US Antarctic Service Medal is awarded by the United States Department of Defense
This is a service award from the US Armed Forces that may be awarded to civilians or citizens of a foreign nation who participate in a U.S. Antarctic expedition on the continent at the invitation of a participating U.S. agency.
Bob received this for serving as an instructor on a training course at the U.S. National Science Foundation's McMurdo Antarctic Research Station, located on Ross Island, Antarctica (78deg S) for 4 weeks in 2018.
More on this medal: https://en.wikipedia.org/wiki/Antarctica_Service_Medal