Why Do They Call It A Sounding Rocket?

When scientists use the term “sound” in relation to the upper atmosphere, they are referring to a process of using instruments carried by rockets to gather data about the properties of the atmosphere at different altitudes. This process is known as “sounding”, and it involves measuring various physical properties of the atmosphere, such as temperature, pressure, and composition, at different heights.

The term “sound” in this context is borrowed from the field of acoustics, where it refers to the process of using sound waves to probe the properties of a medium, such as air or water. Similarly, in the field of atmospheric science, sounding rockets are used to probe the properties of the atmosphere at different altitudes.

The first sounding rocket was launched on February 16, 1949, from the White Sands Missile Range in New Mexico, USA. The rocket, named the WAC Corporal, was developed by the United States Army and reached an altitude of 80 miles, marking the first time that a rocket had penetrated the Earth’s upper atmosphere. The WAC Corporal was also the first rocket to carry scientific instruments for the purpose of measuring atmospheric properties.

The WAC Corporal was a two-stage rocket, powered by a solid-fuel rocket motor in the first stage and a liquid-fueled rocket motor in the second stage. The rocket was 18 feet long and weighed 1,300 pounds. It carried a suite of instruments, including a cosmic ray detector, a thermometer, and a barometer, to measure temperature, pressure, and other atmospheric properties. The launch of the WAC Corporal marked a major milestone in the history of rocketry and paved the way for future scientific research using sounding rockets.

Since then, thousands of sounding rockets have been launched for a wide range of scientific purposes, including studying the aurora borealis^[1], measuring radiation in the upper atmosphere, and testing new technologies for space exploration.

Sounding rockets can provide valuable information about the structure and dynamics of the upper atmosphere, which can in turn be used to better understand weather patterns, climate change, and other aspects of Earth’s environment. For example, sounding rockets can be used to study the aurora borealis, which is caused by interactions between charged particles from the Sun and Earth’s magnetic field.

By measuring the properties of the upper atmosphere during auroral events, scientists can gain insights into the physical processes that drive these phenomena. Sounding rockets come in a variety of shapes and sizes, depending on their intended mission. Some are small enough to be launched by hand, while others can be several meters long and weigh hundreds of kilograms. They can be single-stage or multi-stage, solid-fueled or liquid-fueled, and can carry a range of scientific instruments and payloads.

The basic elements of a sounding rocket are a solid-fuel rocket motor and a science payload. Larger, higher-altitude rockets have two to three stages to increase efficiency and payload capability. The freefall part of the flight is an elliptic trajectory with a vertical major axis allowing the payload to appear to hover near its apogee. The average flight time is less than 30 minutes; usually between five and 20 minutes.

The rocket consumes its fuel on the first stage of the rising part of the flight, then separates and falls away, leaving the payload to complete the arc and return to the ground under a parachute. Overall, sounding rockets are an important tool for scientific research, providing scientists with a relatively inexpensive and accessible means of studying the upper atmosphere and conducting experiments in space.