Mine safety in coal mines, which in turn can initiate more extensive coal dust explosions. For this reason, rock dusts such as limestone dust are spread throughout coal mines to diminish the chances of coal dust explosions as well as to limit the extent of potential explosions, in a process known as rock dusting. Coal dust explosions can also begin independently of methane gas explosions. Frictional heat and sparks generated by mining equipment can ignite both methane gas and coal dust. For this reason, water is often used to cool rock-cutting sites. Miners utilize equipment strong enough to break through extremely hard
DAMP Project in New Jersey so that it could be evaluated and a summary report be forwarded on to the project sponsor, ARPA. During this period of operation, communications via satellite did not yet exist. As a result, communications between the DAMP ship and New Jersey was through the use of single-sideband (SSB) radio, generally through the use of a 10 kW transmitter. The DAMP ship generally transmitted upper sideband (USB) voice and/or lower sideband (LSB) frequency-shift keying radioteletype in the area of 16 and 22 MHz when atmospheric conditions were favorable. When communications became difficult because of atmospheric conditions, the DAMP