Public and private space enterprises are aiming to extract water from the Moon, which they hope to turn into rocket fuel to fly missions farther into our solar system. However, it's not yet clear how much water is available on or below the lunar surface.Why it matters: If NASA and others can extract water from the Moon, it would change exploration as we know it.Heavy rocket fuel would no longer have to be launched from Earth. Instead, resources from the Moon would effectively supply a stopover where spacecraft could fuel up for farther afield missions.That lunar water could be broken apart into oxygen and hydrogen, two elements needed for rocket fuel today.The fuel could then be transported to a depot in orbit that's easily accessible for ships that need to fill up before flying into deeper space.But, but, but: While scientists are pretty sure there's some water on the Moon, it's still not clear how much or whether it could be accessed easily and used as fuel.What's happening: NASA plans to send astronauts to the south pole of the Moon in 2024 as part of its Artemis mission."It's been dawning on the scientific community slowly, since the early 1960s, that the lunar poles might provide such an [ice-rich] environment," Ian Crawford of Birkbeck, University of London told Axios.The craters in the poles are thought to be potentially rich in ice — 100 million to 1 billion metric tons, according to some estimates — because they are permanently in shadow. But scientists still don't know much about the ice that might be there.NASA plans to find out how much ice is on the Moon in the coming years, with new missions like the Lunar Flashlight spacecraft expected to launch in 2020.If water is found and the agency can learn how to harvest it, NASA could potentially go on to mine resources from other bodies — like Mars, which would make missions to and from the Red Planet easier and cheaper.Yes, but: Mining on Earth is already incredibly difficult, with equipment parts that constantly need to be changed out. Mining elsewhere in the solar system will likely be even more challenging.Mining operations would also require large amounts of power, so that kind of infrastructure would need to be put in place on the Moon as well."The dose of realism is huge," says Clive Neal, an engineering professor at Notre Dame and organizer of a recent workshop about resource utilization on the Moon.Flashback: The LCROSS experiment slammed into the Moon in 2009 as the Lunar Reconnaissance Orbiter watched, catching a glimpse of water spewing from the impact site in a permanently shadowed crater.While the presence of that small amount of water is promising, it was just one sample from one area.Where it stands: In addition to NASA, some private spaceflight companies, like Jeff Bezos' Blue Origin, are focusing efforts on lunar water.The company's Blue Moon lander is expected to one day be fueled by hydrogen and oxygen extracted from water found on the Moon."Ultimately, we're going to be able to get hydrogen from that water on the Moon and be able to refuel these vehicles on the surface of the Moon," Bezos said in May at a press event unveiling Blue Moon.Editor’s note: This story has been updated with details related to Moon mining. Go deeper:Special report: Factory MoonWhat's in a moonshotHow NASA's Moon missions got their names