Mohawk Valley Astronomical Society

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The Inferno Below

by Perry Pezzolanella

Venus is the closest planet to Earth coming at times within 25 million miles, but it remains poorly understood. Even with the dawn of the Space Age over sixty years ago it still has many well-kept secrets. Part of the problem is that it is completely and perpetually cloudy making it impossible to visually see the actual surface. The other problem is the intensely hostile atmosphere where surface temperatures approach 900ºF, atmospheric pressure exceeds 90 times Earth, and the carbon dioxide atmosphere is laced with sulfuric acid. This makes it impossible for a spacecraft to last more than a few hours on the surface.

Before the Space Age, the cloudy veil fed wild theories as to what the surface of Venus might be like. Because it was closer to the Sun than Earth and covered in thick clouds, it was thought that these clouds were loaded with water. Torrential downpours drenched steamy tropical jungles covered in huge, lush vegetation with prehistoric-like creatures roaming about. Venus was a planet teaming with life; however, scientists were soon able to analyze the sunlight reflected off of the clouds and found no water, but instead about 3% carbon dioxide, or about 100 times Earth’s. With that much carbon dioxide and being closer to the Sun, Venus was thought to be covered in a global ocean of steamy seltzer. Further analysis raised the surface temperature to as high as 200ºF so it was thought that Venus was a vast, scorching desert with sand dunes and dust storms with no chance for life. This would turn out mostly correct, but it was not until the Space Age that it was finally revealed that Venus was even more hostile than could ever be imagined.

Mariner 2 became the first spacecraft to successfully fly past a planet back in 1962 when it flew past Venus. It was a brief encounter, but revealed a world where the surface temperature sizzled at 800ºF. Gone forever were the dreams of a lush, prehistoric planet teaming with life. The Soviet Union was determined to land a probe on Venus. It designed a probe that could withstand the intense heat but failed to realize the intense atmospheric pressure; thus, several of its early probes were crushed like eggs far above the surface. Venera 7 was built with brute force to withstand 900ºF heat and pressure 100 times Earth; it became the first spacecraft to land on another planet on December 15, 1970. It confirmed the intense heat at 887ºF and an atmospheric pressure 90 times Earth. It did not carry a camera but did prove that the surface was hard so it was most likely a rocky, dusty desert. The Soviet Union then designed tougher probes that would last at least an hour on the surface and carry cameras that would image its surroundings. Because of the thick clouds, it was thought that the sunlight would be dim, therefore early probes were equipped with spotlights. The probes would also carry instruments to analyze the surface and atmospheric composition.

Venera 9 was a true accomplishment of Soviet engineering when it successfully landed on Venus on October 22, 1975 and became the first spacecraft to photograph the surface of another planet, plus it survived for 53 minutes in the sizzling 905ºF heat and 90 times Earth’s atmospheric pressure, the worst conditions for any spacecraft to this day! It landed on the flanks of Beta Regio, a possible active volcano. The images showed a boulder-strewn landscape with little erosion while the rocks revealed some shadows, which meant the Sun might be faintly visible through the clouds at times. The winds were slight at 3-4 mph but still forceful in the dense air. The rocks were determined to be basalt and granite, proving their volcanic origin, and the atmosphere was composed of 96.5% carbon dioxide. Venera 10 successfully landed three days later on a smoother, volcanic plain further confirming the hostile conditions.

The Soviet Union’s Venera 11 and 12 landed during Christmas 1978, but returned no images because the lens caps failed to jettison probably due to the intense air pressure. Both detected thunder that was disputed through the years. NASA also sent several probes plunging into the atmosphere with hard landings; one managed to survive on the surface for 67 minutes but was not capable of imaging. NASA also placed a spacecraft into orbit known as the Pioneer Venus Orbiter that crudely mapped the surface. It detected possible lightning clustered around several of the highest peaks giving suspicion that Venus was volcanically active. It may have detected a huge volcanic eruption as the amount of sulfur dioxide in the atmosphere spiked in the late 1970s and steadily declined back to its original levels. This gas is a main emission of volcanoes and remains the smoking gun that Venus is volcanically active today.

The Soviet Union successfully landed Venera 13 and 14 in March 1982 to return the first full color panoramas of the Venus landscape showing it bathed in eerie orange sunlight due to the thick atmosphere, and orbited Venera 15 and 16 in 1983-84 that mapped the surface with radar from orbit. Vega 1 and 2 followed in 1985 with each placing a lander on the night side and each deploying a balloon that explored the clouds for up to 44 hours. NASA placed Magellan into orbit around Venus in August 1990, which successfully mapped 98% of Venus using radar during its four-year mission before burning up in the atmosphere in October 1994 after running out of fuel. It revealed a planet shaped by massive volcanic eruptions possibly only 500 million year ago as nearly the entire surface has been repaved. Lava had flowed down mountains, through valleys, breached hills, flooded pains and solidified creating a young landscape. Volcanoes were creating the landscape, but destroying the atmosphere.

Venus Express, built by the European Space Agency (ESA), orbited Venus from 2006-2014. It detected hot spots up to 1300ºF that then cooled, as well as a huge increase in sulfur dioxide in the atmosphere, which then settled back down to normal, further adding proof that Venus is volcanically active today. It also detected lightning on the turbulent late-afternoon side, and a polar vortex over both poles. Venus Express determined that Venus most likely had shallow seas that boiled away as the Sun grew brighter and hotter, and that the volcanic eruptions added vast amounts of carbon dioxide into the atmosphere triggering a runaway greenhouse effect. Venus may have once been Earthlike and possibly had life, but died, thanks to its volcanoes.

Japan finally placed Akatsuki into orbit around Venus in December 2015 after failing to do so in December 2010 due to engine failure. Its main goal is to study the deep atmosphere of Venus, especially in infrared. It can observe the night side of Venus with an infrared imager. The fierce 900º surface glows brightly in the infrared and backlights the clouds revealing fine detail that cannot be readily seen in visible light. The brighter areas are the hotter areas from deeper down, meaning thinner clouds to block the heat. The thicker clouds appear darker as they block more of the heat from being seen from below in infrared. This kind of imaging is clever as the night side glows like a lit light bulb that has been painted randomly with streaks. Fine detail such as eddies, wind shear, and turbulence are revealed at varying levels. Akatsuki is revealing a new Venus that is in dire need of further exploration.

Venus will continue to compete with Mars, Europa, Titan, and Enceladus for future missions, but it is crucial to our understanding of Earth as it is nearly the same size and composition. Venus is often thought of as Earth gone wrong, but Earth may be turning into another Venus. Is Earth the oddball in the universe, or is it Venus? It is time to return to Venus to help answer these questions once and for all.