4 ms·

I wonder how expensive it would be to design an "affordable" space telescope which could be produced in a small series. The Falcon 9 should be able to launch a

by _ph_ 6y ago

I wonder how expensive it would be to design an "affordable" space telescope which could be produced in a small series. The Falcon 9 should be able to launch a roughly hubble-sized telescope. So the launch costs would be a fraction of the shuttle costs back then. This means, more than one telescope could be launched and the telescope to be more designed to be "expendable". Which once again reduces costs a lot. I think one driver for the enormeous cost of a lot of space missions is the amount of overdesign happening as due to the high costs, failure is not an option. Just designing for 5 years and allowing for the early failure, costs should be so low that a failure is no longer a big issue. Also, if there is one basic platform, sending different telescopes with quite different sensor packages would be an option.

JBorrow 6y ago
A lot of the cost for space based missions is also in instrument design. When you make a telescope, you don’t need to just design the mirror and the stuff that holds it up, and a camera with a series of filters. You need to design spectrographs and other complex systems that need to be “space-hardened” and extremely well tested. A “sensor package” doesn’t really cut it. See for example this spectrograph: https://www.eso.org/public/images/ann13071c/ https://www.eso.org/public/images/ann13071c/ Huge instruments like these that actually power today’s science is another reason why ground based astronomy is required, and why we can’t just move all observation to space if satellite clusters ruin the night sky.
- _ph_ 6y ago
  Hubble is mainly a set of cameras attached to the telescope, it doesn't have anything comparable to what you linked. Yes, I am aware of all the advantages of ground based astronomy, which just got a huge boom by segmented mirrors basically removing the mirror size limit. The flexibility and costs of ground-based astronomy are superior for anything which can be done well from the ground. I have nowhere suggested to stop or defund ground based astronomy. We need ground based astronomy and space based one. So we need to come up with a replacement of Hubble, thats where my suggestions come from. And yes, I am aware of the challenges of space-going equipment. But if a system is designed for a life time of rather 5 than 30 years, things become a bit easier. Also, if you look at the camera equipment of Perseverance, a lot of it is off-shelve, only slightly enhanced for its intended purpose.
  - SiempreViernes 6y ago
    Uh, missions are designed to last max five years, so you're not gonna find any savings there. Maybe if you cut the high reliability requirements to five months you can skimp on some stuff, but I'm not sure that actually relaxes demands so much as that's still a lot of thermal cycles to maintain instrument alignment over.
  - JBorrow 6y ago
    As another commenter said, they are designed to work for 5ish years. That we have had Hubble so long is essentially a miracle. Same thing for the Mars rovers that limped on for years despite only being designed to last months. Also your claim about the instruments on Hubble is incorrect. See: https://www.nasa.gov/content/goddard/hubble-space-telescope-science-instruments https://www.nasa.gov/content/goddard/hubble-space-telescope-....
jeffrallen 6y ago
A giant mirror is not expendable, and takes more than 5 years just to make. So until the astronomers tell the engineers, "hey no problem, we can do good science with little cheap mirrors", engineers are going to be stuck engineering the rest of the telescope around the economics of the mirror.
- tigershark 6y ago
  You don’t need a single giant mirror. https://en.m.wikipedia.org/wiki/Segmented_mirror https://en.m.wikipedia.org/wiki/Segmented_mirror Also the James Webb space telescope uses this technique: https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope
- _ph_ 6y ago
  At about 2 meters of aperture, you can quite well still do a single mirror at reasonable costs. If the launch costs like 60 million, the telescope would realistically have a budget of 60-120 million for the platform. On that scale, a series of 2m mirrors should be affordable - you would of course order more than one mirror, so you have a reasonable supply. Considering that a single shuttle launch costet close to 1 billion and the Webb telescope costs many billions, spending 1 billion on a set of 5 telescopes including launch costs sounds like a worthwhile program. Which could be scaled to more telescopes as long there is budget.
  - JBorrow 6y ago
    2m is pittance for professional astronomy. Hubble may have a 2.4m mirror, but remember that is a 1980s era telescope. Current and future telescopes target 10-30m mirrors, purely for light capture reasons. We’d need to put something that big in space for it to be worthwhile.
    - _ph_ 6y ago
      No, even Hubble still delivers great contributions to science which are not quite matched by earthbound telescopes. Those win on aperture for sure, but Hubble is the only large telescope outside of the atmosphere. This gives access to wider wavelengths and removes all other atmospheric influences. That is the reason, the final passing of Hubble would be a huge loss, if not replaced. There are several aspects we could improve on the current situation: make "better" telescopes or make more telescope. Having only 1, soon 0 space-based telescopes is cutting it very thin. Having 5-10 would increase our research a lot as more things could be observed. Of course, eventually there will be a need for large space telescopes too, probably those will be enabled by Starship. But first we should use the currently available technology to make sure we don't fall back into the level of the 80ies when Hubble dies. And use modern technology to make this a "cheap" effort vs. the extremely expensive Hubble.
okl 6y ago
Something like Astrosat or cheaper? At ~$25M it's rather cheap in relation to launch prices. https://en.wikipedia.org/wiki/Astrosat https://en.wikipedia.org/wiki/Astrosat > Also, if there is one basic platform, sending different telescopes with quite different sensor packages would be an option. Satellites are usually designed around an integrator's platform, called "bus". https://en.wikipedia.org/wiki/Satellite_bus https://en.wikipedia.org/wiki/Satellite_bus
- _ph_ 6y ago
  I was more thinking of roughly hubble-sized telescopes, but as a program optimized for having several telescopes. Like spending 1 billion in total for a larger amount of telescopes, which can be easily replaced should one fail or new instruments are required.
JBorrow 6y ago
Also - we are currently launching another Hubble, called WFIRST. This was provided by a 3 letter US agency and required a mirror redesign. Launch costs are not a factor now, and weren’t then either.
- _ph_ 6y ago
  "Currently"? It is worked on and might launch after 2025. Also, it is different from Hubble, so not a direct replacmenet. But indeed, with a total budget of over 3 billion dollars, launch costs are no longer the problem. Remains the question: why is it so expensive? Because it will have been worked on for more than 10 years and probably is over-engineered like hell, as you must not fail with a 3 billion dollar telescope.
  - JBorrow 6y ago
    The reason it is so expensive is, as I said in my other comments - the instruments. These are one-off, heavily tested prototypes.
    - _ph_ 6y ago
      You are saying the magic word: prototypes. That explains the huge budgets, time and cost overruns. They certainly have an important place in science, because sciences often is about doing things the first time. But there is also a place for production runs. Because you are no longer just making prototypes but start to reuse the experiences and expenses. Hubble is 30 years old, and there isn't any direct replacement in sight at all. At latest now, with cheap launches and much improved technology, it is more than time to replace it and as it is more or less a direct replacement, use the scale of production. Don't build one telescope for 3 billion, build 10 at like 100-200 million each. If one ore more of them fail, so what?
      - JBorrow 6y ago
        Well the reason that we would build the one 3 bn telescope, rather than 10 100-200 m telescopes, is because they can tell you fundamentally different things about the Universe. In many ways, to move forward, we must go bigger with the tech, not wider. What you are essentially suggesting is a survey - we already have instruments and telescopes to do exactly that, with new ones coming online soon (see the LSST). Deep observations like Hubble was meant to do can actually be done better from the ground now (e.g. the VLT, ELT, etc.). As such, focus has shifted to those for optical observations. The community at large, however, has decided where it would like to spend its budget. That was on Webb for the IR wavebands, to study so-called 'high redshift' objects that Hubble struggles to see, and leave the more detailed imaging to those ground based observatories. Look, I would love another Hubble. That would be really useful! And that's why WFIRST exists. But an in-place replacement doesn't make sense. The tech on Hubble (not necessarily the mirror, but the _instruments_, the spectrographs, the interferometers) is really old. You can't take an off-the-shelf component, because it needs to be built to withstand space. So you need to create a one-off, 'prototype', space-hardened instrument. It is also not a case of worrying about them 'failing', but you also must worry about them slowly drifting out of a calibrated range. On the ground, you could fix the instrument, or re-calibrate it. That's not possible in space. That's not a 'random' style error, where we can get out of it by upping the number of them - they are systematic, so all 10 of your proposed telescopes would be ruined.

by _ph_ 6y ago

JBorrow 6y ago

A lot of the cost for space based missions is also in instrument design. When you make a telescope, you don’t need to just design the mirror and the stuff that holds it up, and a camera with a series of filters. You need to design spectrographs and other complex systems that need to be “space-hardened” and extremely well tested. A “sensor package” doesn’t really cut it. See for example this spectrograph: https://www.eso.org/public/images/ann13071c/ https://www.eso.org/public/images/ann13071c/ Huge instruments like these that actually power today’s science is another reason why ground based astronomy is required, and why we can’t just move all observation to space if satellite clusters ruin the night sky.

_ph_ 6y ago
Hubble is mainly a set of cameras attached to the telescope, it doesn't have anything comparable to what you linked. Yes, I am aware of all the advantages of ground based astronomy, which just got a huge boom by segmented mirrors basically removing the mirror size limit. The flexibility and costs of ground-based astronomy are superior for anything which can be done well from the ground. I have nowhere suggested to stop or defund ground based astronomy. We need ground based astronomy and space based one. So we need to come up with a replacement of Hubble, thats where my suggestions come from. And yes, I am aware of the challenges of space-going equipment. But if a system is designed for a life time of rather 5 than 30 years, things become a bit easier. Also, if you look at the camera equipment of Perseverance, a lot of it is off-shelve, only slightly enhanced for its intended purpose.
- SiempreViernes 6y ago
  Uh, missions are designed to last max five years, so you're not gonna find any savings there. Maybe if you cut the high reliability requirements to five months you can skimp on some stuff, but I'm not sure that actually relaxes demands so much as that's still a lot of thermal cycles to maintain instrument alignment over.
- JBorrow 6y ago
  As another commenter said, they are designed to work for 5ish years. That we have had Hubble so long is essentially a miracle. Same thing for the Mars rovers that limped on for years despite only being designed to last months. Also your claim about the instruments on Hubble is incorrect. See: https://www.nasa.gov/content/goddard/hubble-space-telescope-science-instruments https://www.nasa.gov/content/goddard/hubble-space-telescope-....

jeffrallen 6y ago

A giant mirror is not expendable, and takes more than 5 years just to make. So until the astronomers tell the engineers, "hey no problem, we can do good science with little cheap mirrors", engineers are going to be stuck engineering the rest of the telescope around the economics of the mirror.

tigershark 6y ago
You don’t need a single giant mirror. https://en.m.wikipedia.org/wiki/Segmented_mirror https://en.m.wikipedia.org/wiki/Segmented_mirror Also the James Webb space telescope uses this technique: https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope
_ph_ 6y ago
At about 2 meters of aperture, you can quite well still do a single mirror at reasonable costs. If the launch costs like 60 million, the telescope would realistically have a budget of 60-120 million for the platform. On that scale, a series of 2m mirrors should be affordable - you would of course order more than one mirror, so you have a reasonable supply. Considering that a single shuttle launch costet close to 1 billion and the Webb telescope costs many billions, spending 1 billion on a set of 5 telescopes including launch costs sounds like a worthwhile program. Which could be scaled to more telescopes as long there is budget.
- JBorrow 6y ago
  2m is pittance for professional astronomy. Hubble may have a 2.4m mirror, but remember that is a 1980s era telescope. Current and future telescopes target 10-30m mirrors, purely for light capture reasons. We’d need to put something that big in space for it to be worthwhile.
  - _ph_ 6y ago
    No, even Hubble still delivers great contributions to science which are not quite matched by earthbound telescopes. Those win on aperture for sure, but Hubble is the only large telescope outside of the atmosphere. This gives access to wider wavelengths and removes all other atmospheric influences. That is the reason, the final passing of Hubble would be a huge loss, if not replaced. There are several aspects we could improve on the current situation: make "better" telescopes or make more telescope. Having only 1, soon 0 space-based telescopes is cutting it very thin. Having 5-10 would increase our research a lot as more things could be observed. Of course, eventually there will be a need for large space telescopes too, probably those will be enabled by Starship. But first we should use the currently available technology to make sure we don't fall back into the level of the 80ies when Hubble dies. And use modern technology to make this a "cheap" effort vs. the extremely expensive Hubble.

okl 6y ago

Something like Astrosat or cheaper? At ~$25M it's rather cheap in relation to launch prices. https://en.wikipedia.org/wiki/Astrosat https://en.wikipedia.org/wiki/Astrosat > Also, if there is one basic platform, sending different telescopes with quite different sensor packages would be an option. Satellites are usually designed around an integrator's platform, called "bus". https://en.wikipedia.org/wiki/Satellite_bus https://en.wikipedia.org/wiki/Satellite_bus

_ph_ 6y ago
I was more thinking of roughly hubble-sized telescopes, but as a program optimized for having several telescopes. Like spending 1 billion in total for a larger amount of telescopes, which can be easily replaced should one fail or new instruments are required.

JBorrow 6y ago

Also - we are currently launching another Hubble, called WFIRST. This was provided by a 3 letter US agency and required a mirror redesign. Launch costs are not a factor now, and weren’t then either.

_ph_ 6y ago
"Currently"? It is worked on and might launch after 2025. Also, it is different from Hubble, so not a direct replacmenet. But indeed, with a total budget of over 3 billion dollars, launch costs are no longer the problem. Remains the question: why is it so expensive? Because it will have been worked on for more than 10 years and probably is over-engineered like hell, as you must not fail with a 3 billion dollar telescope.
- JBorrow 6y ago
  The reason it is so expensive is, as I said in my other comments - the instruments. These are one-off, heavily tested prototypes.
  - _ph_ 6y ago
    You are saying the magic word: prototypes. That explains the huge budgets, time and cost overruns. They certainly have an important place in science, because sciences often is about doing things the first time. But there is also a place for production runs. Because you are no longer just making prototypes but start to reuse the experiences and expenses. Hubble is 30 years old, and there isn't any direct replacement in sight at all. At latest now, with cheap launches and much improved technology, it is more than time to replace it and as it is more or less a direct replacement, use the scale of production. Don't build one telescope for 3 billion, build 10 at like 100-200 million each. If one ore more of them fail, so what?
    - JBorrow 6y ago
      Well the reason that we would build the one 3 bn telescope, rather than 10 100-200 m telescopes, is because they can tell you fundamentally different things about the Universe. In many ways, to move forward, we must go bigger with the tech, not wider. What you are essentially suggesting is a survey - we already have instruments and telescopes to do exactly that, with new ones coming online soon (see the LSST). Deep observations like Hubble was meant to do can actually be done better from the ground now (e.g. the VLT, ELT, etc.). As such, focus has shifted to those for optical observations. The community at large, however, has decided where it would like to spend its budget. That was on Webb for the IR wavebands, to study so-called 'high redshift' objects that Hubble struggles to see, and leave the more detailed imaging to those ground based observatories. Look, I would love another Hubble. That would be really useful! And that's why WFIRST exists. But an in-place replacement doesn't make sense. The tech on Hubble (not necessarily the mirror, but the _instruments_, the spectrographs, the interferometers) is really old. You can't take an off-the-shelf component, because it needs to be built to withstand space. So you need to create a one-off, 'prototype', space-hardened instrument. It is also not a case of worrying about them 'failing', but you also must worry about them slowly drifting out of a calibrated range. On the ground, you could fix the instrument, or re-calibrate it. That's not possible in space. That's not a 'random' style error, where we can get out of it by upping the number of them - they are systematic, so all 10 of your proposed telescopes would be ruined.