WHAT’S THE STORY?

IT was 50 years ago today that humans first knew for certain that we would not be going to live on Venus for the foreseeable future, if ever.

For it was on October 18, 1967, that the USSR’s Venera 4 spacecraft made it to Venus and descended through the planet’s atmosphere, transmitting back scientific data which showed that Venus was much hotter than previously thought, and its atmospheric pressures were far greater than predicted by astronomers and physicists. The planet was also shown to have lost most, if not all, of its water aeons ago.

Venera 4 may even have been the first spacecraft from Earth – who knows, there may have been others from elsewhere – to land on another planet, but we’ll never know as transmissions ceased when its lander was about 17 miles from the surface.

It was still a triumph for the Soviet space industry, and they had established a lead on researching Venus which they would keep for nearly 30 years.

THE COLD WAR IN SPACE?

AFTER the USSR launched Sputnik 1 in 1957, the USA had been behind in space exploration until 1962 when the Mariner series of spacecraft flew to Venus and Mars.

Mariner 2 did a “fly by” of Venus in 1962, becoming the first robotic probe to successfully survey another planet. Two years later Mariner 4 becoming the first mission to successfully send back pictures and data from the Red Planet.

The first images of the surface of another planet caused a sensation, and many scientists had to change their views about Mars.

Be in no doubt about it, this was a very competitive space race. The Soviet Union had tried and failed twice in 1960 to send a spacecraft to Mars before turning their attention to Venus, the closest planet to Earth that orbits the Sun at a minimum of 24 million miles from Earth and 67 millions miles from the Sun – the distance between Earth and Venus varies greatly due to their different orbits, but every 584 days the two planets are at their closest.

Throughout 1962, a series of launch failures meant no progress for the Soviets in their goal of reaching Venus and sending back useful data.

It was not until 1964 that their Zond spacecraft flew by Venus, but all communications were lost, as also happened with the Venera 2 and 3 probes.

On June 12, 1967, Venera 4 was launched from the Baikonur Cosmodrome, home of the Soviet Union’s space industry. As we shall see, it was a successful mission.

All that Venusian achievement by the USSR was forgotten, however, when Neil Armstrong took the first steps on the moon in 1969, the Americans having achieved President John F Kennedy’s target of putting a man on the moon before the end of the 1960s.

WHAT WAS VENERA 4 ALL ABOUT?

AFTER Venera 3 ceased all communications when nearing Venus, the Lavochkin Bureau, which designed Soviet spacecraft, decided to build a much stronger probe that could theoretically land on Venus and send back signals.

They gave Venera 4 a landing capsule – known as the lander – that had a heat-shield that could withstand temperatures of 19,800F, or 11,000C, while its parachute was designed to withstand temperatures of 450C. The only problem was that no-one knew the density of Venus’s atmosphere or what the pressure would be like on the planet’s surface. The lander was also designed to float in case it landed on a liquid, or perhaps even water – that’s how little we knew about Venus back then.

The main hub of Venera 4 contained a range of instruments which would measure such things as hydrogen and oxygen before releasing the landing capsule which contained instruments for measuring the atmosphere as it descended to the surface.

DID IT ALL GO TO PLAN?

ALMOST. The launch went well and a mid-course correction was spot on – the Soviet scientists knew they were dead on target. In the early hours of October 18, Venera 4 reached Venus and the main hub detached the lander before itself disintegrating on reaching the planet’s atmosphere.

Down went the lander for more than 90 minutes, sending back data from its measuring instruments. As the lander neared the surface, the temperatures and pressure soared to unexpected heights, and 17 miles above the surface, communications were lost. Did it land? Unlikely, but we’ll never know.

Venera 4’s descent findings, later confirmed by other Soviet and American probes, showed that Venus’s atmosphere consisted of 90 to 95 per cent carbon dioxide, water vapour was negligible, the surface temperature was probably 500C and pressure at the surface was 75 times greater than on the surface of the Earth. All of these results surprised scientists and proved one thing – our nearest neighbouring planet is not going to be colonised any time soon.