Mason smashed the berries, added a water, detergent and salt mixture, and filtered the concoction through cheese cloth. He poured some isopropyl ethanol into the resulting red liquid and then watched as a white substance — the DNA — floated to the top.

“So that’s pure DNA. It looks a little bit like snot,” he told the students as they all yelled, “Eww!”

Mason then explained he would be using DNA, extracted from the blood and stool of identical twins, to study how space travel affects the human body.

Mason, a Case High School graduate who grew up in Racine, is one of 10 scientists recently selected by NASA to study astronaut twin brothers Scott and Mark Kelly. Scott Kelly will spend a year in zero gravity on the International Space

Station while Mark Kelly stays on Earth as an experimental control. Scientists will see if Scott Kelly’s body changes in any ways that Mark Kelly’s body does not.

Mark Kelly is the husband of former Arizona Congresswoman Gabrielle Giffords.

Mason, 35, of Brooklyn, N.Y., will look at the brothers’ DNA and RNA while others study any changes to their vision, cognition and more.

Their work will shed light on what happens to people during lengthy periods of time in space, something important now because “somewhere around the year 2030 they’re hoping to send people to Mars” and that will require six months of zero-gravity space travel, Mason said.

The students at Schulte, 8515 Westminster Drive, were especially interested in travel to Mars. Mason asked how many of them would like to live on the red planet someday and nearly every hand shot up.

Mason, a geneticist and assistant professor in the Department of Physiology and Biophysics at Cornell University’s medical college, spent about an hour and a half talking with the students.