You can't stop the signal once it's been sent, and that had been exactly what they had done. The Acorn had descended through the atmosphere rather shakily, but it had proven itself sturdier than expected of a squirrel-built spaceship. It was probably a good thing that Sam had been the pilot rather than River, and especially the Park groundsmen would have been happy about that had they known that the spaceship landing not for from the clinic could have caused a lot more damage to the surroundings with someone less experienced piloting it.
[For Miranda visitors returing.]