That could explain why interest in Venus dwindled. Scientists quickly realized that this planet would not be a home for future human exploration, nor an outlet on which to search for life. It would be downright difficult to study at all, even for short amounts of time. Recent research has even suggested that it might have looked like Earth for three billion years, with vast oceans that could have been friendly to life.
That could mean that Venus was somewhat surprisingly the first habitable planet in the Solar System — a place where life was just as likely to arise as it was on Earth.
That alone is a reason to return to the former ocean world. Although Earth and Venus began in a similar fashion, the two have wandered down drastically different evolutionary paths — diverging perhaps as recently as million years ago.
That might seem like a reason not to visit, but scientists now argue that it makes the planet even more intriguing. If researchers could only understand what caused Venus to undergo such a deadly metamorphosis, they might gain a better understanding of what caused Earth to become such a haven for life.
It is a crucial question now that astronomers have uncovered thousands of planets outside our Solar System — many of which are rocky worlds that orbit their stars at distances similar to those of Venus and Earth from the Sun. That means that many of these worlds could be Venus-like.
When ISRO announced the mission late last year, it published a list of a dozen instruments proposed by Indian scientists that have already been chosen — providing a sneak peek of the mission. But given that even basic information on Venus is lacking, any small step will contribute to science. Although those radar maps remain the foundation of Venusian geoscience today, they show topographic details at a horizontal resolution of just 10—20 kilometres per pixel, on average the image resolution can be two orders of magnitude higher.
That is particularly tantalizing, because many scientists think that tectonic activity is a crucial ingredient for life. Over millions of years, that process has kept Earth from growing too hot or cold by cycling heat-trapping carbon dioxide between the atmosphere and the deep Earth. It acts as a natural thermostat, which might mean that fidgety planets are more likely to host life. As such, scientists are eager to decipher the conditions that allow plate tectonics to arise.
Scientists agree that subduction is the first step in the path towards plate tectonics, and yet there are no clear signs of large moving plates on Venus — at least not in the decades-old maps produced by Magellan. But future maps might uncloak such tectonic features. Such a discovery would explain why Venus preserved an Earth-like environment for billions of years, Smrekar says — that natural thermostat would have kept CO 2 in check.
And it would explain how Venus turned hellish. When plate tectonics ceased, CO 2 levels would have increased in the atmosphere and trapped so much heat that the oceans vaporized.
But that is only one possible finding. A computer-generated view of the volcano Maat Mons on Venus with an exaggerated vertical scale shows dark lava flows in the foreground. There could be as many as five Venus missions including a balloon among the dozens of proposals to study various objects in space. Both Smrekar and Garvin are hopeful that each of their missions will be selected, in part because they proposed similar missions in the last Discovery competition, and both were chosen for further study, along with three others.
If one of the Venus missions is successful, it will launch in the mids. Mariner 2 revealed its blazing hot surface could never support life. While rovers on Mars have sent back lots of vivid panoramas showing the stark beauty of the red planet, images of the surface of Venus are hard to come by. The heat and intense pressure simply obliterate spacecraft. Still, some researchers have proposed that life might eke out an existence on Venus by residing up in its slightly-less-hostile yet highly acidic clouds.
Just last year, one group said it had detected signs of a gas known to be linked to life in the planet's hazy atmosphere. Its work showed that much of the planet was covered with volcanic flows.
But the volcanic history is controversial. Was resurfacing of the entire surface a rapid event, followed by little activity, or has it been more steady and more Earth-like? A discovery of geologically recent volcanism has reopened this debate and provided new insights into the sources of volcanism.
Several volcanic locations previously identified as hotspots areas where hot mantle plumes create volcanism, like Hawaii show signs of recent volcanism. Thanks to its dense atmosphere, it is even hotter than planet Mercury, which orbits closer to the Sun. This false-colour image was taken in ultraviolet light with the Venus Monitoring Camera on 23 July It shows a view of the southern hemisphere from equator right to the pole left from a distance of 35 km from the surface of the planet.
Scientists think that Venus once looked a lot like Earth, but underwent an irreversible climate change that is often used as an extreme example of what happens in a runaway greenhouse effect.
An atmosphere traps some of the outgoing energy, retaining heat — the so-called greenhouse effect.
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