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dv82matt
SFN Regular
760 Posts |
 Posted - 07/12/2007 : 21:23:06 [Permalink]
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Originally posted by Dave W.
Actually, yes, it does. Sure, you could synthesize an aperture of 1,000 meters with just two one-meter telescopes, but they'd still need to be 1,000 meters apart.
In orbit, a lot of little 'scopes spread out over 1,350 meters would get you the required angular resolution to read a newspaper, but due to different amounts of gravity and atmosphere tugging on them, the only way you'd get the required pointing accuracy to achieve that resolution would be to physically tie them all together with rigid beams.
In other words, there'd still be a 4,400-foot thing floating in orbit. And since the pitifully small-by-comparison 191-foot International Space Station can be photographed as it crosses in front of the Sun, imagine the outcry at the "secret" monster telescope used to read a newspaper from orbit. |
Physically tying them together would be counterproductive I think, better to use some sort of image stablization, adaptive optics or mathematical correction. Why do you think pointing accuracy would be the limiting factor? Can you provide a reference for this?
It may be that such a setup would indeed be impractical I'm no astromomer but I don't think it actually violates any physics as we currently understand it. |
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JEROME DA GNOME
BANNED
2418 Posts |
Posted - 07/12/2007 : 21:34:10 [Permalink]
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The blackbird could fly as high as 15 miles.
Satellites can orbit as low as 124 miles.
The difference is only about eight times.
The need for a monster telescope does not seem true.
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What a man believes upon grossly insufficient evidence is an index into his desires -- desires of which he himself is often unconscious. If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way. - Bertrand Russell |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 07/12/2007 : 21:40:36 [Permalink]
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Even assuming, for argument's sake, that you could get image stabilization down pat with a couple of reasonably small orbiting primary mirrors using that false aperture technique, wouldn't you still be collecting too few photons from that newspaper?
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
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dv82matt
SFN Regular
760 Posts |
Posted - 07/12/2007 : 22:01:40 [Permalink]
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Originally posted by HalfMooner
Even assuming, for argument's sake, that you could get image stabilization down pat with a couple of reasonably small orbiting primary mirrors using that false aperture technique, wouldn't you still be collecting too few photons from that newspaper? |
Yeah, that's a good point. In some situations increasing the exposure time might be feasible but I suppose really you'd have to add additional units to the array to collect more light. |
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JEROME DA GNOME
BANNED
2418 Posts |
 Posted - 07/12/2007 : 22:20:38 [Permalink]
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What technology are we currently using to replace the retired blackbirds ability to read newsprint?
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What a man believes upon grossly insufficient evidence is an index into his desires -- desires of which he himself is often unconscious. If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way. - Bertrand Russell |
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pleco
SFN Addict
USA
2998 Posts |
Posted - 07/13/2007 : 04:55:37 [Permalink]
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| Amazing how you completely ignored Dave's post here. Any thoughts about the physical attributes required for such a device? Or will you ignore this and continue suggesting that unknown super-military technology already exist that no one knows about but you? |
by Filthy
The neo-con methane machine will soon be running at full fart. |
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| Edited by - pleco on 07/13/2007 04:57:16 |
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HalfMooner
Dingaling
Philippines
15831 Posts |
Posted - 07/13/2007 : 05:22:27 [Permalink]
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Originally posted by JEROME DA GNOME
What technology are we currently using to replace the retired blackbirds ability to read newsprint?
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Spy planes are not built for reading newspapers.
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“Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive. |
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furshur
SFN Regular
USA
1536 Posts |
Posted - 07/13/2007 : 06:14:32 [Permalink]
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| What technology are we currently using to replace the retired blackbirds ability to read newsprint? |
Jeeze, I gave you all you need to determine that we do not have the ability to read newsprint from satellites or the Blackbird (as Dave pointed out), do you want us to do the calculations for you?
Your 'friend in the Pentagon' would be violating his clearance if he talked to you at all about the spy satellites. So he was just blowing smoke, I did the same thing when I had a secret security clearance and was on the trident submarine USS OHIO. People would always ask questions I could not legally answer, like, how fast does it go, so I would say in excess of 75 knots. Which of course is absurd.
The company I work for made the light weight mirror for the Hubble Space Telescope. The factory that made that mirror has made many more light weight mirrors. I do not know who is buying these mirrors, but I do know that they are not a big as a football field and there are not thousand. of them.
By the way, why would we go to the huge (not to mention the impossiblity) expense of making a system that could read the newspaper. It would be much cheaper to simply by the newspaper and read it in your office. Or do you think that the bad guys sit outside on park benches on a nice sunny days to read top secret documents? 
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If I knew then what I know now then I would know more now than I know. |
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pleco
SFN Addict
USA
2998 Posts |
Posted - 07/13/2007 : 06:50:22 [Permalink]
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The original "point" was that there are no pictures of the lander on the moon (implying that the landing never took place?)
We do have a satellite in orbit around Mars with a magnificent camera: the Mars Reconnaissance Orbiter.
Here is a picture it took of the Rover Opportunity:
| This view is a portion of an image taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on Oct. 3, 2006. The complete image is centered at minus7.8 degrees latitude, 279.5 degrees East longitude. The range to the target site was 297 kilometers (185.6 miles). At this distance the image scale is 29.7 centimeters (12 inches) per pixel (with 1 x 1 binning) so objects about 89 centimeters (35 inches) across are resolved. |
So, is it possible to take a picture of the landers on the Moon? Possibly, but this would require a satellite in orbit around the Moon with a camera of this quality, which we don't have right now.
But to take a picture like this from Earth to the Moon? Not going to happen... |
by Filthy
The neo-con methane machine will soon be running at full fart. |
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| Edited by - pleco on 07/13/2007 06:52:00 |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 07/13/2007 : 06:59:58 [Permalink]
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| We need a smiley of a plane getting shot down in flames... |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 07/13/2007 : 08:09:25 [Permalink]
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Originally posted by dv82matt
Physically tying them together would be counterproductive I think, better to use some sort of image stablization, adaptive optics or mathematical correction. Why do you think pointing accuracy would be the limiting factor? Can you provide a reference for this? |
Say your pointing accuracy equaled your angular resolution. Between any two telescopes in the array, you'd have an average of 50% overlap between identical pixels, which would completely screw up the interferometry required to synthesize the larger aperture. If I remember correctly, Hubble has a pointing accuracy a couple orders of magnitude smaller than its image resolution, but that superb stability is required for long exposures and some limited astrometry.
Hell, GeoEye-1, the current name of the telescope that Jerome linked to earlier, has a per-pixel resolution of 41 cm, but a pointing accuracy of three meters. So launching more copies of that satellite and trying to create a synthetic aperture out of them would be a disaster.
Large ground-based synthetic-aperture visible-light telescopes tend to be placed on immense, vibration-resistant foundations in order to meet insanely tight pointing accuracy requirements. The shaking caused by passing trucks can be a significant percentage of the wavelength of the light, messing up the interferometry and thus ruining the images.| It may be that such a setup would indeed be impractical I'm no astromomer but I don't think it actually violates any physics as we currently understand it. |
No, what would violate physics is a single one-meter telescope (for example, something some government agency could "sneak" into space and which few people would notice) with a resolution matching a 1,350-meter telescope. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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JEROME DA GNOME
BANNED
2418 Posts |
Posted - 07/13/2007 : 08:26:13 [Permalink]
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Originally posted by HalfMooner
Originally posted by JEROME DA GNOME
What technology are we currently using to replace the retired blackbirds ability to read newsprint?
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Spy planes are not built for reading newspapers.
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| Dude said :I recall having seen pics from SR-71 cameras that you can read nametags on uniforms. |
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What a man believes upon grossly insufficient evidence is an index into his desires -- desires of which he himself is often unconscious. If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way. - Bertrand Russell |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 07/13/2007 : 08:58:46 [Permalink]
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Originally posted by JEROME DA GNOME
Originally posted by HalfMooner
Originally posted by JEROME DA GNOME
What technology are we currently using to replace the retired blackbirds ability to read newsprint? |
Spy planes are not built for reading newspapers. |
| Dude said :I recall having seen pics from SR-71 cameras that you can read nametags on uniforms. |
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Yes, of course, nametags are always printed in a 12-point font. They are exactly the same as newspapers. How silly of me to not see that. Thanks, Jerome, for pointing it out. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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furshur
SFN Regular
USA
1536 Posts |
Posted - 07/13/2007 : 09:21:40 [Permalink]
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Originally posted by HalfMooner
Originally posted by JEROME DA GNOME
What technology are we currently using to replace the retired blackbirds ability to read newsprint? |
Spy planes are not built for reading newspapers. |
| Dude said :I recall having seen pics from SR-71 cameras that you can read nametags on uniforms. |
Wiki states:
SR-71 has a 6" resolution. I think a reference beats an 'I recall'. But I know that will not slow you down Jerome.
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If I knew then what I know now then I would know more now than I know. |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 07/13/2007 : 09:43:25 [Permalink]
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| At 83,000 feet, that's something like a three-and-a-quarter-inch lens. Pretty small, considering the size of the plane. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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