Researchers have discovered two new examples of the rarest space rocks found on Earth: meteorites from the moon and Mars. The two rocks are the 15th and 17th meteorites to be found from the moon and Mars, respectively, making them the least common among the estimated 22,000 meteorites discovered on this planet. News of the discoveries was announced this month and will be reported in the July 2001 bulletin of the Meteoritical Society, an international organization devoted to the study of extraterrestrial material.