2012 National Reconnaissance Office space telescope donation to NASA

The aging Hubble Space Telescope has conducted many significant astrophysical observations.

The 2012 National Reconnaissance Office space telescope donation to NASA was the declassification and donation to NASA of two identical space telescopes by the United States National Reconnaissance Office. The donation has been described by scientists as a substantial improvement over NASA's current Hubble Space Telescope.^{[citation needed]} Although the telescopes themselves were given to NASA at no cost, the space agency must still pay for the cost of instruments and electronics for the telescopes, as well as the launch of the telescopes. On February 17, 2016, the Nancy Grace Roman Space Telescope (then known as the Wide Field Infrared Survey Telescope or WFIRST) was formally designated as a mission by NASA, predicated on using one of the space telescopes.^[1]

Background[]

While the Hubble Space Telescope of the National Aeronautics and Space Administration (NASA) has collected a large amount of astrophysical data, has outlived all expectations, and has been described as one of the space agency's most successful missions, the instrument will soon succumb to the extreme environment of space.^[2] In addition, with the James Webb Space Telescope costing at least US$9 billion, the agency's astrophysics budget is extremely strained. As a result, NASA's other astrophysics missions have been delayed until funding becomes available.^[3]

In January 2011 the National Reconnaissance Office (NRO) revealed to NASA the existence of two unneeded telescopes, originally built as reconnaissance satellites, and available to the civilian agency. NASA accepted the offer in August 2011 and announced the donation on 4 June 2012.^[4] The instruments were constructed between the late 1990s and early 2000s, reportedly for NRO's unsuccessful Future Imagery Architecture program;^[5] in addition to the two completed telescopes, a primary mirror and other parts for a third also exist.^[6]

While NRO considers them to be obsolete, the telescopes are nevertheless new and unused. All CCDs and electronics have been removed, however, and NASA must add them at its own expense. When the telescopes' specifications were presented to scientists, large portions were censored due to national security. An unnamed space analyst stated that the instruments may be a part of the KH-11 Kennen line of satellites which have been launched since 1976, but which have now been largely superseded by newer telescopes with wider fields of view than the KH-11. The analyst stated, however, that the telescopes have "state-of-the art optics" despite their obsolescence for reconnaissance purposes.^[3]

Potential uses[]

The early consensus for the usage of the telescopes was to follow the NASA Astronomy and Astrophysics Decadal Survey of 2010, which lists the Wide Field Infrared Survey Telescope (WFIRST) as its highest priority.^[2][6] Observing in the infrared section of the electromagnetic spectrum, WFIRST will be used to study the role of dark energy in the Universe, as well as to directly image Jupiter-sized extrasolar planets.^[7]

The NRO telescope design has several features which make it useful for Roman/WFIRST and superior to the Hubble. The NRO instrument's 2.4-meter (94 in) primary mirror is the same size and quality as the Hubble's.^[3][6] With double the mirror diameter of the original WFIRST design, it allows for up to twice the image resolution and gathers four times the light.^[7] Unlike civilian telescopes, the NRO instrument also has a steerable secondary mirror for additional precision.^[3] The telescope has a much wider field of view than Hubble due to its shorter focal length, allowing it to observe about 100 times the area at any given time as Hubble can.^[4] This has led to the donated telescopes' characterization as "Stubby Hubbles".^[7] Their obstructed design, however, may make imaging extrasolar planets more challenging,^[8] and would be unsuitable for imaging the most distant galaxies at its longest infrared wavelengths, which requires cooling beyond the original NRO design temperature range.^[6]

Whether using the NRO telescopes would save NASA money is unclear. While each is worth at least $250 million, their larger size compared to the proposed WFIRST design would require a larger rocket and camera. According to one NASA estimate using an NRO telescope would raise the cost of WFIRST by $250 million above its $1.5 billion budget.^[6] Another estimate states that NASA would save up to $250 million. The agency's deputy acting director for astrophysics Michael Moore states that using both telescopes may ultimately save NASA $1.5 billion.^[9] David Spergel estimated that using an NRO telescope would add about $100 million to WFIRST's cost, but would prefer to spend another $200 million for a coronagraph to improve its direct-imaging capability.^[6]

Due to the budgetary constraints arising from the continued construction of the James Webb Space Telescope, NASA has stated that Roman/WFIRST may not be launched until 2024 at the earliest,^[9] despite early speculation that by using an NRO telescope the mission might launch by roughly 2020, at about the same time as the European Space Agency's Euclid.^[6] In addition, the availability of a telescope is believed to increase the probability that the mission will be launched at all.^[4]

While the first telescope is now in use as the basis for Roman/WFIRST,^[10] NASA currently does not have plans or funding for the usage of the second.^[4] Astronomers had studied possible additional uses,^[11] and NASA considered dozens of proposals;^[12] the only prohibition is Earth observation, a condition of the NRO donation.^[13] Possibilities include observing Earth's aurora and ionosphere, or asteroids and other faint objects within the solar system.^[6] NASA has also suggested that the telescope could be sent to Mars, photographing the surface with a resolution about four times finer than the current Mars Reconnaissance Orbiter's HiRISE instrument. From Martian orbit the telescope could also view the outer Solar System and the asteroid belt.^[14]

See also[]

• Multiple Mirror Telescope - an astronomical telescope in Arizona, built with donated NRO mirrors

References[]