Plasma Wave Subsystem

{{short description|Instrument on board the Voyager space probes}}

File:Voyager-pws.gif

File:Voyager Captures Sounds of Interstellar Space.webm

Plasma Wave Subsystem (sometimes called Plasma Wave System), abbreviated PWS, is an instrument that is on board the Voyager 1 and Voyager 2 unmanned probes of the Voyager program. The device is 16 channel step frequency receiver and a low-frequency waveform receiver that can measure electron density.{{Cite web|url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1977-076A-13|title=NASA - NSSDCA - Experiment - Details|website=nssdc.gsfc.nasa.gov|access-date=2019-09-20}} The PWS uses the two long antenna in a V-shape on the spacecraft, which are also used by another instrument on the spacecraft.{{Cite web|url=https://voyager.jpl.nasa.gov/mission/spacecraft/instruments/pws/|title=Voyager - Spacecraft - Planetary Radio Astronomy (PRA) and Plasma Wave Subsystem (PWS)|website=voyager.jpl.nasa.gov|language=en|access-date=2019-09-20}} The instrument recorded data about the Solar System's gas giants, and about the outer reaches of the Heliosphere, and beyond.{{Cite web|url=https://astronomy.com/news/2018/07/forty-years-and-still-going-strong|title=Forty years and still going strong|first=Doug|last=Adler|date=July 2, 2018|website=Astronomy.com|access-date=2019-09-20}} In the 2010s, the PWS was used to play the "sounds of interstellar space" as the spacecraft can sample the local interstellar medium after they departed the Sun's heliosphere. The heliosphere is a region essentially under the influence of the Sun's solar wind, rather than the local interstellar environment, and is another way of understanding the Solar System in comparison to the objects gravitationally bound (e.g in orbit) around Earth's Sun.

The PWS instrument plan was introduced in 1974 during the development of the Voyager program.{{Cite web|url=http://www-pw.physics.uiowa.edu/plasma-wave/voyager/ssr/PWSINST.HTM|title=A Plasma Wave Investigation for the Voyager Mission|website=www-pw.physics.uiowa.edu|access-date=2019-09-20}} It was hoped it would help increase understanding of wave particle interactions and record data on the magnetospheres of planets like Jupiter and Saturn. The instruments went on to record radio waves at Jupiter, Saturn, Uranus, and Neptune.

The PWS instrument is one of the instruments that is a part of the Voyager interstellar mission, and they have operated for several decades after their 1977 launch into the 2010s.{{Cite web|url=https://voyager.jpl.nasa.gov/frequently-asked-questions/fast-facts/|title=Voyager - Fast Facts|website=voyager.jpl.nasa.gov|language=en|access-date=2019-09-20}}

Frederick L. Scarf of TRW was the first PI. After Scarf's death in 1988, Donald Gurnett became the PI.{{Cite web|url=https://space.physics.uiowa.edu/~dag/Voyager/|title=Voyager PWS|website=space.physics.uiowa.edu}}