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posted by martyb on Wednesday January 30 2019, @10:12PM   Printer-friendly
from the BIG-eyes-on-the-sky dept.

The James Webb Space Telescope may only last 5-10 years, and its successor (LUVOIR) may not be launched until the mid-2030s or later. Extremely large ground telescopes could fill in the gaps for astronomers:

A solution to [the] future space telescope gap may come from the ground. A new generation of what are known as extremely large telescopes, or ELTs, are under development and expected to enter service in the 2020s. With mirrors of between 25 and 40 meters in diameter, they're far larger than anything foreseen for space for decades. Even with the limitations of operating on the ground, like weather and atmospheric distortions, they have capabilities that will be unmatched for years.

[...] A problem for many astronomers, though, is that [Giant Magellan Telescope (GMT)] and [Thirty Meter Telescope (TMT)] are being developed not by government agencies but by consortia of universities and nonprofit organizations. Astronomers who are not part of the consortia won't be able to use them.

That's why, at the AAS meeting, there was a concerted push for what's called the U.S. ELT Program, a proposal to provide those two observatories with federal funding in exchange for open access to any American astronomer, just like NASA-operated space telescopes. A specific proposal for the program called for a combined $1 billion in National Science Foundation funding for GMT and TMT, in exchange for 25 percent of the observing time on each.

[...] The two observatories say they would be willing to give up a share of their observing time to the broader astronomical community in exchange for the financial support and stability the NSF would provide. "Their financial support will be very helpful for staying on schedule and meeting our overall plan," said Pat McCarthy, vice president of GMT. "There's a real advantage to knowing that the entire U.S. community is behind us."

[...] ELT advocates have no problem with NASA jumping on board. "We would welcome NASA investment in our giant machines," said Silva when asked at an AAS session about the space agency contributing to the U.S. ELT Program. But, he added, no one from NASA could comment on the idea. Thanks to the shutdown, no one from NASA could attend.


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  • (Score: 3, Interesting) by bob_super on Wednesday January 30 2019, @11:26PM (3 children)

    by bob_super (1357) on Wednesday January 30 2019, @11:26PM (#794282)

    How about grabbing those frames donated by NRO to NASA, putting some basic electronics, more than 4 gyros, and a couple decent modern cameras with a 5 or 10 year life expectancy, and shooting the whole thing into space on a couple F9 or FH for a cool billion or so, TCO for the pair ?

    F9 fairing is 13m x 5m, which kinda matches Hubble (11m x 4.2). Hubble was 11t, totally F9able.

    We can send a suitcase to Mars to beam pictures of a probe landing. The problem we have with space telescopes is that they don't happen often, so people go bonkers on the specs, and schedule and budgets just explode.
    We're gonna lose Hubble one of these days. Yes, we want better than Hubble for our next set of billions. But with the progress of optics and cameras since the last service mission, and a lot of experience too, we should be able to hack together an improved replacement to bridge the gap until the much-optimized JWST takes over, or after it dies (hoping it ever works at all). Hubble still discovers things. Hubble+ would too. For cheap. Ask the Pentagon whether a billion is a big deal.

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  • (Score: 2) by takyon on Thursday January 31 2019, @01:55AM (2 children)

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday January 31 2019, @01:55AM (#794332) Journal

    First off, given the time frame and planning involved. I say ditch F9/FH, and assume a working BFR (Starship Super Heavy). Bigger payloads, much larger payload fairing, cheaper launches (at least by $/kg, if not immediately cheaper than F9).

    https://soylentnews.org/~takyon/journal/3463 [soylentnews.org]

    We could assemble a giant modular space telescope using multiple launches. This ought to be something that could be done autonomously, but humans could be put in the loop, and the telescopes could be assembled at the LOP-G (assuming we go through with that) or China's upcoming space station (which will be open to the whole world, according to China).

    LUVOIR [wikipedia.org] is the planned JWST successor and is the direct successor to Hubble (it will cover a similar range of wavelengths from near-infrared, optical, to ultraviolet). It would have an aperture of 8 or 15 meters depending on what launch vehicles are available. A modular telescope could have a much larger aperture. Beating the 39.3 meters of the Extremely Large Telescope should be possible. 100 meters is considered a limit for ground-based optical telescopes due to pesky gravity. You could bust past that limit in space. If we do it right, maybe we can start using the modular space telescope while it is small, and keep adding onto the aperture diameter with each additional launch. There's also the possibility of setting up an optical interferometer telescope in space for a larger effective aperture at the expense of light collecting capability.

    On the other hand, we could forget about modular and just launch the biggest telescope possible that can fit within a fairing. The smaller 8-meter LUVOIR-B design could be able to fit into the 9-meter BFR payload fairing without any potentially wonky folding mirrors. With BFR, you can launch a larger telescope than JWST (6.5 meters). Given the relatively low launch cost predicted for BFR, you could take the rocket out of the equation and launch as many telescopes (to low Earth orbit) as can be produced. If we built a larger-than-JWST optical telescope using existing technologies, maybe we could build 10 of them. Without any unfolding mirrors or complex heat shields, the cost could be much lower. Launching multiple copies from the start means you can skip the years of tedious and expensive testing. Just do a couple of passes on the first one, launch, see if it works, and repeat.

    JWST is important because it can see highly redshifted objects better than optical/near-infrared telescopes could. But given how productive and overbooked little old Hubble has been, we know there is an essentially infinite demand for space telescopes. If you run out of proposals, you could stare at targets for longer, or include random targets of opportunity. If we could launch low-cost better-than-Hubble, larger-than-JWST telescopes, we could advance astronomy in a big way.

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    • (Score: 2) by bob_super on Thursday January 31 2019, @02:04AM (1 child)

      by bob_super (1357) on Thursday January 31 2019, @02:04AM (#794339)

      Not disagreeing, but you're pushing back too far. BFR, 8m designs ...

      I'm talking about using the NRO frames, which exist and are proven, modifying them, which was evaluated a few years back and deemed a bit expensive by people protecting JWST, and fitting them in a known-good cheap launcher (which wasn't available then).
      Doesn't buy you as much improvement over Hubble, for sure, but it's all feasible in literally a couple real years, not 5 Elon-years.

      I'm looking at the short-term stopgap if Hubble wobbles again. Then we can do your vastly improved version. Both easily fit in the cost of an aircraft carrier.

      • (Score: 4, Interesting) by takyon on Thursday January 31 2019, @02:30AM

        by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday January 31 2019, @02:30AM (#794347) Journal

        Hubble has had health scares in the last few months, but it actually has a good amount of redundant components that can be switched to. It could last into the 2020s, or even the 2030s.

        Sierra Nevada Corporation is getting money for its Dream Chaser spacecraft [soylentnews.org]. There is a tentative plan to use Dream Chaser to service Hubble [spaceflightinsider.com]. This plan will probably get more attention in the event of Dream Chaser successfully being flown to the ISS, or if Hubble experiences an unexpected failure.

        I don't think it matters if you tack on some Elon years to the BFR timeline since I don't expect anything Hubble-sized-or-better to be launched within the next few years, with the exception of JWST, which could go up in 2021 and operate until 2026-2031. I don't think we will have a gap in which BFR is not operating. It doesn't matter how many NRO frames are available, because we can see from the WFIRST [wikipedia.org] experience [soylentnews.org] that just having a donated frame does not mean we get rapid deployment of a new telescope. What we need to make things better here is a revolution in our approach to space telescopes or an increase in funding priority. BFR can be a game changer, or at least an eye opener.

        LUVOIR has been in planning for some time now, although it probably wouldn't launch until late 2030s (which shows us that something is very wrong). The 8-meter size is a compromise that would allow it to not require SLS Block 2 (although maybe the larger 15-meter version could fit into BFR, with folding).

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