Lunar Radio Astronomy

Two groups of engineers and scientists are looking at projects that would put an array of radio telescopes on the far side of the Moon to study what astronomers call the "dark ages"-- the time immediately after the Big Bang, before there were galaxies, or even stars. Studying that era, when simple hydrogen atoms dominated the universe, physicists hope will result in a better understanding of the Big Bang itself.

One of the projects being considered is called DALI, the Dark Ages Lunar Interferometer. It would be an array of perhaps one thousand radio telescopes deployed over an area of perhaps 30 square miles. Working together, they would constitute one huge instrument, like arrays operating now in Australia, the Netherlands, and New Mexico.

DALI would have the advantage over those arrays of being on the far side of the Moon; the Moon itself would block all the radio noise of Earth, allowing scientists to pick out the faint glow of the first hydrogen. Such an array, of course, would also be ideal for pursuing another first, the first radio signal from an extraterrestrial civilization. To pursue that project, the individual telescopes would need to be steerable, which would add complexity to what would already be a huge, complex construction job, but the pay off could be dazzling.