Magnetometer (MAG):
Functioning on Voyager 1 and 2
The Voyager magnetometers are used to measure changes in the Sun's magnetic field with regard to both distance and time, as well as to study the magnetic fields around the outer planets and how they interact with their respective moons. Each Voyager carries several magnetometers that are spaced out along a deployable “boom” that minimizes interference from the spacecraft itself; some are near the base of the spacecraft, one magnetometer is 23 feet (7 meters) from the boom base, and the farthest nearly an astonishing 43 feet (13 m) from the base. Currently, the magnetometers are generating data regarding the magnetic field at the edge of the solar system and in interstellar space.
Almost as amazing as the magnetometers themselves, rarely given any credit, and worth mentioning is the magnetometer boom itself, which allowed the entire MAG experiment to succeed. The delicate 43-foot-long (13 m) arm that attaches the magnetometers to the space probes had to be deployed after the Titan-Centaur rockets had released the Voyagers from their nosecones into space. During launch, the boom and the attached magnetometers were largely compressed into a canister only a few feet in length. Once safely freed of its launch vehicle, latch pins on the Voyagers were released and the boom deployed to its full length, allowing the magnetometers to function. The magnetometer boom is a true marvel of engineering.
Low Energy Charged Particle (LECP) Experiment:
Functioning on Voyager 1 and 2
The LECP looks for and measured electrons, protons, alpha particles, and other heavy elements both around planets and in interplanetary space. The LCEP is made of up two subsystems: the Low Energy Magnetospheric Particle Analyzer (LEMPA) and the Low Energy Particle Telescope (LEPT). The LECP was used to help identify the shape of the magnetospheres around Saturn and Uranus.
Plasma Wave Subsystem (PWS):
Functioning on Voyager 1 and 2
This device was used to analyze the plasma wave and low-frequency radio wave spectra in the magnetospheres of Jupiter, Saturn, Uranus, and Neptune. The PWS continues to take measurements both within and beyond the heliopause (the boundary where the solar wind is stopped by the interstellar medium). The PWS also famously recorded the “sound” of interstellar space which can be heard below: