NASA lost contact with two mini Mars spacecraft and they don't know exactly why

NASA's Mars InSight mission is moving along nicely, with the robotic lander preparing for many months of research that will tell scientists more about the interior of the planet than ever. Unfortunately, two of the machines that helped NASA track InSight's perfect landing now refuse to answer calls from the space agency, and nobody knows exactly why. The success of the MarCO mini satellites -- named WALL-E and EVE in honor of the futuristic Pixar flick (which isn't as good as A Bug's Life) -- wa...