The thread for space cadets!

Imagine just for a second they find it is in fact an Anderson disk. What would people reaction be? Worldwide celebration? Would people feel happier? Worried? leaving religion in mass? Embracing religion in mass? Plain terror? Relative indiference?

I think i would experiment a mix of all but, would such information be made public at all?

hobbsyoyo said:

The Most Mysterious Star in Our Galaxy

Excerpt:

The link has the full article.

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That's super cool. Thanks a ton for sharing that, I don't see nearly enough interesting space news and theorizing these days.

Yeah no problem. I really appreciated the tone of the whole piece, starting with the title (which wasn't OMG ALIENS clickbait). I didn't even suspect that aliens would play any part in it until they brought it up and they were very clear that this theory isn't even the leading theory. It was a very interesting read.

China’s Space Station Planners Put out Welcome Mat

China is soliciting international participation in its future manned space station in the form of foreign modules that would attach to the three-module core system, visits by foreign crew-transport vehicles for short stays and the involvement of non-Chinese researchers in placing experiments on the complex, the chief designer of China’s manned space program said Oct. 12.

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Follow the link in the title for the full article.


This was interesting for a few reasons.

For one, when the US had the Constellation program with the explicit goal of going back to the moon, China also announced their own program of going back to the moon and they always had a 'first landing date' that was set a year or two ahead of the US. And whenever the US would move their landing date back, so would the Chinese but they would always make sure it was a year or two ahead of the new US date.

Now that the US is no longer planning on landing on the moon, China isn't talking about it either but are instead focusing on their space station efforts. I still come across some sources that say they are working on a lunar landing but it's on the back burner and more of a long term R&D effort. It is worth noting, however, that China is pretty good at following through on these kinds of long term R&D efforts in a way that the US isn't. For example, the manned Chinese space program took over 30 years to deliver a taikonaut to orbit but they did get their eventually. The US manned space program, on the other hand, can't even stick to a deadline that is only a decade out - see the cancellation of Constellation and the continuous slips in the manned commercial space program (SpaceX and Boeing - which are funded via NASA which keeps seeing its budget cut for this program).


The other things that are notable is that the time frame for when they want to put up this space station is the same time frame that the ISS is ostensibly scheduled to be retired. Given strain on NASA's budget and the continual threats from Russia to pull out of the ISS, I can see there being a time when the Chinese (and only the Chinese) have a space station up. This will cause everyone else (well, basically just the ESA unless the other space powers up their game significantly in the next decade) to want to partner with them. Of course, NASA will be left out of any collaboration entirely because by law, they aren't allowed to work with China. In fact, a recent visit by a NASA official to China to discuss potential collaboration caused a lot of consternation from some congresspeople.

If China gets a station up and America doesn't have one, America is going to get one. That's just how it seems to work with your politics.

No the way it works is if China gets one, the US will get fifteen of them and slap awesome space fighters and tomahawk missiles on them.

Remember, Russia never even got to the moon and the US landed there not once but six times just to say 'eff you for even trying'.

hobbsyoyo said:

Yeah no problem. I really appreciated the tone of the whole piece, starting with the title (which wasn't OMG ALIENS clickbait). I didn't even suspect that aliens would play any part in it until they brought it up and they were very clear that this theory isn't even the leading theory. It was a very interesting read.

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So the leading theory is comet debris from a passing star yes?

Still a cool idea to think about. What's the theoretical limit on how much you can make out via at a given distance via an optical telescope, assuming a clear line of sight (i.e. no nebulas or stars or whatever in the way)? Could an advanced human civilization make, say, an optical lens the size of the moon and actually "see" something as small as a moon a billion light years away?

To the first question - yes, that's the leading theory. They claim it is a very unlikely scenario, however, this was the only star like this out of (IIRC) 150,000 that the satellite looked at. So the fact that only one star was like this almost validates the unlikeliness of the theory in the first place. And all of the other theories (save the ET one) just don't fit - so it's almost certainly a scattered cloud of comets.


As to the latter question - I don't know what the theoretical limit is. However, you can string together a ton of smaller telescopes strung across a large distance and through interferometry, you can get image qualities that approaches that of a single large telescope of equivalent diameter. So you wouldn't have to make a single lens the size of the moon, just launch a bunch of little lenses and station them such that the distance between them is ~the size of the moon and that would work.


I guess though that theoretically you can push the resolution as high as you want with this technique and could see something as small as a moon a billion light years away. I think the bigger trick there wouldn't actually be the resolution (just add more lenses for better resolution) but in pointing all of the satellites well enough to focus on something so small so far away.

hobbsyoyo said:

And all of the other theories (save the ET one) just don't fit - so it's almost certainly a scattered cloud of comets.

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I believe this would be the most appropriate time in the history of the internet to say

illram said:

Still a cool idea to think about. What's the theoretical limit on how much you can make out via at a given distance via an optical telescope, assuming a clear line of sight (i.e. no nebulas or stars or whatever in the way)? Could an advanced human civilization make, say, an optical lens the size of the moon and actually "see" something as small as a moon a billion light years away?

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No. At a billion light years distance, a perfect lens the size of a moon would not even be able to resolve an earth-like planet orbiting a star. To see something like a moon, we would be talking about lenses the size of earth's orbit. And even then we would just be able to resolve that something is there without any information what it actually looks like.

hobbsyoyo said:

As to the latter question - I don't know what the theoretical limit is. However, you can string together a ton of smaller telescopes strung across a large distance and through interferometry, you can get image qualities that approaches that of a single large telescope of equivalent diameter. So you wouldn't have to make a single lens the size of the moon, just launch a bunch of little lenses and station them such that the distance between them is ~the size of the moon and that would work.

I guess though that theoretically you can push the resolution as high as you want with this technique and could see something as small as a moon a billion light years away. I think the bigger trick there wouldn't actually be the resolution (just add more lenses for better resolution) but in pointing all of the satellites well enough to focus on something so small so far away.

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For interferometry, the position of the small telescopes relative to each other needs to be controlled with sub-wavelength precision. Yes, in theory there is no limit to the resolution, if you can place telescopes at arbitrary distance with sub-wavelength precision - but there will be practical limits to that.

uppi said:

No. At a billion light years distance, a perfect lens the size of a moon would not even be able to resolve an earth-like planet orbiting a star. To see something like a moon, we would be talking about lenses the size of earth's orbit. And even then we would just be able to resolve that something is there without any information what it actually looks like.

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I see, thanks. To what degree is that better than what we have now, i.e. figuring out "something" is there? Like "I see a tiny brown dot" as opposed to just noticing the dimming of the star? I guess what I am getting at is there any way to get a decent look at interesting interstellar mega-structures that we suspect may be out there from the comfy confines of our solar system?

hobbsyoyo said:

Now that the US is no longer planning on landing on the moon, China isn't talking about it either but are instead focusing on their space station efforts. I still come across some sources that say they are working on a lunar landing but it's on the back burner and more of a long term R&D effort. It is worth noting, however, that China is pretty good at following through on these kinds of long term R&D efforts in a way that the US isn't.

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Hmmm.

illram said:

I see, thanks. To what degree is that better than what we have now, i.e. figuring out "something" is there? Like "I see a tiny brown dot" as opposed to just noticing the dimming of the star? I guess what I am getting at is there any way to get a decent look at interesting interstellar mega-structures that we suspect may be out there from the comfy confines of our solar system?

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Being able to resolve that brown dot has two advantages: The first one you sort of noticed yourself, as you get the extra information "brown". If you can resolve the planet, you can get much better results when trying to analyze its spectrum and thus can potentially characterize its composition much better, tell whether it has an atmosphere and so on. The second advantage is that it would not require the planet to pass between us and the star. With the dimming method we can only detect the subset of planets which have a suitable orbit.

Whether we can detect mega-structures, depends on how big we envision them to be. If their length scale is supposed to be smaller than those of planets, there is essentially no chance: We are talking about moon-sized telescopes again, even for the nearest stars. Something much bigger than a planet could obviously be detected, but we might not be able to tell it is an artificial structure.

Thedrin said:

Hmmm.

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I was writing specifically about manned lunar landings. That was the context of the whole post. I'm fairly certain that the Chinese lander/rover have come up in this very thread before, it's not news.

So when do we send the stupid message telling them how wonderful we are and how good we have it here?

To a bunch of self involved suckers getting on an alien ship, shouted by a skeptic... "How to Serve Man, its a cook book!" - Outer Limits iirc.

We already sent it. We have been broadcasting signals with enough power for aliens to pick up for decades. But because of the distance involved, it will take decades or centuries or millennia more to reach them.

We should put a seismograph on the moon to see if there's any current geological activity.

Yeah I agree. The Apollo missions did leave behind seismographs and they did pick up moonquakes but they ceased operating long ago.

Link to video.

Absolutely hilarious!