Today's Top Space Headline: The Milky Way Appears to be Swarming With Venus-Like Exoplanets --"May Hold the Secret of Earth's Fate"
Without figuring out why Venus and Earth evolved differently, we have no hope of predicting all the beautifully bizarre planets that will no doubt be discovered. We may also learn something about the fate of our own planet. That is why NASA needs to green-light a robotic mission to Venus.
Traditional conceptions of the so-called habitable zone for terrestrial bodies assume that within our solar system, only Earth is in the sweet spot for life to form and survive. But that presumption overlooks the temporal variation of habitability: Both Venus and Mars likely had liquid water as far back as 3.6 billion years ago. In fact, exoplanets may even be more Venus-like than Earth-like. Recent research suggests that the number of exo-Venuses is comparable to, or even exceeds, the number of exo-Earths.
There is growing recognition of the importance of understanding Venus, which has long been known as Earth’s twin. Learning the story of the twin planets—how one ended up hot and dry and the other comfortably warm and wet—would illuminate what makes or breaks a planet’s habitability. As a planetary dynamics laboratory, Venus offers a glimpse of what happens in an extreme greenhouse atmosphere. It also informs our understanding of the evolution of rocky planets.
Although Venus is shrouded in thick clouds, windows in the carbon dioxide spectrum allow mapping of the surface from orbit, with up to six different wavelengths proposed for future missions. High emissivity has been interpreted as evidence for recent volcanism.
Mariner 2 became the first spacecraft to visit another planet in 1962 when it observed Venus’s carbon dioxide atmosphere and high surface temperature and pressure. During the space race of the 1960s and 1970s, the US and the Soviet Union launched dozens of spacecraft to Venus, and the Soviets accomplished the impressive task of landing and acquiring data on the surface multiple times. The US sent several orbiters and probes to Venus, culminating in the launch of the Magellan mission in 1989, which provided topography, radar imaging, and gravity data. Venus was then abandoned until the European Space Agency sent Venus Express in 2005, followed by Japan’s Akatsuki in 2010.
As space agencies have spurned Earth’s twin, scientists have posed more and more compelling science questions that can be addressed only by studying Venus up close.
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