Hundreds of CubeSats have been
launched to Earth orbit since 2003. Now, though, two of the small-form-factor craft are
set for a deeper space mission. According to Spaceflight Now,
The twin CubeSat mission, known as Mars Cube One, will launch on an Atlas 5 rocket in March 2016 with NASA’s InSight lander. The CubeSats will relay status signals from InSight as the landing probe descends through the atmosphere, eliminating potential delays in verifying the success of the mission. ... Each Mars Cube One, or MarCO, CubeSat spacecraft measures 14.4 inches (36.6 centimeters) by 9.5 inches (24.3 centimeters) by 4.6 inches (11.8 centimeters) when closed up for launch, according to the Jet Propulsion Laboratory, which announced details of the mission Friday.
The standardized and small CubeSat has made satellite design and launching accessible to schools and others; going to Mars costs a lot more (in this case it's a "$13 million secondary mission"), but it could conceivably put interplanetary probes possible for deep-pocketed universities or corporations.