Knowledge of the magnetization of planetary bodies constrains their origin and evolution,
as well as the conditions in the solar nebular at that time. On the basis of magnetic
field measurements during the descent and subsequent multiple touchdown of the Rosetta
lander Philae on the comet 67P/Churyumov-Gerasimenko (67P), we show that no global
magnetic field was detected within the limitations of analysis. The Rosetta Magnetometer
and Plasma Monitor (ROMAP) suite of sensors measured an upper magnetic field
magnitude of less than 2 nanotesla at the cometary surface at multiple locations, with
the upper specific magnetic moment being <3.1 × 10−5 ampere–square meters per
kilogram for meter-size homogeneous magnetized boulders. The maximum dipole moment
of 67P is 1.6 × 108 ampere–square meters. We conclude that on the meter scale,
magnetic alignment in the preplanetary nebula is of minor importance.