Beyond the James Webb Space Telescope

The James Webb Space Telescope is sending back pictures of space that are amazing this past week.

Imagine we could have thousands of space telescopes that can see billions of times better. I’d like to share how in my video in three steps.

NOTE – I was talking about how the $10 billion was spent and assuming that at least another $10 billion will be spent. The Luvoir space telescopes are under serious consideration and are already talking about taking almost 20 years and over $10 billion. I am talking about how to spend some part of NASA $25-30B annual budget. Yes, there are other space telescope proposals. But they would not do nearly what gravitional lens scopes could do in terms of surveying the surface of exoplanets and possibly finding alien life. Sseveral would take about as long or longer and cost more.

LUVOIR-A (2039 estimate) folds so it only needs an 8-metre wide payload fairing. Initial cost estimates are approximately US$10 billion, with lifetime cost estimates of $18 billion to $24 billion. LUVOIR-B (2039) was designed to launch on a heavy-lift rocket with an industry-standard 5 metres (16 ft) diameter launch fairing. Lifetime cost estimates range from $12 billion to $18 billion. Luvoir could have 25 kilometer resolution of planet and moon surfaces WITHIN our own solar system. It could look at OUR OWN Jupiter and its moons in less detail than gravititional lensing could observe in other solar systems.

11 thoughts on “Beyond the James Webb Space Telescope”

  1. The 550 a.u. is such a potential game stopper. Take that R&D money and use it to try and *make* *big* telescope mirrors out in space. Or combinations of them. Would have the added advantage of seeing things inside the solar system as well as outside.

  2. Nice video. One thing to consider is that further than 600 AU, the ‘Einstein Ring’ of gravity induced magnification becomes substantially larger. This in turn relaxes the specifications for the so-called star-shield, a critically important aspect of using gravitational lensing as your video and others before you envision.

    The ‘problem’ is that the things in the background that you wish to image are trillions to quadrillions of times less-bright than the gravitation source, the star in front. The reaonably easiest approach is to have a circular star shield between the micro-Einstein craft, and the gravitational lens star. It need not be very far removed, perhaps a few light-minutes. On the order of distance as Earth-Sol itself.

    The star shield produces a fine black umbra of the gravitational lens star, back at the small imaging telescope. This allows the distant objects to be detected. Reasonably so.

    Using the greater-than-600 AU distance, also allows more micro-steering and thus ‘scanning’ of distant planetary and moon objects. The craft need only ‘jet’ (drift slowly) a few meters, to be magnified into a scan of several dozens of kilometers. Depending on the target system distance, of course.

    Just saying… GoatGuy

    • You need the shadow disk to be larger than the telescope, as a function of the distance from the telescope, to get full coverage of the Sun’s disk, of course. Once any part of the telescope mirror is in the penumbra, it’s all over, given the brightness discrepancy. This limits how much space you can put between telescope and shadow disk without the latter becoming infeasibly large.

      *Ideally*, you want the shadow disk to be larger than that minimum, to allow the telescope to scan the target without requiring the shadow disk to actively coordinate. And to compensate for navigational errors. But this implies that the Einstein ring has to be far enough from the Sun that you won’t eclipse too much of it due to the larger shadow disk. So, further is better.

      Of course, further is also inevitable, because your telescope is going to be traveling at high speed.

      • From goatguy-
        Thanks again. Turns out that you are again (why am I not surprised?) right again about the size of the starshield being significant with increasing scope-shield separation.

        With a distance of 800 AU (1.197×10¹⁴ m), and a scope diameter of 0.15 meters, at 1,000 km shield-scope distance, the shield needs to be 11.5 m diameter.

        The real problem is that the about-the-axis wiggle is 0 … zero. Because this is an exact solution. Not terribly useful. Double the star shield diameter, and you only double the about-axis umbral spot size. Dang! Not overly useful. Well, since both the scope and the shield would be actively jiggered to remain in alignment, maybe it isn’t such a problem.

        I guess, since there aren’t really any notable gravitational or other inertial-challenging forces working on a spacecraft at 800 AU, well, once aligned and calibrated, such a system could rather easily remain so aligned for years. With an optical amplification of billions of times, and a spacial magnification of well over 1,000,000 times, it really would represent a fine, fine telescope, even if eternally focussed on one stellar planetary system, parsecs away.


        • It’s not as bad as it sounds, as the sun shield doesn’t have to be substantial, a spin stabilized solar sail would do the trick nicely. In fact, this kind of suggests that you DO want to use a solar sail for the initial boost, then have the telescope separate from it, and navigate further down range in its shadow.

          But this does confirm that you will be a freaking long ways out before it would be possible to scan the telescope independently without leaving the umbra.

          I guess what you do, then, is give the telescope some Sun sensors out on booms that peek out into the penumbra, and a lot of lateral delta V, and scan the sun shield, and just let the telescope track it. Neither is going to be jinking around fast, that’s for sure.

          The biggest problem, after just getting out there, is getting to the right location. The magnification here is almost too much, in that regard.

          • No such thing as a spotting scope for a gravitational scope, I mean; The target is behind the Sun, so gravitational lensing is the only way to see it, and you can’t reduce the magnification on that. Well, not without a simply enormous scope that would obliviate the need for a spotting scope.

            And the target location is an unmarked line in space, only a few km wide. How do you find it?

            In theory I suppose you can use an extremely large, high resolution conventional scope to do a detailed survey of the celestial neighborhood of the target. Then you get as close as you can by dead reckoning, and do a scan, and try to recognize which part of that neighborhood you chanced into viewing. Then you have some hope of navigating to the correct line.

            Incidentally, my name and email address mysteriously auto-filled with somebody else’s data. I wonder how that happened?

    • BTW: I am clearing all held comments daily. No comments have been flagged as spam. No comments have been held by the system. I deleted clear spam but everything else is going through. If there is a problem with a comment. Please go to the trouble of typing in a google doc in another tab and then copy pasting it into comments. This means it would be easy to adjust and try again. Email me blwang at gmail dot com and I will try to promptly help post comments. Please include the link to the article. Thanks

    • BTW: $10 billion for James Webb or $40 billion for SLS do not necessarily take money away from favorite tech projects. There is money for those other applications and tech development.

      James Webb space funding is competing against other telescope project funding.

      SLS funding is 20% competing against other space launch funding or 80% going to projects that particular senators want for their state or going to that specific vendor (ULA).

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