The RAT is located on the arm of the rover and weighs about 1.6 pounds. It uses three electric motors to drive rotating grinding teeth into the surface of a rock. Two grinding wheels rotate at high speeds. These wheels also rotate around each other at a much slower speed so that the two grinding wheels sweep the entire cutting area. The RAT is able to grind through hard volcanic rock in about two hours.
Once a fresh surface is exposed, scientists can examine the abraded area in detail using the rover's other science instruments. This means that the interior of a rock may be very different from its exterior. That difference is important to scientists as it may reveal how the rock was formed and the environmental conditions in which it was altered. A rock sitting on the surface of Mars may become covered with dust and will weather or change in chemical composition from contact with the atmosphere.
These latest discoveries have led to some consternation among the gambling community. Book-makers have stopped taking bets on the question of whether there was ever life on Mars. A major bookmaker's spokesperson says the latest odds in favor of past life on Mars were 16-1. Back in the 1970s, when the first bets were placed, the odds were 1,000-1.