In 2001, a team at the Carnegie Institute of Washington reported the most precise measurement of the isotopic signatures of lunar rocks.[53] The rocks from the Apollo program had the same isotopic signature as rocks from Earth, differing from almost all other bodies in the Solar System. This observation was unexpected, because most of the material that formed the Moon was thought to come from Theia and it was asserted in 2007 that there was less than a 1% chance that Theia and Earth would have had identical isotopic signatures.[54] Other Apollo lunar samples analyzed in 2012 showed the same titanium isotope composition as Earth,[55] which conflicts with what would be expected if the Moon formed far from Earth or was principally derived from Theia. These discrepancies may be explained by variations of the giant-impact theory. For instance, a high-speed drive-by hit by the impactor could have allowed it to return to Earth a second time but more slowly, and mix more thoroughly.[56] This hit-and-run-and-return scenario could explain some of the apparent contradictions between material evidence and other theories.[57]