Ancient Near-Collisions May Have Cracked Open Icy Moons

Long-ago close encounters with planetary building blocks may have cracked open the surfaces of icy moons in the outer solar system — and could perhaps even have created the gigantic Martian canyon system Valles Marineris, a new study suggests. Icy moons display "brittle elastic behavior," making them similar in certain ways to Silly Putty, said study lead author Alice Quillen, of the University of Rochester in New York.