On December 28, 1964, a Thor-Able-Star rocket launched a small satellite named Transit 5B-5 into orbit. This marked the start of satellite-based navigation, a precursor to today’s GPS, aimed at helping U.S. submarines determine their location. Originally designed to last around five years, this satellite has surprisingly remained operational for over sixty years.
Transit 5B-5 is still up there, still transmitting signals. Right now, an amateur radio operator with a simple antenna might be picking up its broadcast, first sent when Lyndon B. Johnson was in office.
For nearly three decades, the U.S. Navy hasn’t monitored this satellite. The program was officially retired in 1996, when GPS took over. But Transit 5B-5 just kept going.
### The Secret to Longevity
What makes Transit 5B-5 so resilient? Unlike many early satellites that relied on chemical batteries or solar panels, it uses a SNAP-3 radioisotope thermoelectric generator. This small nuclear power source converts heat from decaying plutonium-238 into electricity. With a half-life of about 88 years, the generator still produces around 65% of its original power today.
This means the satellite keeps broadcasting a low-frequency signal at about 136.65 MHz. It doesn’t rely on sunlight or batteries. There are no moving parts to wear out or computers to malfunction. It’s simply a power source linked to a transmitter, floating in orbit and functioning perfectly.
### Listening to History
If you have the right radio receiver, you can hear Transit 5B-5’s signal while it passes overhead. Amateur radio operators describe it as a rhythmic warble, which can be decoded into telemetry data—information about the satellite’s systems and performance. Receiving its signal doesn’t require military access or expensive equipment; a basic software-defined radio (SDR) device can do the job for about thirty dollars.
Hobbyists have preserved the legacy of Transit 5B-5, as the Navy has long since moved on.
### A Modern-Day Discoverer
Scott Tilley, a Canadian amateur radio operator, has gained attention for tracking down what he calls “zombie satellites.” These are space missions that were thought to be silent but are still transmitting. Tilley famously picked up a signal from the IMAGE satellite in 2018, which NASA declared lost in 2005. He notes that Transit 5B-5 is the oldest satellite he’s tracked, a testament to its enduring design.
### A Lesson from the Past
Transit 5B-5 tells a fascinating story about technology. This satellite, initially built during the Cold War, has outlived its purpose and its handlers. It functions without supervision, still doing its job 61 years later. The early engineers never envisioned that ordinary people would eventually listen to its signals using affordable technology.
Today, we often expect devices to fail quickly and replace them regularly. However, Transit 5B-5 was designed with longevity in mind. Its creators prioritized durability, wanting to make the most of their substantial investment in space.
### What’s Ahead?
As we look to the future, it’s worth noting that Transit 5B-5 serves as a reminder that innovation can outlast its creators. In an era of fast-paced technological change, we can learn from satellites like this—sometimes, overengineering pays off.
In a world where we replace gadgets every few years, Transit 5B-5 zooms overhead, a relic of the past still relevant today. The Navy relinquished control long ago, yet the satellite continues its silent journey, a small piece of history drifting through space.
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