A 20-year old secret: Is it true that the Hubble Space Telescope is a converted spy satellite that the military gave to NASA for testing purposes?

More than thirty years ago, the Hubble Space Telescope was launched into orbit and began to obtain images of the Universe that ground-based telescopes could not previously acquire. Thanks to it, scientists have greatly advanced their scientific knowledge of space, and Hubble is by far the most famous spacecraft. But still few people know that it was created on the basis of a US spy satellite.

This had to be officially recognized in 2012, when the US space intelligence agency announced its readiness to transfer to scientists two space telescopes stored in their possession with a main mirror of the same diameter as Hubble’s.

From the official version, set out in all articles, scientific and pseudo-scientific, you can learn about the long and difficult project to create a unique scientific instrument, about the dramatic history of its launch, about correcting errors in flight that were made during its manufacture. Only this will not be entirely true. Hubble was not created, but converted from a very expensive apparatus, not developed for peaceful purposes. But they did it as efficiently and effectively as possible.

The first space telescope to successfully go into orbit in 1968 was OAO-2 (OAO-1’s battery broke, so its three-day flight does not count). The main goal of this particular mission was to develop space observation technologies, target aiming, data transmission exposures to Earth, as well as the selection of optimal engineering solutions for scientific instruments in general. This project was so successful that it was approved as the basis for a large orbiting telescope.

The Large Space Telescope was developed really slowly and tediously over several decades, because the government had higher priorities for funding. In conditions of financial difficulties, the apparatus had to be significantly limited, even deprived of several devices. As the project shrank, the first word in the name was replaced with Hubble which was launched in 1990.

Space spies

But what does this have to do with spy satellites? The answer can be found in such a small detail as the telescope mirror, which after the upgrade remained the same size – 2.4 meters, since that was the only thing that was fundamentally important. It all started with the fact that, in connection with the Cold War, the United States intelligence became the basis of national security. The most important thing was not to miss the moment when the enemy was about to strike with nuclear weapons.

At first, surveillance was carried out using balloons, then manned aircraft, but they were successfully shot down. A safe alternative to reconnaissance was spy satellites, which were launched in 1960 (KeyHole devices of the Corona series, which have a camera on board). Initially, these models were intended to be only temporary until a sophisticated reconnaissance apparatus was developed. Then it turned out that these simple and cheap probes were best suited for the task at hand.

The next generation of spy satellites was equipped with a reflecting telescope. There were two mirrors: the main one with a diameter of 112 cm and a flat swinging one with a diameter of 12 cm. The latter made it possible to point the satellite at a target without rotating its body. Over time, the sizes of mirrors only increased, which made it possible to collect information from large areas in better quality.

Another undoubted advantage of optical-electronic telescopes was that they transmitted all data in real time. The first device to be equipped with a 2.4-meter mirror was the KH-11 KENNEN. If we compare its characteristics with Hubble, they will be similar in mass and size, not to mention the mirror. They were also transported in similar containers.

A gift of mirrors

In 2012, the US government donated space telescopes to NASA that were intended for spy satellites, but were not useful. They had mirrors exactly 2.4 meters in size. Their focus was shorter, which allowed the optical system to expand the field of view. These devices have been lying in the warehouses of the intelligence department since the “zero” after an unsuccessful scientific project to create a revolutionary satellite.

After an unexpected gift, the space satellite WFIRST grew suddenly in size. It was originally supposed to be 1.3 meters in size, destined to study the sky with a large field of view. This would allow to build maps of the distribution of dark matter by gravitational lensing and estimate the parameters of supernovae that exploded in distant galaxies. All this data would allow us to answer the question of how fast the Universe is expanding.

Now WFIRST will have a 2.4 meter mirror with a short focal length. Surprisingly, it turned out that it is this that provides a larger field of view (100 times larger than that of Hubble). However, the mirror had to be upgraded by applying a silver coating to it, because aluminum is not suitable for the spectral range of the telescope. But this does not change the fact that WFIRST, like Hubble, will have quite a lot of spy satellite parts in its design.

Of course, one cannot say that Hubble is simply a “spy satellite deployed 180 degrees,” if only because for astronomers the spectral characteristics of the objects being studied are a matter of primary interest, while intelligence officers figured out what to do with the spectrum only towards the end of the 2000s.

Accordingly, the systems for receiving and processing images from Hubble and reconnaissance vehicles differ significantly. The orbits were also different (the reconnaissance aircraft flew significantly lower), which also influenced the design.

Thus, if this spacecraft has become unique in some way, it is as an extremely effective and spectacular example of the conversion of a very expensive device that was not created for peaceful purposes.

And what is extremely important, it was Hubble, like nothing else, that clearly showed that without a person, without human hands in space, even the most perfect automatic device is meaningless. In four flights, US astronauts not only repaired the on-board systems of the space telescope, but also installed additional non-standard equipment that corrected manufacturing defects in the optical system. Robots capable of this will not appear tomorrow.