Long-term high-resolution orbital imaging at Mars has led to extraordinary advances in understanding martian ice and its connection to climate. Icy seasonal phenomena such as flows in gullies, avalanches, and exotic defrosting patterns characterize the present climate. Interannual variability over a martian decade helps us deduce climatic averages and current trends. Observations of polar ice layers have characterized periodicities related to orbital change over longer timescales up to millions of years.Here, I’ll describe the HiRISE camera and its continued mission to describe a dynamic Mars over 20 years of observations, with a special focus on north polar avalanches. HiRISE has uniquely high resolution and benefits from high signal-to-noise (even at the poles); a near-polar orbit that allows imaging of almost any location within two weeks; color bands that are sensitive to ice; and sufficient imaging stability to construct high-quality meter-scale DTMs. The scientific impact of HiRISE owes much to rapid data releases and community targeting via our online tool HiWISH, ensuring acquisition and analysis of data relevant to today’s scientific questions.
