Diesel-powered vehicles, especially older ones, are rarely thought of as being "silent." But for the purposes of the National Radio Astronomy Observatory in rural West Virginia, the old clatter-traps fill the transportation needs for the facility with a minimal amount of electronic "noise"— just what's needed for the ultra-sensitive equipment at the facility.
Vehicles at the Green Bank, West Virginia facility are primarily diesels more than 30 years old. Although the facility would like to replace the fleet with more modern vehicles, newer-model vehicles produce too much electronic "noise" to be suitable for the needs of the facility. When getting especially close to some of the facility's radio telescopes, only mechanically-injected diesels are allowed to come close, due to the almost complete lack of electronic noise from the engines.
The National Radio Quiet Zone is a 13,000 square-mile area in rural western Virginia and eastern West Virginia. Significant restrictions are put on use of mobile phones, radio stations, and other electronic devices within a 10-mile radius of the Green Bank facility, and employees of the outpost routinely go on patrols in the area to seek out and mute sources of radio interference.
Blogger Raoul Pop takes an in-depth look at NRAO and the NRQZ in a seven-part blog series, including the facility's aging fleet of diesels, which although seemingly out-of-step with the advanced scientific mission of the facility, serve its purposes perfectly with their old-tech engines.