Continuing Canadian Leadership in Small-satellite Astronomy

Micro- and nano-satellites offer cost-effective platforms for space technology development and for targeted investigations in astronomy.The original 1999 CubeSat design, based on 1 litre-sized cubes, is now the standard '1U' prototyping architecture.The Canadian Space Agency was an early adopter of micro-satellites.The MOST (Microvariability and Oscillation of Stars) telescope was Canada's first astronomy satellite.Launched in 2003, MOST offered a dedicated platform for asteroseismology that demonstrated the advantages of uninterrupted, long-duration staring observations well before the Kepler Mission adopted the same technique to discover thousands of extrasolar planets.MOST opened the astronomy time domain from space.The subsequent BRITE (BRIght Target Explorer) Constellation was the first space astronomy mission to be carried out with nano-satellites, with Canada designing all and contributing two of the six 8U-sized satellites.Its greatest advantage was its ability to stay pointed on a wide field (24 x 24 degres) monitoring up to 30 bright stellar targets for up to 6 months. Micro-satellite adoption remains slow in astronomy, mostly because of the need for large telescope apertures.However, as demonstrated by MOST and BRITE, time-domain photometry of bright objects, such as Milky Way stars and planetary systems, can be well-served by modest apertures.Improving detector technology is now opening micro-satellite platforms to fainter objects, multi-band photometry, non-optical wavelengths, and polarimetry. Canada is in a strong position to lead micro-satellite astronomy. Building small and cost-effective - but capable - space platforms will ensure that Canada stays at the forefront of space technology development. Focusing on a few key micro-satellite investigations will optimize the science impact of Canadian space astronomy.Early experience with Canadian micro-satellites also enhances Canadian expertise and HQP training for participation in larger international follow-on missions. The Canadian Space Agency currently operates two astronomy small-satellite missions, the Near Earth Object Surveillance Satellite (NEOSSat) and BRIght Target Explorer (BRITE) Constellation, and has two more missions under study: the Photometric Observations of Extrasolar Planets (POEP) and the Extrasolar Planet Polarimetry Explorer / Explorateur Polarimétrique des Planètes Extrasolaires (ÉPPÉ).NEOSSat's first Guest Observer call for proposals in September 2019 was heavily (4.8:1) over-subscribed, reflecting intense astronomy interest. BRITE Constellation has already demonstrated to be one of Canada's highest-publication impact observatories. Both POEP and ÉPPÉ promise novel, science-enabling capabilities in space-based time-domain astronomy with applications well beyond their primary exoplanet-focused goals. Reliable, dedicated funding to support research with the existing missions and to expand the astronomy small-satellite program will solidify Canada's trademark in space astronomy innovation.White paper identifier W05