DARPA has released the first video of its robot Legged Squad Support System (LS3) walking untethered and in the wild. Scroll down and watch in awe as a robotic quadruped scales a rocky, forested hill while carrying a heavy load on its back.

The last time we saw LS3 (aka AlphaDog), back in September, it was tethered to external hydraulics. This made it impressively quiet, but obviously it couldn’t go outside. In the last few months, those hydraulics have been squeezed onto AlphaDog’s chassis, and an on-board petrol-driven motor powers the whole thing.

What will now follow is an 18-month platform-refinement test cycle to test and validate LS3’s performance, culminating in an actual field exercise where it will act as a pack mule for the US Marines. Before LS3 can be deployed, it must prove that it can carry 400 pounds (181kg) for 20 miles without being refueled and within 24 hours. Testing will also focus on AlphaDog’s vision sensors, which allow it to avoid obstacles or track (friendly) soldiers.

DARPA and Boston Dynamics (the dog’s creator) are currently looking at adding voice commands, so that Marines can tell AlphaDog to “sit”, “stop”, or “come here.” Hopefully an enterprising software engineer at Boston Dynamics also adds a “roll over” command — though maybe that’s not so wise if AlphaDog is tasked with carrying weapons. As an aside, and thanks to that petrol motor, AlphaDog also has a power outlet, which is obviously rather useful when you’re trekking across the desert and your iPod runs out of juice.

The end result is that American soldiers will no longer have to carry 100 pounds (45kg) of gear into battle. Presumably AlphaDog could also carry wounded soldiers, too — or, and I’m just throwing this out there, couldn’t infantry actually ride AlphaDogs into battle? Finally, let’s not forget that LS3 is a squad support system, which means that we could be looking at one AlphaDog for every nine soldiers in the US Army — imagine that marching into battle… perhaps with a few Cylonesque Petman robots thrown in for good measure…

Read more at DARPA, or check out more of our robotics coverage