The closest planet to the Earth, Venus, has been in the news recently with the discovery of phosphine gas in its atmosphere. An international team of astronomers has presented evidence that the cloud tops of Venus contain traces of phosphine, a toxic gas that is produced by microbial life here on Earth. No currently known non-biological processes can create phosphine in the conditions found on Venus. The researchers are not claiming that they have found life in the clouds of Venus, but the results are certainly intriguing and will be investigated further.
While about the same size as Earth, Venus is different in almost every other way. The carbon dioxide atmosphere is nearly a hundred times thicker than Earth’s and the surface temperature is 900 degrees Fahrenheit, hot enough to melt lead. A day on Venus is longer than its year. It only takes Venus 225 days to complete one orbit around the sun, but a Venusian day is 243 Earth days.
The last major NASA mission dedicated to exploring Venus was launched in 1989. The mission was named Magellan, for Portuguese explorer Ferdinand Magellan who organized a Spanish expedition to the East Indies from 1519 to 1522, resulting in the first circumnavigation of the Earth.
The Shuttle Atlantis launched from Kennedy Space Center on May 4, 1989 on mission STS-30. Atlantis would carry the Magellan Venus Probe to low Earth orbit where it would be deployed from the shuttle’s cargo bay. A booster attached to the probe known as the Inertial Upper Stage was fired after deployment and would send the Magellan on its long journey to Venus. The probe would arrive in orbit on August 10, 1990.
Magellan was designed as a radar mapping mission to unveil the surface of the cloudy planet. Since the thick clouds of the carbon dioxide atmosphere hide the surface from view, Synthetic Aperture Radar would be used to reveal the surface in unprecedented detail. The mission lasted until Oct. 13, 1994 and was a huge success for NASA.
Magellan revolutionized our understanding of Venus, returning high-quality radar images of the Venusian terrain that showed evidence of volcanism, tectonic movement, turbulent surface winds, miles of lava channels, and pancake-shaped domes. Magellan also found that at least 85 percent of the Venusian surface is covered with volcanic flows. The lack of water makes erosion an extremely slow process on the planet, so surface features can persist for hundreds of millions of years.
With the renewed interest in Venus, several new missions have recently been proposed by NASA. With many mysteries left to explore, investigations of our nearest planet are sure to continue.