Stuff in Space

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paperburn1
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Re: Stuff in Space

Postby paperburn1 » Mon Jul 24, 2017 8:00 am

I have been pondering your question about seeing things in orbit at 20 LY away.
Even our space station is puny when compared to our planet. Measuring 357 feet end-to-end, the International Space Station largest object orbiting the Earth. That isn’t large enough to register on Earth-observing instruments such as the DSCOVR satellite's EPIC camera, which takes pictures of the Earth from a million miles away. The smallest objects EPIC's camera can make out are about eight to 10 kilometers wide. At that range, the ISS wouldn’t even register as a blip in an image of the Earth.
Even with closer satellites and higher resolutions are out of luck. NASA's Terra and Aqua satellites carry the MODIS (or Moderate Resolution Imaging Spectroradiometer) instrument and operate only about 440 miles above the Earth’s have a resolution of one kilometer you would probably only get a few pixels of resolution.
There are a few military objects in space that can do better but they are optimized for the other direction and right now I am focusing on commercial systems. The new James Webb long-wavelength (orange-red) visible light, through near-infrared to the mid-infrared (0.6 to 27 micrometers). While the Hubble Space Telescope has a 2.4-meter (7.9 ft) mirror, the JWST features a larger and segmented 6.5-meter-diameter (21 ft 4 in) primary mirror and will be located near the Earth–Sun L2 point . In theory it should be able to image exo-planets with 8 to 10 pixels of resolution .( This is a guess does anyone have better info?) and it is still not optimized for UV. It might pick up a orbital power generation station that was very large (Gigawatts?).

It seems once again we will need a bigger telescope. Good news if James Webb proves out we then could have something that big built up there.
I am not a nuclear physicist, but play one on the internet.

hanelyp
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Re: Stuff in Space

Postby hanelyp » Mon Jul 24, 2017 12:25 pm

The telescopes I'd like to see in space would be far too large to launch from Earth in one piece and deploy in orbit. They'd have to be constructed in space. And probably in deep space, as tidal effects in low Earth orbit would distort the structure far too much.
The daylight is uncomfortably bright for eyes so long in the dark.

Tom Ligon
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Re: Stuff in Space

Postby Tom Ligon » Mon Jul 24, 2017 1:29 pm

The thing about shiny metal is that it is not the size of the object that counts, its how good a mirror is it.

If I were to hold up a playing card ten miles away from you, you would not see it. You would not see it with a good pair of binoculars. With a good telescope, you might make out that I was holding my arm up. With the Hubble, and no atmosphere, you could easily read the card.

If I held up my signal mirror, a square of shiny metal two inches per side, I looked thru the hole in the center at the sighting tool, and lined that up on your position, you would clearly see the flashes, naked eye. From experience, at two miles, you'd be asking me to cut it the hell out, because it is bright enough to be annoying.

Per the suggested resolution of a 3300 mile diameter planet being visible, an object like the ISS is orders of magnitude too small. But as a flashing mirror, maybe not. The fact that they could theoretically see the body heat from a bumblebee at lunar distances suggests that my signal mirror should be clearly visible at the same distance with a good space telescope. You might not resolve a good image, but the flash should be easier to detect than, for example, ambient light on a grey rock.
Last edited by Tom Ligon on Mon Jul 24, 2017 1:37 pm, edited 2 times in total.

Tom Ligon
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Re: Stuff in Space

Postby Tom Ligon » Mon Jul 24, 2017 1:35 pm

hanelyp wrote:The telescopes I'd like to see in space would be far too large to launch from Earth in one piece and deploy in orbit. They'd have to be constructed in space. And probably in deep space, as tidal effects in low Earth orbit would distort the structure far too much.


And we will.

That could be delayed if we ever get enough junk in space that one collision sets off a cascade that turns LEO into a cage of frag, or if we suffer a war or economic collapse that throws us back into the 19th century.

paperburn1
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Re: Stuff in Space

Postby paperburn1 » Mon Jul 24, 2017 2:30 pm

I see your point, I don't think it would be possible with anything smaller than James Webb but I am far from being and expert. Don't we have someone out there that could chime in?
I am not a nuclear physicist, but play one on the internet.

Tom Ligon
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Re: Stuff in Space

Postby Tom Ligon » Tue Jul 25, 2017 3:10 am

I think the James Webb or larger.

We're still thinking small. I have been willing for some years to let Hubble go. Its old. We need a new one. The Webb will be a good instrument but they screwed around with it, wound up spending more by trying to delay it. The price is badly bloated.

I think we should have at least six large space telescopes, much further out than Hubble, capable of being arranged into very long baseline arrays that can resolve pimples on the arse of Ming the Merciless at 20 LY. Or at least spotting Earth-sized planets and getting something like an image. We should put one up every couple of years and get more observing done. And we should have enough transportation capacity that sending a crew up to service them is not a Big Deal.

kunkmiester
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Re: Stuff in Space

Postby kunkmiester » Tue Jul 25, 2017 5:18 am

With Falcon Heavy the price of big stuff is dropped like a hot rock. You could probably throw ten small telescopes up for the price of one big one, and with modern controls, it will be easy to make arrays even in the visible spectrum.

There's also the fact that you'd not be looking for just one object. A civilization like ours will have thousands of objects in orbit, adding up tona much larger reflective "surface" than just the ISS. Once again, quantity has quality.
Evil is evil, no matter how small

Tom Ligon
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Re: Stuff in Space

Postby Tom Ligon » Tue Jul 25, 2017 1:46 pm

There's a conundrum with going to telescopes with more and more "power". Since our goal is to be able to resolve smaller objects, we typically use the larger aperture for more resolution instead of more light gathering for faint objects. This means we're narrowing the field of view. Observing extrasolar planets is clearly in this narrow-field class.

There are exceptions. Wide field astronomy has yielded some marvelous results, and we've got swarms of small telescopes looking for asteroids and scanning for supernovae.

But the "sexy" telescopes are looking at narrower and narrower patches of sky. This has been the emphasis since Galileo pointed his first crappy first telescope at Jupiter. Better optics and more power.

But we are now building instruments to scrutinize objects Galileo never suspected were there, and now have vastly more galaxies to look at than he had stars to look at. The more powerful these scopes get, the more prospective targets there are, and the fraction of them we can study with a single instrument plummets. There may be a few planets in range that have orbiting satellites making detectable flashes. But we might never see them because we don't know they are there, and we built one huge telescope used primarily to look at galaxies from 13+ billion years ago. We might not afford the time to observe specific systems to spot flashes around a likely planet ... too much observation time on a valuable instrument. We could have a planet swarming with satellites around Eta Cassiopeia, and never spot it because we're too interested in supernovae and colliding black holes at the edge of the Universe. I predict the users will be in fisticuffs, fighting for a chance to use it.

More powerful scopes means a need for more of them to cover more area.

SETI research has a similar problem. You'd be surprised just how little observing time they get. They'll get a little sliver of observing time on the Allen Array, or Green Bank, etc, covering a small patch of sky, and spend years analyzing that. Some alien signal could be blasting at us from another direction, outside their band, not when they're listening, and we'd be clueless. The odds of them missing such a signal vastly outweigh the odds of them detecting one. So there's an amateur SETI League, with the goal of creating a network of small, inexpensive radiotelescopes (based on ICOM microwave receivers available for a few hundred $ on e-bay, plus old satellite dishes and an obsolete PC). Their sensitivity is sufficient to pick up the "WOW!" signal, but nowhere near what the Allen Array can. But they are dedicated SETI instruments, and could be operated in vast numbers, covering more of the sky.

ladajo
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Re: Stuff in Space

Postby ladajo » Tue Jul 25, 2017 3:16 pm

kunkmiester wrote:With Falcon Heavy the price of big stuff is dropped like a hot rock. You could probably throw ten small telescopes up for the price of one big one, and with modern controls, it will be easy to make arrays even in the visible spectrum.

There's also the fact that you'd not be looking for just one object. A civilization like ours will have thousands of objects in orbit, adding up tona much larger reflective "surface" than just the ISS. Once again, quantity has quality.



As I stated earlier, this is where my thinking is. I don't think we are that far from it. Think of the possibility of placing some linked sensors at a couple of Lagrange Points, and playing 'I have a massive interferometer', or 'massive synthetic aperture array'?

We are already playing with this on the ground...
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

KitemanSA
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Re: Stuff in Space

Postby KitemanSA » Wed Jul 26, 2017 7:53 pm

Tom Ligon wrote:The Webb will be a good instrument but they screwed around with it, wound up spending more by trying to delay it. The price is badly bloated.
Reminds me of the USS Gerald R. Ford. When NewNews Shipbuilding first provided an estimate for the Ford, it was ~7 years and $7billion." The Navy said "that is too much per year, what happens if we spread it out over 10 years?" NewNews replied, "that would then be 10 years and $10 billion".

Face it folks, it takes a certain amount of money every year to keep a capability intact. It seems that the cost to keep a supercarrier construction capability intact is ~$1B/a.

ladajo
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Re: Stuff in Space

Postby ladajo » Fri Aug 04, 2017 12:46 pm

We are almost there in regards to detecting signatures of orbital stuff...

Nature Article on Detecting Atmospheres
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

paperburn1
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Re: Stuff in Space

Postby paperburn1 » Mon Nov 13, 2017 4:48 am

We talked about this once, now the first step for setting a legal colony
An odd but intriguing experiment in technology, diplomacy, governance and space exploration, among other things, has officially begun its journey.

After being delayed one day, an Orbital ATK Antares rocket carrying a cubesat named Asgardia-1 launched from NASA's Wallops Flight Facility in Virginia early Sunday. The milk carton-sized satellite makes up the entirety of territory of the self-proclaimed "Space Kingdom" of Asgardia.

"Asgardia space kingdom has now established its sovereign territory in space," read an online statement.

Over 300,000 people signed up online to become "citizens" of the nation over the last year. The main privilege of citizenship so far involves the right to upload data to Asgardia-1 for safekeeping in orbit, seemingly far away from the pesky governments and laws of Earth-bound countries.
[url]/https://www.cnet.com/news/asgardia-1-space-kingdom-nasa-orbital-atk-launch-nation/[url]
I am not a nuclear physicist, but play one on the internet.

hanelyp
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Re: Stuff in Space

Postby hanelyp » Tue Nov 14, 2017 12:37 am

paperburn1 wrote:The milk carton-sized satellite makes up the entirety of territory of the self-proclaimed "Space Kingdom" of Asgardia.

And what, beyond good manners, prevents someone from shooting down the self proclaimed sovereign nation?
The daylight is uncomfortably bright for eyes so long in the dark.


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