"In addition to the primary ISS construction mission, STS-127 is carrying two 19-inch spherical satellites scheduled for deployment on Mission Day 16. The two spheres, Castor and Pollux http://eludium.stensat.org.nyud.net/ANDE/Main.html, are part of the Atmospheric Neutral Density Experiment (ANDE) that studies atmospheric perturbations in the LEO environment. Castor http://eludium.stensat.org.nyud.net/ANDE/Castor.html contains an ARM processor, while Pollux is running an Atmel ATMega CPU. Pollux http://eludium.stensat.org.nyud.net/ANDE/Pollux.html also contains student payloads developed with Arduino on Atmel AVRs. Both satellites transmit telemetry using the FX.25 FEC format http://www.stensat.org.nyud.net/Docs/Docs.htm developed by the Stensat guys http://www.stensat.org.nyud.net/satellites.htm. Many components are commercial-grade, purchased from Digikey. This is the second ANDE mission, following the successful deployment of MAA and FCal http://www.usna.edu.nyud.net/Users/aero/bruninga/fcal.html on STS-116 (both also flying commercial components.)"