ECOSat-II

ECOSat-II was developed entirely at the University of Victoria for the second round of the Canadian Satellite Design Challenge. It took first place in the competition.

The project provides undergraduate and graduate students with hands-on experience developing a satellite from the ground up. Every system on ECOSat-II has been designed from scratch by students, from the onboard computer to the payload to the communications system.

Mission

ECOSat-II flies a scientific payload, an amateur radio payload, and two flight demonstrations for attitude and orbit control.

  • Mission A explores the properties of optically excited pyrolytic graphite.
  • Mission B operates as an amateur radio repeater.
  • Mission C is a proof of concept attitude determination and control system which uses the earth’s magnetic field for both attitude determination and control.
  • Mission D is a proof of concept deorbit system using magnetorquers.

Mission A: Optically Excited Pyrolytic Graphite

Experiment 1

Pyrolytic graphite is the strongest known room temperature diamagnetic material. A research team in Japan has recently discovered that the diamagnetic properties of pyrolytic graphite change when excited with light (see video to the right).

ECOSat-II will mount a sheet of pyrolytic graphite with 200mW semiconductor lasers pointed at the corners. By exciting the corners of the graphite sheet, we theorize that the unbalanced repulsive force against the earth’s magnetic field will result in a moment. The roll rate change induced by this moment will be measured with the satellite’s IMU to determine the magnitude of this effect and examine the feasibility of using diamagnetic materials for spacecraft attitude control.

Experiment 2

The secondary experiment examines the radiation shielding properties of pyrolytic graphite, which is already known to be an effective neutron moderator. Two semiconductor radiation detectors will operate continuously. One will be exposed to space, the other encapsulated in 2mm of pyrolytic graphite. The total dose measured by each detector will be compared to evaluate the feasibility of using pyrolytic graphite for lightweight radiation shielding on nanosatellites.

 

Mission B: Orbiting Satellite Carrying Amateur Radio (OSCAR)

ECOSat’s communications system is a highly flexible software defined radio platform developed in-house at the University of Victoria. This allows the satellite to operate as an amateur radio relay satellite in addition to a scientific satellite.

ECOSat-II’s communications system operates with a 70cm band uplink and a 2m band downlink (mode U/V). The uplink noise figure is 3 dB and the downlink transmitter power is 2W. Uplink and downlink both use a 192 kS/s quadrature baseband rate at 16 bits per sample, providing excellent dynamic range. This dynamic range allows multiple amateur radio services to operate simultaneously off of one communications system.

Planned amateur radio services are:

  • Narrowband FM repeater
  • Linear transponder
  • 12 kBit/sec packet-switched digital mode shared with experiment data (pi/4 QPSK with soft-decision R=1/2 K=7 convolutional code).

With a combination of high transmit power, good sensitivity, and multiple services, we believe that ECOSat-II will be an extremely valuable addition to the amateur radio satellites currently on-orbit.

 

Mission C: Magnetorquer ACS

As part of the full-build, ground-up strategy, UVic developed an attitude control system from scratch. The ACS uses magnetorquers exclusively for attitude control. ECOSat-II will test the system on-orbit.

Mission D: Magnetorquer De-Orbit

The goal of this mission is to use magnetorquers in reverse to remove energy from the orbit of the satellite in order to accelerate de-orbiting time of the satellite.

The system will use the magnetorquer coils in reverse as the coils of wire pass through the Earth’s magnetic field a current is induced in the wire. When a coil of wire passes through a magnetic field a current is induced in the wire by dissipating this current into a resistive load energy will be removed from the orbit energy of the satellite, resulting the satellite decaying faster and eventually burning up.