The quest for alien life has been boosted by a major discovery about exoplanets.
Scientists say that “water worlds,” or exoplanets that contain lots of water, are actually very common.
A team of experts has been digging into data obtained by the Kepler space telescope, as recently revealed at the Goldschmidt conference in Boston.
Kepler has discovered more than 4,000 exoplanets so far, some of which could support alien life.
And it turns out that around 35 percent of the planets that are bigger than Earth are “likely” to have water.
Even more excitingly, some are believed to have as much as 50 percent water — far more than Earth’s 0.02 percent water-weight.
Water is very important in the search for aliens. It has many features that make it ideal for supporting life — even in outer space.
Its strong hydrogen bonds encourage compounds to come together and it can transport electrons — which is important for producing energy.
The search for water in space is difficult because examining the composition of planets isn’t easy given their distance from Earth.
That’s why scientists have struggled, until now, to work out how many “water worlds” actually exist.
“It was a huge surprise to realize that there must be so many water worlds,” said Harvard University’s Dr. Li Zheng.
Using information from NASA’s Kepler and the European Space Agency’s Gaia satellite, scientists were able to make predictions about the composition of exoplanets.
“We have looked at how mass relates to the radius and developed a model which might explain the relationship,” Zheng explained.
It emerged that exoplanets with a radius around 1.5 times bigger than Earth and with a mass roughly five times that of Earth tended to be rocky.
And exoplanets with a 2.5-times radius of Earth and a mass 10 times bigger than Earth are probably “water worlds.”
They were then able to apply these findings to Kepler’s huge roster of exoplanets, predicting that many would feature significant amounts of water.
“This is water, but not as commonly found here on Earth,” revealed Zheng. “Their surface temperature is expected to be in the 200- to 500-degree Celcius (392 to 932 degrees Fahrenheit) range.”
“Their surface may be shrouded in a water vapor-dominated atmosphere, with a liquid layer underneath.”
“Moving deeper, one would expect to find this water transforms into high-pressure ices before we reach the solid rocky core. The beauty of the model is that it explains just how composition relates to the known facts about these planets.”
Zheng said around 35 percent of “all known exoplanets which are bigger than Earth should be water-rich.”
Importantly, this is only the beginning of the quest for more “water worlds.”
NASA recently launched a new satellite called TESS, designed to survey the sky.
It’s part of NASA’s search for exoplanets and is expected to discover huge numbers of planets we never knew existed.
It works by spotting planets as they “transit,” moving in front of their host stars — like Earth, to the sun — blocking out light.
TESS, which launched in April, will survey 200,000 of the brightest stars to find these transiting planets.
“TESS scientists expect the mission will catalog thousands of planet candidates and vastly increase the current number of known exoplanets,” explained NASA.
“Of these, approximately 300 are expected to be Earth-sized and super-Earth-sized exoplanets, which are worlds no larger than twice the size of Earth.”
Using powerful cameras, the spacecraft will “stare” at each sector for at least 27 days, looking at the brightest stars.
“This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances,” NASA wrote.
“No ground-based survey can achieve this feat.”
Speaking about the new “water worlds” discovery, MIT’s Professor Sara Seager, who helps lead the TESS mission, said: “It’s amazing to think that the enigmatic intermediate-size exoplanets could be water worlds with vast amounts of water.”
“Hopefully atmosphere observations in the future — of thick steam atmospheres — can support or refute the new findings.”
Source: Read Full Article