Would 'cheap' FTL make powerful telescopes obsolete?
Imagine we have a faster-than-light drive which costs ~$250,000 USD per drive and can propel an ISS-sized craft at 1000 times the speed of light. It is reliable and has safeguards that stop it from plowing into things at high speed. How the FTL drive works is irrelevant; it could be an Alcubierre drive or powered by lalalaicanthearyouium.
The drive has its own included fuel/power supply which, for all intents and purposes, is infinite. (eg: unlimited or easily replenish-able, etc.) Additionally, this universe has no FTL communications other than mail carriers fitted with FTL drives.
Would there still be any value in building and operating (optical/radio/whatever) telescopes for (e.g.) locating exoplanets, studying stars, etc.?
Would telescopes be gradually retired and replaced by exploration ships?
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2 answers
Yes and no.
It'd be worth keeping some of the larger telescopes around, simply because they have a wider area of coverage. A large radio telescope can cover a significant portion of its sky and listen for incoming signals from that zone. This is an advantage, because you then don't have to send an exploration ship out to every possible area that the telescope would have covered to get the same information.
However, for more detailed explorations of a target identified as interesting by the telescopes, exploration ships would be incredibly useful - you can get to the target in no time flat, get some good images of it, and get back home again in the same no time flat.
Essentially, the two would work together. The telescopes have a wide area but little detail; the ships have a narrow area but lots of detail. It's a perfect complement. Things like SETI and the search for other habitable planets would become easier by orders of magnitude.
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Not quite. Possibly.1
Advantages of faster-than-light travel for astronomy:
- You can see events happening in the present. Astronomers stuck on Earth can only observe objects in the past. Even our observations of the closest star system Alpha Centauri, are four years out of date. Sometimes, the finite speed of light really sucks. But with faster-than-light travel, you can get to the stars and then transmit the information back to astronomers on Earth very quickly. This is great because if the faster-than-light travelers see an event happening (like a supernova or stellar merger), we'll all know in advance when the light from that will reach Earth, and we could even build instruments specially to observe it.
- We can actually get up close and personal with astronomical objects. Earth-like exoplanets are hard to detect because they're hard to find from so far away. But traveling to another star system would make confirming detection easy. Like the first point, any space travel has these plusses, but only faster-than-light travel makes it really feasible for astronomers on Earth. This also means that we can take images of much greater resolution, and extinction from dust will be less of a problem.
- It's cool, and will get funding. Seriously, it's going to be much easier to convince people, companies, and governments to fund a faster-than-light starship than the convince them to fund a telescope. Telescopes are really cool, but, to most people, spaceships that can outrun a photon are cooler. So astronomers will get a lot more money, I would predict.
- There's no atmosphere or Sun to block observations. This is a problem for astronomers on Earth, which is why space telescopes are so popular. Sure, the central star in a system would still make observations tricky. But there's plenty of places a faster-than-light ship could go to mitigate this, assuming adequate fuel and piloting ability.
- We can see more of the sky. Currently, the Galactic center creates the Zone of Avoidance, an area of the sky we can't see very well because it's blocked by gas and dust. There are interesting objects there, including a view galaxies in the Local Group. FTL travel might enable us to view them.
Advantages of still using telescopes on Earth:
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Observing via different wavelengths is easy. The Hubble Space Telescope is pretty much the number one source of visible and near-infrared images of astronomical objects. A lot of other images we get from telescopes are false color. You'll need to drag a telescope along on your ship anyway to properly detect objects in these wavelengths. In some cases, this is easy. But try dragging the Very Large Array or Arecibo Observatory on a trek across the stars. Logistically, it's hard to bring along something that big in a single spacecraft.
The Arecibo Observatory. Image courtesy of Wikipedia user JidoBG under the Creative Commons Attribution-Share Alike 4.0 International license.Sure, you could try to put a bunch of radio telescopes in an array in space. eLISA will hopefully do that to search for gravitational waves. But eLISA involves only three different spacecraft. Coordination is relatively easy, and they'll be staying in a heliocentric orbit. Putting the 27 25-meter-wide telescopes of the VLA in space and then bringing them hundreds or thousands of light-years away is monumentally difficult.
They're (generally) not too complicated to use. These faster-than-light ships are apparently pretty cheap, but given that there's no faster-than-light communication besides using these ships, you either need a human crew (difficult) or an autonomous probe (a terrible idea, given that encounters with aliens would not go well, and I don't think people would trust it enough in those cases). Telescopes on or orbiting Earth are much better.
I don't think we'd see an instantaneous leap towards using faster-than-light travel in lieu of powerful conventional ground-based telescopes, but things would definitely slowly change. You'd initially see a balance between the two, with radio telescopes being gradually phased out if (and only if) radio arrays were feasibly on these spacecraft. Eventually, you'd see only a few telescopes left on Earth or in Earth orbit - and maybe, one day, those will be gone, too, obsolete relics of a bygone age.
1 Over two years later, yes, I've changed my mind on this. I've come up with more advantages, and they're pretty nice, come to think about it.
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