Earth’s nearest natural neighbor, the Moon, has been a focus of human exploration since the dawn of the space race. But lately, with NASA’s announced “Journey to Mars”, and SpaceX’s recent announcement of a 2018 Mars mission, the Moon has waned in importance when it comes to space exploration. Just this week, Congress chastised NASA for investing in a possible asteroid mission at the expense of the Moon.
As recently as 2008, with the (now canceled) Constellation program, the Moon was NASA’s the next target for human footprints, at least for the United States. So, what changed? And what does it mean for human exploration of the solar system?
After such a long absence, enthusiasm for going back to the Moon never materialized. In his only address at Cape Canaveral, President Obama declared in 2010 that we’d “been there before.” It wasn’t Obama’s fault, per se, that American zeal for going back to a place we went to 50 years ago was paltry. Josh Lyman, fictional West Wing character, put it best: “It’s like if, 30 years after Columbus, Spain expected people to get hot and bothered about a trip to Mallorca.”
First, the Moon is way closer to Earth.
Mars also grew in importance. At the time of Obama’s visit, NASA’s robotic exploration program—led by JPL—was basking in the success of the Spirit and Opportunity rovers, which landed on the Red Planet in 2004 (Opportunity is still roving today). Not long after, the even larger Curiosity rover touched down to raucous international attention. In parallel, SpaceX ascended as a prominent leader in space exploration, targeting Mars from the beginning.
I’ve been an unabashed “Mars-next” promoter, but there are features of the Moon that make it an attractive target for long-term human colonization in its own right:
First, the Moon is way closer to Earth. On average, the distance to Mars is almost 600 times the distance to the Moon. Compared to the (generally) easy-going couple of days in transit faced by Apollo Astronauts, a Mars mission would require about eight months in transit just to reach the surface. For most mission architectures, the orbital position of Mars and Earth means that any crew would need to spend about 500 days in the vicinity of Mars before a return to Earth would be possible.
Second, the lack of an atmosphere makes it a heck-of-a-lot easier to get off the lunar surface. In the short term, this means future Armstrong’s and Aldrin’s will be able to get back to Earth a great deal easier than if they were on Mars. But in the long term, it opens intriguing options for deep space missions to other destinations. A mass-driver, or electromagnetic launch device, could propel missions to the outer planets with a fraction of the energy needed by chemical rockets originating from either Earth or Mars. NASA’s kicked around this idea on Earth—combining it with a scramjet to get through our thick atmosphere—but the notion has never gotten off the ground.
Mars is a hop-skip-and-science away from becoming a warmer world.
The Moon’s dark side is also an ideal location for radio observations of the universe. Although frequently illuminated, the dark side is shielded from much of the interference found in the inner solar system. During the lunar night, it may be possible to observe energy emanating from the one of the most mysterious periods in our universe—fittingly called the “dark ages”. The private firm, Moon Express, has proposed one such mission.
But perhaps most intriguingly, the Moon is likely to be a robust resource of the one of the solar system’s yet-untapped energy sources: Helium-3. He-3 can power nuclear fusion reactions cleanly, providing vast amounts of energy. If a way could be found to safely mine He-3 from the lunar regolith and transport it back to Earth, a permanent presence on the Moon could become a key stepping stone for the solar system. He-3 mining was taken to dramatic effect in Duncan Jones’ 2009 film, Moon, starring Sam Rockwell. While not achieving the budgetary or cultural impact of the 2015 blockbuster The Martian, it was a solid picture.
While the above advantages of the Moon make it an intriguing target for human exploration and colonization, it lacks arguably the most important resource necessary for the future of humanity within the solar system: the prospect of being terraformed to support life. With its carbon dioxide atmosphere, abundant water ice, and trickling brines, Mars is a hop-skip-and-science away from becoming a warmer world.
Watch this, uh… “space”… for details.