Voyager 1 Reaches 1 Light-Day From Earth, Stretching Signal Delays to 48 Hours

Q: As Voyager 1 crosses the historic one light-day mark this month, what functioning instruments remain to transmit data back to Earth?

Voyager 1 is still returning data from two functioning science instruments: its magnetometer and its Plasma Wave Subsystem. NASA and related mission updates indicate those are the only active scientific instruments still operating on Voyager 1 as it nears the one-light-day milestone in November 2026. The magnetometer measures the strength and direction of magnetic fields in interstellar space, while the Plasma Wave Subsystem detects plasma waves and helps scientists infer properties such as electron density in the surrounding medium. A third instrument, the Low-Energy Charged Particle experiment, was shut down in 2026 to conserve power. That left the magnetometer and plasma-wave instrument as Voyager 1’s remaining science payload. Engineers recently carried out a power-saving reconfiguration, known informally as the “Big Bang,” to help keep those two instruments running longer as the spacecraft’s radioisotope power source continues to weaken. Those measurements remain valuable because Voyager 1, along with Voyager 2, is the only spacecraft directly sampling interstellar space beyond the heliosphere.

3 articles · Updated · ScienceDaily · Nov 6

Voyager 1 has become the first human-made object to reach one light-day from Earth, a distance at which a radio message now takes 24 hours to arrive.
That pushes the fastest possible round-trip exchange to about 48 hours, underscoring how difficult communication has become as the spacecraft travels deeper into interstellar space.
NASA plans to mark the milestone on Nov. 17 with its "Shine Bright for Voyager's Light-Day" activation.
The achievement comes as NASA highlights a busy November skywatching calendar that also includes the Leonid meteor shower, a Mars-Jupiter pairing 1.2 degrees apart, and a Nov. 24 supermoon.