Around the launch of the Hubble Space Telescope, I remember comments in the media that the Hubble may be related to certain espionage satellites. The Hubble was designed and built around the time that the KH-9 series was operated by the NRO. In 2012, a KH-9 was shown to the public for the first time.
KH-9 during assembly
This shows the KH-9 to be rather different from the Hubble. The optical path is different (the KH-9 looks through an opening in its side, Hubble looks through its top), the camera technology is not even remotely related (film versus digital).
Now that we know a bit more about Hubble's contemporaries, can a definitive answer be given as to the relationship between the two programs?

  • $\begingroup$ There is no reason to think there is a link between the KH-9 design and the HST design. The KH-9 is a film system and uses a whiskbroom scan to achieve a super wide field of view. The HST is a electro-optical staring system with a very narrow field of view. You could think there is a link between the KH-11 design and the HST design, since the KH-11 is also an electro-optical satellite. Unfortunately the KH-11 is still classified, so you're not going to get any solid information on it. $\endgroup$ – gosnold Aug 9 '16 at 11:08

It was, in the sense that all spacecraft have relationship to each other. Okay, beyond that, let's see how they are related. Wikipedia talks about the design of Hubble:

Once the Space Telescope project had been given the go-ahead, work on the program was divided among many institutions. Marshall Space Flight Center (MSFC) was given responsibility for the design, development, and construction of the telescope, while Goddard Space Flight Center was given overall control of the scientific instruments and ground-control center for the mission. MSFC commissioned the optics company Perkin-Elmer to design and build the Optical Telescope Assembly (OTA) and Fine Guidance Sensors for the space telescope. Lockheed was commissioned to construct and integrate the spacecraft in which the telescope would be housed.

Okay, so let's take that apart. Marshall Space Flight Center designed it, Goddard build the instruments. Both of those are branches of NASA. So, who builds the spy satellites? Well, that's a bit tricky, but Wikipedia again takes a stab, and based on the fact that Hubble was designed so long ago, this should be fairly accurate. We're interested in the IMINT missions, Image Intelligence, and more specifically Electra-optical. Of these, the most similar is the Misty satellites, which, like Hubble, were launched from a Space Shuttle. The Misty satellites are believed to be built by Lockheed Martin, which would indicate a different design path entirely.

Okay, so the primary systems don't seem to bear a resemblance, but, as has been mentioned in comments, the optics were built by Perkin Elmer, for both Spy Satellites and Hubble. So, let's look at that a bit. If they were exactly the same design, then spy satellites would have suffered from the same problem that Hubble did, a blurring of the images that shouldn't be there. But I have little doubt that the basic technology is the same, and there's even a good chance that the same machinery was used to make the mirror that is made for spy satellites. They probably use similar materials as well, and similar processes.

My feeling is that there are definitely some commonalities, especially in the optics, but they are fundamentally different. Hubble will have to be more sensitive than a spy satellite, because the nebulas it is designed to see are too dim to see otherwise, while Earth is kind of bright. They probably have similar optics, but Hubble will be forced at infinity focus, while a spy satellite might adjust slightly. Both have similar pointing requirements, and wavelength requirements. The biggest difference, however, is the way sensors are designed. Hubble uses a framing camera, not much different that a camera you own. Most spy satellites use broom cameras, which are more like a fax machine, the Earth moves beneath them.

Last point of interest is that the question of if Hubble can image Earth has been asked, and the answer states that it can't, because the exposure would blur the image beyond recognition.

If you were going to compare a spacecraft imager to a spy satellite, I would take a look at MRO's HiRISE Camera. The design is quite similar to what I would expect from a spy satellite, although the optics would probably be a bit bigger. But Hubble doesn't really have all that much in common with a spy satellite, although they probably share similar technology.

  • $\begingroup$ Two words: PerkinElmer $\endgroup$ – Deer Hunter Jan 21 '14 at 5:13
  • $\begingroup$ The backup mirror for Hubble was OK. It was made by Kodak instead of P-E. The design and manufacturing process was ok, P-E just used a bad null corrector (and unbelievably trusted it even when other things said the mirror was bad). nytimes.com/1990/07/18/us/hubble-has-backup-mirror-unused.html $\endgroup$ – Organic Marble Nov 17 '15 at 2:10
  • $\begingroup$ The optics for spy satellites were built by Itek (KH-1 to 4), Perkins-Elmer (KH9) and Eastman Kodak (KH-7 and 8). The 2.4m telescopes NRO gave NASA were made by ITT Exelis, but that does not mean Exelis built the KH-11 optics. So you cannot be sure who built the KH-11 optics. Also a telescope for earth observation goes through much more thermal cycling than the HST telescope, so materials may be different. Finally the pointing requirements are very different between an observation satellite and Hubble: an observation sat has to repoint very quickly. $\endgroup$ – gosnold Aug 9 '16 at 11:18
  • $\begingroup$ @gosnold The Exelis division that built the declassified NRO mirrors was the same divested Kodak division that did Corona, the Hubble backup mirror, and a whole host of commercial imaging satellites. They didn't get that expertise out of thin air. $\endgroup$ – Kevin Thibedeau Sep 4 '18 at 16:15

This answer addresses the headline question, rather than the detailed content that suggests a connection between HST and a KH9.

There may be a connection between the Hubble and a KH11. Refer here and here. These links identify the prime contractor as Lockheed in both cases and also suggest a rough gemoetric similarity based on an anecdote about the shipping container having been used, with some difference such as the mirror size. This link shows a ground photo though little can be discerned from it, even the scale, other than the outline geometrical shape.

HST is an electro-optical system, where as the KH9 used photographic film returned in a series of re-entry vehicles.

Also this article suggests a few differences rather than similarities and asserts that two KH11 based imagers were offered to NASA by the NRO - though this point seems to be directly refuted in the Wiki KH11 article, which states that the hardware was related to a different NRO program and even goes a little way to describing the optical path.

Its interesting, certainly, though I would be rather circumspect about all of this information unless you are prepared to spend a while auditing each paper/web trail and, being realistic, it wouldn't surprise me if you find nothing you can be sure of.

So, apologies for being vague but I think that comes with the territory. I don't expect you are going to get much in the way of hard facts until sometime in the distant future when and if some declassification occurs.

  • $\begingroup$ If you are not going to quote new facts or come to new conclusions, I'm not going to upvote you. In fact, quite the opposite. $\endgroup$ – Deer Hunter Nov 16 '15 at 23:47
  • $\begingroup$ Suit yourself, though I did provide new information, seemingly as relevant as the previous answer and a useful conclusion too in alerting the reader to the difficulty in knowing what to believe in relation to classified programmes. I also added the key point that in this situation it will require some personal legwork and it does not make sense to expect to be spoonfed "facts". $\endgroup$ – Puffin Nov 17 '15 at 0:41
  • 1
    $\begingroup$ I've made some improvements, bringing a little more information in from the references. $\endgroup$ – Puffin Nov 17 '15 at 10:23
  • $\begingroup$ Interesting answer. In my question, I assumed the KH-9, but that was just guesswork. Confirming a link between Hubble and KH-11 will be difficult until the KH-11 is declassified. The linked articles give some interesting hints, but you can see the amount of guesswork going on when describing the KH-11. $\endgroup$ – Hobbes Nov 17 '15 at 13:06
  • $\begingroup$ I had heard the point about the shipping containers elsewhere, i.e. that Hubble had arrived for launch in a container bearing KH11 related markings, so it was interesting to see it in the wiki. If true it could be a starting point to infer features about the structural hard points on the satellte being compatible though I would put that at strictly "hear-say" and unverifiable. $\endgroup$ – Puffin Nov 17 '15 at 14:00

Reading Wikipedia's KH-11 Kennen I found this ...

"KH-11s are believed to resemble the Hubble Space Telescope in size and shape, as the satellites were shipped in similar containers. Their length is believed to be 19.5 meters, with a diameter of up to 3 meters.5,22 A NASA history of the Hubble,23 in discussing the reasons for switching from a 3-meter main mirror to a 2.4-meter design, states: "In addition, changing to a 2.4-meter mirror would lessen fabrication costs by using manufacturing technologies developed for military spy satellites."

5Richelson, Jeffrey T. (2001). The Wizards of Langley. Inside the CIA's Directorate of Science and Technology. Westview Press, Boulder. ISBN 0-8133-4059-4.p.199-200

22Mark Wade (9 August 2003). "KH-11". Encyclopedia Astronautica. Archived from the original on 20 June 2012. Retrieved 23 April 2004.

23The Power to Explore, NASA. In particular, Chapter XII – The Hubble Space Telescope Chapter 12, p. 483

(see the article itself for links to the sources.)

So it seems fairly definitive that there was certainly some relationship.


tl;dr: Yes, related! Assuming Wikipedia's discussion that the Hubble mirror was chosen to be 2.4 meters in diameter to use the same "technology" as that for the spy mirror, and assuming that actually took place, then definitely. (here and here and here and Wikipedia) Making a telescope mirror is hard, difficult, and exacting work. Making one that is not necessarily a simple parabola, and that must have a figure better than diffraction limited is extremely hard. If there is a source for 2.4 meter mirrors that meet these constraints and you've got one shot, you are definitely going to leverage that technology and tooling!

Remember that unlike most telescopes larger than a meter, Hubble would be in space and so there would be no atmospheric seeing. The resolution of every image would be potentially diffraction limited, which certainly was not the case for surface telescopes at the time the Hubble was being designed and built. Today we have adaptive optics that can restore a large amount of the resolution taken away by seeing, but not so much back then.

That means that conventional 2-3 meter astronomical mirror-making may not necessarily have the same exacting specifications as Hubble would demand from space!

Instead of re-quoting Wikipedia's KH-11 Kennen here I'll just point out that it has been nicely quoted in this answer where it states that Hubble's initial 3 meter diameter design was changed to 2.4 meters to take advantage of spy satellite technology.

Also both this and this answer mention that the boxes for the telescopes were similarly shaped.

Let's look at that quantitatively.

If Hubble's mirror's 2.4 meter diameter was dictated by existing fabrication equipment and tooling for primary mirror figure correction (a complicated process, and one that ultimately went wrong for Hubble anyway) then that would be a significant step towards "related".

Wikipedia sez (about the "leftover mirrors"):

The f/1.2 primary has a diameter of 2.4 m, and is refocused by the secondary to give an overall f/8 focal ratio, making the optical telescope assembly shorter than that of HST.

That means D = f/1.2 or 1.2D = f = 2.88 meters for the spy satellite primary.

enter image description here Source

This Hubble Press Kit says:

The secondary mirror has a magnification of 10.4x. It converts the primary-mirror converging rays from f/2.35 to a focal ratio system prime focus of f/24 and...

That means D = f/2.35 or 2.35D = f = 5.64 meters for the Hubble primary.

Hubble vs Spy Satellite Primary Mirrors


So Hubble's primary while still fast, had only half the curvature of the spy mirror. Still, since the 2.4 meter diameter would fit all of the tooling necessary to make the spy mirrors, and at least some of the tooling to measure the figure during grinding and polishing to do corrections, then that would be an excellent savings in cost and time plus potentially the experience and documentation of the engineers doing the work!

enter image description here

above: Estimating Hubble's secondary mirror size from 20 years of Hubble Space Telescope optical modeling using Tiny Tim

enter image description here


enter image description here

enter image description here


Don't worry that the almost 60 meter focal length of Hubble's primary plus secondary seems too long to fit inside the instrument. There are plenty of more optical goodies back there to further massage (shape, size and apodize) the beam for the instrument package!

The reason that the spy mirror had such an incredibly short focal length was to allow for large magnification by the secondary into a long combined focal length (for magnification) while sitting sideways in the spacecraft, looking out the side:

enter image description here

enter image description here

  • $\begingroup$ but if they'd used existing tooling to fabricate the mirror, surely showstopper bugs would have been ironed out already? The KH-11 predates the HST by 14 years. And Hexagon = KH-9. $\endgroup$ – Hobbes Dec 16 '18 at 19:25
  • $\begingroup$ @Hobbes Humans in the loop are always able to find new ways to make mistakes. After so many successful Soyuz spacecraft bringing people to and from the ISS, the most recent one has a random hole drilled in it, and a Soyuz launch vehicle malfunctioned, sending astronauts into an emergency ballistic (and early) return to Earth. Surely showstopper bugs would have been ironed out already? $\endgroup$ – uhoh Dec 16 '18 at 19:37
  • 1
    $\begingroup$ I was with you till you brought in the -9. The connections between that and HST are tenuous. $\endgroup$ – Organic Marble Dec 17 '18 at 3:05
  • $\begingroup$ @OrganicMarble First few sentences set the scope of my answer. If you can call something specific into question, I can address it, thanks. $\endgroup$ – uhoh Dec 17 '18 at 3:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.