Presentation #317.02 in the session Hybrid Missions Introduction.
ORCASat (Optical Reference Calibration Satellite, https://www.orcasat.ca) is a 2U CubeSat constructed in 2019-2022 for the precise photometric calibration of ground-based optical observatories. A primary motivation for potential large improvements in photometric precision using calibrated artificial light sources above the Earth’s atmosphere such as ORCASat is a resulting improvement in measurements of cosmological dark energy parameters using SNe Ia survey photometry. ORCASat’s optical payload consists of 660 nm and 840 nm laser diodes, each with approx. 100 mW of output optical power, both directed into a single 2” inner diameter integrating sphere. The light within this integrating sphere is monitored by two sphere-mounted photodiodes (one Si, one InGaAs), and the light is output toward the Earth’s surface via a 12.7 mm diam. exit port in the sphere. The ORCASat light source was precisely and SI-traceably calibrated prior to launch in 2022 at the Spectroradiometric Calibration Lab within the National Research Council facilities in Ottawa, ON. ORCASat was then launched from Kennedy Space Center to the International Space Station (ISS) on Nov. 26, 2022 onboard commercial resupply mission CRS-26. ORCASat was then deployed out of the ISS into its own low-Earth orbit, initially at an alt. of approx. 405 km ASL, on Dec. 29, 2022.
We began our ground-based observation campaign of the ORCASat optical payload in late Jan. 2023. Using a 30 s r-band exposure of DECam on the NOIRLab 4m Blanco Telescope at CTIO, temporally centered at 05:23:00 UTC on Jan. 31, 2023, we obtained a high-quality image of the 660 nm output of the ORCASat light source. We also obtained a 20 s exposure i-band image of the ORCASat streak on Mar. 4. We have made several other ORCASat observation attempts during the campaign so far; and our observation campaign continues. Due to increased solar activity over the past four months, the lifetime of ORCASat will be less than its original estimation of approx. one year: ORCASat will likely begin to heat up beyond usability in late July of this year. Until then we will continue our observation campaign of ORCASat; and we will analyze the image data for the precise photometry of the ORCASat streak, in comparison with photometry of multiple stellar standards on images that we take prior to and following the ORCASat overpass image during each ORCASat observation attempt. We’ll discuss this, as well as some potential prospects for precise artificial photometric calibration source missions of various highly-complementary types (e.g. LEO small sats, high-altitude balloons, and higher orbit small sats) for the future.