The US National Reconnaissance Office (NRO), which builds and operates US spy satellites, has donated two spare, unused telescopes to NASA. With a 2.4m (7.9ft) aperture, they are almost identical to the celebrated Hubble Space Telescope launched in 1990, but are smaller and provide a wider field of view, earning them the nickname "stubby Hubbles".
Hubble was widely rumoured to have derived from an NRO telescope, something neither NASA nor the NRO will confirm.
The telescopes, called simply Telescopes A and B, are in storage in a clean room at a facility in Rochester, New York belonging to US aerospace technology company ITT Excelis. One of the two is officially space-qualified, meaning it has undergone rigorous tests to ensure it will be operable in space.
Although the lenses and control mechanisms are complete, the telescopes lack some major components, including cameras and control software.
The donated telescopes are almost identical to the Hubble Space Telescope
Originally constructed in the late 1990s and early 2000s, the NRO declines to identify the programme for which they were intended, or why they were never completed.
However, observers believe the telescopes are likely to come from the cancelled Future Imagery Architecture programme.
NASA has had official possession of the telescopes for 18 months, the agency says, and has been using the time to assess their viability. NASA personnel working on the project say the telescopes are well-suited for use on astronomy's top priority, the wide-field infrared survey telescope (WFIRST). The former NRO telescopes are significantly more capable than NASA's previously planned WFIRST, but have not been officially dedicated to the programme.
"[Use of] the telescopes would eliminate about one-third of the cost of starting from scratch," NASA points out.
Despite the significantly lower cost, NASA has precious little resources with which to finish and launch the telescopes. The majority of its spending is committed to the Space Launch System launch vehicle and the James Webb Space Telescope (JWST).
"There is no budget," says NASA. "The earliest we'd be able to work with these would be the middle of the next decade, after JWST is launched."
Although details are classified, the US military space budget, which funds the NRO, is widely acknowledged to be significantly greater than NASA's. The NRO is in the middle of a particularly active launch schedule, with one classified satellite launched so far in 2012 and three more launches scheduled before the end of the year.