This flotilla of 21st-century moon explorers should arrive bristling with technologies that will help them map the moon’s uncharted regions and prospect for resources that could one day sustain lunar outposts and missions further afield.
The crew of the final Apollo mission lifted off from the moon’s Sea of Serenity on 14 December 1972. After that, three robotic Soviet spacecraft made it to the surface, the final one in 1976. For the next few decades, the moon’s only visitors were a dozen or so orbiters and deliberate crashes.
Launched on 2 December, the Chang’e-3 mission was scheduled to touch down in a 235-kilometre-wide crater known as the Bay of Rainbows. The spacecraft has already slipped into an orbit that takes it within 15 kilometres of the surface. To make the soft landing, it needed to fire retrorockets to adjust its position, cut off its engine and ultimately drop from a height of 4 metres.
“Hopefully the lander doesn’t tilt,” says Bernard Foing, director of the International Lunar Exploration Working Group, a forum sponsored by multiple space agencies. Once on the surface, the lander should set free a rover named Yutu – which translates as “Jade Rabbit” – after the mythological pet of lunar goddess Chang’e.
India and South Korea are also in the running to send missions to the moon that would involve combinations of landers and rovers. India could launch its Chandrayaan-2 mission by 2017, while the newly proposed Korean mission won’t be lifting off before 2020.
“The moon is the nearest island in space out from the Earth,” says Igor Mitrofanov at Russia’s Institute for Space Research in Moscow, the project scientist for two planned Russian-led rover missions. As countries develop their space programmes, the moon is a natural first foray beyond Earth that allows remote-controlled robots to get their sea legs while staying within a 10-second call of the planet’s shores.
But the moon is more than a test bed for space missions. China’s Yutu rover will venture a few kilometres away from its landing site to snap images, take stock of minerals with on-board spectrometers and probe below the surface with radar. It could reveal different episodes of volcanism at the site, which is covered with solidified lava.
“To know the origin and evolution of the moon is to know those of Earth,” saysTatsuaki Hashimoto of the Japan Aerospace Exploration Agency, the lead scientist for a proposed lunar rover called SELENE-2. The moon is thought to have coalesced from the debris of an impact between a Mars-sized world and Earth some 4.5 billion years ago. “It’s a part of the Earth,” says Foing. “I call it the eighth continent.”
Several of the proposed exploration missions are targeting the moon’s poles, which have never been visited by a lander. But data from orbiters support the idea that the rocks and shadowed craters at both poles contain millions or even billions of tonnes of water ice. Studying the water’s isotopes and any organic material it might hold in deep freeze could shed light on where Earth got its water and the building blocks of life, says Foing.
The damp moon could also be a useful resource for future robotic and human exploration, says Paul Spudis of the Lunar and Planetary Institute in Houston, Texas. Astronauts could drink moon water extracted from its rocks, or use it as radiation shielding.
Water’s hydrogen and oxygen could also be broken apart for use as rocket fuel. Much of the weight of today’s rockets comes from their own propellant, so having a source of fuel already in space would pave the way for much more ambitious human missions.
“If we’re really interested in extending our reach to Mars and beyond, we don’t want to have to bring fuel with us,” says Anthony Colaprete of NASA’s Ames Research Center in Moffett Field, California. He is the project scientist on a proposed robotic mission called Resource Prospector, which could launch in 2018 to try to extract water from lunar rocks.
Private groups are also hoping to get in on the action. The Google Lunar X Prize is offering $20 million to the first team that by the end of 2015 launches a lunar spacecraft that can land on the moon, travel 500 metres and send back video. Some of the teams vying for the prize also have their sights set on selling lunar-derived rocket fuel. And a US-based firm called Shackleton Energy Company says it wants to send robots and teams of human miners to the moon to supply water for fuel depots that it would place in Earth orbit.
Scott Pace, director of the Space Policy Institute at George Washington University in Washington DC, is sceptical that a private company will be able to raise the money needed to put together such a massive project. Still, he agrees that mining fuel from the moon makes sense, and he notes that most of the world’s space agencies, with the exception of the US, want to send astronauts to the moon.
Once again China may be leading the renewed charge, with a potential human mission that could take place after 2025. “I personally believe that this is the beginning of the epoch of the permanent stay of humans on the moon,” says Mitrofanov.