Space agencies from around the world including NASA, the Russians and even the Europeans are planning trips to Venus that could provide valuable insight into the universe and perhaps even give scientists clues about how life originally formed right here on Earth.
Venus holds a special place in the sun's family of planets as it is the most inhospitable world in the solar system. On the surface, temperatures soar to a whopping 460 degrees Celcius which can melt lead and burn a human to death in seconds. That's if the weight of the world's gravity didn't crush you to death with an atmosphere that is 92 times denser than the Earth. If being crushed and burned wasn't enough, you would suffocate very quickly in the toxic sulphuric acid atmosphere that cloak the planet.
"Venus and Earth are, superficially, the two most similar planets in the solar system," says Colin Wilson, of Oxford University. "They are almost exactly the same size while their orbits both lie in a relatively warm habitable zone round the sun. Yet one of these worlds is balmy and pleasant while the other has turned out to be utterly inhospitable. The question is: why?"
Right now scientists do not have those answers. Why good planets go bad such as Venus still remains a mystery and this lack of knowledge great impacts our ability to find habitable exoplanets elsewhere in the galaxy.
"We may be able to use powerful space telescopes to detect an exoplanet in a promising orbit round a star but that may not be enough to say it is habitable," says Richard Ghail, of Imperial College London. "It could turn out that the planet that we are looking at is another Venus, a world hostile to life even if it is in a promising location. So we need to know what factors favored Earth and what ones doomed Venus if we are to have hope of finding other planets that could support life."
This mystery has led to a plethora of proposed missions to the planet in an effort to learn everything we can about the planet. One of the missions currently led by Ghail would place a probe in orbit around Venus and allow scientists to peer through the dense clouds that shroud it in mystery. NASA and other groups also have plans for trips to Venus. One such plan known as Raven would take advantage of improvements in SAR technology first used in the Magellan spacecraft to map the surface.
While Venus lives in the Goldilocks zone of the solar system where conditions are right for planets to support life, astronomers can only theorize about the why its environment is so toxic. One theory is that the complete lack of water on the planet led to the atmosphere found there today.
"The atmosphere on early Earth was made of water vapour and carbon dioxide," says Wilson. "Various processes, including the appearances of living organisms, led to a decrease in carbon dioxide and an increase in oxygen. That never happened on Venus though we suspect its early atmosphere was also made of water vapor and carbon dioxide. Its proximity to the sun made it that little bit hotter and its water may have then been driven off into space leaving only carbon dioxide which, of course, is a potent greenhouse gas. Hence the heat there."
The parameters that make Earth the perfect home for life may actually be tighter than scientists originally believed. Venus, Earth and Mars all live in what scientists call the goldilocks zone of our solar system, but Venus is toxic and Mars is lifeless, meaning scientists need to tighten the area in which they believe life could exist. "All three were thought to lie with the sun's habitable zone," says Wilson. "But we now know Venus is uninhabitable and that Mars looks lifeless. So it may be we will have seriously to tighten up our idea of what is a habitable zone around a star."
