The Magnetospheric Multiscale mission (MMS) by NASA now holds the Guinness world record for the highest altitude fix of a GPS signal. The fix was taken from a height of 43,500 miles (70006 kilometres) above the surface of the Earth.
Next year, the MMS will enter phase two of its mission, when it is expected to set a new world record, from at least twice the altitude of the current record.
The MMS spacecraft fly in a tetrahedral formation. Image: NASA.
The MMS spacecraft fly in a tetrahedral formation. Image: NASA.
The MMS is a flock of four satellites in a tight formation that are in an extremely elliptical orbit around the Earth. The mission holds another record for being the closest flying spacecraft in a formation, with a distance of only four and a half miles (roughly seven kilometres) between two satellites.  At their closest approach to Earth, the four satellites move at a blistering 22,000 miles per hour, which is also the fastest known use of a GPS receiver.
The four satellites are flying in a pyramid shaped formation to study a phenomenon in the magnetosphere of the Earth, known as magnetic reconnection. The phenomenon occurs due to the interaction between the magnetic fields of the Earth and the Sun.
The satellites use GPS tracking to stay in formation and obtain high resolution, three dimensional observations. The precise GPS coordinates are required for the sensitive, position and orbital calculations.