Seeing the ship slowing due to his sister's weight and mass (not that Sam was suicidal enough to EVER voice that thought), Cannonball figured that as the Zebulon peeled off that it was time to help Lizzie out a bit with dropping that ship. Triggering the rocket propulsion from his palms to get closer, Sam spread his field against the top of the ship so he wouldn't shove all the way through.
And with that, he pushed down, triggering his propulsion so he was helping shove the ship down towards the ground. Once it hit, he did scrape off some of the metal on the hull just because his propulsion kept him moving even when the ship was at rest.
Which didn't bother Sam. He just crashed into the ground to suck up some of that kinetic impact with his field, liking having that little bit extra to play with. Walking up and hearing Jeb on the communicator asking if these guys knew how bad of a hurting they were in, Sam drawled "If not, they ought to now." Drawing a pistol, Sam said "Guess it might be polite to knock and welcome 'em." Grinning at how his family could misconstrue 'knocking' Sam asked "Anyone want to knock first, or do ah get the honors?"