Science Posted on Jun 5, 2019 in Astronomy

Recent research suggests that Venus might have looked like Earth for three billion years, with vast oceans that could have been friendly to life. “That’s what sets my imagination on fire,” says Darby Dyar, a planetary scientist at Mount Holyoke College with NASA’s Solar System Exploration team. “If that’s the case, there was plenty of time for evolution to kick into action.”

This led Dyar to suggest mean that Venus was the first habitable planet in the Solar System — “a place where life was just as likely to arise as it was on Earth.” reports Nature. That alone is a reason that the world’s space agencies from NASA to European Space Agency (ESA) and Russian space agency Roscosmos are planning missions to return to the former ocean world. The Indian Space Research Organization (ISRO) will be first to lift off when it launches an orbiter to Venus in 2023.

“Why are we investing so much time looking for life on Mars when it only had liquid water for 400 million years?” Dyar asks. “And then there’s Venus with three billion years of water and no one loves her.”

James Garvin, the chief scientist at NASA’s Goddard Space Flight Center, is convinced that whatever they find, whether is be that Venus was formerly an ocean world or that it’s tectonically active today, it will be “beyond our wildest dreams. We need to find out. Because she’s waiting to tell us something and I would hate to miss the boat.”

Momentum is building to explore Venus, in part because scientists say it could hold the secret to understanding what makes a planet habitable. “Venus is like Earth in so many ways,” observed Stephen Hawking. “A sort of kissing cousin. She’s almost the same size as Earth, a touch closer to the Sun. And, she has an atmosphere that could crush a submarine.” Venus today is a hellish abode where surface temperatures reach more than 400 °C and deadly clouds of sulfuric acid float through the sky.

“If researchers could decipher why conditions on Venus turned so deadly”, writes Shannon Hall in Nature, “that would help them to assess whether life might exist on some of the thousand-plus rocky worlds that astronomers are discovering throughout the Galaxy.”

So what went wrong with the once water-rich Eden? Although Earth and Venus began in a similar fashion” writes Hall. “The two have wandered down drastically different evolutionary paths — diverging perhaps as recently as 715 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.”

“Venus plays a key role in understanding ourselves here — how life evolved on our own planet,” says Adriana Ocampo, science program manager at NASA headquarters in Washington DC.

“There is growing realization within the exoplanet community that Venus is the best analogue in the Solar System for many of the rocky exoplanets we have found,” says Laura Schaefer, an astronomer at Stanford University in California who studies exoplanets.

“It might be the start of a new decade of Venus,” says Thomas Widemann, a planetary scientist at the Paris Observatory. Venus hosts rifts, mountains, continents and volcanoes, making it the most geologically Earth-like planet in the inner Solar System, writes via Twitter. “Not understanding why Venus did not make it and finished second, means we will never be sure why and when the Earth made it over its long-term evolution.”

With such a tantalizing question left unanswered, it’s easy to see why ISRO’s return to Venus has created so much excitement. “I’m thrilled that ISRO is doing this,” Dyar says. “I’m thrilled that the international community is taking note of Venus and proposing missions. That’s fantastic.”

Earlier Research –Flowing Rivers & Ice?

In the findings of a study conducted by the National Aeronautics and Space Administration (NASA) in 2002, it was suggested that Venus shared similar traits to the Earth and even had water around 4.5 billion years ago. However, as the planet increasingly warmed, more water vapor was in its atmosphere resulting to more heat being trapped which continued until its oceans completely evaporated.

Venus was created at about the same time as Earth, in about the same place, and it’s roughly the same size – it would therefore have started with the same materials as us, drawn together from the same region of the planet forming dust left over from the sun. But Venus now has only 0.001% of our water content, and a couple of flybys by the Venus Express may have revealed the reason.

In 2008, the probe discovered hydrogen and oxygen streaming off the night side of the planet in a 2:1 ratio, which you might recognize as the ratio in H20. It seems that what little water Venus has left is being blasted apart in the atmosphere by the solar wind, a vast stream of charged particles blown out by the sun. Venus Express has passed by the dayside and measured almost three hundred kilograms of hydrogen a day being lost into space. It hasn’t found any oxygen, but the search continues.

“Venus today has a thick atmosphere that contains very little water, but we think the planet started out with an ocean’s worth of water,” said John T. Clarke of Boston University.

Scientists are still trying to determine whether water existed on the surface of Venus or only high up the atmosphere, where temperatures were cooler. If the surface temperature stayed below the boiling point of water long enough, rivers might have once flowed on the planet. Venus may have even had ice.

The Daily Galaxy, Sam Cabot, via Nature.com, NASA and Goddard Space Flight Center

Image credit: NASA Venus through Time