WASHINGTON: The U.S. space agency is planning to use two former spy telescopes to study mysterious dark energy in space.

NASA received the two telescopes from the National Reconnaissance Office (NRO) intelligence agency.

They were originally intended for the "Future Imaginary Architecture" programme aimed at creating a new generation of reconnaissance satellites for U.S. intelligence.

The spy telescopes given to NASA can be used in a project named "WFIRST-AFTA" (the Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets).

The launch date is planned for 2024, Space.com reported.

The aim of the WFIRST-AFTA project is to study dark energy which is thought to be accelerating the expansion of the universe and search for exoplanets -- planets that orbit a star other than Sun.

The two former spy telescopes have the same resolution as NASA's Hubble space telescope.

"We are going to use these telescopes as they are and we do not have to make modifications, but we do have to resurface the mirror, as it has been sitting in storage," Paul Hertz, NASA's astrophysics chief, was quoted as saying.

If approved, one telescope will be used for space observations and the other will be an engineering test bed on the ground for some time and then will be freed for other uses.

The NASA team is debating whether these should be closer to the Earth so that these can send the data to the researchers more quickly or farther away so the telescopes can get a broader view without being blocked by planet Earth.

The team may place the telescopes either in an orbit a few thousand miles from the Earth or at a stable gravitational point around 1.5 million km from our planet.

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