A silvery star shines in the morning or evening twilight far brighter than any other. It is actually the planet Venus, named for the goddess of love, but its twinkling light belies its real personality. Through a telescope Venus is nothing more than a featureless planet with dazzling white clouds. In spite of its innocent appearance, those clouds hide the most fearsome environs in the Solar System.
Before the Space Age it was wildly speculated that the thick clouds dumped heavy rains on Venus. With it being closer to the Sun than Earth, it was assumed that Venus was warmer and the surface might be covered with steamy swamps overgrown with lush vegetation thanks also to the high levels of carbon dioxide. It was even theorized that creatures similar to dinosaurs roamed Venus and that the poles were cool enough for snow! Another theory was that Venus was covered with oil, which would explain the high levels of carbon dioxide that had been detected from Earth. Still another theory pictured Venus as being totally covered with an ocean of seltzer and raging storms. A final theory had it nearly correct, that Venus was a scorching hot vast desert with huge dust storms. When Mariner 2 arrived in 1962, a true inferno was revealed with temperatures of at least 800ºF, killing the dreams of any ocean or dinosaurs.
Exploring Venus proved difficult. The Russians were determined to land on the surface and built spacecraft to withstand the heat, but were unaware of the tremendous atmospheric pressure at the surface. Spacecraft after spacecraft were crushed like eggs miles above the surface, but by 1970 Venera 7 made it to the surface, confirmed searing temperatures of nearly 900ºF and an air pressure of 90 times Earth’s! Venera 8 landed on Venus in 1972 and further confirmed the inferno conditions. The Russians succeeded again in October 1975 when it landed Veneras 9 & 10, both of which transmitted the first black and white pictures from the surface. The pictures revealed a vast, desolate, rocky desert where Venera 9 landed on the slopes of a volcanic mountain, and a flat, vast plain of plate-like rocks from Venera 10 in the lower plains. The weather conditions were as nasty as ever with temperatures around 870ºF and an atmospheric pressure of about 90 times Earth’s. All the landers confirmed the atmosphere was composed primarily of carbon dioxide laced with sulfuric acid mist with a very slight breeze at the surface. Lightning and thunder were also detected making the surface worse than any version of Hell! The Russians sent several more spacecraft, including Venera 13 & 14, which both transmitted the first color pictures from the surface. The scenery was bathed in an orange light due to the dense carbon dioxide atmosphere that effectively absorbs the blue component of sunlight and scatters the red. No lander lasted more than two hours on the surface.
The U.S. launched Pioneer Venus in 1978, a dual mission of atmospheric probe and orbiter. The orbiter coarsely mapped the surface with its radar until its demise in 1992. It revealed a mountain higher than Everest and mapped large volcanic mountain ranges and uplands that appeared like continents, along with canyons deeper than the Grand Canyon and vast rolling plains and lowlands. It also detected an unusually high concentration of sulfur dioxide in the atmosphere when it arrived in 1978 that steadily decreased and then stabilized. This hinted at volcanic activity since sulfur dioxide is a major volcanic emission, meaning that Venus may be volcanically active today!
Magellan mapped Venus from orbit from 1990-94 using more sensitive radar, which revealed volcanism beyond the wildest imagination; almost the entire planet was most likely volcanically resurfaced around 500 million years ago. Such beautiful landscape is immersed in an environment far too hostile for spacecraft exploration, let alone human, but scientists are planning to return with several missions equipped with spacecraft capable of withstanding Venus’ corrosive, pressurized inferno for months.
The European Space Agency’s (ESA) Venus Express is currently in orbit around Venus exploring the clouds and atmosphere and has made many discoveries including the confirmation of lightning. Japan launched Akatsuki on May 20, 2010, which will use a sounding device that will map the clouds and circulation along with detecting volcanic eruptions and thunder. It will also map the characteristics of the surface and heat flow as well as locate volcanic hot spots. There have been suspicious hot spots as high as 1300ºF that have been detected and need to be verified. The U.S. is planning a $3 to $4 billion flagship mission that may launch between 2020-25, which would include an orbiter, two balloons, and two long-duration landers capable of withstanding the ferocious heat for at least a month. One lander would land high in the mountains while the other would land in the lowlands. This would give a better idea of the weather at different locations and elevations. It would also give a better chance to sample different soils and observe different geology. Both landers would take high-resolution color panoramas of the landing sites and it is hoped that they will last long enough to detect possible Venusquakes. The balloons would drift in the clouds for several weeks and study the atmosphere while the orbiter would map the surface of Venus at a resolution twice that of Magellan.
Another mission being considered is the Surface and Atmosphere Geochemical Explorer (SAGE). This is a single, robust lander that will descend onto the flank of a suspected active volcano on Venus known as Mielikki Mons, about 200 miles across and 4,800 feet high. The lander will dig down about four inches into the surface and analyze the composition and texture of the soil. It will take spectral measurements of the rocks on the surface and then scrape off the top layer and take measurements underneath. The lander will carry descent and panoramic cameras. As the lander descends it will be able to sample a large region of the atmosphere at varying heights and photograph incredible views, much like flying in an airplane, and will include a full color, high resolution panoramic photo of the landing site once it lands. The lander will be built to survive the harsh surface environment for at least three hours. With a price tag under $1 billion, it has a better chance of being funded; launch should occur before 2018.
What would a journey to the surface be like if we were brave (suicidal?) enough to go? A vast sea of wind-whipped yellow-white clouds would sprawl out below us upon approach. As we fall into the clouds we would be buffeted by 200 mile per hour winds and temperatures as frigid as -40ºF. We would soon discover that the yellow tint in the clouds is due to a sulfuric acid mist. Lightning might flash and thunder boom as we plunge through the 35-mile deep triple cloud decks. When we emerge beneath them at about 30 miles above the surface, the temperature would soar to 200ºF with an atmospheric pressure five times Earth. The winds would still be howling at 100 miles per hour, but they would have no cooling power. Far below the scorched surface ripples in the heat and orange murk. As we continue to plunge, everything around us would be suffused in a sickly yellowish light and below 20 miles we would begin to see the ground quite clearly as the air would be clean and dry. We would see towering mountain ranges, gapping canyons, dune fields, and old rivers of hardened lava. At 12 miles above the surface it would be 600ºF with an air pressure 21 times Earth’s and the winds would calm to 30 miles per hour. The light would startlingly shift to a strong orange cast and it would feel like we were sinking through water instead of air. We would land at last and kick up a cloud of dust. The wind would be nearly calm at 3 miles per hour but the temperature would soar to 905ºF with the air pressure 94 times Earth’s. The rocks around us split in the intense heat and everything would be bathed in an eerie orange light. The Sun struggles to shine through the clouds and lightning flashes with thunder booming in the distance. Nighttime would be no cooler than daytime and it would be no cooler at the poles. The highest mountain peaks would be the coolest places where temperatures dip as low as 700ºF, but the deepest canyons and basins broil at nearly 1000ºF! Lead, tin, and zinc would melt and it would be so hot that much of the surface of Venus may glow a dull red at night!
As hostile as Venus is, it is important that we explore it as it may hold important clues as to how it became such an extreme inferno. The knowledge we gain from Venus will help us learn more about how Earth’s global warming works. Ultimately the exploration of Venus may aid in determining our fate and if Earth is also headed for an inferno of red glowing rocks.