When Thomas Romney Robinson, director of the Armagh Observatory, invented the cup anemometer in 1846, little did he know that one day his invention would be recording the alien breeze on the surface of another world.

Fast forward 130 years: On 20 October 1975, a small capsule detached from the Soviet Venera 9 spacecraft headed for Venus. After drifting silently through space for two days, the capsule fell through Venus’s atmosphere and landed on the surface where it survived for 53 min, not a small feat given the inhospitable conditions at the planet “next door”.

Left: The Robinson cup anemometer at the top of Armagh Observatory. Right: The Venera 9 lander, complete with cup anemometer (circled).

On board the probe was the ISV-75 anemometer, a space-age variant of Robinson’s original cup design, built to withstand the scorching temperatures and crushing pressures found at Venus’s surface. Anemometer data beamed back to Earth from the lander were the first ever wind measurements from the surface of another planet. They showed a very gentle breeze blowing across the landing site, only a few feet per second. This was not entirely unexpected because the incredibly dense Venusian air moves sluggishly, as sea currents might do. 

Although there are many modern methods to measure wind speed and direction, the cup anemometer design is noted for its simplicity and robustness. This is probably why it was chosen for such a challenging mission, carrying T. R. Robinson’s legacy across the solar system.


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