Who in the US actually "sends" astronauts to the Moon? The executive or the legislative branch?

Question

The sources cited in this question and in the news mention that in a recent speech to the US space council, vice president Pence announced that NASA should land astronauts on the south pole of the Moon within five years literally "by any means necessary".

This would require substantial restructuring of NASA's budgets and programs, as well as their trajectories over time.

Can this be done by the executive branch alone, or would this really have to be directed and implemented by the US congress through budgetary restructuring? How much say does the executive branch ultimately have in where manned missions will be sent?

Answer 1

It's a bit of both. US Congress controls the purse strings. US government executes the budget.

At one extreme, when Congress is on the same side as the White House, the latter sometimes sends a budget that, bar a few cosmetic amendments, gets voted more or less as is.

At the other extreme, when both houses in Congress are on opposite side of the White House, entire swaths of the budget can get largely rewritten.

In this particular case it basically depends on whether Democrats get behind Trump's initiative. If they don't they could bluntly rip it out of the budget, or, if Trump really feels strongly about it, support it with strings attached (e.g. if they get to fund their own pet projects or rip out some other stuff).