10 YEARS AGO — APRIL 8, 1999

Spacecraft gives close-up of the moon: The Lunar Prospector spacecraft is being launched into a 18.5-mile orbit around the moon, helping scientists better estimate the concentration and form of hydrogen detected at the north and south lunar poles. Scientists at NASA Ames Research Center, Moffett Field, Calif., suspect that hydrogen may indicate the presence of ice deposits. The mission will assist in magnetic and gravitational field mapping and confirm initial global maps.

30 YEARS AGO — APRIL 12, 1979

Construction equipment — Moving the earth with technology: To commemorate our 50-year anniversary, Machine Design takes a look at the changes that have evolved over the past 50+ years i n construction equipment and how it has changed the face of the Earth with machines that steadily have grown in size, power, speed, and precision.

50 YEARS AGO — APRIL 2, 1959

Electrostatic chuck holds any metal, some nonmetals: A new electrostatic chuck rigidly holds all electrically conductive materials, as well as any solid nonmetallic material if its chucking surfaces are flashed with a conductive coating only 5 millionths of an inch thick. Developed by Electroforce Inc., Fairfield, Conn., the chucking equipment includes a Dri-Box, where the work is kept moisture- free at slightly above room temperature. A coolant pump and filter supply clean dielectric coolant. Chucking procedures are similar to those used in magnetic chucking, with work instantly gripped and released by a simple control switch. The chuck operates on 110 Vac and is adaptable to standard machines.