At a consistent $12,000 to $22,000 per kilogram, it’s not getting any cheaper to send satellites into space, so researchers are trying to figure out how to make them lighter. One extreme solution: hockey-puck-sized satellites. At defense research center Aerospace in El Segundo, CA, engineers are creating early prototypes in which propellant tanks, thruster nozzles, and other key components are laser-carved from a special type of glass. Other necessities such as metal valves, tiny microelectromechanical gyroscopes, guidance electronics, cameras, and other sensors are bonded to the structure. Led by aerospace scientists Siegfried Janson and Henry Halvajian, the team is testing the devices’ maneuverability on a platform similar to an air-hockey table; if the tests go well, the small satellites could ride into space on the sides of other, larger satellites within four years. Once in space, they would be deployed as needed to send back pictures of their host satellites’ condition. Eventually, Janson says, fleets of these satellites could replace some of today’s hefty sensing and communications satellites.