What is Moonbounce?
The practice of Earth-Moon-Earth (EME) bouncing of radio waves off the moon has a common name called moonbounce. In this practice, the moon is used as a passive communication satellite which bounces off radio waves that are sent to it from an earth-based transmitter and sends them back to the earth. Moonbounce is commonly used by amateur radio operators.
The science of radio, electromagnetic and other types of waves provides the base for moonbouncing. When there is a radio transmission radio waves travel away from the point of origin. For example, when a person speaks into a microphone, his voice travels away from the point of origin. In EME, the transmission on a specific frequency is sent off the earth to the moon and this transmission gets bounced back from the moon’s surface to another point on the earth, at which that reflected transmission can be detected.
The possibility of moonbounce was first proved by Mr. W. Bray who worked in the British General Post Office in 1940. The EME experiments were conducted by the American military after the end of World War II. However, on 10 January 1946, the first successful moonbounce was observed. Before the advent of communications satellites, EME was considered an efficient wireless and secure communication medium. It included a teletype satellite-like link between the Navy’s Washington D.C. headquarters and the Pearl Harbor naval base.
But there are certain limitations related to moonbouncing. Because the distance between the moon and the earth is very large, a two-way communication by using the EME is not much efficient. The distance of moon from the earth is nearly 250,000 miles (402,336 km) approximately. And 186,000 miles or 300,000 km is the speed of radio waves. So a lapse of 2.7 seconds takes place for a question to reach the respondent. And 5.4 seconds is the total lag time for a simple question and its answer.
The radio waves also tend to scatter upon reflection as the moon is not a good reflector of electromagnetic waves. Due to this reason, advanced devices that include high-powered and highly sensitive antenna are required to make a successful moonbounce. It is seen that distorted transmissions are received back on the earth because the moon has an irregular surface which consists of mountains and craters and moreover, it also shifts slightly as it turns.
Since the advent of EME in 1953, amateur radio operators have used moonbounce for a while. The location from where the transmission is to be done should have a clear view of the moon so that a successful moonbounce can be observed. And the area should also have few man-made radio transmissions. A rotatable antenna, a receiver that supports sensitive narrowband transmissions and a transmitter which is able to produce 1500 watts of radio-frequency output are recommended by experts in this field for an effective moonbounce. It should also be checked that there are no laws which prohibit the use of these instruments and there is no disturbance to a nearby locality.
An amateur operator can achieve successful moonbouncing with patience, skill and time. Moonbouncing is still very popular among radio fans even after 60 years of its invention. Some people like it as they are able to touch the moon’s surface in a way by using proper devices on a clear night.
Category: Technology