The US space agency says its Dawn probe should now be in orbit around the asteroid Vesta.
(first i've heard of this! Picture links in comments)
The robotic satellite will be spending a year at the 530km-wide body before moving on to the "dwarf planet" Ceres.
New pictures on Dawn's approach to Vesta show the giant rock in unprecedented detail.
The asteroid looks like a punctured football, the result of a colossal collision sometime in its past that knocked off its south polar region.
Confirmation that Dawn is safely circling the rock should come on Sunday (GMT) when the probe is due to return data on its status.
Vesta was discovered in 1807, the fourth asteroid to be identified in the great belt of rocky debris orbiting between Mars and Jupiter.