About Simplesat
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
