Plasma Wave Subsystem (PWS)

Assembled from 10 blocks · 2 evidence · 17 related

1. Story
2. A pair of long antennas and a receiver that listen for electric-field oscillations in the surrounding plasma. Its importance to this mission is a consequence of a failure: Voyager 1's plasma science instrument stopped working in 1980, so when the spacecraft crossed into interstellar space in 2012 there was no direct density measurement available. The plasma wave instrument supplied one indirectly. A disturbance from the Sun sets the local electrons ringing at their plasma frequency, and that frequency depends only on the electron density, so measuring a tone near 2.6 kilohertz gives a density of about 0.08 electrons per cubic centimetre. That number, far above what solar wind at 121 AU would give, is the measurement on which the claim of interstellar arrival rests. The instrument is still operating on both spacecraft in 2026. Not a place.
3. Knowledge
4. Plasma Wave Subsystem (PWS)
5. Connections
6. Voyager 1
7. The 2012 crossing is confirmed from plasma oscillations
8. Evidence
9. Voyager 1's plasma wave instrument recorded electron plasma oscillations near 2.6 kHz in October–November 2012 and April–May 2013, implying an electron density of about 0.08 cm⁻³ and indicating that the spacecraft had been in interstellar plasma continuously since the boundary crossings of July–August 2012, dated 25 August 2012 at 121.6 AU. V55 verification basis: the paper is on a publisher domain blocked to this session, but search results carried the frequency, the density and the crossing date and distance and attributed them to this paper.
10. Voyager 1's cosmic ray subsystem was switched off on 25 February 2025 and Voyager 2's low-energy charged particle instrument on 24 March 2025; both spacecraft lose about four watts of generator output per year; three science instruments continued to operate on each; Voyager 1's low-energy charged particle instrument was to run through 2025 and be switched off in 2026, and Voyager 2's cosmic ray subsystem was scheduled for shutdown in 2026, with the plan expected to keep at least one instrument running on each spacecraft into the 2030s. V55 verification basis: the release was not fetched — jpl.nasa.gov and science.nasa.gov are both blocked by this session's network egress proxy — but search results carried these specific figures and dates and attributed them to this release.