Brazilian rain forest under watch 24/7. (Tech Talk).

A vast network of air, space and ground sensors looking over the Amazon has become the world's largest environmental monitoring program. Called SIVAM (System for the Vigilance of the Amazon), the $1.4 billion project connects more than 500 data-collecting elements, such as airborne sensors, ground-based sensors, air-traffic control radars and satellites. SIVAM covers a 2-million square-mile area, which contains 33 percent of the Earth's tropical forests and 20 percent of the world's fresh water. The Brazilian government uses SIVAM to try to catch illegal miners, drug traffickers, forest burners, illegal loggers and invaders of indigenous lands.

SIVAM's prime contractor is an American firm, the Raytheon Co. The U.S. Export-Import Bank provided most of the financing for the project.

"The countries that really need environmental protection don't have the money to pay for systems like SIVAM," said a Raytheon official. "The countries that have money, already have destroyed the environment," thus making SIVAM less useful for environmental monitoring. Wealthier countries are more likely to want to employ SIVAM to watch their borders for illegal immigrants.