We could have been on Mars 30 years ago. At the peak of the Apollo era in the early '70s, NASA was already planning its next step into the unknown.

Its plans included building multiple space stations, continued trips to the Moon, and the first crewed mission to Mars by the 1980s. Can you imagine watching astronauts walk on Mars the same time the walkmen came out?

But NASA never sent humans to Mars in the '80s. And here we are 30 years later, still dreaming of the possibility. But the reason isn't necessarily a matter of technology or innovation. It actually comes down to politics.

As a government agency, NASA's goals are determined by the Executive Branch. Since its inception, NASA has served under 12 presidents. And it was clear near the start that not every president would support NASA equally.

By the end of Nixon's administration in 1974, NASA's budget had plummeted from 4% of the federal budget to less than 1%. Fully-funded Apollo missions 18 and 19 were abandoned along with Apollo 20.

At the same time, Nixon pulled NASA's focus away from the Moon and Mars and instead toward low-Earth orbit. His parting gift was to sign into effect what would eventually become NASA's Space Shuttle program.

Peter Diamandis: "So what's happened throughout all of space history after the Apollo program was over was to start, stop, start, stop, cancel. President comes in like Bush comes in to go to the Moon, back to Mars and next president comes in and cancels that. The agency is unable to sustain consistent funding to do anything."

It wasn't until the Space Shuttle Program was nearing retirement that a crewed mission to Mars was finally considered and funded by a US president.

George W. Bush, in 2004, announced:

"We will give NASA new focus and vision for future exploration. We will build new ships to carry man forward into the universe to gain a new foothold on the Moon."

As a result, NASA's Constellation Program was born. Never heard of it? That's because it was canceled a few years later. It aimed to send a crewed mission to the Moon in 2020 and land the first humans on Mars by the 2030s.

By the time Obama was sworn in, the Constellation Program was behind schedule and over budget. One year later, Obama canceled 100% of the program's funding.

"All that has to change. And with the strategy, I'm outlining today it will." -Barack Obama in 2010.

Obama shifted NASA's focus from sending people to the Moon and Mars to, ultimately, just Mars. In the process, he asked Congress to increase NASA's budget by $6 billion over the next 5 years.

As a result, NASA launched its "Journey to Mars" initiative in 2010, with the goal to send humans into orbit around Mars by the early 2030s. And, until recently, NASA was on track, more or less. Then, this happened.

"President Trump has launched the National Space Council and at the council's inaugural meeting in October, we unanimously approved a recommendation to instruct NASA to return American astronauts to the moon and from there to lay a foundation for a mission to Mars." -Mike Pence in 2017

Oddly enough, the space policy under Trump and Obama look nearly identical, save for 63 words. In those 63 words, Trump's administration has shifted the focus once again to a Moon-first, Mars-later initiative.

NASA isn't new to this. It's learned to recycle old projects to fit new missions. For instance, the Orion capsule was first developed for Constellation and has since been redesigned for the Journey to Mars.

But even that can't prevent the inevitable changes NASA programs now face under the new president.

"We're also going to realign the organizational structure to best meet this new exploration focus. I've asked Stephen Jurczyk the current head of space exploration to lead and effort to design a new organizational approach." -Robert M. Lightfoot, Jr. in 2018

As NASA pushes on, a new possibility has grown on the horizon. Privately-owned space companies like SpaceX also has its sights set on the red planet.

Diamandis: "The scientists and engineers at NASA are amazing and they've done extraordinary things. But they're risk aversion. That doesn't allow us to do new and novel things that are on the edge. Doing anything big and bold in space is hard and it's risky. So, it's entrepreneurs taking the risks these days, willing to put everything on the line."

The race for Mars is on. While NASA has closely partnered with SpaceX and other privately-owned space companies in recent years, ultimately, NASA may not be the ones who write the next chapter in human space exploration.