inferometry question

[bushuser]

The question of long base inferometry was raised on another forum, specifically, the use of Mars-based equipment in combination with earth-based observation. My grasp of physics breaks down somewhere between wave equations and inferometry.<br />My questions are, do we currently have the technology to do this, with the Earth-Mars distance constantly varying? What new capabilities could it give astronomers?

 

[qso1]

Several of Earths larger telescopes including the Keck in Hawaii and the ESO array in Chile will eventually be interferometers but the baselines are nowhere near the distance between Earth and Mars.<br /><br />An interferometer with the baseline your describing should be capable of imaging Earthlike worlds 20 light years away in enough detail to see continents, oceans, and cloud patterns. Whereas the Keck would see a pixel or two of reflected light.<br /><br />But I have also read interferometry is more about cancelling starlight to see reflected light and that the reflected light is not necessarily magnified. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[doubletruncation]

Long base-line interferometry is currently practiced with radio telescopes only. The technical problem is that you need to compare the phase of the electromagnetic wave observed from different locations. In the radio you can actually measure and reccord the phase of the wave, so then you can later compare the observations taken from different locations to reconstruct the image. You can use the motion of the earth around the sun, or even of the sun through the galaxy to extend your baseline even father than on the planet. In the optical, however, it has so far been possible only to record the intensity of the wave averaged over phase. To do optical interferometry you have to compare the radiation observed from different positions in real-time using for example fiber-optics to combine the two beams. As a result it is much more difficult to do optical interferometry over very-long baselines (unless you can somehow record the phase of the light) since you have to be able to bring the light together over a long distance while preserving all the phase information.<br /> <div class="Discussion_UserSignature"> </div>