Voyager Golden Record Carries 4.5-Billion-Year Uranium Clock as 14 Pulsars Provide a Second Date
Updated
Updated · spacedaily.com · May 22
Voyager Golden Record Carries 4.5-Billion-Year Uranium Clock as 14 Pulsars Provide a Second Date
2 articles · Updated · spacedaily.com · May 22
Summary
Each Voyager record cover includes a 2-centimeter patch of ultra-pure uranium-238, letting any finder date the message by measuring decay since the 1977 launch.
The isotope was chosen for its 4.5 billion-year half-life, which keeps the clock readable far longer than faster-decaying materials would; NASA lists its activity at just 0.00026 microcuries.
The cover also carries a pulsar map tied to 14 pulsars whose slowing spin rates offer a second, independent way to estimate when the record was made.
Together the two clocks make the message self-checking across interstellar timescales, even though the spacecraft were not aimed at any recipient and are unlikely to pass near another star for tens of thousands of years.
The often-cited roughly 1 billion-year lifespan refers to how long the gold-plated copper record may remain physically readable in space, while the uranium clock is designed to outlast that durability estimate.