Resolution to see exo-planets

Dook · 2005-12-21 19:10:52

Does anyone know what resolution we would need to actually see exo-planets?

Would a large interferometer on the dark side of the moon joined with the VLA and maybe the Hubble together be enough?

GCNRevenger · 2005-12-21 20:09:02

Forget trying to tie Hubble and the VLA into a Lunar array, that would definatly be more trouble then its worth.

Build megascope on the Moon's far side by sending multiple meter-scale scopes' powerd by RTGs and linked either via satelite (easy but high op costs) or fiber optics (hard but cheap op costs). Send lots of them.

chat · 2005-12-22 06:11:03

Dook,

Getting pictures of Pluto with the best of what is available seems beyond the current tech.

Pluto with no glaring star in the way and 4000 x closer than even the nearest exoplanet would could possibly image points out the tech difficulties.

A gigantic array of telescopes on the moon i think is the only way we will ever get terrestrial sized exoplanet images, and a moon base.

Dook · 2005-12-22 13:48:10

Well you wouldn't have to tie the Hubble with the VLA and a lunar interferometer but have each take a picture on a certain day at a specific time and then compile all of the pictures together with a computer.

Other stars would help you align the three pictures.

We may have to take pictures at 2 or 3 month intervals in order to catch the exo-planets in there orbit that reflects the most light from their native sun.

John Creighton · 2005-12-22 14:55:16

Well you wouldn't have to tie the Hubble with the VLA and a lunar interferometer but have each take a picture on a certain day at a specific time and then compile all of the pictures together with a computer.
Other stars would help you align the three pictures.
We may have to take pictures at 2 or 3 month intervals in order to catch the exo-planets in there orbit that reflects the most light from their native sun.

I am wondering how significant of improvements you can make by just combining pictures together. Interferometers, make dramatic improvements of resolution because the compare the phase of the light as well as frequency and intensity. If all you needed to do was take a bunch of pictures then couldn’t you do the same thing with just one telescope by taking repeated pictures?

chat · 2005-12-22 16:24:17

John Creighton,

Interesting and brilliant idea!

I don't see a reason you couldn't have 1 very large space telescope and combine months of pictures together to gain the theoretical limits of the available light over a huge area.

You would need a big computer and lots of time for image interferometer for many pictures, but the telescope in theory could produce lens coverage miles or hundreds of miles in scope with one decent sized lens.

Dook · 2005-12-22 17:37:33

Photons spread as they travel. You could examine a certain area of the space for long periods to resolve a dot but I'm not sure that provides us with enough information.

If you spread your light collectors then you can begin to identify shading and darker areas to form a picture.

I want to be able to resolve a bright Venus 4 light years away and be able to determine the elements that make up that planet.

Yang Liwei Rocket · 2005-12-22 19:25:04

follow up observations carried out with NASA's Hubble Space Telescope are providing important supporting evidence for the existence of a candidate planetary companion to a relatively bright young brown dwarf star located 225 light-years away in the southern constellation Hydra.
www.newmars.com/forums/viewtopic.php?t=3209
Astronomers at the European Southern Observatory's Very Large Telescope (VLT) in Chile detected the planet candidate in April 2004 with infrared observations using adaptive optics to sharpen their view. The VLT astronomers spotted a faint companion object to the brown dwarf star 2MASSWJ 1207334-393254 (aka 2M1207). The object is a candidate planet because it is only one-seven-hundredth the brightness of the brown dwarf (at the longer-than-Hubble wavelengths observed with the VLT) and glimmers at barely 1800 degrees Fahrenheit, which is cooler than a light bulb filament.

John Creighton · 2005-12-22 21:10:58

Photons spread as they travel. You could examine a certain area of the space for long periods to resolve a dot but I'm not sure that provides us with enough information.
If you spread your light collectors then you can begin to identify shading and darker areas to form a picture.
I want to be able to resolve a bright Venus 4 light years away and be able to determine the elements that make up that planet.

That’s kind of my point. Well partly. I am saying it is probably not enough to have two separate images in different places. You need to be able to measure the phase of the light and the time of the images. There is no instauration on Hubble to measure the phase of the light that hits the camera.

However, lets think about the problem a little more. The light from each point on the planet takes a different amount of time to reach the telescope. As the planet rotates the image of the planet facing the scope changes. As a consequence the frequency composition of the light entering the scope should change. The, image facing the scope at different latitudes on the planet change at different speeds. The image changes fastest at the poles and slowest at the equators. Thus if you had a planet with a constant image (a solid planet with no cloud color). There should be enough information over time to theoretically deduce the image of the planet if you could look at the planet for an infinitely long period of time. I am not sure the amount of images needed or the number of digits of precession required to perform such computations. I suspect you probably would need a few super computers to tackle the problem and it may be cheaper and faster just to build the interferometers.

chat · 2005-12-23 04:33:26

Dook,

You might be right about trying to get a crisp picture of a Venus sized object at 4 light years with this method.

But since all the pictures taken would be at slightly different host orbit times, the star would stay centered in the picture and any planet should produce a blurred circle or partial circle as it orbits.

You should be able to get size, distance, makeup of planet etc from multiple images, but not sure about a crisp picture.

This might turn out to be the method used to find stars with planets and get fuzzy pictures with lots of information about them, or even decent pictures of the planets.

With enough pictures i think its possible to get actual images of whatever is there, but computer time would be pretty large to sort out data.

Once a planet is found the same method could be used on other spectrum to gain even more information.

SpaceNut · 2005-12-23 06:42:59

Possibly a blurred circle around the star but if you think of this as if you were looking at the rings of saturn. One can then see that if we are edge on, that we would still not see the planets that might be there.

John Creighton · 2005-12-23 11:03:29

Going further, there is no reason we couldn’t combine better instruments like a lunar interferometer with a less superior instrument with the Hubble space telescope. Again the effectiveness of combining several independent measurements depends both on the computer power available and the sophistication of the algorithms developed to use that computing power. I suspect it will be about 20 years before we develop such powerful techniques which combine the fields of estimation theory, image processing and optics. At that time computer power and telescope power and availability will have also advanced significantly and the detail we will be able to see the universe will look like majic to people today.

chat · 2005-12-23 15:26:59

SpaceNut,

Even if the planet was directly pointing towards us we would still produce a blurred image of the orbiting body, it might take more images to make sense of what it is.

Any orbit should produce blur results.

John Creighton,

Thinking more about the computer time involved, it might be possible right now with little computer power.

A time stamp on images and relative location of each picture taken should make the computer work simple.

Or we could revert to non computer methods with hologram interference, a human could align 2 pictures in the best alignment possible then send them to the computer in correct best interference location.
100 people working on 200 images could produce pretty quick results and little processing work on the computer.

John Creighton · 2005-12-23 19:07:04

SpaceNut,
Even if the planet was directly pointing towards us we would still produce a blurred image of the orbiting body, it might take more images to make sense of what it is.
Any orbit should produce blur results.

John Creighton,
Thinking more about the computer time involved, it might be possible right now with little computer power.
A time stamp on images and relative location of each picture taken should make the computer work simple.
Or we could revert to non computer methods with hologram interference, a human could align 2 pictures in the best alignment possible then send them to the computer in correct best interference location.
100 people working on 200 images could produce pretty quick results and little processing work on the computer.

It sounds like you are suggesting optical computing. It should be possible to store a holographic image of a planet, then transform the image based on they dynamics of the system. Then recombine the predicted holographic image with the new snap shot. Over time the interference pattern should form the entire image of the planet.

chat · 2005-12-24 05:29:53

John Creighton,

Exactly

The nice part is the humans only have to correctly align the star.
The blur of any planet can be handled by the computer when all the images are correctly located.

Even a decent sized computer should have no trouble working out the movements and combining what the blur represents.

With time very crisp pictures could be built up since no time limits exist like a regular telescope, capturing light and adding it to the final image for as long as you need.

With this method I'm starting to wonder why this couldn't be attempted right now?

SpaceNut · 2006-01-04 10:57:29

Out of this world: Nasa funds revolutionary ideas

Giant camera in space generates most interest

The idea that has generated most interest recently at Nasa is the New Worlds Imager space telescope, designed to take pictures of planets outside our solar system. Taking such pictures is difficult because light coming from the planets is obscured by stars. To get around this, Webster Cash, of the University of Colorado, at Boulder, planned a pair of spacecraft - a starshade (the astronomical equivalent of sunglasses) and a collector - that works as a giant pinhole camera. The starshade would be one kilometre in diameter with a 10-metre hole at its centre and would sit more than 124,000 miles (200,000km) from the collector and would block the stars' dazzling light.
The imager is an idea that builds on previous Niac research on formation flying. "The New Worlds Imager observatory has components that are physically disconnected and the components may be positioned over several kilometres," said Dr Cassanova. "You can't physically tie these things together but you still have to control the spacing very accurately." Formation flying is where different components in space "fly reasonably close very accurately", he said. The imager might resolve details on distant planets, even linking up to objects about 60 miles across, giving us our first views of the clouds, oceans and continents on planets far from our solar system.

Also another Lincoln native helping design world’s biggest telescope

The 30-Meter Telescope Project is an astronomer’s dream.
The telescope will have 10 times the light-collecting area of each of the twin Keck telescopes in Hawaii — which rank as the world’s largest — and more than 20 times the collecting area of the James Webb Space Telescope, the planned successor to Hubble.
What will give the 30-meter telescope its great light-collecting capability is the mirror. Instead of one giant mirror found in traditional telescopes, the 30-meter telescope project will have a segmented mirror made up of 738 hexagons — all working together like a huge jigsaw puzzle to focus light emitted from stars and galaxies as much as 10 billion light-years away.

Sounds alot like the method that the JWST will employ to achieve its goals.

chat · 2006-01-05 06:31:49

SpaceNut

It does sound like a similar light gathering idea.
They are trying to collect light from 738 hexagons and combine it into one to take a single picture.

Does it make more sence to send up just 1 hexagon and take 738 pictures if the resolution is still identical?

That is 737 less of them to build and launch.

SpaceNut · 2006-01-05 09:26:17

The idea of the multiple mirrors increases the light gathering capability or maginification of it. Less weight than a large single mirror as well since each would not be as thick.

chat · 2006-01-05 13:09:27

SpaceNut,

Still its 738 separate mirrors with a maximum resolution for each mirror.
No matter how you combine the light from the mirrors it will not surpass a single mirror theoretical resolution, juts more sources of the same thing at slightly different angles.

Wont 1 mirror of the same size as the other 238 do just as good for the light it collects for just 1 picture?
And take 238 pictures at slightly different angles and combine that light?
Same thing as having 238 mirrors.

My thought is to make 1 costly very good quality bigger mirror and take a few hundred pictures with it, then combine the light source.

Like the difference of having 100- 1 megapixel digital cameras set up take 100 pictures all at once to make 1 picture.
Or 1- 25 megapixel digital camera that takes 100 pictures and combines it to be 1 picture.

The theoretical limit for the 25 megapixel camera should be much higher than the 1 megapixel camera will ever attain.

Yang Liwei Rocket · 2006-02-07 12:25:52

Canceling NASA's Terrestrial Planet Finder: The White House's Increasingly Nearsighted "Vision" For Space Exploration

http://www.spaceref.com/news/viewnews.html?id=1092

According to NASA's FY 2007 budget documentation "The Terrestrial Planet Finding project (TPF) has been deferred indefinitely." In other words, it is dead. NASA is just afraid to say so.

SpaceNut · 2006-02-13 09:27:53

Are you ready for some more Grffin waffling:
Griffin Builds Hopes For Terrestrial Planet Finder And Hubble Rescue Missions

NASA Administrator Michael Griffin said last week that, in effect, reports of the demise of the Terrestrial Planet Finder - and perhaps other major space-exploration projects for the future - have been exaggerated.
NASA's budget proposal, released last week, said essentially that funding constraints had forced the TPF's postponement indefinitely.
The James Webb Space Telescope, a near-infrared instrument intended to replace the aging Hubble, also would be deferred, the NASA document said, with an eye on a "launch date of no earlier than 2013."
Griffin said, "it is important to note that we are delaying missions, not simply abandoning them.

Commodore · 2006-02-13 11:37:38

Why doesn't he just say he will do what he can afford. If you want me to afford more talk to Congress.

MarsDog · 2006-02-26 05:41:08

Does anyone know what resolution we would need to actually see exo-planets?

Ultimate telescope

Launch smaller telescopes orbiting at distances similar to Neptune
Combine into one large interferometer operating at near IR

Look at an alien 100 light years away

Neptune orbit 4.504 x 10^12 m diameter = 9 x 10^12 m
Light year 9.5 x 10^15 meters
wavelength λ=10^-6 meter for near IR

resolution = 1.2 * 10^-6 * 9.5 10^17 / 9 10^12
0.129 meter or 13 centimeter resolution

If we spied an Alien orbiting in the Alpha Centuary system
Resolution is 5 millimeter or 1/5 inch
.

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#1 2005-12-21 19:10:52

Re: Resolution to see exo-planets

#2 2005-12-21 20:09:02

Re: Resolution to see exo-planets

#3 2005-12-22 06:11:03

Re: Resolution to see exo-planets

#4 2005-12-22 13:48:10

Re: Resolution to see exo-planets

#5 2005-12-22 14:55:16

Re: Resolution to see exo-planets

#6 2005-12-22 16:24:17

Re: Resolution to see exo-planets

#7 2005-12-22 17:37:33

Re: Resolution to see exo-planets

#8 2005-12-22 19:25:04

Re: Resolution to see exo-planets

#9 2005-12-22 21:10:58

Re: Resolution to see exo-planets

#10 2005-12-23 04:33:26

Re: Resolution to see exo-planets

#11 2005-12-23 06:42:59

Re: Resolution to see exo-planets

#12 2005-12-23 11:03:29

Re: Resolution to see exo-planets

#13 2005-12-23 15:26:59

Re: Resolution to see exo-planets

#14 2005-12-23 19:07:04

Re: Resolution to see exo-planets

#15 2005-12-24 05:29:53

Re: Resolution to see exo-planets

#16 2006-01-04 10:57:29

Re: Resolution to see exo-planets

#17 2006-01-05 06:31:49

Re: Resolution to see exo-planets

#18 2006-01-05 09:26:17

Re: Resolution to see exo-planets

#19 2006-01-05 13:09:27

Re: Resolution to see exo-planets

#20 2006-02-07 12:25:52

Re: Resolution to see exo-planets

#21 2006-02-13 09:27:53

Re: Resolution to see exo-planets

#22 2006-02-13 11:37:38

Re: Resolution to see exo-planets

#23 2006-02-26 05:41:08

Re: Resolution to see exo-planets

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