The rubber tracks (3) allow the Viking to travel over soft terrain such as desert, snow or mud because its load is evenly distributed over all four tracks, all of which are driven.
Skis were widely utilized in Central Asia and Europe, while snowshoes were common in the New World - probably because snow was more compact and less soft in the Old World, theorizes Huntford.
The experiment fell into deep snow in the far north of Sweden - and the possibility of a soft landing has the Strathclyde team hoping even more data can be recovered.