Hacker News Reader

Comment by adhesive_wombat | Hacker News Reader

Since the JWST design started, there's been a revolution in the "easiness" of launches.

I wonder if a future evolution of space telescopes will be some kind of interferometric (obviously extremely hard for IR or visible light, but easier for radio and microwaves) swarm of cheap semi-disposible telescopes than one enormous one.

Then you can add to the swarm, upgrade elements, and retire failed elements without having to eat a multi-billion helping of humble pie.

And rather than have a fearsomely complex integrated sunshield, you could have a similar swarm of simpler satellites that provide a large cool area at L2, and then the observers just need to handle their own heat.

I suppose this could be described as microservices...in spaaaaace. Draw what parallels you will from that!

View on HN

Astronomer here, we are thinking about doing interferometers in space[1,2], but it won't be a catch-all for everything. One reason is that the instrumentation is equally as important as the telescope optics itself, and it's non-trivial to have your swarm of satellites both collect light, but also do science experiments with the light. One thing we are thinking of is to fly more proto-typing missions to get the technology readiness of various components to mature stages before assembling it all together for the real thing (I would say we did not do this as well for JWST).

[1]: https://www.life-space-mission.com/ [2]: https://lisa.nasa.gov/

Is there any sense in using internet providing sattelites for astronomy? Like if starlink published it's noise data from all sattelites in realtime could it be used as one huge radiotelescope?

Probably pretty difficult to find too many compelling cases. The bands starlink transmits in are designated communication bands, so interference from other satellites is going to be so high that it will drown out any signals. There are astronomers working on removing this foreground, but it's really difficult! It's actually becoming quite a problem in radio astronomy with the amount of the electromagnetic spectrum that is quiet enough for science.

> Since the JWST design started, there's been a revolution in the "easiness" of launches.

Producing novel observation platforms is going to be expensive regardless of which platform, because of launch costs.

> I wonder if a future evolution of space telescopes will be some kind of interferometric (obviously extremely hard for IR or visible light, but easier for radio and microwaves) swarm of cheap semi-disposible telescopes than one enormous one.

With space recovery and repair mission capabilities like https://nexis.gsfc.nasa.gov/osam-1.html growing, a single large asset could be easier to repair than constant refresh.

Anyways, small satellites = small sensors.

There is a big difference between a projected life of 1-3 years, and a prestige mission with a long lifespan. Hubble has been operating for ~30 years now.

> Then you can add to the swarm, upgrade elements, and retire failed elements without having to eat a multi-billion helping of humble pie.

Keeping a swarm of space assets ideally situated over time, with proper attitudes and control is a non-trivial problem. Look at Magnetospheric Multiscale Mission, that is considered a hard problem.

Software solutions don't always translate to hardware.

"Hubble has been operating for ~30 years now."

Right, and the GPS constellation has been active for almost thirty years too. I think the GP is probably right that it would be great if the risk associated with a single mega launch/deployment could be spread over a fleet, but ultimately it does no good if you can't use that configuration to get the observations you want, hence the question. It has less to do with it being a "software solution" and more just whether it would actually practically work.

To their point, though, lots of ground-based radio telescopes are now also arrays of many dishes [1], so it's not at all hard to imagine that a similar configuration could be of value in space.

[1]: https://public.nrao.edu/telescopes/vla/

The fearsome requirements imposed by optical interferometry are a real killer here: the JWST mirror segments can be controlled with 10nm precision for a reason.

Radio is a billion times easier (at least in naive terms): wavelengths in the kilometers rather than hundreds of nanometers

Ah, that is a helpful distinction. I had been thinking that JWST was for radio observations, but it's the opposite of course; JWST is for making high energy observations of things like gamma rays.

On the contrary, JWST is mostly focused on the near infrared. Good for seeing through dust and for capturing highly red-shifted faraway objects.

Well of course its not going to be simple, and I doubt it would even be possible for the JWST successor, which I assume are already being sketched out, but its an interesting idea to think about. Satellite swarms are a very active area of research, along with cheap launches enabling cheap hardware based on substantially COTS electronics, which means 10 "unreliable" things, of which 9 may fail may be cheaper than 1 gold-plated one that will definitely not fail.

And yes, they have small elements, that's the whole point. A small element is disproportionately easier to produce than a bigger one. The point of The Swarm would be to offset the small area individually small elements with a large number of them. ALMA does this, and they even pick the dishes up with giant forklifts and move them around to reconfigure the array.

Optical interferometric arrays are very hard and only recently even possible, so it's unlikely you could do it in space "soon" (even LISA is still a long way out, and that's been planned since I was at school). I obviously don't have a handle on if the added noise from positioning errors outweighs the literally astronomical baseline advantage.

And yes, Hubble might have lasted 30 years, but JWST has about 10 years life, and then it's dead and will fall away from L2 unless they can get a refuel/regas mission launched (it does have the ports for it) to it in time.

Of course any number of practical issues can torpedo such a thing from the phase space of feasible implementations, but they're still fun to think about.

> Producing novel observation platforms is going to be expensive regardless of which platform, because of launch costs.

This is exactly the point: launch costs are coming down, and there is widespread anticipation that they will start to plummet as the next generation of launchers comes online. If/when Starship (a) becomes available + (b) has any significant competition, launch costs could plummet by an incredible factor.

> There is a big difference between a projected life of 1-3 years, and a prestige mission with a long lifespan. Hubble has been operating for ~30 years now.

Is there anything other than manoeuvring/orbit-correction propellant that puts an upper limit of t5he James Webbs projected life? (At least until micro meteors trash too much of the optics?) Is it possible a resupply mission capability could effectivel7y extend its useful life indefinitely? (Did they even bother putting a fuel filler on it?)

Resupply is definitely a possibility.

Though resupply missions are not yet going out to those orbits, it is completely conceivable that they will in time. For the price of a $100M mission they'll be able to recoup or fix more expensive ones. I normally hear about batteries, reaction wheels, and fuel limiting life, but I think that would relate most to orbit, propulsion type, etc. IDK about a fuel filler.

There's a lot of miscellaneous things that can break on a spacecraft

Reaction wheels (which use momentum to help you point the vehicle) are a semi common failire. There's usually some redundancy built in, but if enough of them wear out you'll lose stability and pointing accuracy.

Even radiation-hardened electronics will wear out over time. If you look at unprocessed images from the Hubble, there's a shitload of pixels that have been fried in the cameras (the effect kind of look like stuck pixels in a computer monitor)

The other thing to bear in mind is the size of up coming launch vehicles. SpaceX Starship will be 9m and Blue Origin’s New Glen is expected to be 7m in diameter. Both of those could take a telescope the size of James Webb with much lest or no “unfolding” required.

Annother option with some of these cheaper launch vehicles is to build the telescope into the upper stage, using it as a bus/platform. So for example you could convert a Starship upper stage into a telescope, using its full 9m diameter for a mirror. Fully assembled on the ground before launch.

Now that the folding trick has been proven and loaded into institutional memory, I'd rather use it, e.g. LUVOIR-A at 15m in diameter, planned for the 8.4m fairing on SLS but suitable for the 9m fairing on Starship.

I do love me a scientific megaproject, but I still do wonder if a glorious $24 billion (and that's before the overruns) monolith is the most effective thing in terms of science per dollar, especially if it also has a limited lifespan due to consumables.

That's fabulously expensive: you could have four LHCs, have enough change to replace Arecibo with 10 FASTs and then maybe a aircraft supercarrier on top just for funsies.

It feels like JWST again: it's so expensive that it cannot be allowed to fail, so it's engineered to near perfection, but that costs so much that it has to be engineered even more to be sure, and so on until it's 1900% over budget, a decade late and muscling other science out of funding.

But, also dayum it's a piece of art.

> I do love me a scientific megaproject, but I still do wonder if a glorious $24 billion (and that's before the overruns) monolith is the most effective thing in terms of science per dollar, especially if it also has a limited lifespan due to consumables.

The 2nd mission with which I got involved, an Air Force Captain explained to me that continual trend was to massively underbudget a mission, and then make it whole through cost overruns.

Of course, my work was all about increasing the security capabilities of the constellation, which likely added in the tens, to hundreds of millions in cost to the system.

> It feels like JWST again: it's so expensive that it cannot be allowed to fail, so it's engineered to near perfection, but that costs so much that it has to be engineered even more to be sure, and so on until it's 1900% over budget, a decade late and muscling other science out of funding.

Launch costs are dropping and the space body of knowledge is changing rapidly

System Engineering tools are in their infancy, so rework or changing requirements are pricey. I expect this will really the cost of missions over time, since it directly relates to labor costs.

Simultaneously, the space operator mentality of "extreme availability at all costs" is meeting the hard reality of "space is now an offensive and defensive cyber domain".

We're building too many one-offs and too few constellations, both the birds, and the sensors. If you want lower cost we need to get past unit volume of one.

> the most effective thing in terms of science per dollar

> muscling other science out of funding

But we don't need four LHCs. We do need a way of observing dim and distant infrared light with high resolution. There's no other instrument that can observe EM radiation from 13 billion years ago. So it's not one or the other; something like the JWST was going to be built sooner or later.

24B is peanuts. Public spending has a greater than 1 multiplier, especially infrastructure, science and R&D.

It took a supply shock and a demand shock and trillions for the economy to see inflation, and unfortunately almost all of that is just due to fucking fertilizer and lack of livable wage for logistics workers, not science equipment manufacturers hiking prices...

I much rather launch 5 9m telescopes then one 15m telescope. And work on the technology to build even larger one in space in the generation after that.

These mega project that cost a gigantic amount and are hilariously oversubscribed are not actually the best return on investment in my option.

I don't know anything about astronomy but my intuition is that since we aren't going to the kind of places you see with a 9m space telescope any time soon the goal should be pushing the boundary rather than filling in a complete picture. In other words, I'd rather the one 15m telescope.

Could you explain what I'm missing? Have we reached a point where the returns of increasing size are very low or is it more that there are enough big mysteries to solve at the smaller size so it isn't much worth increasing until it can be done cheaper?

My question is similar but slightly different: is it possible to throw a "lot" of much "worse" hardware at the problem and solve it through a different kind of brute force than just building ever-bigger mirrors (which will only ever get to low double digit metre diameters at least in the foreseeable future without orbital assembly capabilities).

Say for JWST, there are 18 segments. Could you have 1800 mini Webbs and offset the inaccuracies that come from that with the vastly higher total area? Does that eventually reach an asymptote where a adding more units isn't useful? Does it reach a point where the data re-integration becomes the intractable issue? Can it ever be as good as a gigantic monolith even with an arbitrary number of units? Would the cheapness of individual units be outweighed by the number of them needed?

Its not that a bigger size wouldn't be better, its more that you have lots of scientists who would like to do lots of research in lots of different directions.

Combine a wealth of data sources in many different directions and many different observations can also lead to new insides.

When majority of the community, a whole generation of scientists, all have to wait for one massive telescope that can then only do 1/1000 of what people like to do with it, are you really gaining more insight?

Sometimes yes, sometimes no.

Instead I believe JWST will be the last telescope with reflective optics we will launch. The new thing will most likely be based on diffraction based optics (Aragoscope). It is much easier to launch in space a disc of some light and bendy material of some lightweight material than a set of hyperdelicate and precise mirrors.

According to the simulations performed in [1], an aragoscope of 1km would be able to directly image objects the size of Jupiter's moons (so basically exoplanets even on the small side) 23 light-years away.

EDIT: Took the time to scavenge the numbers: JWST has 0.1 arcseconds angular resolution, a 100m aragoscope would have a 1 milli-arcsecond angular resoulution, a 1km aragoscope 0.1 milli-arcsecond which translates to be able to alpha centauri in a 70x70 pixels patch (and so see its sunspots) or as I mentioned above exoplanets on the smaller scale at 23 light years away (Europa is 1560 km in diameter).

[1] https://www.nasa.gov/sites/default/files/atoms/files/2014_ph...

>in spaaaaace

in recognition of getting old(er), i wonder how many youngins even know there's a reference to be caught here.

How could you feel old about something that jus... 10 years?!

wrong reference if you think it is only 10 years old

Got a young one here. Try 40 years.

Not what you meant, but The Young Ones was 40 years ago. https://en.wikipedia.org/wiki/The_Young_Ones_(TV_series)

Are you telling me this is NOT Portal 2?

Yes, the original reference is not Portal. I don't even know what Portal 2 looks like not being a gamer, but the spaaaaace reference is much older than Portal 2 and possibly older than the people that created Portal 2.

In the final scene of Portal 2, a robot that was obsessed with going to space [1] drifts across the background and interrupts the villain, screaming "spaaaaaace!" out of excitement for finally being in space. The Portal usage is probably not related to the Lost/Pigs in Space usage.

[1]: https://youtu.be/BVn1oQL9sWg

Unless you're talking about The Young Ones, what "spaaaaace" reference is claimed for 40yo ?

I took zargon's comment to mean that the person implying the reference was only 10 years old was self identifying them self as a youngin without realizing it.

.....Ah. The possibility of someone being on HN born AFTER Portal 2 didn't even occur :-(

Would you care enlightening about the reference?

On duckduckgo I only found some references to The Muppets, a Springer article and a streaming playlist on archive.org

i've never played the game, but i think it's from portal 2

I've never played it either, but I actually know the reference thanks to this video[1] (which in turn comes from the once-viral Keyboard Cat[2]).

[1]: https://www.youtube.com/watch?v=c7C_1QfhpMQ

[2]: https://www.youtube.com/watch?v=J---aiyznGQ

Ahhh, sorry. Thanks for playing. We've got some lovely parting gifts for you...

https://www.youtube.com/watch?v=EmI77ZBeJrQ

I believe GGP was referencing the far older Muppet Show bit of Pigs in Spaaaaace :)

Ding ding ding. Now, let's take a look at the prizes...

Due to budget cuts the only prize I can offer is back pain and a vague sense of nostalgia for a time when modems made a weird noise and your wierd aunt wasn't on the Internet.

ha! modems. we were all too busy trying to figure out Who Shot Jr(tm) to be worried about the internet! i can only imagine the forum insanity over that consipiracy

that would be "PIGGGGGGGSSSSS INNNNNNNN SPAAAAAAAAAACE". did they ever just say "in spaaaaaace"?

no, but the obvious emphasis was on spaaaaaace which is the part that matters. doesn't really matter what it is that's in spaaaaaace, its just the fact that it's in spaaaaaace that needs the emphasis. you can almost imagine a theramin playing in the background level of campy going one with the theme.

telescopes in spaaaace is so much more than lowly terrestrial scopes. i mean, we don't say telescopes on earrrrrth.

ah, https://en.wikipedia.org/wiki/This_Island_Earth and https://en.wikipedia.org/wiki/Forbidden_Planet spaaaaaaace.

I thought the comment was referring to Portal 2, but apparently it was really referencing pigs in space, and now I learn it's 50s camp?

https://muppet.fandom.com/wiki/Pigs_in_Space

How about Tim Curry escaping capitalism in SPAAAAACE! https://www.youtube.com/watch?v=g1Sq1Nr58hM

https://youtu.be/EmI77ZBeJrQ

TIL, I am youngling.

still trying to decide if youngins and littluns are the same group, or if one graduates from littlun to youngin.

for that matter, how many people have seen the beginning of Half Life 1 (dated, but still one of the best intros to a game I've seen, althiough it takes a bit to get to the good part)? https://www.youtube.com/watch?v=hsTEoGoAxUk

Yes, small satellites are simpler and cheaper. Larger systems are complicated and expensive.

But the entropy of a large system is low, because it's physically attached with the Strong Force of physics. There is a low risk to other neighbouring satellites (space junk collisions). A swarm of small satellites has high entropy, and is loosely-coupled with the Gravity force of physics.

At what point do we want to accept the financial tradeoffs involved? Humans and the economy also benefit from the large projects, and the management structures also teach efficiency to more people who can go on to create other exciting new sensors.

We could start with a small satellite like Sputnik, and make them grow. Eventually it will reach a point of stability with the neighbouring environment. That could be much larger than we expect. "That's no moon, it's a spaceship!"

> But the entropy of a large system is low, because it's physically attached with the Strong Force of physics. There is a low risk to other neighbouring satellites (space junk collisions). A swarm of small satellites has high entropy, and is loosely-coupled with the Gravity force of physics.

I'm going to go and assume that you used the strong force and gravity as metaphors here.

One advantage of L2 is that it's a point of gravitational metastability when entropy inevitably hits, your satellite will slowly fall away from the point, and either depart for a long, initially slow, fall back to something rocky, or spiral out from the Earth-Moon system into interplanetary space.

An L2 swarm isn't bound together by gravity, it actually has to maintain active control to stay there, so it's a "self cleaning" area.

"Satellites are livestock, not pets"!

Reply on news.ycombinator.com