Overwhelmingly Large Telescope Closer to Reality

An anonymous reader submits: "The 100m OWL telescope proposed a few years ago by the European Southern Observatory group (ESO) may actually be built. Currently, the largest aperture for a telescope is the Very Large Telescope (VLT) at a 'very tiny' 16.4m by comparison. This monster is predicted to have a light gathering resolution of about 40 times the Hubble Space Telescope and a sensitivity several thousand times greater. Among many other things, it should be powerful enough to detect and gather spectroscopic data of extra-solar planets in order to determine the atmospheric composition and any signatures for life, like oxygen." We mentioned the OWL in this previous article too.

Comments

Active and adaptive correction

[ObviousGuy]

A space-based telescope wouldn't have to compensate for atmosperic disturbances...

What is the space station for, if not for this kind of thing? Vanity?

Re:Active and adaptive correction

[australopithecus]

also, the location in the atacama has negligible atmospheric disturbance, as outlined in the article.

Re:Active and adaptive correction

[taliver]

And to add to this comment, there are some good reasons for thinking of the moon:

1) Low gravity as opposed to no gravity
Any degassing from equipment or other debris would settle to the ground, instead of hanging around the mirror... Of course, you would alos need periodic "cleaning" of the mirror.

2) Raw materials
You could imagine that since the moon is made up of silicates and other minerals like titanium, you'd have a chance of constructing the mirrors in place. Like solar powered robots mining and the extruding glass and mirror in the vacuum to be then formed into mirror and placed. (I still need to work out the minor details...)

3) Stability
Vibrations could quickly be damped, and astronauts would have less problems as they bumped it around.

There are problems, like the issue of the sun blinding it for a decent part of the month, but I'm sure these effects could be minimized by placing it in a crater or other such terrain.

Re:Active and adaptive correction

[photonic]

First of all the space station is not the place where you want your extremely sensitive telescopes. I guess that the pointing of the telescope would be lost if an astronaut did so much as breathing.

Second, there is now and in the foreseable future no way to launch a telescope the size of a football-field into orbit. Think about the costs: Hubble, with a primary mirror of only 2 meters, costed several billions for the launch and all the maintance flights. The OWL would cost the same order of magnitude and would give you a diameter of 100 meter!

It is true that some wavelengths (x-ray, UV, far IR) can only be viewed in space, but the visible and near IR can convienently be viewed from earth. (If you have the adaptive optics working.)

Just my 2 eurocents.

5000m?

[morty4321]

Now how the heck would they manage to transport a 100m mirror to a mountain peak at 5000meters? I seem to recall when they built the first VLT that the mirror has to come in one piece and transporting a 100m mirror to that location would the way I see it, be a job only superman can do.

Re:Better in space?

[Anonymous Coward]

Wouldnt a large array of telescopes in a grid give you just as much resolution these days? You can integrate the images from lots of smaller mirrors pretty easily in software, and a small mirror is much easier to make than a big one.

You mean like the VLT (very large telescope)?

Already obsolete

[Anonymous Coward]

Although it sounds great, it'll take more than 15 years to build from the start of the construction project - so we're talking at least 20 years.

By then, it is predicted that computing will have advanced enough to build a globally-large coordinated telecope ("GCT").

GCT is where the 'scopes are situated anywhere on earth, and computer processing converges the images into one single image. This highly distributed method will require a degree of measurement so far unprecendented. But given the next generation of atomic clocks and earth rotation measurement, it'll be very reasonable.

The advantage is spacing. Since the telescopes can be located anywhere on earth, minor local variances of weather are, for all intents and purposes, irrelevant. In addition, even space-based telescopes (Hubble) could participate in the system.

And a GCT system uses many devices, so if any one is unavailable, the others will still operate, resulting in very high availabilty.

Finally, a GCT is relatively inexpensive. I estimage it'll take about $100,000 per site. Just a rough guess, but not unreasonable. That's lots less than OLT.

Therefore, I conclude that OLT is merely a way for to amass large grants, and not a way to do better science.