When NASA lost contact with the Pioneer 10 spacecraft in January 2003, it was more than 12 billion kilometres from Earth and still faintly transmitting on a 30-year-old transmitter weaker than a refrigerator bulb, and the final signal took eleven hours to crawl back across the void before fading into noise forever.

When NASA lost contact with the Pioneer 10 spacecraft in January 2003, it was more than 12 billion kilometres from Earth and still faintly transmitting on a 30-year-old transmitter weaker than a refrigerator bulb, and the final signal took eleven hours to crawl back across the void before fading into noise forever.

On 23 January 2003, a faint radio whisper reached the Deep Space Network’s 70-metre dish in Madrid from a transmitter NASA engineers had launched when Richard Nixon was still in his first term. The signal had crawled across roughly 12 billion kilometres of vacuum, taking more than eleven hours to arrive. Pioneer 10 was speaking for the last time. Two weeks later, when controllers reached out again, the dish heard nothing but the cold hiss of bac…