View Full Version : Hubble question

2003-Aug-27, 10:21 PM
Ok, I KNOW I've seen a page or book address this somewhere, but I can't find it.

Somebody on a board I visit frequently said he has a buddy who claims that the Hubble was originally supposed to be a spy satellite.

Here's the quote:

He said it was actually originally designed to be a spy satellite. The defense department ordered a number of satellites and part of the deal was the contractor had to build one more than needed in case of a launch mishap or if one got up there and didn't work for some reason they would have a spare. As it turned out everything went without a hitch and they didn't need the spare. The contractor reconfigured it a bit and sold it to NASA for a bargain.

I would think the Hubble couldn't possibly be a spy satellite, and remember reading why somewhere, but can't find the info.

Also, I wouldn't think something like the Hubble could be "reconfigured" from a spy satellite to a deep space telescope. My reasoning (which admittedly is probably flawed) was that since the Hubble can't be pointed at a bright light source because it'd blow the optical electronics out. So you'd have to change the optical electronics. Which seems like it would fundamentally change the optics themselves. Baseically it seems like you'd need two competely different design approaches for a spy satellite vs a deep space telescope, which would mean you coudn't turn one into the other with a few minor changes.

Somebody school me please.


2003-Aug-28, 12:10 AM
You are quite right! The HST is not at all designed to image the earth.

The optics for something that would image the ground are completely different. Plus a spy satellite wouldn't have a host of spectrometers or other such cameras designed for it -- the instrument design process takes years! The HST was in the design process for 20+ years. Oh, and it wasn't a bargain at all... 1.5 billion dollars construction cost is pretty expensive!

That poster was just plain wrong.

A few articles on building the HST:

Kodak talking about building the "spare" mirror.

The Space Telescope Science Institude overview page. Partway down it talks about the design history.

Donnie B.
2003-Aug-28, 01:36 PM
However, your friend may be partly right. The Hubble requires many of the same techniques in its design and operation as do spy satellites: accurate pointing, high stability, high-quality optics and detectors, and so on. It's likely that Hubble's design took advantage of many technologies that were originally developed for the KH (and similar) spy scopes.

But Hubble itself was designed as an astronomical instrument from the ground up (so to speak).

2003-Aug-28, 01:46 PM
Wasn't it that the company who made the main mirror (Perkin-Elmer?) got the contract because of their expertise they got in military projects, that may be making mirrors for spy satellites?

Just found something:

Perkin-Elmer had considerable experience with precision mirror fabrication and had previously made mirrors somewhat like the HST primary for military reconnaissance satellites. The specifications and performance of these, however, remain classified. The military units were optically tested after assembly. The HST was not tested in this way, a "saving" that permitted Perkin-Elmer to submit the low bid for the mirror contract. Such a test would have unambiguously revealed a spherical aberration of the magnitude present in the HST.