Although the precession dynamo can be viable for the strong early lunar field, the possible long-lasting and weak field until recent times may still require an alternative explanation.
One conclusion is that the excavation models yield such disparate results that lunar-field testing is prudent.
Finally, we removed data points for which the magnetic field magnitude measured at Wind (time-shifted by solar wind travel time) did not match that measured at LP to within 20%, thus minimizing the effects of solar wind inhomogeneities and local field compression above strong lunar crustal fields.
Moreover, such a huge collision on the far side would have shifted much of the magma ocean that then underlay the moon's surface to the near side, which led to the formation of the maria.More evidence may surface when the Gravity Recovery and Interior Laboratory mission, an American spacecraft designed to map the moon's gravitational field, arrives in lunar orbit in around six months' time.
IN the morning, we explored a landscape that was almost lunar - great fields of boulders, breathtaking views and immense silence.
The lunar gravity field is a foundation to study the lunar interior structure, and to recover the evolution history of the Moon.
LGM2011 can be used as an a priori model for lunar gravity field simulation and inversion studies, evaluation of past and future lunar gravity field missions, improved topographic mapping, lunar inertial navigation, and the prediction of lunar gravity acceleration and vertical deflections at any future landing sites.
The location is uncertain because the Eagle ascent stage was not tracked after it was jettisoned, and the lunar gravity field is sufficiently non-uniform to make the orbit of the spacecraft unpredictable after a short time.
Nowadays, the moon has no global magnetic field, but that was not always the case; between 4.25bn and 3.56bn years ago, the lunar magnetic field was similar to that of the Earth.
"What we don't have a good grasp on yet is what generated the lunar magnetic field," said Tikoo.
