It's a briefcase. Pizza box? No - it's a mini-satellite!

New York

RECENTLY, officials in California announced that the Camp Fire, the deadliest wildfire in the state's history, had been fully contained. The achievement was made possible through the hard work of firefighters on the ground, with some help from above: a swarm of tiny, orbiting satellites that represent the next phase of the space age.

The satellites are operated by Planet Labs, a company in San Francisco that runs the world's largest fleet of Earth-observing satellites. Its craft number around 140. All of them carry cameras and telescopes. In size, most rival a loaf of bread.

As a group, the satellites can view the same spot on the ground once or even twice a day. Until now, commercial satellites could observe a location only weekly or monthly, if at all. The quicker pace enables the close monitoring of rapid environmental change, including fires, floods, volcanic eruptions, earthquakes, hurricanes and the effects of such events on urban areas.

"You can't fix what you can't see," said Will Marshall, the company's chief executive. The Camp Fire, which started Nov 8, was closely monitored the next day by a Planet Labs team in Sacramento, which began streaming surveillance data to the war room where state officials coordinated the response.

The governor's office of emergency services used the satellite imagery to help map the fast-moving flames and determine whether individual buildings were intact, damaged or destroyed. "It's situational awareness," said Brittany Zajic, head of disaster response for Planet Labs. "The damage assessments were done neighbourhood by neighbourhood."

The Planet Labs fleet is part of a larger trend towards miniaturisation. Satellites may be shrinking in size but are expanding in ambition. Made smaller, the craft are less expensive and more accessible to a wider group of interests, and they enable, among other advances, the ability to observe Earth's environment more completely and regularly than ever before.

The debut of the iPhone in 2007 signalled to a new generation of satellite-makers that their creations, too, could shrink. Early models were called PhoneSats because their electronic cores were made of smartphones. The satellites cost just US$7,000 apiece.

Typically, the new spacecraft cost so little to build and send aloft that universities and even high schools are getting into the act. On Nov 10, students from six high schools in Irvine, California, cheered as their tiny craft was carried into orbit. Its mission: to study Venus. NYTIMES