<http://schema.org/alternativeHeadline>
"Billions of years ago, Mars may have been rich in RNA, the molecules that used to pass traits on between generations before DNA took over that role."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/space/stories/meteorite-reveals-that-mars-had-key-component-to-life>