A sounding rocket or probe rocket, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight.
Sounding rockets are one or two stage solid propellant rockets used for probing the upper atmospheric regions and for space research. They also serve as easily affordable platforms to test or prove prototypes of new components or subsystems intended for use in launch vehicles and satellites. Sounding rockets made it possible to probe the atmosphere in situ using rocket-borne instrumentation.
The rockets are used to launch instruments from 48 to 145 km (30 to 90 miles) above the surface of the Earth, the altitude generally between weather balloons and satellites; the maximum altitude for balloons is about 40 km (25 miles) and the minimum for satellites is approximately 121 km (75 miles). Certain sounding rockets have an apogee between 1,000 and 1,500 km (620 and 930 miles), which is the maximum apogee of their class.
Sounding rockets take their name from the nautical term “to sound,” which means to take measurements. This type of testing is unique because it’s simple, cost-effective and time efficient. The experiments for the payload can be developed in about six months. The rockets are divided into two parts: the payload and a solid-fueled rocket motor. Many of the motors used are surplus military motors.
These rockets are basically divided into two parts: a solid-fuel rocket motor and a payload. Many of the motors used in sounding-rocket programs are surplus military motors, which keep down the cost of the rocket.
After the launch, as the rocket motor uses its fuel, it separates from the payload and falls back to Earth. Meanwhile, the payload continues into space and begins conducting the experiment. In most cases, after the payload has re-entered the atmosphere, it is brought gently down to Earth by way of a parachute and is then retrieved. By recovering parts of the payload, it can be refurbished and flown again, resulting in tremendous savings.
The sounding rocket program of the International Geophysical Year (1957–58) brought a number of results: the detection of X rays and auroral particles high above Earth; photographs of the solar ultraviolet spectrum from above the masking layers of the Earth’s lower atmosphere; and records of atmospheric pressure, temperature, composition, and density to altitudes of nearly 320 km. Sounding rockets have also determined regions of intense turbulence below 96 km altitude. In addition, they permit the dynamic testing of prototype instruments designed to be used in satellites and space probes.