I'm always going on about how we should spend more money on exploring the deep oceans instead of planning on another trip to the moon but now I might change my mind. It has to do with impact events and the effect they've had on the Earth. There could be tonnes of earth rock on the moon which could contain fossils or organic signals of microbial activity at the start of life on this planet.
The evidence of life on Earth as long ago as 3.8 billion years is based on rock chemistry rather than fossils. Finding sedimentary rocks of the kind that could contain fossils older than 3.5 billion years is a virtually impossible task considering plate tectonics. They still could be found as geologists discovered Ophiolites, the remnants of the ancient seafloor crust which had escaped the tectonic re-cycling.
The moon's surface is littered with rocks many of which could be from Earth and older than found here. Asteroid impacts fling huge quantities of material into space.
The K/T (Cretaceous/Tertiary) event which is generally thought to have wiped out the dinosaurs has left an impact layer spread all over the world. While most material fell back to Earth, some would have been propelled into space even landing on Mars but the closest landing would have been the moon.
In 2001, John Armstrong joined with L. Wells and G. Gonzalez to calculate how much material would reach the moon after a large impact. They calculated that the impact of a body, 100 metres in diameter would deposit about 120 kilograms of Earth rock on each squae kilometres of the lunar surface.
Between 4.2 and 3.8 billion years ago, in a heavy bombardment of a solar system wide event, Earth was struck by thousands of asteroids that were K/T sized or bigger. So rocks landing on the moon and containing evidence of the beginning of life on Earth would still be lying around. As life on Mars and Venus might have been going around this stage, there may be proof of this as well.
It's worth a trip to answer a rocketship load of questions about our origins. As long as we keep the military in any country from having anything to do with it.