An autonomous Sail Drone has circumnavigated Antarctica. It left New Zealand on January 19, 2019 and arrived on August 3, 2019. It completed the 22 000 kilometer mission in 196 days.
The whole trip was GPS loged. I downloaded the kml file, extracted the dates and locations using Convert KML File Data to CSV Format for Geo Data App, which calculated the ECEF cartesian coordinates for the recorded locations. This coordinates were then loaded into my Display Geo adata App, from which the screenshot above was taken. The App alows me to select 3 arbitrary points in a row at the same elevation and it calculates the radius of the arc from this points. As we see above it gives very accurately the known radius of the earth.