Currently the US income tax forms asks:
"Do you want $3 of your federal tax to go to the Presidential Election Campaign Fund?"
Personally, I have never checked the option, but I have thought of how I would like my tax dollars spent/invested. I suggest that the tax form ask citizens:
"Do you want $3 of your federal tax to go directly to a NASA fund?"
I think many citizens would like for NASA to send probes to investigate the old deep water oceans of Europa, create a permanently occupied base on the moon, and send astronauts to explorer the mountains, valleys & ice caps of Mars. If this option were on tax forms, citizens could have more direct influence on how their taxes are spent, and I suspect many like myself would like the taxes spent on exploration and discovery