Solar breeze

Abstract

With the assistance of the Moon's gravitational field, NASA will launch the Wind spacecraft November 1 to the forward libration point to study the physics of the solar‐terrestrial system. Eight instruments aboard the 1250‐kg satellite will measure various quantities in the solar wind about 1 hour before it reaches the Earth. The highly quantitative measurements will help scientists predict how changes in solar wind affect the Earth's atmosphere. “Extensive use has been made of ‘intelligent’ instruments, and they are able to operate in a wide variety of modes and productivity will be high,” says Keith Ogilvie, deputy project scientist. “It's pretty modern stuff,” Ogilvie says. Wind is the first of two missions of the Global Geospace Science (GGS) initiative, the U.S. component of the International Solar‐Terrestrial Physics program. The launch of Polar, the second GGS satellite, is slated for late 1995. Polar is designed to measure the flow of plasma within Earth's magnetosphere. Both craft, which together cost about $458 million to develop, are part of a larger project to provide simultaneous, interactive data on key regions of Earth's space environment, from beyond the Earth foreshock region to the magnetosphere to transient gamma ray events.