A scientific outpost, a graveyard, a stepping stone to Mars: It all starts with the moon.

When the first astronomers turned their eyes to the heavens, tens of thousands of years ago, their view was unobscured by the glow of city lights. At night, a pristine black sheet stretched across an unreachable ceiling overhead. The centerpiece of this ancient nightscape was a flat grey disc that hung in the sky: the moon.

We used to worship the moon, tell each other stories to explain its mysteries. In Australia, the Indigenous Yolngu people named it "Ngalindi," believing a full moon represented an indolent, pot-bellied man with several wives. As the moon cycled through its phases, the Yolngu believed Ngalindi's wives had taken to his body with their axes, slicing pieces away, leaving only a crescent slither. Similar stories abound in Aztec culture and the myths of ancient Mesopotamia, East Asia, India and Greece. 

But on July 20, 1969, we stepped onto a lunar sea and saw the moon's surface, up close, for the very first time. The ground was dead and cratered. Only dusty plains stretched out before us. 

The moon was no longer a god to be worshiped. It was a destination. A place we could visit, an object we could touch. 

Over the next three years, 12 humans walked on the surface of the moon, piloting rovers across Rima Hadley and Stone Mountain. They pilfered moon soil, studied rocks, visited impact craters and planted flags. On Dec. 14 1972, NASA astronauts in the Apollo 17 mission climbed back into their lunar spacecraft and departed the moon for Earth. It was the last time humans ever set foot on the moon. 

But in 2019, the moon is being probed and explored once again. In January, China landed the first spacecraft on the far side of the moon. Israel's Beresheet lander became the first private spacecraft to reach the moon, crashing onto its surface in April. And NASA doubled down on efforts to put humans back on the moon before 2025 "by any means necessary." It's an ambitious goal, with the hope of establishing a permanent human presence on the moon and in lunar orbit at the end of the next decade.

The immediate future of the moon will see us build on those first steps taken in July 1969. We'll send more robotic landers and rovers to conduct experiments on our behalf. China already has another Chang'e mission planned for this year and India, too, will look to land on the surface before the end of the year. In our stead, the robots will search for water and explore the lunar highlands for the resources necessary to establish a more permanent presence.