Proposed Space Telescope Uses Huge Opaque Disk To Surpass Hubble

Required Snark writes NASA has funded a study of a geo-sychrounous orbit telescope that uses a half-mile diameter opaque disk to provide images with 1000 times the resolution of the Hubble. It uses diffraction at the edge of the disk to focus light, resulting in a very high quality image. It's named the Aragoscope, after the scientist Francois Arago, who first noticed how a disk affects light waves. "When deployed the Aragoscope will consist of an opaque disk a half mile in diameter parked in geostationary orbit behind which is an orbiting telescope keeping station some tens to hundreds of miles behind that collects the light at the focal point and rectifies it into a high-resolution image. 'The opaque disk of the Aragoscope works in a similar way to a basic lens,' says CU-Boulder doctoral student and team member Anthony Harness. 'The light diffracted around the edge of the circular disk travels the same path length to the center and comes into focus as an image.' He added that, since image resolution increases with telescope diameter, being able to launch such a large, yet lightweight disk would allow astronomers to achieve higher-resolution images than with smaller, traditional space telescopes."

Comments

Re:Visible from Earth?

[RivenAleem]

A disk 1/2 mile wide in geostationary would be the equivalent to a 1.4 inch disk a mile away (Geostationary orbit being 22,200 miles).

So most definitely not naked eye visible.

Re:keeping station behind it?

[PurpleAlien]

The unit for acceleration is m/s^2. In this case, 'g' is used as a unit to distinguish acceleration due to free-fall (gravitational) from general acceleration (and is usually measured with an accelerometer). The unit is defined as 1g == 9.80665m/s^2. This unit definition does not change with location - on the moon it is around 0.18g.

why not call it what it is -- a fresnel lens

[volvox_voxel]

http://www.edmundoptics.com/te... "Huge opaque disk" seems a lot more confusing then calling it a massive lightweight lens.

Re:why not call it what it is -- a fresnel lens

[Anonymous Coward]

why not call it what it is -- a fresnel lens

Because it is not a Fresnel lens, and doesn't even use refraction to focus the light. This is closer to a really simplified zone plate, which uses diffraction. Sometimes zone plates get called Fresnel zone plates because of some contributions he made there, but they are still different in construction and principle than a Fresnel lens.