Stratospheric Astronomical Station

Stratospheric Astronomical Station 

a complex of scientific instruments, a lifting system, recovery devices, and flight control devices that is raised into the stratosphere for the conducting of astronomical observations. The astronomical instrumentation of the station usually includes a telescope or two coupled telescopes equipped with cameras, spectrographs, spectrophotometers with photoelectric scanning devices, bolometers, X-ray counters, and gamma counters. The lifting system consists of a stratosphere balloon filled with hydrogen or helium. The recovery devices used include parachute systems and shock absorbers, which soften the impact when the station lands. Flight control (tracking and commands) is carried out through radio signals transmitted from ground control centers and from the station.

Stratospheric astronomical stations have made it possible to overcome a number of limitations imposed on astronomical observation by the effects of the earth’s atmosphere. Such limitations include the vibration and blurring of the images of celestial objects; the screening of virtually the entire infrared region of the spectra of celestial bodies by telluric (of terrestrial origin) spectral lines and bands; and the impossibility of daytime observation of faint objects, such as the solar corona, because of the brightness of the sky.

The first successful launchings of stratospheric astronomical stations were carried out in the 1950’s by the French astronomer A. Dollfus and the American astronomer M. Schwarzschild. The largest solar station was launched in the USSR in 1966; the primary mirror of the telescope has a diameter of 50 cm. In a flight made in 1973, the diameter of the primary mirror was 1 m. In the 1960’s and 1970’s the Stratoscope II station with a mirror diameter of 94 cm was developed in the USA for nighttime observation. Large stations rise to heights of up to 20–30 km. Small stations designed for observing hard X rays and gamma rays ascend to heights of up to 40 km.

Important results in the area of the physics of the solar atmosphere were obtained between 1970 and 1973 by the Soviet solar station. In particular, the structure of the photosphere was found to have two components, one of which, the network of intergranular lanes, lies lower than the bright granules, which rise up to the chromosphere. Another discovery was the expansion of elements of the chromosphere in comparison with the granules. This fact indicates the rising of magnetic flux loops into the chromosphere and corona.

Observations made by Stratoscope II showed the existence of water vapor in the atmosphere of supergiant stars. A determination was also made of the dimensions of the nucleus of the Seyfert galaxy GC 4151.

Stratospheric astronomical stations have made it possible to determine the dimensions and luminosity of the nucleus of the Galaxy and to observe objects that are sources of hard X rays and gamma rays, for example, pulsars.

V. A. KRAT