The Download: ice-melting robots, and genetically modified trees

At long last, NASA's Europa Clipper mission is on its way. It launched on October 14 and is now en route to its target: Jupiter's ice-covered moon Europa, whose frozen shell almost certainly conceals a warm saltwater ocean. When the spacecraft gets there, it will conduct dozens of close flybys in order to determine what that ocean is like and, crucially, where it might be hospitable to life. Europa Clipper is still years away from its destination--it is not slated to reach the Jupiter system until 2030. But that hasn't stopped engineers and scientists from working on what would come next if the results are promising: a mission capable of finding evidence of life itself. Living as long as a thousand years, the American chestnut tree once dominated parts of the Eastern forest canopy, with many Native American nations relying on them for food.