It was a quiet Saturday morning when a satellite the size of a tissue box began its mission to help us better understand the Universe. On November 26, 2022, the University of Victoria student-developed satellite, known as ORCASat (for Optical Reference Calibration Satellite), took to the skies from NASA's Kennedy Space Center aboard a SpaceX Falcon 9 rocket. By early Sunday morning, it was docked to the International Space Station. The small satellite was successfully sent into orbit on December 29, 2022, on its mission to provide a unique artificial reference light source in orbit to calibrate ground-based telescopes.
Ground-based telescopes have allowed us to intimately view space since the time of Galileo and, in modern times, make it possible for us to view faraway galaxies from the comfort of our homes. On its way down to Earth, light is lost in telescope images in 3 different places: within the Earth's atmosphere, within the optical components of a telescope (i.e. mirrors, lenses and filters) and within the detector of a telescope camera. It's important to calculate the total fraction of light lost to be able to make precise astronomical measurements. Developed primarily under the Canadian CubeSat Project led by the Canadian Space Agency, the University of Victoria and the National Research Council of Canada (NRC) collaborated on ORCASat so that this fraction of astronomical light loss can be measured precisely.
Justin Albert, one of ORCASat's lead researchers, had worked with experts at the NRC's Metrology Research Centre on precision astronomical photometric calibration in the past and knew they could contribute expertise to the mission. So, Justin contacted long-time collaborators Arnold Gaertner and Éric Côté, researchers in photometry at the NRC, for help. Together, they carried out 2 intense weeks of calibration for the laser light sources. They provided critical light intensity measurements for ORCASat's 2 laser light sources to determine exactly how much they emit. Then, when a ground-based telescope or observatory measures the light emitted from the satellite, researchers are able to compare it to the NRC's absolute intensity measurements and thereby calibrate their instruments. Researchers and technicians at the NRC's Aerospace Research Centre, led by Viresh Wickramasinghe, provided key lab equipment for the project, performed modal testing to extract structural dynamics, conducted 2 shaker qualification tests of the prototype and flight hardware and undertook crucial system design assessments to ensure a successful launch. At the same time, they also supported and trained young engineers.
A training ground for Canadian students
The University of Victoria prides itself on shaping the next generation of Canadian space scientists, engineers and entrepreneurs by providing valuable hands-on experience for students. The innovative ORCASat space and ground elements were designed and built entirely by students—over 25 full-time co-op students and 150 part-time volunteer students under the mentorship of Canada Research Chair and Professor Afzal Suleman (engineering) and Justin Albert (physics) have contributed to ORCASat and learned about space mission design in the process. As the mission carries on, the primary objective of the ORCASat project will be to continue training highly qualified personnel in space science and technology.
All for a better understanding of the Universe
ORCASat carries 2 laser light sources that astronomers can observe in orbit. At the same time that a ground-based telescope is measuring the light from ORCASat, the satellite itself is measuring how bright the light is as well as its altitude, attitude and position. It also measures the health of the spacecraft and light source. The discrepancy between how bright ORCASat appears to be on the telescope and how bright it should have appeared determines the amount of light diminished by the atmosphere and the telescope optics. Astronomers can then apply this information to other light measurements of celestial bodies in the night sky.
By measuring the absolute brightness of Type Ia supernovae―the powerful and luminous explosion of a star caused by the collapse of white dwarfs, or the hot, dense remnants of ancient stars―we can determine how fast they're moving away from us, thus making it possible to measure the expansion history of the Universe. ORCASat will further reduce the uncertainty surrounding how bright these supernovae are and provide higher accuracy and precision and improve our understanding of universal expansion. ORCASat is expected to stay in orbit for about 6 to 8 months, but a longer mission lasting 18 months has not been ruled out, as long as the conditions in space permit.