An airborne observatory is an airplane, airship, or balloon with an astronomical telescope. By carrying the telescope to a sufficiently high altitude, the telescope can avoid

cloud cover Cloud cover (also known as cloudiness, cloudage, or cloud amount) refers to the fraction of the sky obscured by clouds on average when observed from a particular location. Okta is the usual unit for measurement of the cloud cover. The cloud co ...

, pollution, and carry out observations in the infrared spectrum, above water vapor in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

which absorbs infrared radiation. Some drawbacks to this approach are the instability of the lifting platform, the weight restrictions on the instrument, the need to safely recover the gear afterward, and the cost compared to a comparable ground-based observatory.

History

Balloon-borne telescope A balloon-borne telescope is a type of airborne telescope, a sub-orbital astronomical telescope that is suspended below one or more stratospheric balloons, allowing it to be lifted above the lower, dense part of the Earth's atmosphere. This has ...

s have been used for observation from the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...

since the Stratoscope I was launched in 1957. A number of different instruments have since been carried aloft by balloons for observation in the infrared, microwave, X-ray and gamma ray bands. The BOOMERanG experiment, flown between 1997–2003, and the MAXIMA, which made flights in 1998 and 1999, were used to map the Cosmic Microwave Background Radiation. In 1965, a USA military Boeing NC-135 flying laboratory performed its first solar eclipse observing mission. The aircraft was used also for other airborne astronomy missions in a scientific program continuing until 1975. Solar eclipse missions continued until 1980. In 1973, the French Concorde prototype, c/n 001, was modified with roof-top portholes for a

solar eclipse A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six month ...

observation mission of 30 June 1973, at the end of the French testing programme. Observational instruments were installed on board, and the aircraft flew across Africa for 74 minutes. The airplane is now at the Le Bourget Air and Space Museum on permanent display in eclipse livery, with the portholes displayed. The Kuiper Airborne Observatory, first flown in 1974, consisted of a aperture

Cassegrain reflector The Cassegrain reflector is a combination of a primary concave mirror and a secondary convex mirror, often used in optical telescopes and radio antennas, the main characteristic being that the optical path folds back onto itself, relative to th ...

carried aloft on a C-141A jet transport to perform infrared observations. In terms of aperture, the largest aircraft-borne instrument to date is a reflector telescope carried by a modified

Boeing 747 The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, t ...

for the

Stratospheric Observatory for Infrared Astronomy The Stratospheric Observatory for Infrared Astronomy (SOFIA) was an 80/20 joint project of NASA and the German Aerospace Center (DLR) to construct and maintain an airborne observatory. NASA awarded the contract for the development of the aircraf ...

(SOFIA) project. This instrument was put into use for astronomical observation in 2010. On 29 June 2015, the dwarf planet Pluto passed between a distant star and the Earth producing a shadow on the Earth near New Zealand that allowed SOFIA to study the atmosphere of Pluto.

List of specially-built airborne observatories

Airplane-based observatories

Balloon-based observatory

NASA is planning the largest ever balloon observatory in 2020 with a 400 foot balloon and 2.5 metre telescope. ASTHROS (Astrophysics Stratospheric Telescope for High Spectral Resolution Observations at Submillimeter-wavelengths) will launch from the Antarctic and is envisioned to last three weeks.

References

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History

List of specially-built airborne observatories

Airplane-based observatories

Balloon-based observatory

See also

References