These two images, separated by nearly half a century, represent the dreams of human exploration of space. Together they tell a story of lost opportunity and future promise.

Forty-five years ago today astronaut John Glenn completed an epoch space mission making him the first American to orbit the Earth. The Port Arthur News reported: “Glancing at the Earth at altitudes ranging from 100 to 160 miles, Glenn had a breathtaking panoramic view stretching 1,800 miles from horizon to horizon. He described the view as ‘tremendous’ and a ‘beautiful sight.’”

Just a few weeks ago the Cassini spacecraft snapped the above picture of Titan, the biggest of the 56 known moons orbiting Saturn and the second largest moon in our solar system. The Cassini spacecraft is the first to explore the Saturn system of rings and moons from orbit.

As planetary scientist (and 2005 Pop!Tech speaker) Carolyn Porco writes in a fabulous New York Times Op-Ed piece published today, in the 1960s the possibilities for human space travel were intoxicating: plans were laid for the establishment of a 50-person lunar base, a 100-person Earth orbiting space station and human landfall on Mars by the 1980s.

Instead, by abandoning the Apollo space program the country lost a capital investment of close to $160 billion and the collective knowledge of the tens of thousands of space engineers and scientists.

Yet Porco also paints an amazing vision: one of a revitalized NASA with plans to return to the Moon with a party of humans by 2020, a solar-powered human-tended research outpost by 2025 and preparations for a Mars trip soon after.

As she says: “Humanity’s future need not be confined to mere survival on our home planet. Other worlds beckon, we know how to reach them and we will once more be outward bound.”

It’s an ambitious and inspiring vision of the future–and one that maybe this time around, we can get right.