Extremely Large Telescope
projectescape.eu
projectescape.eu
The target cost of getting stuff to LEO using Starship/SuperHeavy is $2m per 100000kg, or $200k per Hubble. It would only cost $43 million to launch the light-gathering equivalent to the ELT. Now, $20/kg to LEO is very optimistic, but even at 5-10x that rate, a more believable $100-200/kg, that would still make the launch possible for 200-400m, which is roughly the cost of a Delta Heavy launch. Scaling this up, a 100m telescope (The OWL) would be 1,735.69 Hubbles and cost $350m to launch at the optimistic price, but still less than $3.5B at the believable price.
Basically, if Starship is successful it could have a dramatic effect on astronomy. 216 Hubbles may sound a bit insane, but mass producing them would drive the cost for each down considerably. Without the atmosphere, you don't need the fancy laser-actuator correction mechanism, and you certainly don't need to fight local activists for one of very few locations worldwide where you can plausibly put these things (AFAIK, there are only 3 such locations worldwide - Canary Islands, Cerro Amazones and Hawaii). Not only that, but if you had a constellation of Hubbles, they could be spread out and use interferometry to construct a telescope larger than the Earth (this is the technique that Event Horizon Telescope used).
So the question is, is it possible to design a standardized, flatpack hubble-sized mirror+cam sattelite and pull it off for the price of a regular telescope? At ~1.2Eur for the ELT, that would imply $45m per "hubble". Seems doable.
The lifetime cost of the hubble is about 10 Billion and the development cost of the James webb telescope is approaching 10 Billion. James Webb will launch on an Ariane 5 rocket, which costs about 140 million per launch. This is about 1-2% of the development costs.
If you launch cheaper satellites more often: - you get to iterate so you can make improvements at a much faster pace - there is less problems from a single failure - more scale effects
You can enter a virtuous cycle.
There are limits! It can be that it's hard to make a useful satellite once you go below some certain size. And reliability suffers if you try to skimp on good practices.
On many scientific satellites, the instruments are one off anyway and are complex, hard and hand built with astronomical costs, so it might not save so much even if the launch and the bus were a lot cheaper.
Microcomputers came about because, at some point, we could make small computers with just enough processing power that they could be useful.
Mainframes didn't really go anywhere - they are still doing heavy lifting in large corporations, and modern mainframes employ every trick we use to make x86's fast and then a couple that would make x86's prohibitively expensive.
I think the reason these things keep getting built on Earth is because until now no one has dared to dream of putting that much mass in orbit for that cheap.
You can do this with optical fiber, a pixel at a time, for sufficiently slowly changing scenes. Each big mirror is then responsible for collecting enough photons so they can all interfere constructively and deliver a useful brightness level.
The output goes through a diffraction grating to get a spectrum for each pixel, so they need it pretty bright.
That was using radio waves, something that can be measured in each telescope, saved as data, and then combined in a computer. At optical wavelengths we cannot record the data as accurately/quickly and so must instead use extraordinarily precise mirrors and fiber optics to join the light from each telescope in real time. These links must be accurate in distance to within a wavelength.
The JWT has been re-scheduled many times with the latest attempt scheduled for 2021. I'm sure that'll get pushed, yet again.
I still think that 2026 remains a reasonable estimate.
Interferometry is HARD. The Keck telescopes which sit 100m apart on the surface of the earth were designed to be used as an interferometer and never lived up to the expectations. The interferometry abilities were shut down about a decade ago. Here's an article which includes a quote from one of the people who designed it who talks about spending 100s of nights trying to get this to work [1]. This only works because these telescopes are physically connected (see the discussion of the VLT in [2]). You are cavalierly talking about getting this working with 1000s of telescopes in space. If you are wondering how we got the event horizon interferometer if it is as hard as I am claiming, things become much easier at long wavelengths [2]. That's why we have lots of radio (ALMA, SKA) interferometers and almost no optical.
> At ~1.2Eur for the ELT, that would imply $45m per "hubble".
One of these is on a mountain, the other is in space. One you can plug into the mains, the other you need batteries and solar panels etc. One you know how it is oriented (its on the earth) the other you need gyroscopes and control systems and etc. One you can plug an ethernet cable into to get the data, the other you need some sort of transmitting receiving system. One I can go fix with a spanner if something goes wrong, the other costs another X if it does.
> Seems doable
If you ignore all the complexity of being in space, all the complexity of working with an array of telescopes, the fact that interferometry is way harder in optical, yeah it sounds great!
[1] https://skyandtelescope.org/astronomy-news/closure-looms-for... [2] https://www.eso.org/public/usa/teles-instr/technology/interf...
Apart from that SpaceX is building comms satellites that can handle gigabit speeds at costs around several hundred thousand dollars per satellite or at most the low-millions. Solar and batteries are far ahead from where they were when the Hubble was first built.
As I mentioned in another comment, the real reason is because Starship and Starlink are still not quite real. These telescope projects take a long time to design, fund, build, etc, so realistically they can only happen once those two have proven themselves, which will hopefully happen this decade.
Physical connections aren't needed for optical signals when deep space is already perfectly transparent.
Communicating with satellites is a long-solved problem.
Hard? Sure. Impractical? That's not obvious.
https://en.wikipedia.org/wiki/Overwhelmingly_Large_Telescope
For a single launch, that's quite remarkable.
https://www.popularmechanics.com/space/a22240382/neptune-gro...
But ironically, you may begin to get grief from astronomers if you really start to scale (see, Starlink).
Compared to space, radiation shielding on the moon is trivial - humans belong underground except for short stints on the surface.
[1] https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...
Tremendous Trump Telescope
I would love to learn about this technology, in depth, because my own knowledge in this area is close to zero.
Can anyone point me to any web pages, books, articles, courses, explainer videos, anything in this field... Also, what is the correct terminology around this subject area?
This technology seems to exist at some confluence of the science of optics and the computer discipline of image correction... but maybe there's a better name, a better set of terminology for it... well, any and all comments about this area would be welcome!
Has anyone heard of terrascopes? (telescopes using celestial bodies)
https://www.youtube.com/watch?v=jgOTZe07eHA
if it is workable, it sounds fantastical but probably not something I'd see in my lifetime either way
I wonder if it is now easier to launch the raw components, and manufacture it in space. There are some engineering challenges of course, but it might be a worthy industrial exercise.