BBC News | In Depth | War on terror

The war in Afghanistan has seen the US extend its surveillance capabilities with a new unmanned surveillance aircraft, the Global Hawk. Designed to fly for up to 24 hours at up to 60,000 feet, it aims to circle a target without being shot down. The aircraft collects information with:

Optical/photographic equipment

Infra-red scanning

Synthetic Aperture Radar
Synthetic Aperture Radar produces radar images which are so sharp they appear to be aerial photographs. Coupled with infra-red images, it could provide extremely detailed information of a target area which may, for instance, reveal an entrance in the side of a mountain.

See also:
Synthetic Aperture Radar (US Govt site)
More on surveillance aircraft

		3. Aerial surveillance The war in Afghanistan has seen the US extend its surveillance capabilities with a new unmanned surveillance aircraft, the Global Hawk. Designed to fly for up to 24 hours at up to 60,000 feet, it aims to circle a target without being shot down. The aircraft collects information with: Optical/photographic equipment Infra-red scanning Synthetic Aperture Radar Synthetic Aperture Radar produces radar images which are so sharp they appear to be aerial photographs. Coupled with infra-red images, it could provide extremely detailed information of a target area which may, for instance, reveal an entrance in the side of a mountain. See also: Synthetic Aperture Radar (US Govt site) More on surveillance aircraft