Comments on: Adaptive Optics, Or: Laser Eye Surgery For Telescopes.

By: Hentzau

Hentzau — Mon, 28 Jan 2013 14:45:02 +0000

One of the things that’s stuck with me from my uni undergraduate course was being told that satellite/probes being launched at the time (circa 2002-2003) were running on the equivalent of a 486 processor, this being what was current at the time the satellites were proposed.

By: pertusaria

pertusaria — Sat, 26 Jan 2013 18:38:11 +0000

Wow, great read. I really liked the point about the surprisingly late use of old storage technology.

By: Gap Gen

Gap Gen — Thu, 24 Jan 2013 11:02:22 +0000

Note: This is why I work in simulations, where if I fuck up I don’t have to send a team of astronauts to fix my mistake.

By: Smurf

Smurf — Wed, 23 Jan 2013 16:49:21 +0000

I did like that they eventually checked it again on another device that DID show there was an error, but they dismissed it because the first null corrector didn’t show an error so they assumed the second device was faulty. Rather than there actually being and error.

I wouldn’t do that in my work, never mind if I was working on a billion dollar space telescope for NASA.

By: Hentzau

Hentzau — Wed, 23 Jan 2013 15:52:20 +0000

The problem with the mirror was that 1) it had to be made to insanely precise specifications, 2) this precluded the use of conventional null correctors to calibrate the mirror so a special one had to be made that would produce a mirror with the required specifications and 3) this led to the company that made the mirror only calibrating it on a single null corrector that happened to have one of the lenses 1.3 mm out of place. So while using the special corrector meant the mirror was incredibly precise, the out-of-place lens meant it was incredibly precisely *wrong*.

By: innokenti

innokenti — Wed, 23 Jan 2013 14:18:51 +0000

That right there is incredibly cool. Thanks for the revelation!

By: Gap Gen

Gap Gen — Wed, 23 Jan 2013 14:13:15 +0000

I heard the problem with the mirror was that they calibrated it on something attached on the ceiling, and fucked up the measurement between the distance to the mirror and the thing on the ceiling. But yeah, AO is certainly part of the reason why the JWST is focussing on wavelengths outside of visible light – AO is just so damn good at correcting for atmospheric turbulence in visible wavelengths.

Also, the Imax 3D film about the Hubble repair mission is well worth a look, if it happens to still be on anywhere. Some amazing people who risked their lives to fix an old telescope.

By: Hentzau

Hentzau — Wed, 23 Jan 2013 13:23:09 +0000

They were very lucky that a solution was even possible. If the same thing happens with the James Webb telescope all the way out at L2 NASA is going to be so completely boned.

By: Smurf

Smurf — Wed, 23 Jan 2013 12:21:20 +0000

Fixing the hubble mirror issue is one of the more impressive problem solving projects I’ve ever read about. I love that hubble is basically wearing glasses.