15 December 1970: Venera 7 probe lands on Venus

The father of the Soviet space programme, Sergei Korolev, once wrote ‘the moon’s surface is hard’ on a napkin. This allowed work, which had stopped, on the landing gear of the Soviet lunar spacecraft to continue. In the end it was too late, and the United States beat the USSR to the moon.

The next race on the calendar was to Venus. And on this day in 1970, the Soviet Union won. The Venera (Russian for Venus) 7 spacecraft landed on the surface of Venus and transmitted a brief weak signal before its batteries ran out.

The Venera programme began in 1961. Officially, there were 16 numbered launches. In reality, there were more, but the Soviet Union only counted those that were relatively successful. The very first launch in February 1961, for example, failed to leave the earth’s orbit, so it was renamed and not publicly announced until much later.

However, Venera 7 was successful and was the first designed for a ‘soft’ landing on Venus. The journey took 120 days, and the probe arrived with all its equipment working. Soon after going into orbit, the craft released the lander and it began hurtling down to the surface.

At approximately 60km above ground, the parachute opened and allowed for atmospheric testing to begin. The first results were beamed back to earth and showed that 97% of the air on Venus was carbon dioxide.

Then disaster struck. Somewhere along the descent, the parachute failed and the lander hit the ground at 16.5 metres per second, much faster than anticipated.

Scientists guess that the spacecraft probably bounced off the surface and fell on its side. As a result, the main antenna was not aimed correctly to beam strong signals back to earth. It appeared lost. However, back on earth, the tapes that recorded transmissions from the lander kept rolling.

It wasn’t until a few weeks later that scientists began reviewing the tapes and discovered that about 23 minutes of very weak signals had been sent from Venera 7. The craft had managed to survive long enough to send one reading from the surface back to Earth – the surface temperature of Venus, which on 15 December 1970, was 475°C.

The Venera programme continued until 1984, providing invaluable information, including photographing and mapping the planet’s surface.