Drones could mitigate terrorist attacks.

• Author: Tadjdeh, Yasmin

* When a pressure cooker bomb exploded in April 2013 during the Boston marathon, three people were killed and hundreds were injured. Had a drone been employed to watch over the race, it is possible the attack could have been prevented, said one unmanned aerial vehicle expert.

Before the explosions, the terrorists--Dzhokhar Tsarnaev and Tamerlan Tsarnaev--dropped bags that contained the bombs near the crowded race route.

"If we had had drones with the appropriate kinds of cameras, with the appropriately trained people watching the video feeds ... there is a possibility ... [law enforcement] would have had a much better chance of spotting that suspicious activity," said Michael Braasch, a professor of electrical engineering at Ohio University who specializes in UAV technology.

Drones provide law enforcement with a unique vantage point and serve as eyes in the sky. Such technology, coupled with surveillance payloads, works well in crowd situations where police officers often have limited situational awareness.

Historically, police departments have used helicopters to keep watch over crowds, but they can be noisy and expensive.

"It's not really the best way to be conducting surveillance," he said. "Having drones allows law enforcement to do the surveillance much more economically and, frankly, much more efficiently."

Using a variety of sensors, including electro-optic and multi-spectral, officials may be able to pinpoint the location of bombs. Multi-spectral sensors can detect...