The Astronomy Thread

Ukerric · Jul 2, 2018

Space telescopes is a kind of weird optimization. They take advantage of being in vacuum (less optical distortions), but can't be manned (vibrations destroy the distortion advantage). So they end up as autonomous units, and that means we have to launch them. So a space telescope is a one-shot conception, limited by the size of the launcher.

Hubble was lucky; it was LEO so we could service it. JWST is not: once launched, it performs or not, and once he's out of fuel, its useful life is essentially over (there's a couple tricks that let you do stuff, but they're horribly limited). So, you need it to be perfect... and it's not.

A Lunar Observatory gets almost all the benefits of a space telescope, and none of the drawbacks. One, it's build, not launched. You can start small, then expand. Or go straight for a 30 feet telescope, and simply assemble the mirrors one by one. New technologies can be deployed on site later, for a lot less than building a new telescope. It's only drawback is that there's this thing called the Moon that blocks over half of the sky.

(there's also the problem of the lunar day/night temperature cycle, which any lunar base has to face. But where a base can be buried safely, the telescope must be on the surface, which means the best spots are a sufficiently deep crater on any of the poles... and then, you need TWO if you want to cover almost all the sky)

We still are short of the funding that would have been necessary to make a lunar test base, but we could have spent most of the JWST money on a lunar base testing, and we'd be in a better position to get science from it.

Big Phoenix · Jul 2, 2018

Its pure pork at this point.

Cybsled · Jul 2, 2018

For a lunar observatory, dark side of the moon would be best (esp if a radio telescope). The actual base could be located at the light/dark border

Tuco · Jul 2, 2018

Cybsled said:
If they scrapped it, though, then the replacement would be like 2035 or some shit and we'd all be saying "lol what a waste, should put the funds towards the moon base observation station".

Assuming you're talking about the JWST, I don't think so. I think that SpaceX is so massively changing the space-game that by 2025 the strategy and tech around deploying a huge satellite to an L2 orbit will be much easier and cheaper.

edit: and it'd be much easier to contemplate a permanent installation since getting fuel to it will be cheaper.

Mudcrush Durtfeet · Jul 2, 2018

The cost savings implied in the above post ignore the cost of being able to build anything on the moon, which at the moment would make the JWST cost look like peanuts. So at the moment, NOT a cheaper alternative.

pharmakos · Jul 2, 2018

Cybsled said:
For a lunar observatory, dark side of the moon would be best (esp if a radio telescope). The actual base could be located at the light/dark border

There is no dark side of the moon, tho. Each side is dark half the time.

Cybsled · Jul 2, 2018

"Dark side" is always facing away from the Earth, though, which makes it ideal for radio observatories.

Malinatar · Jul 2, 2018

It's a Beautiful Baby Exoplanet! Historic Photo Is 1st View of Alien World Being Born

meStevo · Jul 2, 2018

Bigger: https://pbs.twimg.com/media/DhHESjvVAAAD08Z.jpg

Ukerric · Jul 2, 2018

Cybsled said:
For a lunar observatory, dark side of the moon would be best (esp if a radio telescope). The actual base could be located at the light/dark border

The "dark side" is anything but dark. The far side of the moon gets exactly the same day/night extremes of temperatures as the near side, so the only thing you gain is that there's not that ball in the sky that's lighted most of the time (but, given that there no atmosphere, it simply blocks observation on a small blob of the sky. If you're not looking toward earth, it is mostly irrelevant).

*EDIT* For radio astronomy, it's much better. But you still have to deal with the infernal day-night cycle and the 250°C difference between both.

Ukerric · Jul 3, 2018

Cybsled said:
If they scrapped it, though, then the replacement would be like 2035 or some shit and we'd all be saying "lol what a waste, should put the funds towards the moon base observation station".

Just in time, xkcd weights in:

spronk · Jul 3, 2018

Why haven’t we found aliens yet?
In their new paper, titled “Dissolving the Fermi Paradox,” the FHI researchers dispute this method by demonstrating how this technique typically produces a value of N far higher than it should, creating the illusion of a paradox.

Therefore, the researchers represented the full range of possible values on a logarithmic scale and ran millions of simulations to obtain more statistically reliable estimates for N. They then applied a technique known as a Bayesian update to those results. That means mathematically incorporating the information that we have not discovered extraterrestrial intelligence yet (because the absence of evidence of aliens is evidence itself!).

This two-stage process produced striking results: Based upon the current state of astrobiological knowledge, there’s a 53 to 99.6 percent chance we are the only civilization in this galaxy and a 39 to 85 percent chance we are the only one in the observable universe.

Well thats a bummer

Ukerric · Jul 4, 2018

spronk said:
Why haven’t we found aliens yet?
In their new paper, titled “Dissolving the Fermi Paradox,” the FHI researchers dispute this method by demonstrating how this technique typically produces a value of N far higher than it should, creating the illusion of a paradox.

"I don't like the current estimates in Drake's, therefore I'll push my own versions"

Not to disparage the method, but they start with bullshit, and end up with bullshit. But on a log scale.

The only recent decent work on Drake's equation was the fact that we do have an upper bound to N (the maximum number of civs in this galaxy is a function of the average duration of a technical civ.), so Drake's equation is more of a true equation and less of an inventory of our ignorance.

Cybsled · Jul 4, 2018

Lack of evidence isn't the evidence itself like he postulates. If you traveled to the 1200s and said "guys, illness is caused by microorganisms the eye cannot see!", but lacked the equipment to actually demonstrate this to people, that doesn't suddenly mean that illness is not caused by microorganisms because you cannot produce tangible evidence of it due to technological limitations. Yes, extraordinary claims require extraordinary evidence, but if the limiting factor is technology, you can't just toss up your hands and say "well, I guess it will be a mystery forever!". We've only just recently been able to tangibly demonstrate some of Einstein's theories and only because we finally had the technology to do that.

For all we know, space is awash in transmissions, but we aren't aware of them because we have no means of detecting them because they do not adhere to our current tech. What if a civilization just uses lasers now? Or some sort of exploitation of quantum states of atoms to communicate info over long distances? Our planet has only had radio for around 100 years and we've only had large detection devices for about half or less time then that. So just because we haven't found anything in the few decades we have been looking, that is valid documentation we are alone? That is arrogance on a massive scale. Our planet could have been literally receiving radio transmissions since cavemen were roaming around, but if they ceased before we had invented radio detection, we would be none the wiser. Plus, radiowaves are thought to dissipate a large degree after a few light years in terms of data transmission capabilities. In order to seperate background noise from intentionally transmitted data would be yet another technological requirement.

Sentagur · Jul 4, 2018

spronk said:
Why haven’t we found aliens yet?
In their new paper, titled “Dissolving the Fermi Paradox,” the FHI researchers dispute this method by demonstrating how this technique typically produces a value of N far higher than it should, creating the illusion of a paradox.

Therefore, the researchers represented the full range of possible values on a logarithmic scale and ran millions of simulations to obtain more statistically reliable estimates for N. They then applied a technique known as a Bayesian update to those results. That means mathematically incorporating the information that we have not discovered extraterrestrial intelligence yet (because the absence of evidence of aliens is evidence itself!).

This two-stage process produced striking results: Based upon the current state of astrobiological knowledge, there’s a 53 to 99.6 percent chance we are the only civilization in this galaxy and a 39 to 85 percent chance we are the only one in the observable universe.

Well thats a bummer

I like how they take questionable evidence for intelligent life on Earth and the insignificant amount of observable universe we have actually explored to any extent and extrapolate it to the whole universe.
I am sorry but that whole thing seems like an example of mathematical masturbation.
Edit: they also talk about radio signals for some reason too. Our civilization used radio signals for maybe 100years (out of 100.000 of our existance) and they are already being phased out and on top of that would we even be able to detect artificially made radio signals given the inverse square law or what not?

Ukerric · Jul 4, 2018

Sentagur said:
Edit: they also talk about radio signals for some reason too. Our civilization used radio signals for maybe 100years (out of 100.000 of our existance) and they are already being phased out and on top of that would we even be able to detect artificially made radio signals given the inverse square law or what not?

Phased out? Like, by what? The Internet... powered by the 4000 satellite radio constellation that Elon is putting in orbit?

Sentagur · Jul 4, 2018

Ukerric said:
Phased out? Like, by what? The Internet... powered by the 4000 satellite radio constellation that Elon is putting in orbit?

Maybe i misread that it was a while but there was something about the signals we use now being more similar to background noise than the pure radio signals they used 50 years ago.

meStevo · Jul 6, 2018

Kepler is about done.

NASA’s Kepler Spacecraft Pauses Science Observations

Paused science operations to download data on the spacecraft before, expected to run out of fuel in the next few months.

LachiusTZ · Jul 6, 2018

Ukerric said:
Phased out? Like, by what? The Internet... powered by the 4000 satellite radio constellation that Elon is putting in orbit?

Focused Directional vs Omni, laser, etc. Radio uses less power now. Over long ranges we will switch to more focused or light based.

Interstellar communication with Omni directional radio is idiotic.

That's not even getting into shit we haven't discovered. To think radio is the end tier of communication is dumb.

Someone did the math on it. Might have been Isaac Arthur. But essentially, the odds are zero anything in range will be in the tech period to use radio

MusicForFish · Jul 6, 2018

There are already bases on the moon.

The Astronomy Thread

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