The QuickBird satellite, launched in 2001, can see objects down to 24 inches across, from an orbit 279 miles up. IKONOS orbits higher, at about 430 miles and can see objects as small as three feet.
It's part of a longstanding AAAS project to use image analysis and satellite data such as GPS to monitor humanitarian crises in troubled regions such as Nigeria, Zimbabwe, South Ossetia, Afghanistan and Myanmar.
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The AAAS said its image analysis wasn't perfect -– the high population density in Aleppo means that tall buildings can cast shadows.
But a lot of detail can still be picked up. In a neighborhood called Salaheddine, for example, smoke is visible above an urban area too tightly packed to reveal street-level changes.
Getting information about Syrian troop movements has been difficult at best; few news organizations operate inside the country and those that do have to navigate between areas controlled by the opposition.
Top photo: Recently-constructed "revetments" - barriers to protect from artillery and probably mortar positions - are visible near Aleppo airport on Aug. 9.