  The most abundant components of primitive meteorites (chondrites) are
millimeter-sized glassy spherical chondrules formed by transient melting events
in the solar protoplanetary disk. Using Pb-Pb dates of 22 individual
chondrules, we show that primary production of chondrules in the early solar
system was restricted to the first million years after formation of the Sun and
that these existing chondrules were recycled for the remaining lifetime of the
protoplanetary disk. This is consistent with a primary chondrule formation
episode during the early high-mass accretion phase of the protoplanetary disk
that transitions into a longer period of chondrule reworking. An abundance of
chondrules at early times provides the precursor material required to drive the
efficient and rapid formation of planetary objects via chondrule accretion.
