get-me-a-scientist
Explanation
The Joke
An aide rushes to the President with urgent news: "Mr. President! An asteroid is heading directly for Los Angeles! We have 12 hours until impact!" The President dramatically demands: "Get me a scientist!" In the next panel, labeled "12 hours later," the President is on the phone enthusiastically telling someone: "Great news, Mr. President! The asteroid will set up a detector, blast radius, along miles..." -- he has spent the entire 12 hours excitedly learning about the science of asteroids from the scientist rather than actually doing anything to prevent the disaster. The final panel shows the aide on the phone saying "The data is gonna be amazing," while presumably Los Angeles is about to be destroyed.
The joke is that the President's instinct to "get me a scientist" -- which sounds like decisive leadership -- actually led to him becoming so fascinated by the scientific aspects of the asteroid that he completely forgot to, you know, save Los Angeles.
The Humor
The humor plays on the familiar trope of disaster movies where the President takes charge and demands experts. Here, instead of using the scientist's expertise to solve the problem, the President gets absorbed in the intellectual excitement of the situation. It satirizes a certain type of person (common in SMBC's universe) who is so enamored with knowledge and data that they lose sight of practical concerns. The final line about the data being "amazing" is the darkest punchline -- even as a city is about to be obliterated, the characters are thrilled about the research opportunity.