Describes information learned about Mars from past Mariner probes. Discusses future space probes that are expected. (RH)

Describes scientific research on an Earthwatch expedition to study Arenal, one of the world's most active volcanoes, in north central Costa Rica. The purpose of the two-week project was to monitor and understand the past and ongoing development of a small, geologically young, highly active stratovolcano in a tropical, high-rainfall environment.…

Demonstrates the magnitude of an extinction event by using a simulation to illustrate the massive nature of the loss of a family and the number of species that perish to achieve that result. (RT)