Meteorological Rocket

(weather rocket), a rocket that lifts research instruments into the upper layers of the atmosphere to measure its structural parameters (the temperature, pressure, density, and composition of the air) and the direction of the wind. Such rockets have relatively low weight (up to 300–400 kg) and a limited ceiling (100–150 km). The most common type weighs 80 kg and can reach an altitude of 65–70 km.

Meteorological rockets are launched in various geographical regions, including the arctic and antarctic areas, from land-based points and from ships.

A meteorological rocket consists of two parts: a motor unit and a detachable nose cone, which contains the measuring equipment. The ascending part of the flight is usually at supersonic speeds; therefore, the measuring instruments must have low inertia and the strength to withstand acceleration and vibration. In many types of meteorological rockets a parachute is used during descent to reduce the speed (thus increasing the accuracy of measurement and making possible measurements of wind velocity and direction) and to permit recovery of the instruments. The high speed of the rockets has a major effect on many of the parameters being measured; consequently, some of the transducers are mounted in areas of minimum aerodynamic disturbance. The effect of the disturbance is taken into account by means of special theoretical and semiempirical formulas.

The temperature of the atmosphere is measured with resistance thermometers, microthermistors, or two manometers (with subsequent calculation using suitable formulas). Extensive use is made of the sound-ranging method of determining temperature, which is based on measurements of the velocity of propagation of the sound from successive explosions of grenades ejected from the rocket. The pressure and density of the atmosphere are measured by various kinds of manometers, including the membrane, thermal, ionization, and moving-coil types. The manometer readings are converted into free atmospheric pressures by means of semiempirical formulas. In addition, the density is determined by the falling-sphere method, in which the rate of fall is uniquely related to the density. The horizontal drift of a sphere makes possible determination of the velocity and direction of the wind. These quantities are also measured by radar tracking of the drift of the nose cone of the rocket during its descent by parachute or by locating metal foil ejected from the rocket. The relative composition of the atmosphere is usually determined by methods of mass spectrometry.

The signals from the transducers in the measuring instruments pass through a switching device to the input of the transmitter in a telemetry system and are received and recorded by a telemetry station on the ground. The trajectory of the rocket is measured with cinetheodolites, ballistic cameras, radar (active and passive tracking), and Doppler-radio systems. The methods of processing the data are very complicated and require a knowledge of various additional parameters, above all the aerodynamic coefficients; as a result, computer technology is widely used to process the data.