We present a quantitative estimate of the total carbon footprint for the MIT Kavli Institute for Astrophysics and Space Research (MKI), based on a survey of travel and commuting patterns for our 150 person workforce, and utility consumption in electricity, heat (steam + natural gas), and chilled water cooling of the physical plant. Each of these was independently evaluated over a one-year interval during 2018-2019 before the COVID-19 scaleback of campus research and teaching. Exact start and end dates varied for the different sources considered according to how data were collected. Our best estimate is that MKI produces 1826 metric tons of CO2 equivalent (MTCO2e) per year, or 12 MTCO2e per capita, per year. The largest contributor (40%) is from heating our physical plant, especially the Ronald McNair building which houses a majority of our staff. Air travel comprises 15% of the total carbon footprint; the largest total contribution comes from travel associated with professional development of our junior colleagues and support of current and future experiments, though the largest per capita contribution is from the faculty. Colloquium travel is a negligible contributor to the carbon footprint. MKI’s computing cluster consumes both electricity and chilled water. While the total cooling load of the cluster is difficult to isolate accurately, if one uses standard ratios of total-to-computing power the implied footprint of cluster computing and cooling approaches 200 MTCO2e / year, similar to air travel and roughly 10% of MKI’s total footprint. MKI has already realized a 20% net reduction in carbon footprint relative to 2014 levels, through MIT’s purchase of offsets from a solar farm in North Carolina. To reach 2030 targets set by MIT (which meet or exceed the US Nationally Determined Contribution in the Paris Accord) a further reduction of 15% below present levels, or 220 MTCO2e per year, would be required. This goal could potentially be achieved by replacing the single-pane windows and their deteriorating wood frames on the Ronald McNair building’s North facade, together with reduced emissions caused by pandemic-induced changes in commuting patterns and air travel.