Podcast Summary: The Never Ending Voyager Missions

Podcast: Everything Everywhere Daily
Host: Gary Arndt
Episode Date: September 12, 2025

Overview

In this episode, Gary Arndt explores the remarkable ongoing saga of the Voyager 1 and Voyager 2 space missions. Launched in 1977 for a “grand tour” of the outer planets, these probes not only revolutionized our understanding of the outer solar system but, decades later, continue to send back data from interstellar space. Arndt delves into the technical marvels that have kept these elderly spacecraft operational for nearly half a century, the challenges faced in keeping in contact with them, the fascinating scientific discoveries they've enabled, and their future as humanity’s timeless ambassador to the stars.

Key Discussion Points & Insights

1. Launch and Immediate Success (00:00–02:20)

• Background: Voyager 1 and 2 were dispatched in 1977 during an exceptional planetary alignment, specifically to observe Jupiter, Saturn, Uranus, and Neptune.
• Quote: “They sent back the best images and data available at that time... The program was a smashing success. However, the probes never stopped traveling.” (Gary Arndt, 00:09)

2. The Golden Record and Prior Mentions (05:00–06:00)

• Past episodes referenced the attached Golden Record and planetary visits.
• Both probes are equipped with the Golden Record, a message to any extraterrestrial finders about Earth and its inhabitants.

3. Engineering and Longevity: The Power Problem (06:01–11:24)

• How Do They Still Work?
  • Voyager probes are powered by three radioisotope thermoelectric generators (RTGs), using plutonium-238.
  • Quote: “Inside each unit is 4.5 kg of plutonium 238 dioxide in the form of ceramic pellets. This isotope gives off heat as it undergoes natural radioactive decay. The heat is then converted directly into electricity.” (Gary Arndt, 08:50)
  • The half-life (87.7 years) is “in the sweet spot”—not too fast, not too slow for space missions.
  • At launch, each spacecraft generated about 470W; by 2025, only about 250W remains.
  • As power declined, NASA methodically disabled non-essential systems to prioritize core science and communications.

4. Sacrifices and Surprises: Instrument Management (11:25–16:00)

• All cameras and some instruments are now off.
• Some instruments operate in extreme cold without their heaters, surprisingly still functional.
• Current Operations:
  • Voyager 1: Magnetometer, cosmic ray subsystem, low energy charged particle detector, plasma wave instrument.
  • Voyager 2: The same, plus a working plasma science experiment—key for interstellar measurements.

5. The Communications Challenge (16:01–22:45)

• Distance and Signal Weakness:
  • Voyager 1: 168 AU (≈15.6 billion miles; 23 hours 19 minutes for radio signals to reach Earth).
  • Voyager 2: 140 AU.
  • By Earth, Voyager 1’s 20W signal is a billionth of a billionth of a watt—"less than an attowatt.”
  • Quote: “That signal degradation isn’t linear either. When you double the distance, it becomes a quarter the strength…” (Gary Arndt, 18:20)
• The Deep Space Network:
  • Three massive facilities (California, Spain, Australia) ensure that as the Earth spins, at least one can receive the faint signals.
  • Most data now comes at just 160 bits per second—“slower than the baud rates of early modems from the 1960s.”

6. Ancient Spacecraft, Old Computers (22:46–27:00)

• The Voyagers use 1970s computers; “the processing power in the key fob for your car is literally much more powerful.”
• Code updates became necessary in the 2000s:
  • NASA had to recall retired engineers to consult on, and sometimes hand-write, new assembly code.
  • Example: Voyager 1’s primary thrusters degraded—backup thrusters unused since 1980 were activated after 37 years, thanks to "old binders" and consultations.
  • Quote: “NASA literally called them back to consult, teach, and in some cases, even hand code new routines.” (Gary Arndt, 26:33)

7. Major Discoveries in Interstellar Space (27:01–33:00)

• Voyager 1 crossed into interstellar space in 2012; Voyager 2 did so in 2018.
• Major findings:
  • The interstellar medium is denser than expected (Voyager 2 detected particles 40x more dense).
  • Cosmic rays are more intense beyond the Sun’s magnetic influence.
  • The heliosphere is a dynamic, irregular boundary—not a smooth shell.
  • Voyager 1’s Plasma Wave Instrument picked up “the first sounds of the galaxy’s background activity.”
  • Quote: “Their instruments have shown that the interstellar medium just outside the heliosphere is denser than expected...” (Gary Arndt, 29:16)
• These findings inform our understanding of:
  • The solar system’s boundaries
  • The challenges of cosmic radiation for deep-space travel
  • The broader structure of our stellar neighborhood

8. The Future and Final Fate of the Voyager Probes (33:01–End)

• Power will continue to dwindle; more instruments will shut down; communications may end between 2026 and 2036.
• Long-term fates:
  • Voyager 2 will pass within 1.7 light years of Ross 248 in about 42,000 years.
  • Voyager 1 will take 300 years to reach the Oort Cloud, 30,000 years to traverse it, and in 40,000 years will be near Gliese 445.
• The Golden Records will persist:
  • “Their mission will never truly end. It only shifts from an active scientific exploration into a passive, almost archaeological role as the first emissaries to the stars from the planet Earth.” (Gary Arndt, 36:47)

Memorable Quotes

• On the Voyager probes’ resilience:
  “If you made a coffee mug out of ceramic plutonium 238 dioxide, it would be able to keep a cup of coffee warm for decades from the heat produced by its radioactive decay.” (Gary Arndt, 09:55)
• On the data rate:
  “Today, Voyager 1 typically sends only about 160 bits per second, which is slower than the baud rates of early modems from the 1960s.” (Gary Arndt, 21:40)
• On the legacy:
  “Both probes will coast through the Milky Way for millions and possibly billions of years, carrying with them the golden records which serve as a symbolic greeting to any intelligence that might encounter them.” (Gary Arndt, 35:21)

Episode Structure (Timestamps)

• 00:00–02:20 — Introduction: The Voyager launch and initial mission
• 06:01–11:24 — How the Voyager probes manage power and stay alive
• 11:25–16:00 — Shutting down instruments and the surprising resilience of remaining science payloads
• 16:01–22:45 — Communication challenges: Deep Space Network, data rates, and faint signals
• 22:46–27:00 — The obsolete computers and NASA's engineering improvisation
• 27:01–33:00 — Major scientific findings in interstellar space
• 33:01–End — The probes’ final destiny and their eternal role as Earth's distant ambassadors

Tone and Style

Gary Arndt’s delivery is clear, accessible, and curious—he is enthusiastic about space history and dives into technical details in ways that invite listeners to share his sense of wonder about the Voyagers’ achievements and ongoing legacy. The episode is rich in analogies and wry observations about technology, balancing depth with clarity.

Takeaway

The Voyager missions stand as one of humanity’s greatest scientific and engineering successes, turning what were supposed to be brief planetary flybys into a never-ending exploration stretching across interstellar space—and, perhaps, cosmic time. These silent craft, still sending whispers home after decades, illuminate not just distant stars, but the spirit of curiosity and perseverance that defines our species.