  We propose the concept of a space mission to probe the so called flyby
anomaly, an unexpected velocity change experienced by some deep-space probes
using earth gravity assists. The key feature of this proposal is the use of
GNSS systems to obtain an increased accuracy in the tracking of the approaching
spacecraft, mainly near the perigee. Two low-cost options are also discussed to
further test this anomaly: an add-on to an existing spacecraft and a dedicated
mission.
