Today's planned launch of the twin GRAIL (Gravity Recovery and Interior Laboratory) spacecraft, which are being sent into orbit about the Moon at the end of the year, are the latest in a series of unmanned spacecraft that have in the past few years revolutionised our understanding of our nearest neighbor in space.
GRAIL will measure minute fluctuations in the Moon's gravity field, changes that reveal what's going on beneath the surface and down to its core. Inside information is essential to understand the Moon, how it formed and how it developed into a world of craters, mountains and vast lava plains. For some the more we find out about the Moon the greater is the urge to add to the twelve sets of footprints made in the lunar soil forty years ago. But when we return seems more uncertain than ever.
There is a moment in the film Apollo 13 when Tom Hanks, portraying astronaut Jim Lovell, surveys his crippled spacecraft, and turns to his colleagues and says, "We just lost the Moon."
Of the Moon President Obama has said, "We've been there. Buzz has been there." In place of the previously planned and much studied manned return to the Moon there was to be a manned mission to an asteroid in 2025, and a Mars orbital flight some 10 years later. President Obama says that we've been there - and we have, but only six times, with the longest stay being just three days and three hours. The US has taken a decision that will result in it losing the Moon.
Sending a crew to rendezvous with a passing asteroid in deep space way beyond the Moon's orbit is in many respects a more challenging mission than a lunar landing. It will involve a new spacecraft, months in space, advanced life-support systems and rendezvous techniques, as well as technically demanding spacewalks.
Beyond that, there is the Red Planet. Undoubtedly Mars is the first true "world" of the cosmos, a place of far greater variety and importance than our seemingly barren Moon. In a sense, the manned landing on the Moon was just a precursor to the landing on Mars - with its mountains, canyons bathed in morning mist, outwash plains, shifting sand dunes and the possibility of life. But the wonders of Mars do not distract from the promise of the Moon.
Just as the United States is turning away from the Moon, Russia's major space company has said it is designing a new spacecraft that would carry six astronauts into space. Room for a few money-spinning space tourists no doubt, but also the basis for a lunar spacecraft. China has an expanding space effort, and although it hasn't formally said so, it intends to land astronauts on the Moon. In reality, they would be making a few short-duration, Apollo-like trips more than 50 years after the US did it, but that won't stop many Americans disliking the fact that the Chinese will be on the Moon and they will not. The head of Nasa, former astronaut Charles Bolden, once told a congressional committee it didn't matter if China landed on the Moon before the US. "It does to me, and I think it does - with respect - to a lot of Americans," the Republican representative for Virginia, Frank Wolf, interjected.
For the exploration of space, a base at the lunar south pole has more long-term importance than a manned flight to Mars or a trip to an asteroid. Using current technology manned flights to Mars are too expensive and would never get funded. It just has to be the moon. The Mars mission is in 25 years away, at least. We could have a Moonbase in 15, possibly sooner.
We should let future generations of science-hungry children have science lessons from the rim of Shackleton Crater at the lunar south pole at a place called by some the "peak of eternal light". It is in sunlight for all but a few hours every month because from this part of the Moon the Sun skirts the horizon and never truly rises or sets. These shadowlands, where the shadows move like the hands of a clock, are a perfect place for solar panels to generate electricity. Next to the peak of eternal light are the craters of perpetual night; there is nothing like them on any other world in our solar system, and in their depths may be ice deposits.
The Moon of today is far different from the Moon we thought we understood when the Apollo astronauts returned home with their boxes of Moon rocks. Orbiting unmanned spacecraft have discovered vast deposits of ice in the darkness of some polar craters. In lunar rocks there is everything required for supporting life - and many industrial processes. It's all there: hydrogen, aluminum, iron, helium and oxygen. The discovery of ice at the lunar poles changed everything. Before, it was thought that hydrogen was the scarcest commodity on the Moon, but now that ice has been detected the economics of a lunar outpost have changed dramatically. Water - oxygen and hydrogen - is also rocket fuel. By any ergonomic and strategic analysis, the Moon base sits at the heart of a sensible solar system exploration plan.
Generations of inspiration-deprived schoolchildren have grown up without watching a man on another world. What type of a world have we made when we limit the next generation's ambitions, or when a child cannot dream of walking on the moon?