Planets orbiting distant stars.

Are there any future plans to replace the aging Hubble Space Telescope with anything more powerful?

The photographs from this telescope are amazing to say the least.

With new planets being discovered orbiting distant stars by detecting the ''wobble of the parent star, do we have the technology to build an orbiting telescope and actually ‘‘see’’ these orbiting gas giants?----------Thanks!
An Astronomy buff.

Work is currently underway on the Webb Space Telescope (formerly known as the Next Generation Space Telescope), which will be more powerful than the Hubble. However, it’s not a perfect replacement: The Webb will be primarily an infrared telescope, with some reduced sensitivity in the visible range, while Hubble is primarily visible, with some sensitivity in the near infrared and near ultraviolet. So there will still be some things that Hubble does better than Webb.

And we do have the technology (or very close to it) to build a telescope that could see extrasolar planets. In fact, we could even see ones smaller than the huge gas giants we currently detect, including ones Earthlike in size and orbit. Unfortunately, we don’t have the funding. The project has been on the back burner at NASA for years awaiting funding; it’s called Terrestrial Planet Finder, or TPF.

Wow! Thanks for the reply! Perhaps they should name it the Carl Sagan. I just wish they had the funding like they did back in the 60’s and70’s! There is so much to explore out there!!!

IANAAstronomer, but from what I understand, another technique for finding extrasolar planets is to measure the amount of light coming from the star, which will work if the planet passes between the Earth and the star, even if its orbit wouldn’t permit us to detect the wobble.

Chronos or another expert may come back to tell me to keep from wobbling people’s ideas about astronomy, but I believe that’s correct. crosses fingers :wink:

Kind of like detecting a shadow?
Thanks!

More like taking part in a not-so-obvious eclipse.

Given our ability to tell exact time, and to locate objects in space, and our ability to collect, and collate very large amounts of data, yes, we could build a telescope, or actually an extremely wide spread array of telescopes, to image planets around fairly distant stars. (Well, fairly distant in non stellar terms, distant in astronomic ranges is another whole matter.)

However, how closely you want to look at things really cuts down on the number of things you get to look at. So, searching with less discriminating instruments would still be needed, so you have to set up an array of arrays, having the ability to survey regions of space for candidate targets for your very high resolution array.

And, you have to launch all this stuff into space, in stable, and large magnitude orbits, with very good electrical systems, and communication features. And, basically, it can only look at one thing at a time, so time on the instrument is going to be booked up into the next century soon after it is launched. And first you have to come up with the money to pay for all this, which is going to produce images far less interesting to most taxpayers than the stuff that comes from the Hubble or even the Keck instrument now.

Some really useful information such an instrument would give would be in data matrices that would give evidence about the general nature of non luminous material in the local galactic region that could provide a baseline for comparison to similar data for regions thought to be empty now. Sunday supplement photography is easier to produce without relying on plain old optical imaging.

But, I think we will eventually gain more from that sort of “space program” than sending another dozen or so folks on long trips in cocoons so we can say “another giant step for mankind” has been achieved. If Eugene Cernan remains the last man on the Moon for another century, there is still lots of knowledge to be gained from the study of the universe.

Tris

There is always Darwin.

NASA was also looking at doing a space based multi-aperture nulling interferometric planet finder. I think Ball Aerospace was in charge of the initial research. I did theoretical paper on it a few years back.

It’s a hard problem: you combine the image of an on-axis star captured with multiple apertures, half of which have a pi phase shift added to the optical path. The phase shift needs to be achromatic (best bet is to use either a cats-eye or an anti-symmetric periscope pair) and the path lengths need to be matched to well under 1/20th of a wavelength. Since the light from stars in spatially coherent, the on-axis star is nulled out, i.e. cancelled due to destructive interference. This allows you to see any planets in orbit around the star as they are off axis and their light is not cancelled (the phase shift between apertures is not pi for off axis objects). This type of telescope has only a limited range, say 5 to 25 light years IIRC. The reason for this is the aperture separation needed to resolve and orbiting planet competes with the degree of spatial coherence of the light. This coherence falls off as a Bessel function with aperture separation and so if the apertures are too far apart, the light is not coherent enough to null the star. To see an Earth like planet, the null depth needs to be at least 10^-6 to view the planet at its peak wavelength (in the near/mid IR IIRC). This is ignoring scatter from the solar wind and particle halo that surrounds all stars. Another problem is that all the optics need to be cooled with liquid helium to reduce their emission. Another is that integration times tend to be in the hundreds of hours and the generation of thermal electrons (or electrons from other radiation sources that penetrate the telescope shielding, i.e. solar generated x-rays, etc…) can easily overwhelm the signal from the sensor. It goes on and on, cool technology, remarkably difficult, but probably doable in the long term. I certainly won’t hold my breath but I would apply for the job…

Doh. I didn’t see Chronos’ link to the TPF. This is NASA’s version of Darwin. Always a day late with my answers in GQ with Chronos and QED around. :frowning: