Do not Look Up | by Brian Koberlein

NASA

In the case of telescope mirrors, bigger is usually higher. The bigger your essential mirror, the extra gentle you possibly can seize and the extra faint and distant objects you possibly can see. The issue is that enormous mirrors are troublesome to fabricate. In addition they deform below their very own weight, which implies you want an costly help construction to maintain it in alignment. The most typical strategy to get round these challenges is to make telescopic mirrors in segments, however one other answer is to easily use a liquid mirror.

The essential concept for a liquid mirror telescope is to make use of a skinny layer of mercury, then spin it slowly. The rotation of the body causes the liquid to type a parabolic floor. Mixed with secondary mirrors or lenses, you then have a working telescope. Liquid mirror telescopes are grime low cost in comparison with different telescopes of an identical dimension. The 6-meter Massive Zenith Telescope (LZT), for instance, was constructed for a fiftieth of the price of a similar-sized telescope. The rationale liquid mirror telescopes aren’t extra frequent is that they’ve a few main drawbacks. The primary is that mercury is extraordinarily poisonous, however the second is that they’ll solely observe the sky instantly above them. They will’t be used to trace objects within the sky like different telescopes. However we’d be capable of tackle these challenges, as a current paper in Acta Astronautica exhibits.

Comstock, et al

Quite than utilizing mercury, the examine proposes utilizing a ferrofluid. Ferrofluid mirrors have been utilized in some liquid mirror telescopes, however this examine takes the concept additional by including electromagnets. Rotation could possibly be used to shift the mirror right into a parabolic form, which may then be held in place by magnetic currents. This fashion, a point of orientation could possibly be used with out the mirror shedding its form. On Earth, this wouldn’t be overly efficient since our gravity is comparatively sturdy. However this technique could possibly be fairly efficient for house telescopes. Magnetic currents may form a space-telescope mirror successfully no matter its orientation. The design may be fairly efficient on the Moon, the place gravity is 1/6 that of Earth and prices are at a premium.

The examine appears at numerous coil preparations and present ranges wanted to form a big ferrofluid mirror and finds that it could be possible for a variety of wavelengths. At the least in principle. The issue in the meanwhile is that our tolerance ranges for present electrical circuitry are too massive to supply the required precision. Whereas the concept has some potential, it received’t be an answer for the foreseeable future.