Space exploration since it inception has driven the rest of science across the boards, resulting in a mushrooming effect on the advancement of science. That has led to much of the technology and real economic growth you see around you. The NASA technology transfer history is full of examples of technology flowing both to and from space exploration efforts to our immense benefit. So rather than cut space exploration, I would fund it more and so renew our lead in science and technology which was our real advantage over the rest of the world.
I'd cut corporate welfare, and cut corporate leaders from being phony regulators in charge of most of our government agencies. I'd cut out any possibility of a corporation giving one cent to a politician, even if it takes a constitutional amendment(s). Currently they have the right of free speech which allows them to effectively buy our federal, state, and local representatives.
I'd cut subsidies to coal and oil, which are currently at one trillion dollars each (cumulative).
I'd cut the corporate paid representatives out of government for life.
I'd cut all immigration at the border with force.
I'd deport the rest of them.
Every nation that sent jobs overseas would pay a 1000% tariff on any goods they want to sell here, until they bring back all the jobs they sent out.
I'd end all trade agreements we have signed.
I'd cut off the federal reserve, abolish it, and return monetary policy to congress.
I'd cut off any posibility of ever having another imperial presidency.
I'd pass an amendment that whenever a member of congress votes to give away his responsibilities regarding war, that it is an act of treason.
I'd cut out any possibility of lobbying.
I'd cut every news agency in the country into a thousand smaller companies with no central control, and a mandate to 100% of the time present both sides of every argument with equal gusto. Any news organization not actively doing investigative reporting would lose its license to broadcast and be required to stamp the words, "corporate propaganda" across the front page of their paper. :-) I like this one.
So much more too.