  Research into, and design and construction of mobile systems and algorithms
requires access to large-scale mobility data. Unfortunately, the wireless and
mobile research community lacks such data. For instance, the largest available
human contact traces contain only 100 nodes with very sparse connectivity,
limited by experimental logistics. In this paper we pose a challenge to the
community: how can we collect mobility data from billions of human
participants? We re-assert the importance of large-scale datasets in
communication network design, and claim that this could impact fundamental
studies in other academic disciplines. In effect, we argue that planet-scale
mobility measurements can help to save the world. For example, through
understanding large-scale human mobility, we can track and model and contain
the spread of epidemics of various kinds.
