Opinion: Forget the Moon. Let's Go to Mars.

Buzz Aldrin says the Red Planet should be humankind's next destination.

Buzz Aldrin in the ''Eagle'' lunar module during the Apollo 11 mission.


Editor's Note: National Geographic is bringing together astronaut Buzz Aldrin and mountaineer Conrad Anker for a Google+ Hangout on Monday, May 20 at 2 pm ET (7 p.m. UTC). Post your questions below using #LetsExplore.

As an Apollo 11 astronaut, I stood on the talcum-like lunar dust just a few feet from the Eagle, the lander that carried Neil Armstrong and me to the bleak, crater-pocked moon. Looking around at my surroundings on that July day in 1969, I called it "magnificent desolation."

Whenever I gaze up at the moon, I feel like I'm on a time machine. I am back to that precious pinpoint of time, standing on the foreboding—yet beautiful—Sea of Tranquility. I could see our shining blue planet Earth poised in the darkness of space.

Virtually the entire world took that extraordinary journey along with the crew of Apollo 11. We were supported by hundreds of thousands of American workers, the greatest can-do team ever assembled on the face of the Earth. That team was comprised of scientists and engineers, metallurgists and meteorologists, flight directors, navigators, and suit testers—as well as policy makers. So many devoted their lives and professional energies, minds, and hearts to our mission and to the following Apollo expeditions. Those Americans embraced commitment and quality to surmount the unknowns with us.

Fast forward to nearly 45 years later. Today, I see the moon in a different light.

America won the "moon race" more than four decades ago. We do not need to engage in that contest again. Instead, we should set our sights on a permanent human presence on Mars. There is no compelling reason that this can't be done, but great care must be taken that precious government dollars necessary for the great leap to Mars are not sidetracked to the moon.

Robotic exploration of the Red Planet—including the highly capable NASA Mars rover Curiosity—provides us a window on a world that can be a true home-away-from-home for future adventurers. Mars has been flown by, orbited, smacked into, radar inspected, and rocketed onto, as well as bounced upon, rolled over, shoveled, drilled into, baked, and even laser blasted.

Still to come—being stepped on.

The first footfalls on Mars will mark a momentous milestone, an enterprise that requires human tenacity matched with technology to anchor ourselves on another world. Exploring Mars is a far different venture than Apollo expeditions to the moon; it necessitates leaving our home planet on lengthy missions with a constrained return capability. Once humans are at distant Mars, there is a very narrow window during which they can return to Earth—a fundamental distinction between our reaching the moon and sailing outward to Mars. Therefore, we need to start thinking about building permanence on the Red Planet and what it takes to do that. It is a vision of the extension of humanity to Mars.

As outlined in my book Mission to Mars: My Vision for Space Exploration, we can implement a step-by-step vision to plunge deeper and deeper outward. Part of the plan is a sequential buildup of a spaceship network that coincides with an ever-increasing escalation of action on the moon and Mars. The Earth, the moon, and Mars become busy places as people, cargo, and commerce navigate through the inner solar system. (See video: Buzz Aldrin discusses new book on possible Mars mission)

When Neil and I stepped upon the surface of the moon at Tranquility Base, we fulfilled a dream held by humankind for centuries. As inscribed on the plaque affixed to the ladder of our lander: "We Came in Peace for All Mankind." It was, truly, one small step. But more steps are needed.

Nowadays, my dedication—indeed, my passion—is focused on forging America's future in space, guided by two principles: a continuously expanding human presence in space, and global leadership in space.

To move forward, what's required is a unified space agenda based on exploration, science, development, commerce, and security. For instance, our work on the moon should be limited to robots assigned to scientific, commercial, and other private-sector work. We need a unified international effort to explore and utilize the moon. It would be a partnership that involves commercial enterprise and other nations building upon the Apollo legacy.

Earth isn't the only world for us anymore.

There's an opportunity to make a bold, Kennedy-esque statement in July 2019, on the occasion of the 50th anniversary of the first humans to land on the moon: "I believe this nation should commit itself, within two decades, to commencing American permanence on the planet Mars."

In reaching outward with method and intent to Mars, and helping others go where we have already gone, America is once again in the business of a momentous and future-focused space exploration program.

Let's get rolling . . . and roll up our sleeves and begin.

Buzz Aldrin, best known for his Apollo 11 moonwalk, holds a doctoral degree in astronautics and, at the age of 83, continues to wield influence as an international advocate of space science and planetary exploration. He has written three nonfiction books, two science fact/fiction novels, and two children's books.

Leonard David is a space journalist and the 2010 winner of the National Space Club Press Award. He is the Space Insider columnist for space.com, a correspondent for Space News, and a contributing writer for Aerospace America, the magazine of the American Institute of Aeronautics and Astronautics.