The robot and bomb that killed the Dallas shooter

FBI agents check the scene around a police vehicle as it is lifted onto a hauler in the crime scene area in Dallas. Photo / AP

Much has been made of the fact that Dallas police used a robot to kill the gunman who fatally shot five officers last week.

A lot of speculation has gone into exactly what type of vehicle was used to carry the bomb to Micah Johnson's position, in what was widely reported as the first time that tactic was used on US soil.

Now, Dallas police have released additional details about the technology it used to end the standoff.

THE ROBOT

On Sunday authorities reported using a Remotec model F-5 to deliver a one-pound payload of C-4 and detonation cord to the target. In a news conference today, Dallas Police Chief David Brown clarified that officials used a Remotec Andros Mark V-A1.

The Mark V-A1 is manufactured by Northrop Grumman. It is driven by a human via remote control, weighs 358kg and has a top speed of 5.6km/h. It carries a camera with a 26x optical zoom and 12x digital zoom. When its arm is fully extended, it can lift a 27kg weight. The "hand" at the end of the arm can apply a grip of about 22kg of force.

A lot of attention has focused on the novelty of using a robot for offensive purposes and what it might mean for future policing, but it's actually very hard to discuss the ethics of this tactic without talking about the explosive used. The bomb type, how it was deployed, and what, if any, collateral damage may have been caused are all integral to our understanding of the incident.

It's not the bot, it's the bomb that needs an explainer.

THE BOMB

We know that police used a pound of C-4 explosive. But what does that mean? How much damage can that cause?

Well, C-4 is an extremely versatile bomb. Not only can it be used to blow things up wholesale, it can also be molded by hand to produce directional explosions. That allows users to punch holes through objects or break other things cleanly in two.

Unfortunately, without knowing whether or how the police had used a shaped charge, it's more difficult to know what the effects of the blast were. C-4 would probably have caused a great deal of damage, Matt Barnett, who runs Bonetti Explosives in Columbus, Texas, said.

"If I took a block of C-4 in there, or high explosives, there's a good chance I'm going to not just damage this guy really badly, but I'm also going to probably disrupt the building in a really bad way," Barnett said.

When C-4 explodes, the initial shock wave travels at a rate of 8m per second. A little over a pound of C-4 is enough to blow up a truck, which suggests that the payload used by Dallas police probably did quite a bit of damage.

Ann Hatch, a spokeswoman for the Dallas County Community College, which runs the building in which the shooter took refuge, told the Washington Post that college officials have not been allowed to assess the damage done to the building, because it was still under police control. But, she said, descriptions of where Johnson was killed by police - in a "garage" - are inaccurate. In fact, Johnson was on the second floor of a college building that occupies much of an entire city block.

How did the authorities get their robot bomb there? It's possible that they used a bank of lifts to get the robot to the correct floor, Hatch said.

As a parting note, it's important to point out that "robot" in this case simply means a remote-controlled car with an attached camera and an arm (as well as the bomb).

What defines a "robot" in popular language can span a huge range, covering everything from RC vehicles to semi-"smart" machines that can sense and avoid objects to fully sentient Terminator bots.

Although descriptive and sexy, the word "robot" has as much opportunity to mislead or hype as to clarify and illuminate. (Just a reminder not to get too carried away with the term.)