Simplesat is an Optical Microsatellite Experiment with David Skillman as the PI. Objectives Design a low-cost satellite with modest capabilities Construct such a satellite and pass all STS safety reviews Launch and Operate to evaluate on-orbit performance Accomplish all the above (sans launch) without infrastructure Design, construct, and operate using DDF funding levels Demonstration flight for : College/university constructed spacecraft Aircraft/sounding rocket alternative Potential RTOP/Incubator "missions" Mission cost: $200k + 5 work-years Installed on STS-105 (Launched August 10, 2001) Five month orbital lifetime Satellite Characteristics Mass: 52 kg Size: 66 cm tall, 50 cm diameter Telescope: 30 cm diameter optics, commercial CCD camera detector Power: 10 watts orbit-average from solar cells mounted on body 14 amp-hr NiCd battery Attitude: Three-axis stabilized, inertial pointing Attitude, position, time sensor: Four channel GPS receiver Pointing Control: via three reaction wheels 1 degree via GPS, 1 arcsec via star images from camera Momentum control: Torque coils Computer: commercial single board computers Communications: 4800 baud to GSFC via ham radio equipment Satellite Information Downlink Radio Frequency: 400.965 MHz Uplink Radio Frequency: 402.6 MHz Downlink only over Goddard Space Flight Center (no beacon) Unusual Characteristics: no gyros no earth sensors no sun sensors no star-trackers no magnetometer no optical cover no detector cooling Initial rate damping with hysteresis rods reaction wheels driven by stepper motors commercial CPUs (Octagon) commercial NiCd batteries (Sanyo) commercial telescope optics (Meade 12") commercial CCD camera (Apogee) modified commercial aircraft GPS unit (Trimble TANS-Vector) all image data reduction done onboard flight software written in Basic 130 temperature sensors on only two wires (DS1820) electronics cards wire-wrapped