Late last week, astronomers at the University of California and the Lawrence Berkeley National Laboratory made an announcement that stunned the astronomical community. Current cosmological theories say that as gravity applies a celestial brake to the outward thrust provided by the Big Bang, the expansion of the universe will gradually slow down. Not so, said these astronomers. The universe seems to be expanding more and more rapidly. This finding, if correct, will force many basic assumptions about the universe to be reexamined.

Plus... On Thursday, scientists from NASA's Lunar Prospector mission announced that there "is a high probability that water ice exists at both the north and south poles of the moon." This finding agrees with data from the 1996 joint military/NASA Clementine mission, which provided scientists with the first hints of water at the moon's south pole.

The finding comes just two months after the launch of Prospector, which was sent to map the surface of the moon. The signals from the water ice, spotted by an instrument called a neutron spectrometer, indicate that the water ice is not concentrated in any one spot or in a thick layer. Rather, the ice appears to exist as tiny crystals mixed with lunar soil in low concentrations (as low as 0.3 to 1 percent), spread out over a large number of craters in the polar regions.

Moon ice, it is thought, can only exist in permanently shadowed craters. The lunar atmosphere is so thin that if sunlight hit the ice, it would instantly sublime (transform from solid directly to gas). Prospector detected the equivalent of 11 million to 330 million tons of ice - however, because the signal from the spectrometer only can penetrate half a meter into the lunar surface, and scientists believe that ice could exist to a depth of 2 meters, there could be as much as four times that amount actually present. There is twice as much ice at the lunar north pole as at its south pole.

On this segment of Science Friday - a trip to the moon and back, in just thirty minutes.