The New York Magazine describes how President Trump offered some people at NASA to imagine and propose an Apollo-style crash program to get humans to Mars. NASA described getting to humans to Mars in the 2030s. Trump asked if the first humans to Mars could be achieved by 2020 or 2024 with an unlimited budget?
The offer was made to Robert Lightfoot Jr, the acting NASA administrator. in the White House prior to a call to the Space Station.
NASA represented roughly 2.2% of the total US federal outlays from 1959 to 1972. The Apollo project in the same timeframe was about half of NASA’s budget. This was 1.1% of US total federal outlays during this timeframe.
The US federal budget for 2019 will be about $4.4 trillion. 1.1% of the federal budget would be $48 billion per year. The federal budget will increase from 2020 to 2024.
Six years of spending at that level would be about $300 billion.
SpaceX could definitely create complete versions of the SpaceX Super Heavy Starship in that time. Several SpaceX Super Heavies could be sent unmanned in 2022 to Mars. Even if some rockets failed, I think 3 out of 5 would definitely succeed in their Mars missions.
SpaceX could also create and send multiple unmanned Falcon Heavy missions to Mars in 2020 and 2022. Supplies and fuel could be pre-positioned on Mars.
I think there would be volunteers willing to go to Mars in 2024.
Elon Musk would be able to send dozens of Falcon Heavy and Super Heavy Starships to Mars by 2024. They would also be able to create bases on Mars, the Moon and in orbit.
Each Starship would have nearly as much volume as the International Space Station. The space station has an internal volume of about 32,000 cubic feet. The SpaceX BFS (now called Starship) has an internal volume of 29,000 cubic feet. Leaving parked Starships on the moon, Mars and in orbits would be creating International Space Station size bases.
There are estimates that the SpaceX Super Heavy Starships will each cost about $300 to 400 million. This is without bulk purchase discounts. $30 billion of a Mars program budget could easily buy 100 SpaceX Super Heavy Starships.
Elon Musk has already talked about building a Mars base by 2028 and humans to Mars by 2024.
Probably 2028 for a base to be built
— Elon Musk (@elonmusk) September 21, 2018
Just Cancel Space Launch System, Orion and Re-direct the Funds to SpaceX for Mars
If SpaceX had $5 billion per year in additional funding it would be trivial to get the unmanned missions to Mars by 2020 and 2022. A manned mission to Mars in 2024 would be fairly certain as well.
$2 billion per year from 2019 to 2023 could be used to properly fund and accelerate the SpaceX Super Heavy Starship development.
$2 billion per year could be spent on Mars specific program development.
$1 billion per year could be spent on additional Falcon Heavy construction and unmanned missions.