a good investment. Repair robots, while they would be handy, I think are of limited worth. The cost of mounting a repair mission will likly exceed the cost of replacing whatever you are trying to fix. And then there is the risk to consider, that the robot won't have the capability of doing a critical but unforseen task and be useless.

Speaking of risk, you might want to pay special care to these:

"(most complex robot) option, which includes the deorbit module and the instrument replacement, was given just a 32% chance of success."

"by around 2009 engineers believe the spacecraft’s batteries will fail, rendering the spacecraft permanently inoperable since it won’t have the power to keep key systems functioning. While NASA Goddard believes that a robotic repair mission could be ready by the end of 2007, the AoA study... estimated that a robotic mission would take between 57 and 65 months to build, pushing the launch into 2010 even if work started now. At that point, the study noted, there is only a 38% chance that the telescope will even be in a serviceable condition."

I am more inclined to believe the more pessimistic assumption rather then optimistic one in this case. I don't think that NASA can build the robot in under two years and have a reasonable chance of it working. NASA has lost two Mars vehicles now due to small mistakes and not enough attention to detail. If NASA is to do this in two years, there is not enough time for detail... But if NASA doesn't do it quickly, then the chance that HST will lose attitude control drops substantially.

NASA was counting on using Shuttle to fix Hubble before Columbia, but now that this option is off the table, there is no time to do the robot mission. Even if the Aerospace Corp.'s assesment is low by a radical one half, that still places the robot servicing mission option with less then a 50% of sucess.

As for Shuttle... I think that the risk of TPS or other on-orbit failure is fairly high and the cost of the mission will also be quite high. More then that, the risk of another crew of astronauts being killed by the flimsy TSP system is a massive political risk.

...Lets say for a minute that the HST repair is a sucess, the cameras and gyros and batteries are sucessfully replaced and the robot module doesn't disrupt Hubble's operation (or Shuttle doesn't blow up). These fresh batteries and gyroscopes will only last a few more years most likly, just as the ones in previous missions failed after a few years. The problem is inherint, that the gyros and batteries are overworked because of Hubble's low orbit, but this was acceptable since Hubble was going to be serviced. It is not acceptable now.

This is assuming that the peieces that can't be fixed, like the power system that has already knocked out one of Hubble's cameras, and is a full seven years beyond its 15 year design life will hold on for another few to come.

Or we build a new scope or two for around $800M a pop, each with a pair of cameras intended or copied from Hubble, and put them out at a Lagrange point where they will last for a decade or more.

Euler · 2005-01-08 00:14:11

Even hubble-hugger apraisals of the technology estimate that ground based telescopes will reach optical parity with Hubble by aproximatly 2015. Infrared imaging, which is easier then optical with AO, is already aproximatly equal or superior to HST. Ground based telescopes would operate in much more "noisy" environment being under an atmosphere, but I bet that the much larger practical aperature will help offset this problem.

I think that assessment seriously underestimates the progress that has been made since Hubble was launched. The most advanced ground based telescopes have capabilities far beyond those of Hubble. I remember reading an article about VLTI directly measuring the shape of a star 7,500 light years away. Hubble just doesn't come close to having that sort of resolving power.

GCNRevenger · 2005-01-08 10:21:55

Which leaves only low-noise astronomy and Ultraviolet as Hubble's strong points. A new telescope using the cameras slated for Hubble, perhaps with copies of old ones, could be even cheaper then a Shuttle mission.

Readers might be wondering why its such a bad thing if Hubble loses attitude control: the reason is that if that were to happen, Hubble would probobly enter a slow spin, in which case it would be impossible to dock with it, because there would be nothing to grab onto. Hubble is also so heavy that if you were to capture it, it would sling you around with it. Bad news.

RobertDyck · 2005-01-08 12:23:39

Nonsense
A Shuttle mission will obviously still not be cheap nor easy because of the planning, training, and replacement part construction. Space missions do not come free. I imagine that the costs will still run in the region of a billion; the cost of the main tank and SRB refurbishing already top $110-120M alone, Orbiter refurbishing probobly more then this, and then there is integration and checkout. The cost of a new space telescope to fly the replacement HST cameras is estimated at around $800M. I believe the NASA estimate for Shuttle HST repair is around $1.5Bn.

Nonsense

I never said anything about the mission itself, just launch. The per launch cost of the Shuttle is less than an expendible vehicle with the same lift capability. The difference is the space centers necessary to maintain them, but if you're already paying for the centers an additional launch isn't going to cost more overhead.

But $110-120M for the External Tank and SRB refurbishment? I just don't believe that. The total incremental cost of an additional Shuttle launch was $63M in 1988. The will be some inflation, probably double that, but $110-120M just for ET and SRB without orbiter refurbishing and launch prep? No, I would have to see official documents to support that claim.

$1.5B total just for a Hubble service mission? That's hyperbole for the sake of justifying your conclusion.

GCNRevenger · 2005-01-08 13:41:54

The cost of the flight is irrelivent anyway, the cost of the mission is what is being considerd. The actual figure for the NASA Shuttle mission estimate by Goddard space flight center is $1.3 Billion, as reported in the above link. Given the cost of building replacement parts for Hubble and preparing what is certain to be a complex mission, I see no reason why it should cost less then this figure.

Bill has reported on numerous occasions that the Shuttle SRB costs aproximatly $20-25M each to refurbish between flights. Add this to the ~$50M of the new Shuttle tank (older ones going for ~$40M says Lockheed) combined with Orbiter consumeables places the cost of hardware around $100-110M a flight. Your charge that I would have to produce "offical documents" to prove it is unreasonable since NASA nor ATK Thiokol nor Lockheed-Martin would publish such things as cost calculations.

The fact of it is that the "incremental cost" of a Shuttle flight is not as small as you believe, the Shuttle engineers aren't sitting around playing cards between missions, so adding another flight to the already strained schedule will require signifigant reasources that would otherwise not be needed, and these will not come cheap.

Then there is the issue of the emergency logistics/HAB module and crew transfer gear & space suits in the ~1-2% chance of TPS failure which would cost around $500-600M to do most likly too... So you are faced with a question, the certain small damage to NASA of not fixing Hubble or the risk of a fatal blow to NASA of another Shuttle having a broken heat shield and no way to come home. Imagine if the media got wind that the crew had two weeks to live and no hope of survival? Can you fathom the drama that would be?

Unless of course you want to pay all that money for a robot with a 50/50 (or less) chance of sucess, another half a billion for a logistics module, or the extra cost of having a second Shuttle preped and ready to roll out immediatly following the HST flight and pray that it gets there in time.

RobertDyck · 2005-01-08 16:19:18

I think the shuttle can do it just fine, we don't need a robotic mission and we don't need an emergency logistics/HAB module. Just fill the cupboards of the galley, oxygen tanks, tanks for fuel cells, and bring extra LiOH cartridges. Water produced by the hydrogen fuel cell is used for drinking. A Hubble service mission must include the airlock and 2 EMU suits anyway. If an emergency happens stay in the shuttle until another orbiter can rescue them. At 1% chance of failure (over 100 flights and only 1 had TPS failure) that's all you need. I would like to sell to NASA a softball size inspection drone, but NASA is proceeding with an arm extension for inspection. They'll probably lock suit boots into footholds held by CanadArm, but should bring the MMU. You don't even need an EMU for every astronaut, just an ACES suit for ascent/descent. In the remote case a rescue is needed the first shuttle would have 2 EMUs, the second shuttle could bring an extra EMU for each additional astronaut. Total crew for the Hubble service mission would be 4-5, the rescue ship would have 2 astronauts. Shuttle can carry 7.

GCNRevenger · 2005-01-08 17:03:29

Actually no, the TPS system has failed twice and has been damaged thrice. Atlantis sufferd similar damage that destroyed Columbia albeit from a much smaller hole that did not compromise the wing structure. Columbia has also had its RCC panels damaged on a mission before its final flight though they were not breached.

Shuttle only has enough supplies for about 30 days, so the rescue Shuttle would have have to be rolled out within about two weeks and still reach the first Shuttle with safe margins, being that a persuit trajectory would likly take a few days. I think that is an awfully small margin even if you have a second Shuttle and stack ready to mount on the crawler. Doing that can't be cheap either.

The old EMU jet pack has also been retired which doesn't leave you much in the way of options. I think that it is a signifigant risk to try and rendevous and somehow try to get astronauts from one Shuttle to another.

So, having a second Shuttle go up at all is and get the first crew home is a severe risk given the limited consumeables that Shuttle can carry. And then there is the chance that the SECOND Shuttle would be stuck up there too, at least with ISS there is a chance that Russia could do the job with emergency Soyuz and Progress flights.

But just in case readers start thinking that my objections to a Shuttle HST repair missions are purely technical, I reiterate:

~Hubble is obsolete and either is or will soon be outclassed in almost every way by advanced ground telescopes with adaptive optics. The amount of critical science that ground telescopes can't do is probobly not worth the investment of a space telescope.

~Hubble's lifespan cannot be signifigantly extended by any repair mission. Hubble's gyros and batteries were intentionally designed such that they would need replacement every few years because it was assumed Shuttle would be able to service HST regularly. This problem is inherint to Hubble and not because of inferior quality of the parts; Hubble is in a low orbit so that its gyros and batteries must be worked extra hard.

Even then, if super batteries & gyros were installed, the ageing componets that cannot be replaced on Hubble will probobly fail soon anyway. Hubble's power system is likly near complete failure, and has already knocked out one of Hubble's cameras. Hubble is already operating 7 years beyond its original 15 year estimated lifespan.

~Hubble's skills that might not be duplicated by a ground scope, wide field, low noise, and UV astronomy, could be served by a new space telescope for half the money of a Shuttle mission or a third the money of a robot mission. Plus, this telescope would be based in a higher orbit where battery and gyro use would be greatly reduced, and would without a doubt work for much longer.

SpaceNut · 2005-01-13 06:24:58

Here is an example of the work that can be done with adative optics.

New view of distant colliding galaxies captured by Keck laser system

For the first time, astronomers have been able to combine the deepest optical images of the universe, obtained by the Hubble Space Telescope, with equally sharp images in the near-infrared part of the spectrum using a sophisticated new laser guide star system for adaptive optics at the W. M. Keck Observatory in Hawaii. The new observations, presented at the American Astronomical Society (AAS) meeting in San Diego this week, reveal unprecedented details of colliding galaxies with massive black holes at their cores, seen at a distance of around 5 billion light-years.

The images were obtained during testing of the laser guide star adaptive optics system on the 10-meter Keck II Telescope. They are the first science-quality images of a distant galaxies obtained with this new system. This being a major step for the Center for Adaptive Optics Treasury Survey (CATS), and use of adaptive optics to observe a distant galaxy.

"The advent of the laser guide star at Keck has opened up the sky for adaptive optics observations, and we can now use Keck to focus on those fields where we already have wonderful, deep optical images from the Hubble Space Telescope," Koo said.
Because the diameter of the Keck Telescope's mirror is four times larger than Hubble's, it can obtain images four times sharper than Hubble in the near infrared now that the laser guide star adaptive optics system is available to overcome the blurring effects of the atmosphere.

Well how does an Adaptive optical system or false star work:

Adaptive optics (AO) corrects for the blurring effect of the atmosphere, which seriously degrades images seen by ground-based telescopes. An AO system precisely measures this blurring and corrects the image using a deformable mirror, applying corrections hundreds of times per second. To measure the blurring, AO requires a bright point-source of light in the telescope's field of view, which can be created artificially by using a laser to excite sodium atoms in the upper atmosphere, causing them to glow. Without such a laser guide star, astronomers have had to rely on bright stars ("natural guide stars"), which drastically limits where AO can be used in the sky. Furthermore, natural guide stars are too bright to allow observations of very faint, distant galaxies in the same part of the sky, Koo said.

John Creighton · 2005-01-14 10:54:08

It sounds like the adaptive optics have reached parody with Hubble for near infrared light. How well do they work for other frequencies.

GCNRevenger · 2005-01-14 10:58:40

The Hubble-Huggers (that want to see HST kept around until 2030, somehow ignoring its deteriorating condition) predict optical parity within a decade, so probobly somewhere less then this.

GraemeSkinner · 2005-01-18 05:48:41

It sounds like the adaptive optics have reached parody with Hubble for near infrared light. How well do they work for other frequencies.

From the ESA's website on adaptive optics...

For instance, a near-perfect correction for an observation done in visible light (0.6 /265m) with an 8-m telescope would require ~ 6400 actuators

Near infrared the collimation on adaptive optics is not so much of a problem with around 250 actuators required.
So if you only want to work in infrared adaptive optics are quite a good option

The use of sodium lasers to collimate adaptive optic systems has some problems, other astronomers working nearby have to avoid the area the laser is being used in; they require a lot of power; and one person suggested you should not have planes nearby whilst collimation is going on.

Graeme

GCNRevenger · 2005-01-18 10:32:33

6,400? Is that all?

The computer screen I am typing this on has 1.3 million individual cells of liquid crystal, each with wiring to activate them, with a surface area of over 100 square inches.

Now, say you make an array on a PCB of piezo actuators coverd by the flexible polymer/aluminum mirror. This should not be that hard to accomplish, and is only a matter of time, money, and computing power.

GraemeSkinner · 2005-01-18 22:46:20

6,400? Is that all?

Yes, but that would be a minimum, like anything else we always want more

The computer screen I am typing this on has 1.3 million individual cells of liquid crystal, each with wiring to activate them, with a surface area of over 100 square inches.

Honestly? I use a keyboard to type on

I'd say a monitor has a more predictable requirement than adaptive optics, plus the change the crystal cells undergo are quicker than an actuator by there nature.

Now, say you make an array on a PCB of piezo actuators coverd by the flexible polymer/aluminum mirror. This should not be that hard to accomplish, and is only a matter of time, money, and computing power.

But yet you say there is no need for Hubble as ground based adaptive optics can replace it?

In a BBC article http://news.bbc.co.uk/1/hi/sci/tech/4184873.stm]LINK

The American Astronomical Society (AAS) said it endorsed a National Research Council recommendation that Nasa pursue a manned mission to repair Hubble.

Also in the same article

With repairs, Hubble's observing life could extend to 2013.

But I think the most compelling piece of the article would be

The telescope is also slated to be fitted with a new camera and spectrograph.
The Cosmic Origins Spectrograph would be sensitive to very faint UV light, such as intergalactic gas from the early universe, and the Wide Field Camera 3 would be optimised for infrared, ultraviolet and visible wavelengths.

Having an interest in cosmology, its something I'd like to see.

Graeme

GCNRevenger · 2005-01-19 07:59:51

"Could" be extended to 2013? Thats pretty wishful thinking, I doubt that can be achieved, perhaps 2011 or so at best. The AAS has a vested interest in keeping Hubble around for the same reason the NBA kept around Michael Jordan, that its good for publicity... People will jump and click at anything marked "new Hubble pictures" because of its notarity, but will blithely pass over somthing marked "New SIRTF images!" or whatnot.

And as I have said on several different occasions, you can simply put the new super Hubble cameras into a brand new optical space telescope for far less money and have far more life then an HST service mission and be in a much better orbit to boot. The Alternative Options report believes that a new telescope to carry these instruments would cost a mere $800M including launcher.

GraemeSkinner · 2005-01-19 22:53:01

"Could" be extended to 2013? Thats pretty wishful thinking, I doubt that can be achieved, perhaps 2011 or so at best. The AAS has a vested interest in keeping Hubble around for the same reason the NBA kept around Michael Jordan, that its good for publicity... People will jump and click at anything marked "new Hubble pictures" because of its notarity, but will blithely pass over somthing marked "New SIRTF images!" or whatnot.

But earlier in this thread (or previous) you said that a service mission would only give us a couple of years or so. You also claim that ground based AO scopes have parity with Hubble, yet thats really only at infrared wavelengths and will be for some time to come. I'm not claiming or entertaining ideas that Hubble can survive forever, I just don't believe its come to the end of its usefull life yet. Maybe the AAS have a vested interest in Hubble, thats not to say that the reasons they give for saving it or the methods they support are invalid - I'll trust you on the Michael Jordan point (I'm English remember and don't know the guy (I was trying to work our NBA - National B? of Astronomers ))

Many people may just select Hubble images to view and ignore all others, however, you'd have to admit that they are unlikely to have any real interest in the images other that classing them as pretty. If you have a real interest in astronomy/cosmology then you take any image you can, from whatever the source as long as the image is good enough. So with this in mind I regularly try to view as many images as I can from as many sources as I can.

And as I have said on several different occasions, you can simply put the new super Hubble cameras into a brand new optical space telescope for far less money and have far more life then an HST service mission and be in a much better orbit to boot. The Alternative Options report believes that a new telescope to carry these instruments would cost a mere $800M including launcher.

Yes you have said it on many occasions, the fact that you repeat it does not make it any more attractive a suggestion. Hubble II would be good in my view, but it should be developed as a long term project, not just gather together any leftovers and throw them up there or we'll be discussing save Hubble II in ten years time

Graeme

Euler · 2005-01-19 23:52:49

Hubble II would be good in my view, but it should be developed as a long term project, not just gather together any leftovers and throw them up there or we'll be discussing save Hubble II in ten years time

If it lasts ten years then that already makes it more cost effective than repairing Hubble. Then in ten years instead of saving Hubble II we send up Hubble III.

GraemeSkinner · 2005-01-20 01:57:28

Why then worry how long it lasts if we live in such a throw away culture we can just send up replacement after replacement. We can stop designing improved versions of anything and just replace, replace, replace.

Graeme

GCNRevenger · 2005-01-20 06:08:31

Hubble will likly suffer failure of too many gyroscopes to remain functional sometime in early 2008, perhaps 2009. Slapping new gyros and batteries will probobly buy another few years, making it 2011 or 2012 before these fail as well or somthing else breaks.

Ground telescopes have already reached parity with Hubble in the IR, and will in the visible spectrum shortly, perhaps even before a Hubble SM can be put together and will not long after Hubble fails irreperably. The technology is possible today, its just a matter of the application.

"I just don't believe its come to the end of its usefull life yet"

What you believe about Hubble is irrelivent, the question if we should spend the money to try and fix Hubble is a simple, cold, numbers game... a cost/bennefit/risk analysis. Whichever option gives you the best performance for the lowest cost and risk is the one that should be employed... And it is quite obvious that this preferable option is NOT going up to fix Hubble. Sentimental attachment or a breif hiatus of ultrahigh performance astronomy is simply not worth the excessive investment, the high risk failure, and low scientific payoff. Thats the way it is.

""Why then worry how long it lasts if we live in such a throw away culture..."

Ah yes more metaphysical/sentimental "recycling good" talk... Again, this is a simple cost/bennefit analysis. Hubble-II will live for a very long time, easily until 2020 if it is launched by decades' end, will cost no more then Hubble SM4, and have much higher performance.

It won't be a "evil throw away culture" villain because it will last a very long time. "Built to last," so to speak, if you need a buzz-phrase to get you on board... And you are correct, that a good OST with modern technology will last so long that we need not bother with improving the design and servicing it, since it will be obsolete by the end of its life most likly in which case replacement makes more investment sense.

Ultimatly, the cost of servicing missions to repair or upgrade obsolete space telescopes does not make good sense being that replacement telescopes are little if any more expensive, servicing missions really do cost an arm and a leg. Again, thats the way it is.

SpaceNut · 2005-01-20 06:18:08

If the norm is to repair with the same item that will only fail again within the same time frame, IMO do not do the repair. But if the item is repaired with an enhance version that will last long by all means get the job done.
As for the recycling question does it make sense to keep replacing the telescopes every 10 years, why not 15 or even longer. Does the technology evolve that quickly to justify this.

GCNRevenger · 2005-01-20 10:07:24

"enhance version that will last long by all means get the job done."

No. If replacing the old with a new one which will last longer and have even higher performance without costing much if any more, then we should NOT do the upgrade.

GraemeSkinner · 2005-01-20 23:50:40

Ground telescopes have already reached parity with Hubble in the IR, and will in the visible spectrum shortly, perhaps even before a Hubble SM can be put together and will not long after Hubble fails irreperably. The technology is possible today, its just a matter of the application.

Its strange, I say that Hubble still has a usefull life ahead of it, if its repaired, you counter with but we can match it in IR with AO groundbased scopes and will in the visible shortly - now don't groan as I'm about to use a car analogy - I would not throw away my car as in five years time there is a possibility a better option will be available, what happens five years down the line when I suddenly discover that the better option replacement is actually going to take another ten years and will not be much good after all, I'll have spent all those years in which I could have been using my car making do with a bicycle.

"I just don't believe its come to the end of its usefull life yet"
What you believe about Hubble is irrelivent, the question if we should spend the money to try and fix Hubble is a simple, cold, numbers game... a cost/bennefit/risk analysis. Whichever option gives you the best performance for the lowest cost and risk is the one that should be employed... And it is quite obvious that this preferable option is NOT going up to fix Hubble. Sentimental attachment or a breif hiatus of ultrahigh performance astronomy is simply not worth the excessive investment, the high risk failure, and low scientific payoff. Thats the way it is.

Its not just a numbers game though is it, because you have already argued that we don't need Hubble as we can use ground based scopes, money in that argument is not relevant. Your point "whichever option gives you the best performance for the lowest cost and risk is the one that should be employed..." is basically flawed as well, best performance for lowest cost would be a 30 dollar/pound/whatever telescope from your local store, because for the lowest cost it will give you the best performance, and risk is not as much of an issue when you use it in your back garden. "High risk failure, low scientific payoff"? This is a Hubble thread not an ISS one :;): The scientific payoff from Hubble however is and has been something you can not put a value on, we've learnt a great deal from Hubble and can continue to do so.

""Why then worry how long it lasts if we live in such a throw away culture..."
Ah yes more metaphysical/sentimental "recycling good" talk... Again, this is a simple cost/bennefit analysis. Hubble-II will live for a very long time, easily until 2020 if it is launched by decades' end, will cost no more then Hubble SM4, and have much higher performance.

You do have a problem with anything environmental in terminology don't you? But a decade lifespan is not a very long time.

Ultimatly, the cost of servicing missions to repair or upgrade obsolete space telescopes does not make good sense being that replacement telescopes are little if any more expensive, servicing missions really do cost an arm and a leg. Again, thats the way it is.

No, thats just how you perceive it. Servicing missions cost so much because thats the way space agencies want it to be to a certain degree! Put it this way, a car company will never make you a car for life, one that requires servicing every ten years or so, no, you'll be back to the garage twice a year for a service (or whatever, I do it myself so have little idea on that :;): ) and why is that, because it keeps the whole car industry working to do it that way. If you worked for NASA, would you want your staff working on equipment that would last for ever, because once its built you only need a small number of staff to keep it going, or do you build items that have a limited lifespan?

Graeme

Euler · 2005-01-21 00:16:35

Its strange, I say that Hubble still has a usefull life ahead of it, if its repaired, you counter with but we can match it in IR with AO groundbased scopes and will in the visible shortly - now don't groan as I'm about to use a car analogy - I would not throw away my car as in five years time there is a possibility a better option will be available, what happens five years down the line when I suddenly discover that the better option replacement is actually going to take another ten years and will not be much good after all, I'll have spent all those years in which I could have been using my car making do with a bicycle.

Lets say you have a completely obsolete 20-year-old computer that is starting to break down. Do you pay someone a lot of money to try and fix it, or do you just get a new computer?

Your point "whichever option gives you the best performance for the lowest cost and risk is the one that should be employed..." is basically flawed as well, best performance for lowest cost would be a 30 dollar/pound/whatever telescope from your local store, because for the lowest cost it will give you the best performance, and risk is not as much of an issue when you use it in your back garden.

It really depends on how you measure performance. You could argue that, for many purposes, the $30 telescope is effectively useless and has a performance of 0. In any case, your comparison does not really apply here, since we are talking about getting a better telescope that might still cost less then repairing Hubble. If the price and the performance are both better, then it is clearly a better option.

GraemeSkinner · 2005-01-21 00:25:54

Lets say you have a completely obsolete 20-year-old computer that is starting to break down. Do you pay someone a lot of money to try and fix it, or do you just get a new computer?

Buy a new computer, but your opening line makes that obvious completely obsolete something which Hubble is not. If Hubble was completely obsolete I don't think anyone would object.

It really depends on how you measure performance. You could argue that, for many purposes, the $30 telescope is effectively useless and has a performance of 0. In any case, your comparison does not really apply here, since we are talking about getting a better telescope that might still cost less then repairing Hubble. If the price and the performance are both better, then it is clearly a better option.

The comparison does apply though, if you want the lowest cost, no risk option.

Graeme

Euler · 2005-01-21 00:34:40

Buy a new computer, but your opening line makes that obvious completely obsolete something which Hubble is not. If Hubble was completely obsolete I don't think anyone would object.

But Hubble is completely obsolete. A modern telescope that is approximately the same mass and cost as Hubble should be able to get at least an order of magnitude improvement in performance. Telescope technology is improving very rapidly right now; they are more like computers than like cars.

New Mars Forums

Announcement

#51 2005-01-07 15:26:08

Re: Hubble Mistake **2** - Action still Needed

#52 2005-01-07 19:39:50

Re: Hubble Mistake **2** - Action still Needed

#53 2005-01-08 00:14:11

Re: Hubble Mistake **2** - Action still Needed

#54 2005-01-08 10:21:55

Re: Hubble Mistake **2** - Action still Needed

#55 2005-01-08 12:23:39

Re: Hubble Mistake **2** - Action still Needed

#56 2005-01-08 13:41:54

Re: Hubble Mistake **2** - Action still Needed

#57 2005-01-08 16:19:18

Re: Hubble Mistake **2** - Action still Needed

#58 2005-01-08 17:03:29

Re: Hubble Mistake **2** - Action still Needed

#59 2005-01-13 06:24:58

Re: Hubble Mistake **2** - Action still Needed

#60 2005-01-14 10:54:08

Re: Hubble Mistake **2** - Action still Needed

#61 2005-01-14 10:58:40

Re: Hubble Mistake **2** - Action still Needed

#62 2005-01-18 05:48:41

Re: Hubble Mistake **2** - Action still Needed

#63 2005-01-18 10:32:33

Re: Hubble Mistake **2** - Action still Needed

#64 2005-01-18 22:46:20

Re: Hubble Mistake **2** - Action still Needed

#65 2005-01-19 07:59:51

Re: Hubble Mistake **2** - Action still Needed

#66 2005-01-19 22:53:01

Re: Hubble Mistake **2** - Action still Needed

#67 2005-01-19 23:52:49

Re: Hubble Mistake **2** - Action still Needed

#68 2005-01-20 01:57:28

Re: Hubble Mistake **2** - Action still Needed

#69 2005-01-20 06:08:31

Re: Hubble Mistake **2** - Action still Needed

#70 2005-01-20 06:18:08

Re: Hubble Mistake **2** - Action still Needed

#71 2005-01-20 10:07:24

Re: Hubble Mistake **2** - Action still Needed

#72 2005-01-20 23:50:40

Re: Hubble Mistake **2** - Action still Needed

#73 2005-01-21 00:16:35

Re: Hubble Mistake **2** - Action still Needed

#74 2005-01-21 00:25:54

Re: Hubble Mistake **2** - Action still Needed

#75 2005-01-21 00:34:40

Re: Hubble Mistake **2** - Action still Needed

Board footer

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed

Re: Hubble Mistake 2 - Action still Needed