The Large Binocular Telescope just got a new pair of eyes, and while we love our orbiting telescopes we have to admit the LBT looks pretty sharp. The Arizona-based telescope just brought home the clearest pictures of space ever taken from an Earth-based telescope — images three times sharper than those from the Hubble Space Telescope. Oh, and that’s with only one of its two mirrors working.
It’s a lot easier to build and maintain large telescopes on Earth, but snapping photos of the deep cosmos from the ground introduces a host of problems, mostly of the atmospheric variety. Aside from weather events that physically obscure a telescopes view of the sky, the atmosphere itself bends light as it passes through. That’s why we live with and love even occasionally troublesome orbiting ‘scopes like Hubble; from high above the atmosphere they have such a nice view of the universe even though they are often smaller and less powerful than ground-based optics.
But the LBT was just fitted with new adaptive optics that give it clarity far superior even to Hubble. Adaptive optics compensate for the atmosphere’s light-bending nature by gently bending an ultra-thin (0.06 inches thick) secondary mirror that corrects the incoming light. This mirror is so thin that the 627 tiny magnets stuck to its back can bend it into different shapes as dictated by sensors that detect atmospheric distortions.
The mirror compensates in real time with accuracy to the nanometer scale, essentially unbending the bent light so the LBT can get an unblemished picture. Once the atmosphere is out of the equation, its twin 27.6-foot mirrors are free to take in the night sky unhindered (compared to Hubble’s 7.9-foot main mirror). So it’s no surprise it gets better clarity, even being bound to the ground.
Only one of the LBT’s mirrors is currently outfitted with adaptive optics, so we haven’t even seen the $120 million installation working at full capacity yet. For future space-based telescopes that sounds like a challenge. Let’s see what you got, JWST.