The Canadian Satellite Design Competition (CSDC) is a Canada-wide competition for teams of university students (undergraduate and graduate) to design and build low-cost satellite. The CSDC plans to subject the satellites in competition to full space qualification testing, and to launch the winning satellite into orbit to conduct science research. The CSDC is modeled after existing university engineering competitions, such as those sponsored by the National Aeronautics and Space Administration (NASA) or the Society for Automotive Engineers (SAE).
CSDC has other declared objectives as well:
• to promote education, excellence, research, development, and future capability in space activities in Canada.
• to foster innovation in satellite technologies and inexpensive access to space.
• to seek new applications of technologies and space missions for the betterment of Earth.
One of the teams in competition is the University of Manitoba Team, UMSATS. Dario Schor, UMSATS Project Lead, answered a few questions about the T-Sat (triple pico-satellite) designed by the University of Manitoba Team.
Q: What is the scientific payload for the mission you are designing?
A: The University of Manitoba mission carries two scientific payloads: a Tardigrade Experiment and a Solar Spectroscopy Experiment.
The Tardigrade Experiment aims to test the survivability of Tardigrades (a class of extremophile organisms also known as water bears) in space. This will be accomplished by sending a colony of tardigrades in a cryptobiosis state, exposing them to the harsh space environment, reviving them in orbit, and monitoring their behavior by taking bursts of images at predetermined times throughout the first 30-40 days of the mission. The novelty of the experiment is in the on-board revival of the organisms that has not been done in any satellite, let alone a nanosatellite that is only 10x10x30cm.
The Solar Spectroscopy Experiment measures the intensity of light emitted from the Sun over the ultraviolet to near-infrared regime (350nm to 1100 nm) to add and compare the results to theoretical models and data collected by other missions. This type of experiment has been performed on a number of missions with larger spacecrafts, thus demonstrating comparable results on a smaller and cheaper platform can open the door for many other small research groups to conduct similar experiments to collect and analyze their own data.
Q: What hardware do you intend to use? Off-the-shelf boards and software or are you developing your own?
A: The spacecraft uses off-the-shelf components in custom designs for all subsystem boards. The extra efforts and risks from custom designs, manufacturing, and testing are offset by the experience gained by the students on the team. Some examples of the components used include:
• The Command & Data Handling (CDH) subsystem uses the TI MSP430 microprocessor interfaces to a watchdog timer, real-time clock, and memory modules for their operations.
• The Communications (COM) subsystem uses stripped down version of a commercial-off-the-shelf handheld from Yaesu that operates on amateur frequencies. Digital packets are created and encoded using a custom Terminal Node Controller based on the TI MSP430 microprocessor.
• The Power (PWR) subsystem uses fixed solar panels, an off-the-shelf battery, and a custom protection and distribution system to provide power to the spacecraft.
• The Structure (STR) is being built in-house out of Aluminum 6061. The custom design was required to support the two payloadâ€™s requirements for heat, volume, and position within the spacecraft.
• The Thermal (THM) subsystem relies primarily on insulation for its components and uses an off-the-shelf heater to maintain the Tardigrade experiment from freezing.
• The Attitude Determination and Control (ADC) subsystem uses off-the-shelf sensors, such as the Honeywell HMC2003 magnetometer, with customized designs for magnetic torque rods to control the orientation of the spacecraft.
Q: How do you intend to communicate with your satellite from the ground? UHF, Iridium modem, etc.?
A: The spacecraft is designed to communicate with amateur radio stations conforming to the GENSO standard (genso.org). That means using the 2m band (144-148MHz) for uplink commands, and the 70cm (435-438MHz) for downlink telemetry and science, similar to many AMSAT satellites such as AO-51, HO-68, and FO-29. The spacecraft configurations with the two antennas is shown in Fig. 3. All packets are encoded using the AX.25 protocol that is compatible with most amateur ground stations, such as the University of Manitoba Satellite Ground Station.
Q: How do you generate and store power onboard the satellite? Batteries, solar panels? Do you intend to use deployable solar panels?
A: The spacecraft is designed to operate with a minimum of 4 Watts. Power is generated using fixed solar panels on all faces of the spacecraft and storing it in an on-board battery to power the spacecraft during eclipses. The fixed panels provide sufficient power for the mission without the added risks from deployable panels.
Q: Does the attitude determination and control system rely solely on reaction wheels? How do you intend to unload them? Magnetorquers, cold gas thrusters, or have you developed a novel technique?
A: The Attitude Determination and Control (ADC) subsystem uses a magnetometer and Sun sensors to determine the orientation of the spacecraft. Custom built magnetic torquers are used to control the orientation. The torquers are implemented in multilayered flat coils enabling easy integration of the torque rods with the rest of the system.
Q: Do you plan to have any orbit control systems onboard? What is the orbital profile of the mission?
A: There is no orbit control system onboard. This would be very difficult to achieve in a small 10x10x30 cm spacecraft with a maximum mass of 4kg as thrusters and fuel would require a large portion of the mass and volume leaving little room for scientific payloads.
The current goal is for a sun-synchronous orbit with an inclination of 98 degrees, eccentricity ~0, and altitude of approx. 600-800km. A sample profile for a 24 hr period for the mission is shown in Fig. 4. The field of view from the University of Manitoba Satellite Ground Station (operational since 2008) shows the contact points over the 24 hr period.
Q: How do you plan to control the temperature onboard the satellite?
A: The thermal control is mostly passive except for a heater attached to the Tardigrade payload to ensure the water and nutrients for the water bears do not freeze. Analysis of the temperature profiles revealed that the remaining components can stay within their allowed operating temperatures using small layers of insulation.
Q: Who are the members registered with your team? What areas of expertise do they represent?
A: The University of Manitoba team has over 100 registered students from Engineering, Science, Business, Architecture, Art, and Graduate Studies that contributed to the project since October 2010 with the largest group coming from the Department of Electrical and Computer Engineering. This includes students from first year all the way through Ph.D. programs, thus providing a strong core for this mission as well as laying the foundation for future missions at the University of Manitoba. At the moment, there is a core group of 35 students that are working on various aspects of the project.
The students are supported by a team of over 50 advisors from academia, industry (specifically aerospace from Magellan Bristol Aerospace), government, military, amateur radio community, and others. The advisors attend regular review meetings for the full project and some of the subsystems to provide feedback on the design.