The outer dark is still in conversation

Deep Time Radio

A signal from Voyager 1 takes almost a day to become a fact on Earth. Meanwhile its radioisotope power falls, instruments go quiet, and three 70-metre dishes keep turning toward a 23-watt voice.

Geometry snapshot · 2026-07-10 00:00 TDB · other facts dated below · not live telemetry

Act I

Distance is already delay.

Choose a spacecraft. The line changes length; the signal clock changes with it. These are frozen Earth-centred ranges from JPL Horizons, not decorative orbital positions.

Voyager 1

Earth range

One way

Question and answer

Earth-centred distance scale for three deep-space spacecraft Voyager 1, Voyager 2, and New Horizons plotted by dated Earth range. Earth

Linear Earth range, 0–180 AU. One AU is 149,597,870.700 km. Snapshot and calculations are preserved in the local source asset.

Act II

Release one carrier.

Twelve seconds of compressed motion stand for the selected craft's actual one-way light-time. This is a constant-speed schematic through frozen endpoints, not an ephemeris trajectory. Pause or scrub it; reduced-motion mode places it at Earth without animation.

The selected voice

Earth / DSN Voyager 1
Carrier elapsed0 h 00 m 00 s
Remaining
Scale crossed

If all three spoke at the same instant

Act III

What remains is chosen.

The spacecraft does not publish one neat “power remaining” number in the sources used here. NASA publishes a present rate of decline and the decisions made around it. The honest story is subtraction, not a guessed gauge.

3 × about 158 W

Voyager 1's three RTGs produced roughly 474 electrical watts at launch. source

about −4 W each year

This is NASA's current decay rate, not permission to back-calculate an exact 2026 total. source

one instrument goes quiet

LECP was shut down. A 0.5 W motor remained on in case future power savings permit recovery. source

two science instruments remain

Plasma waves and magnetic fields continue returning unique interstellar measurements. source

Inverse-square teaching comparison across Earth range A decreasing curve with New Horizons, Voyager 2, and Voyager 1 marked by range. 1 AU180 AU · logarithmic range

Farther also means thinner.

The curve is not a Voyager link budget. It is an inverse-square teaching comparison for equal transmitter and antenna gain. Voyager's directional high-gain antenna, pointing, coding, receiver noise, and DSN processing determine the actual link.

Inference boundary: relative geometry is calculated here. The approximately 10⁻²³ W/m² Voyager flux near 160 AU is separately cited from JPL, not produced by this curve.

Seventy-metre Deep Space Network receiving dish A diagram of a large parabolic dish concentrating a very weak arriving Voyager signal. ~10⁻²³ W/m² cited Voyager flux near 160 AU focus 70 m aperture

Act IV

Listening is infrastructure.

Voyager's cited transmitter is 23 watts. The JPL technical monograph places its flux density around 10⁻²³ watts per square metre at a 70-metre DSN station beyond 160 AU. The spacecraft did not grow louder. The receiver became enormous, accurately pointed, low-noise, and patient.

  • The geometric area of a 70 m circle; actual effective aperture is lower.
  • Flux × geometric area only, explicitly not receiver system power.
  • 20 kW normal DSN uplinkThe cited Earth-to-Voyager path is roughly a thousand times the spacecraft's transmitter power.
  • Several listening sessions each weekDSN describes continuing captures from both Voyagers.

Calculation boundary: the dish-area product ignores aperture efficiency, atmospheric and pointing losses, receiver noise, bandwidth, modulation, and coding. It is here to make the exponent tangible, not to replace a telecommunications link analysis.

The conversation persists because something small keeps speaking and something very large keeps turning to listen.

Power is conserved aboard the spacecraft. Attention is scheduled on Earth. Between them, a fact spends nearly a day becoming knowable.