London, Jan 14. In a new research, scientists have claimed to detect evidence for granite highlands on Venus in data almost two decades old, which suggests that the planet may have once been far more like Earth, with oceans and continents.
According to a report in Nature News, the data includes nighttime infrared emissions coming from the surface of Venus, which was detected by NASA’s Galileo spacecraft in 1990.
Analyzing these data, an international team led by planetary scientist George Hashimoto, now at Okayama University, Japan, found that Venus’s highland regions emitted less infrared radiation than its lowlands.
One interpretation of this lower infrared emission from the highlands, according to the authors, is that they are composed largely of ‘felsic’ rocks, particularly granite.
Granite, which on Earth is found in continental crust, requires water for its formation.
“This is the first direct evidence that early in the history of the Solar System, Venus was a habitable planet with plenty of water,” said Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman.
“The question is how long Venus remained habitable. But this gives new impetus for the search for microbial life in Venus’s lower atmosphere,” he added.
Before Galileo, researchers had believed that only radar could see through the dense clouds of sulphuric acid in Venus’s atmosphere to the surface, according to co-author Kevin Baines, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.
“Detecting the surface in the infrared is a breakthrough,” he said.
The possible presence of granite also suggests that tectonic plate movement and continent formation may have occurred on Venus, as well as recycling of water and carbon between the planet’s mantle and atmosphere.
According to geophysicist Norm Sleep of Stanford University in California, the implication of continent formation is “quite significant”.
Venus might have once been almost entirely underwater, although without further geochemical data, we don’t know whether this early ocean’s temperature was 30 degree Celsius or 150 degree Celsius, he added.
“Whether tepid or boiling, any ocean on Venus would have lasted only a few hundred million years. As the Sun became hotter and brighter, the planet experienced a runaway greenhouse effect,” Sleep explained.
Nowadays, the planet is a paragon of the uninhabitable, with an atmosphere of 96 percent carbon dioxide and a surface temperature of around 460 degrees C.
“Any life on Venus that hadn``t figured out how to colonize the cloud tops a billion years after the planet’s formation would have been in big trouble,” said Sleep.
ANI
