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Comment by drorco | Hacker News Reader

A more recent similar case would be Starlink. Fast forward a few years and the night sky will be filled with satellites disturbing astronomers. It would be interesting to see how that one ends up. My bet, more outer-space telescopes to compensate for all the new disturbance.

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LEO satellites in earths shadow are effectively invisible to ground based telescopes. Which is why StarLink and other LEO satellites have zero effect on ~98% of current observations, but do impact a few very specific types of observations.

That is the bargain...

IIRC, StarShip will result in something like 1 Million tons of annual launch capacity -- 3 orders of magnitude greater than today. Commercial applications are required, and satellites such as StarLink are a natural start.

Meanwhile, some of that launch capacity can be used to build space-based instruments for much cheaper.

Overall, I'd call it a win.

Except you won't get comparable telescopes with what Spacex Starship offers, or any other launch vehicle currently in development. And we have mostly solved atmospheric interference.

7-8 meter diameter mirror in outer space would be too small? Should be possible to put into orbit in one starship launch. And a system of big mirrors could be probably assembled and aligned together, without gravity and outside vibrations.

Try 39 meters, weighing 400 tons for just the first mirror in sequence of 5, and that's without supports and actuators and everything else.

I assume you're talking about the ELT. It's composed of something like 800 individual segments with their own position-adjusting actuators. I'm not intimately familiar with its construction (and the tolerances!), but I presume it would be possible to launch individual segments for space-based or moon-based construction...

The big, monolithic secondary mirror is entirely within Starship's payload volume (4.2m diameter) and mass (3.5 tonnes).

Bonus: Space-based radio astronomy will achieve much higher SNR!

Edit (since reply is slow): You probably benefit on your mass-related support structure costs due to the lower-gravity (or zero gravity) environments.

ELT pretty much would require space manufacturing base - for the mass involved, you could probably furnish a small moon town.

The problem is that the ones making the mess aren't going to pay for that, and I shudder at the costs involved in just space assembly of something the size of ELT...

Edit to the slow reply ;) - the 400 tons is just the estimate zerodur mirror segments for the main mirror, nothing of the support structures... and didn't include ~65 tons of spare segments (ELT plans to replace two daily or something like that).

Starship will be an incredible game changer for space economics. Look at this progression:

- $50,000/kilogram for 27,500kg of payload (Space Shuttle, 1981-2011)

- $2,500/kg for 22,800kg of payload (SpaceX Falcon 9, 2010-present)

- $20/kg* for 100,000kg of payload (SpaceX Starship, 2022??)

*: This is the estimated operational cost, not the price of a launch

For a ballpark launch cost estimate, assuming that the mirror segments would be mass constrained rather than volume, it would cost $8M (plus however far off the cost estimates are, plus profit) just to get the mass into space. Maybe say $20M just to pad it a bit? There would almost certainly need to be more money spent on designing the whole thing to work in space, of course. But these projects have long planning horizons, there's no way anyone would have considered building something large in space before Starship was announced (other than nation-state level prestige projects).

I suspect we'll see a flood of small to medium sized projects announced once Starship completes its first commercial LEO launch, then larger projects tentatively announced in the following couple of years.

Sources on costs:

https://ntrs.nasa.gov/citations/20200001093

https://en.wikipedia.org/wiki/SpaceX_Starship

Let's admit, this telescope is also one of a kind, and it (ELT) is not online yet, too.

If we care about telescopes which are built by hundreds, their mirrors are an order of magnitude smaller.

OTOH with the massive launch capacity SpaceX is building, we could put a dozen 5m telescopes in various high orbits around Earth. With orbital assembly, very large diameter mirrors can be formed; even if these mirrors had a relatively small area (many holes between mirror elements), the angular resolution could be higher than anything reasonably achievable on the planet surface.

"List of largest optical reflecting telescopes"

8.2 m (323 in)

https://en.wikipedia.org/wiki/List_of_largest_optical_reflec...

So the take away something everyone has access to, and replace it with something only they can provide as a service.

Somebody should get the mayor of NYC on the phone and tell him that I'm supposed to have access to the night sky.

More importantly, take away something, and provide no alternative in any way while taking in lots of money while causing considerable external cost to others. Then offer cheap platitudes and maybe hint at throwing more money their way.

I've long thought human greed is going to be the Great Filter that we won't pass. You've managed to say exactly how that comes to be.

Bs. Take away something and offer it as a service in return. Got it

You never identify who is taking the different sides of this bargain. It is almost as if it is a fate accompli that some people want to pretend is some sort of trade undertaken with some other people, because trade implies consent.

In fact, it is what it always is, a rich person taking something in order to sell you a poor replacement while calling it progress.

Starlink's effect on astrophotography is overstated. Starlink is in a fairly low orbit, so past twilight, the satellites are in Earth's shadow and aren't visible. The Iridium constellation orbits at 780km, for instance, while Starlink is 550km. During the darkest parts of the night, peak time for observation, the satellites aren't visible.

My guess is that there won't be an appreciable difference in the number of space telescopes. Hubble cost $4.7 before it was launched, and it was just a derivative of keyhole, so even though launch prices are cheap these days (compared to the $550 million it cost per Space Shuttle launch) the cost of a space telescope is still pretty steep.

And the funding for comparable spaceborne telescopes will come from where? You can't even take a ride on black budget, because there is nothing to spy on in direction opposite from earth, and and space telescopes with parameters comparable to ground based ones are bigger than what's possible to launch with any of the perspective super-heavy launchers - and critically, would be too big for spy agencies to use against earth targets.

Let's hope the Chinese start asteroid mining soon so we can get the military industrial spending firehose pointed back at the space program

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