Space Telescopes / Keyhole
Keyhole satellites always have been of special interest because of their proposed similarity to the Hubble Space Telescope (HST). The big difference is that Keyholes are military satellites and that they are used for Earth observation instead of space research. For the astrophotographer interesting is the fact that the orbits of Keyhole satellites are highly elliptical. This means that they sometimes can be observed during very low passes above the surface, increasing the chance to capture more detail. But as stated on the page 'Satellites in their last Orbits', it is important to realize that due to the high angular speed of objects passing in low orbits, it is technically a bigger challange to ensure that images of these objects are free of motion blur. This is especially important when objects are tracked fully manually, the technique that I use in all cases.
The Keyhole satellites are a family of reconnaissance satellites launched by the US National Reconnaissance Office (NRO) since the mid-seventies. They are known under different code names, but often named Evolved Enhanced CRYSTAL (EEC). Observers recognize them mostly as KH-11 KENNAN satellites. The later versions are actually newer types often classified as KH-12 or Advanced KENNAN or Improved Crystal. It is often said that the Keyhole satellites are similar to the Hubble Space Telescope. According to sources they were shipped in similar containers and a NASA history stated that they used military Keyhole technology in the Hubble to minimize costs. In 2011, NRO offerend NASA two surplus Keyhole satellites. On that occasion, NASA engineers were able to visit the KH-hardware. It was reported that the focal length of the Keyholes was shorter then that of the Hubble. The shorter telescopes enabled the military to oversee larger areas on Earth. This gain of the Keyholes over the astronomical Hubble was interesting for NASA as it could assist research in different astronomical fields. In 2010, I managed to photograph some of the Keyhole satellites in rare favorable occasions.
The image below shows the KH-129 satellite captured on September 4, 2010 from a range of 336 kilometers, taken during a pass not far from the lowest point of the orbit of the satellite, even below the orbit of the International Space Station. The image is presented in both positive and negative. The model on the right features a proposed presentation of the telescope main shape, without the solar panels.
On the left we see the actual image taken with a 10 inch aperture telescope, on the right we see one of the proposed models developed by insiders. There seem to be incredible similarities. Note especially the thicker bright part of the telescope-tube below. Also some segments in the tube appear to be visible. Interesting are some elements that are mounted on the satellite that could be satellite dishes or solar panels. The biggest difference from the model is the big structure on the right side of the tube that is most likely a solar panel. Although the smaller structure on the left side of the tube suggests something like a dish antenna, it is probably the other solar panel. Other images taken a day later with the same setup under different circumstances seems to confirm the second solar panel. This and other images of the KH-129 also suggest an aperture door like on the Hubble. This is the structure visible on top of the image but it could also be some other element that we not know.
These are the first known detail images of USA-245, at the time of writing, the most recent Keyhole spacecraft in the program captured with a 25 cm telescope on August 5, 2015 near perigee from a distance of 289 kilometers while it was 277 kilometers above the ground. At the time of imaging, the satellite had been in space for almost 2 years. In these images, different elements such as the telescope tube and the thick compartment for the instrument bay can be clearly seen. The thicker instrument unit appears bright in nearly all ground based images of Keyhole satellites. Also, there is a hint of solar panels. USA-245 or NROL-65 was launched from Vandenberg Air Force Base at 18:03 UTC (11:03 local time) on 28 August 2013.
Comparing these USA-245 observations with those of USA-129 earlier on this page, shows many similarities in visible detail.
We can conclude that Keyhole satellites show in all these observations at least clearly a telescope tube, consisting of an longer thinner part and a shorter thicker part. The thicker part is the telescope main mirror housing that shows up bright in all images, indicating that this is a highly reflective element. The thicker part seems clearly flanked by 2 elements that appear to be solar panels but their visibility depends on observing conditions like angle and illumination.
Processings of USA-245 images on August 5, 2015. The different parts of the telescope tube are well recognizable
Processing of one of the USA-245 frames taken on August 5, 2015 that clearly shows an indication of visible solar panels or other types of panels
Below: Unprocessed raw frames of the USA-245 imaging session on August 5, 2015