The Stratoscopes were two balloon-borne astronomical telescopes which flew from the 1950s to the 1970s and observed in the

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

and

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

regions of the spectrum. Both were controlled remotely from the ground. Stratoscope I possessed a 12-inch (30.48 cm) mirror and was first flown in 1957. It was conceived by

Martin Schwarzschild Martin Schwarzschild (May 31, 1912 – April 10, 1997) was a German-American astrophysicist. The Schwarzschild criterion, for the stability of stellar gas against convention, is named after him. Biography Schwarzschild was born in Potsdam ...

and built by the

Perkin Elmer Corporation PerkinElmer, Inc., previously styled Perkin-Elmer, is an American global corporation that was founded in 1937 and originally focused on precision optics. Over the years it went into and out of several different businesses via acquisitions and di ...

with funding provided by the

Office of Naval Research The Office of Naval Research (ONR) is an organization within the United States Department of the Navy responsible for the science and technology programs of the U.S. Navy and Marine Corps. Established by Congress in 1946, its mission is to plan ...

. A small secondary mirror focussed the image from the primary into a 35 mm movie camera, which captured the images on film. Schwarzschild used the telescope to study the turbulence and

granulation Granulation is the process of forming grains or granules from a powdery or solid substance, producing a granular material. It is applied in several technological processes in the chemical and pharmaceutical industries. Typically, granulation inv ...

in the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

photosphere The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...

. Stratoscope II, a 36-inch (91.4 cm) reflecting telescope, flew from 1963 to 1971. This larger project proved to be beyond the ability of the university-led research team funded by ONR and, later, the

National Science Foundation The U.S. National Science Foundation (NSF) is an Independent agencies of the United States government#Examples of independent agencies, independent agency of the Federal government of the United States, United States federal government that su ...

, so was managed by NASA as a beginning of its scientific ballooning program led by

Nancy Grace Roman Nancy Grace Roman (May 16, 1925 – December 25, 2018) was an American astronomer who made important contributions to stellar classification and motions. The first female executive at NASA, Roman served as NASA's first Chief of Astronomy throug ...

. The gondola it was mounted on weighed 3.5 tons. It studied planetary

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

s, the atmospheres of

red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The stellar atmosphere, outer atmosphere is inflated and tenuous, making the radius large and the surface t ...

stars, and

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...

. On early flights of Stratoscope II, photographic film was used, but this was soon replaced by television detectors.

References

External links

*Smithsonian National Air and Space Museum (NASM)
Mirror, Telescope, Stratoscope I
*Smithsonian National Air and Space Museum (NASM)
Perkin Stratoscope II Telescope model
* ttps://stratocat.com.ar/fichas-e/1957/NBR-19570925a.htm Detailed account of the third flight of Stratoscope from New Brighton (MN) 9/25/57br>Detailed account of the third flight of Stratoscope from Huron (SD) 10/17/57
Balloon-borne telescopes Infrared telescopes {{telescope-stub