Apart from all the comments about this being a bad faith post, I wonder about the utilitarian argument, if you take it at face value. If you could provide decent internet at low cost to large parts of the world that are underserved, at the cost of ruining ground-based telescopes, is that a good trade-off? What if it's just certain kind of telescopes, or certain classes of astronomers (as this seems to be)?
I think this is useful if we also consider that part of SpaceX's plan is to make launching satellites cheap (in fact, launching anything cheap). So while ground-based astronomy will suffer, space-based astronomy will get cheaper and easier.
Presumably to the point where people who want to can subscribe to a Hubble-like satellite service and get all the space photos their hearts desire.
Also, we made a similar trade-off a long time ago - most people live in heavily light-polluted cities, because we value having street lighting more than being able to see the stars.
Cost of launch is not really main reason why we don’t see more space based astronomy.
1. Space is a hostile place, and developing telescope that works there is much harder.
2. There are very real limits on size and weight of what can be put there right now, and rocket equation is ruthless.
3. Any type of maintenance or upgrades are basically impossible, compared to earth based.
4. Adaptive optics were such a huge breakthrough, that basically negated need for most of space based telescopes.
Reasons 2 and 3 are big part of why launches of expensive.
There's a feedback loop in space launches: they're expensive, therefore you launch less, so you need to add redundancies and spend more time ensuring the payload will work, which raises the development cost and increases mass, which makes launches less frequent and more expensive.
Conversely, reducing the cost of access to space means you can send more stuff that's less robust, which shortens development time and makes it less expensive, and of course makes technological progress faster.
Which translates to: suddenly space telescopes may be more affordable, and more of them will be launched.
Some ground-based observatories have been productively operated for nearly a _century_, with improvements in instrumentation providing leaps forward in sensitivity. That amortizes the cost of the observatory (mirror, site, etc.) across many years.
Even with cheaper launches it's much harder to get that benefit in space--servicing missions are much more expensive than driving up a mountain...
But now if we are forced to move all ground telescopes on space SpaceX will make profit so is a win-win for SpaceX and the public will have to pay to replace working satellites on the ground with expensive and smaller ones on space.
We should be fair and acknowledge all the downsides, and if you disagree I would ask to waste a bit of effort and explain why we should ignore this costs on the public(maybe the costs are worth it in the long run but we should not ignore them)
Space telescopes are vastly superior to ground ones. There is no competition, imo the decreasing cost of launching will enable incredible telescopes in the future.
That's a bit like saying that forks are superior to knives. They're good at different things.
Ground-based telescopes have a number of very significant advantages over space-based telescopes. You can build much larger and heavier telescopes and instruments on the ground. If you want to observe faint objects, you need more photons. To capture more photons, you need a larger primary mirror.
Space-based telescopes used to give higher resolution, but adaptive optics undo much of that advantage. In fact, because the diffraction limit is dependent on the size of the primary mirror, ground-based telescopes can achieve better resolution than space-based telescopes.
You can attach large, heavy instruments, such as massively multiplexed spectrometers, to ground-based telescopes. And you can switch instruments out and do periodic upgrades and maintenance.
Space-based telescopes have advantages in certain specific areas. They can observe wavelengths that Earth's atmosphere absorbs or emits at (such as the ultraviolet and infrared). They can achieve much better calibration, because there's no atmosphere to calibrate out. They can achieve high resolution across a wide field of view (adaptive optics negates the effects of the atmosphere in a small field of view). Sometimes you need these particular advantages, so space telescopes are critical. Often you don't, and ground-based telescopes are superior.
Shouldn't 2( or more) smaller telescopes 1 positioned on the North pole and 1 on the South both on polar orbits pointing at the same spot solve that issue?
To me it seems like the moment we got a proper space telescope( Hubble) there was a ton of low-hanging fruit to discover at such a degree that so many years later we are still finding out new stuff. Compared to that Earth based telescopes seem to have to go through massive efforts to make headline discoveries( not that any other less discussed paper isn't important, it's just that... how would we know about e.g. the acceleration of the universe from an Earth based observatory?).
> Compared to that Earth based telescopes seem to have to go through massive efforts to make headline discoveries
That's a function of how the media works. Ground-based telescopes are extremely important for astronomy, and I would even venture to say are involved in most major discoveries. Space telescopes are also extremely useful, but they're also much flashier than ground-based telescopes.
> how would we know about e.g. the acceleration of the universe from an Earth based observatory?
By observing type-Ia supernovae (SNe Ia), for example. Not only is it possible to do this with ground-based telescopes, but ground-based telescopes are the primary way it is done. Most of the SNe Ia observations that went into the discovery of the acceleration of cosmic expansion were done from the ground.
AFAIK you can do that with radiotelescopes, but cannot easily with optical telescopes. That is because optical sensors lose phase information of incoming signal.
There are telescopes formed from arrangement of smaller telescopes (like mentioned Very Large Telescope of European Southern Observatory), but these have to be connected optically (by a system of precise mirrors), not just digitally.
That's correct. For optical telescopes, you have to physically combine the signals in real time to do interferometry. The VLT can do optical interferometry, and can create baselines as long as 200 meters (reaching nearly 100x the resolution that the Hubble Space Telescope achieves).[1] If you just combine the images from different telescopes, without doing interferometry, you only get one of the benefits of a larger telescope (you can see fainter objects), but you don't get all the benefits (e.g., higher resolution).
Interferometry is much easier with radio telescopes. You can record the waveform at each dish, and then digitally combine the signals afterwards (there is specialized "correlator" hardware that is purpose-built to do this very efficiently).[2] That means you can put receivers anywhere (on Earth or even in space), as long as you are able to synchronize the timestamps in the data well enough to digitally combine the signals afterwards. One of the major technical challenges faced by the Event Horizon Telescope, which imaged the black hole at the center of M87,[3] was synchronizing clocks at stations on opposite sides of the Earth. They had to physically bring atomic clocks from one location to another. After they took their observations, they flew hard drives with the recorded signals to a centralized location to do the correlation.
The article on interferometry implied that this is "just" a matter of computational difficulty - the higher frequency means that more accuracy and computing power is needed to resolve an image. Is that right?
If so, surely this is a Moore's Law problem, solved by waiting a few years for the needed computing power to be cheap enough to use?
By higher frequency, do you mean optical frequencies? If that's what you mean, then it's not just a matter of computing power. It's a matter of optical detectors not actually measuring the phase of the incoming photons. If you lose the phase information, you lose the ability to do interferometry.
CCDs just count photons (incoming photons kick electrons into the conduction band, and you count electrons after each exposure). There are more advanced detectors that tell you the energy of the photons, but not their phase. If you can't measure the phase of individual photons, you can combine light from different telescopes directly, and let nature do the correlation for you. That's what optical interferometers do.
If you have same size yes but the issue in space you can send only smaller telescopes, this ones are inferior on some dimensions versus the big ones we have on high mountains on deserts but sure a small telescope in space is better then a same size on the ground.
Let me know if somehow I am wrong and for example Hubble is superior to all telescopes on the ground at the time it was launched. The best thing is to have it all, giant telescope arrays on the ground, telescopes in orbit, on the moon, on the other side of the sun/
SpaceX going going to sign on the dotted line to provide free service to observatories damaged by starlinked? Because unless it signs a contract, this whole argument is a load of hot air.
The premise is false. Musk doesn't need to ruin ground based telescopes in order to make Starlink a reality. This issue could be resolved by going slower, Musk just doesn't want to wait.
Musk drives his team for speed because every one of his companies still has the "how much runway do we have" mindset. Lots of people can throw stones from their glass towers knowing they work at a company that will exist in 2030 or 2040, but SpaceX can't say that unless they are always moving.
This exactly. Satellites are incredibly useful and enable trillions of dollars of worldwide economic output that would not be possible otherwise. This is a very meaningful improvement in everyone's lives. We should not stop using them simply because they are visible in the night sky, and make astrophotography a little bit harder (though not much harder -- removing satellite streaks is a default enabled option in astrophotography image stacking software).
I don't think you realize how much economic productivity is enabled by telecommunications satellites, GPS, earth-watching satellites, and more. Even just having a better grasp on the weather is worth many, many billions of dollars annually worldwide. Let alone GPS and knowing where you actually are (and how valuable that is to practically any business that operates in the real world; we're even talking things as far-flung as automated tractors in agriculture that are enabled by GPS).
That's a lot of money. Considering that the company has reversed course on almost every promise it has ever made about Starlink -- orbit altitude, inter-sat networking, service area, cost -- I think it's a good bet that Starlink will ultimately just look like a capital-intensive Iridium-like network without the ability to service mobile stations. I imagine the US military will end up being the main customer.
> Considering that the company has reversed course on almost every promise it has ever made about Starlink -- orbit altitude, inter-sat networking, service area, cost
All of these things are coming, in subsequent revisions of hardware.
Everyone on HN should recognise the pattern - it's very much a launch of a minimum viable product.
