Small and economical "cubesats" already eye our planet from orbit. But such bantam craft are about to start pushing out into deep space, helping researchers study and explore the moon, asteroids and other distant bodies.

Cubesats are an exciting new tool that "will enable some new kinds of measurements to be made and, in some cases, whole new missions to be done," said Robert Staehle, of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, who led a 2013 study investigating the feasibility and potential of interplanetary cubesats.

The basic building block of cubesats is a cube measuring 4 inches (10 centimeters) on each side. Satellites that consist of just a single such block are known as 1U (short for "one unit") cubesats; those that combine two or three of them are 2U and 3U, respectively.