Castor and Pollux, two satellites in the Atmospheric Neutral Density Experiment (ANDE-2) program are ready to fly with the launch of STS-127 from Kennedy Space Center. The ANDE mission consists of two spherical spacecraft fitted with retro-reflectors for satellite laser ranging (SLR). The constant and well-determined cross section and surface properties of the ANDE spacecraft provide an ideal set of objects for monitoring atmospheric drag and the calibration of space surveillance network (SSN) assets both radar and optical.
Castor
Castor is a 19 inch diameter aluminum sphere with a mass of 63 kg. It is as near perfect sphere as possible given the constraints of cost and manufacturability. The sphere is split in half with e delrin disc. The hemispheres are also the satellite antenna. For power, the satellite has 112 19AH lithium primary cells. This provides about 7000 watt-hours of power which has to last for the one year mission.
The satellite has several different types of sensors. There are two main sensors, a Neutral particle wind and temperature spectrometer and an ion mass spectrometer. A group of college students designed and built a MEMS sensor payload to test some commercial gyroscopes and a magnetometer. There are also six light sensors and six temperature sensors mounted in the satellite hemispheres.
Pollux
The Pollux satellite was originally to be a passive satellite with retroreflectors for laser ranging. It has been turned into a high school student project involving several schools in the Fairfax County, Virginia area. The satellite is powered by twenty-eight 19AH Lithium-ion cells configured to provide 14 volts. The battery configuration uses the spare ANDE satellite hardware. The electronics is based on cubesat hardware developed at the Naval Research Laboratory and Stensat Group LLC. The communications board contains the transmitter and receiver. The transmitter operates at 2 meters and can put out up to 1 watt of signal. Power level is adjustable. The transmitter can operate at 1200 baud AFSK and 9600 baud FSK. The transmitter uses the AX.25 protocol. An experimental FX.25 protocol will be tested that adds forward error correction capability to the AX.25 protocol and still allows typical TNCs to decode the packets.
Both satellites will transmit on 145.825 MHz.
Additional details about the telemetry format, as well as the AX.25 and GMSK experiments can be found at https://goby.nrl.navy.mil/ANDE/Main.html
Thanks Ivan, KD4HBO