In the mid-1960s America’s space program was swiftly racing towards the Moon, a exotic land that would be conquered before the decade was out. But in the years leading up to the landing, NASA was already looking toward the future, asking: how could they keep the amazing team that built the Apollo program in place, and where could humans go next, given the technologies on hand?

Writing for Ars Technica, Amy Shira Teitel lays out in detail the plans devised to send astronauts to Venus, to Mars, or to both planets on one epic voyage, using only the equipment that put people on the Moon.

Following a launch during the November 1973 window, the crew would reach Venus sometime around March 3, 1974, and the planet would become their primary science target. Using the telescope’s broad spectrum to look beyond Venus’ thick clouds, the crew would gather data on Venus’ surface, the chemical composition of the lower atmospheric levels, its gravitational field, and the properties of its various cloud layers. They might even release robotic probes, small vehicles that would send data back to the spacecraft in real time about the atmosphere as they completed their one-way missions to the surface. Swinging around Venus would give the crew enough momentum to return to Earth. Planetary geometry following that November 1973 launch window meant the return trip would take a full 273 days.

The whole venture, says Teitel, was predicated on the idea that, after the moon landing, Americans would experience a great surge of enthusiasm for the exploration of the cosmos. That, however, never happened. Given that, even at the time, the majority of Americans weren’t too keen on sending people to the Moon, it was probably never a very realistic dream in the first place.

As Alexis Madrigal wrote at the Atlantic last year, the rosy ideal of the Moon landing as this great coming-together moment of human experience is one heavily tinted by time:

Back in the Apollo days, people loved the space program! Except, as this Space Policy paper pointed out, they didn’t. A majority of Americans opposed the government funding human trips to the moon both before (July 1967) and after (April 1970) Neil Armstrong took a giant leap for mankind. It was only in the months surrounding Apollo 11 that support for funding the program ever reached above 50 percent.

And federal budget makers weren’t any more excited about sending men to Venus or Mars. Funding for the Apollo program petered out by 1973, as NASA’s overall budget shrunk from a peak of $5.9 billion in 1966 to a low of $3.2 billion in 1974. As a percentage of federal spending, NASA’s budget has continued to diminish: in 1966, it made up 4.4 percent of all federal spending. It’s now around 0.5 percent.

The government may not have been so keen on space spending, but “it wasn’t only a lack of funding that doomed the Venus and Mars flyby missions,” according to Teitel. The Venus and Mars proposals “were never intended as a recommendation,” she says. Still, they could have been spectacular. If those plans had been executed, people would have been orbiting our two nearest planetary neighbors just a few years after we set foot on the Moon.

More from Smithsonian.com:

Elon Musk’s Plan for Mars Is Really Vague But Definitely Expensive

Preparing for a Mission to Mars Is Dangerously Boring