9. Toasty Summer Mornings on the Surface of Venus

Morsel:

Venus's surface has temperatures that are hot enough to melt lead.

Meal:

Venus is the second planet from the Sun and one of the brightest sights in the night sky, second only to the Moon. It is similar to Earth in many aspects, earning it the moniker of Earth's “sister planet”, but it is not one would consider a planet suitable for life, as science fiction writers used to describe it.

Looking from space, the surface of Venus is covered in a rather boring, pale beige blanket of thick sulphuric clouds (as seen below), which has none of the striking and memorable features found in the other planets. Underneath the top cloud cover is an atmosphere extremely rich in carbon dioxide. This greenhouse gas has created a stark warning of the runaway effects of such greenhouse warming: the majority of the sunlight that hits Venus is bounced back into space by its reflective blanket, but the sunlight that does pierce the cloud cover is trapped by the carbon dioxide. This results in constant inhospitable surface temperatures of around 467°C. By comparison, that is hot enough to reach the melting point of various metals such as, tin (232°C), lead (327.5°C), and zinc (419.5°C).

The true colour of Venus's upper atmosphere.
Credit: NASA / JHUAPL / CIW / colour composite by Gordan Ugarkovic

A probe seeking to reach the surface must plunge through the 25 kilometre thick atmosphere and withstand being drenched in an acidic rain called virgra, which evaporates before it reaches the surface, or metallic mist, which can settle as shiny snow in the cooler, higher elevations. Once landing safely, this adventurous probe must survive a crushing atmospheric pressure of about 90-100 times that of Earth – equivalent to being underneath one kilometre of water on Earth. The scorching temperatures must also be endured, but if the probe drops through the atmosphere of one of Venus's poles, it must deal with the opposite extreme: average temperatures of -157°C.

Of the many probes sent to Venus by the USA and USSR, very few touched down on its surface. The first successful probe to land on Venus – indeed, on any foreign world – was the Soviet spacecraft Venera 7. Its descent was unfortunately not ideal and the lander is believed to have landed on its side, preventing it from being able to effectively transmit data. Even so, it relayed its instruments' findings for 23 minutes before succumbing to the hostile environment. Its successor, the Venera 9, also became a record setter, taking the first pictures on the surface of an alien planet, and its later sibling, Venera 13, gave us the first colour images. The Russian and American space agencies are currently collaborating on a further landing mission to Venus, named Venera-D, that will hopefully lift-off some time in the late 2020s.

Surface of Venus as captured by Venera 13.
Credit: NASA. Courtesy of Space.com.

While it is clear that probably nothing could survive on Venus's hellish surface, it could be possible that microbes exist in the more bearable higher altitudes. Venera-D may seek to investigate this. Organisms may even fly amongst the sulphuric clouds, which contain a little water and are a more permanent constant feature in Venus's skies than Earth's ephemeral wisps. Even if our sister planet is truly inhospitable, there could be traces of life hidden underneath its surface. Venus is believed to have had oceans of water at one time, which, if long-lasting enough, could have harboured life. A period of particularly violent volcanic action relaid Venus's surface, potentially burying many of these ancient organisms. But not everywhere: the rugged highlands of Venus escaped this resurfacing and could hold potential evidence of life having existed on other worlds.

Recipe:

Anon. 2001. “Blazing Venus.” NASA. Retrieved December 9, 2017.

Bortman, Henry. 2004. “Was Venus Alive? ‘The Signs Are Probably There.’” Space.com, August 26.

Anon. n.d. “Melting Point of Common Metals, Alloys, & Other Materials.” American Elements. Retrieved December 10, 2017.

Rincon, Paul. 2005. “Planet Venus: Earth’s ‘Evil Twin.’” BBC News, November 7.

Anon. 2016. “Venus Express’ Swansong Experiment Sheds Light on Venus’ Polar Atmosphere.” ESA, April 19.

Anon. n.d. “Venera 7.” NASA. Retrieved December 10, 2017.

Howell, Elizabeth. 2012. “Venera 13: First Color Pictures From Venus.” Space.com, November 19.

Clark, Stephen. 2015. “U.S.-Russian Talks on Venus Mission Resume.” Spaceflight Now, November 12.

Wall, Mike. 2017. “Russia, US Mulling Joint Mission to Venus.” Space.com, January 17.