The 'Camera That Saved Hubble' Turns 25 NASA | JPL-Caltech | GSFC | Hubble | 2018 Dec 04
Click to play embedded YouTube video.
Twenty-five years ago this week, NASA held its collective breath as seven astronauts on space shuttle Endeavour caught up with the Hubble Space Telescope 353 miles (568 kilometers) above Earth. Their mission: to fix a devastating flaw in the telescope’s primary mirror.
About the size of a school bus, the Hubble Space Telescope has an 8-foot (2.4-meter) primary mirror. The largest optical telescope ever launched into space, where it could observe the universe free from the distorting effects of Earth’s atmosphere, Hubble had a lot riding on it. But after the first images were obtained and carefully analyzed following the telescope’s deployment on April 25, 1990, it was clear that something was wrong: The images were blurry. ...
During the week of Dec. 6, 1993, the astronaut crew installed two pieces of hardware intended to fix the error. The Corrective Optics Space Telescope Axial Replacement (COSTAR) was designed and built by a team at NASA’s Goddard Spaceflight Center in Greenbelt, Maryland, and would correct for the mirror error in three of the five instruments on Hubble.
The second instrument was the Wide Field and Planetary Camera 2 (WFPC2), designed and built at NASA’s Jet Propulsion Laboratory in Pasadena, California. WFPC2, which actually contains four cameras, would go on to produce many of Hubble’s breathtaking images, helping transform our view of the cosmos. ...
I was watching a program discussing the physics of eliminating diffraction problems in separating points of light when the idea of curved CCD’s came to mind. Sure enough, this wasn’t a unique thought.
The effect this will impose on photography stretches my limited understanding of new camera - sensor tech but could how it affect current systems under construction lengthen concern for us getting the biggest bang for buck
Re: NASA: The 'Camera That Saved Hubble' Turns 25
Posted: Thu Dec 06, 2018 4:50 pm
by Chris Peterson
Fred the Cat wrote: ↑Thu Dec 06, 2018 4:25 pm
I was watching a program discussing the physics of eliminating diffraction problems in separating points of light when the idea of curved CCD’s came to mind. Sure enough, this wasn’t a unique thought.
The effect this will impose on photography stretches my limited understanding of new camera - sensor tech but could how it affect current systems under construction lengthen concern for us getting the biggest bang for buck :?:
Curving the sensor doesn't change the effects of diffraction. So far we have no way to do that except at quantum scales. A curved sensor allows for simpler optics, which translates to reduced cost. And astronomical imagers have been using curved "sensors" for a long time- from the film plates in the 48" Schmidt telescope at Palomar (now the Samuel Oschin telescope), where the film plates were mounted into a jig to curve them and match the curved focal plane, to amateur setups with vacuum backs in cameras to curve the film.
In most cases to date, it has been cheaper to add corrective optics to flatten the field than to build curved CCDs. And there are hybrid options. For instance, the Samuel Oschin telescope has some corrective optics, but also has its camera built with a mosaic of flat CCDs mounted on a curved plate to match the curved focal plane.
Re: NASA: The 'Camera That Saved Hubble' Turns 25
Posted: Fri Dec 07, 2018 2:42 pm
by BDanielMayfield
It wasn't just "The 'Camera That Saved Hubble'". In a way, this fix may have saved NASA, or at least its reputation.
We're still living in the wake of the Hubble mirror mistake. The delays and massive cost overruns of the Webb telescope are a result of the dread of making a similar goof up.
Fred the Cat wrote: ↑Thu Dec 06, 2018 4:25 pm
I was watching a program discussing the physics of eliminating diffraction problems in separating points of light when the idea of curved CCD’s came to mind. Sure enough, this wasn’t a unique thought.
The effect this will impose on photography stretches my limited understanding of new camera - sensor tech but could how it affect current systems under construction lengthen concern for us getting the biggest bang for buck
Curving the sensor doesn't change the effects of diffraction. So far we have no way to do that except at quantum scales. A curved sensor allows for simpler optics, which translates to reduced cost. And astronomical imagers have been using curved "sensors" for a long time- from the film plates in the 48" Schmidt telescope at Palomar (now the Samuel Oschin telescope), where the film plates were mounted into a jig to curve them and match the curved focal plane, to amateur setups with vacuum backs in cameras to curve the film.
In most cases to date, it has been cheaper to add corrective optics to flatten the field than to build curved CCDs. And there are hybrid options. For instance, the Samuel Oschin telescope has some corrective optics, but also has its camera built with a mosaic of flat CCDs mounted on a curved plate to match the curved focal plane.
Yeah. We can only blame our own un-adaptive retinas. They can only see one reality at a time. I'd hope we could make one that could see the devil in the detail.
