How did that get there? How Iran may have obtained their new UAV
A lack of damage to the aircraft suggests it was not fired upon, nor did it have a severe crash. The UAV's landing could have been caused by a glitch in the Army's network, or it could have been the result of electronic warfare.
Of course, Iran is claiming they shot down or hacked the UAV for violating Iranian airspace.
The idea the UAV was brought down by physical force is unlikely due to the lack of damage that was shown in Iranian photographs and video. There are, however, two more likely scenarios in the form of electronic attack or electronic failure.
Now, Iran has been subject to a few severe electronic attacks in their time. Stuxnet, a worm that was unleashed on Iran's nuclear program, proved that Iran would need to evolve their own electronic warfare if they were to compete in today's military environment. Whether this was the cause of the RQ-170's crash is yet to be determined, but the lack of evidence of a physical attack and Iran's claims do make it plausible.
While having the UAV undergo an electronic attack could possibly lead it to an easy descent directly into Iranian hands, other explanations are equally valid. The Department of Defense said they lost control of the UAV earlier in the week, and that it simply ended up descending into Iran with absolutely no control.
The UAV did not suffer a harsh crash, but it has been speculated that the aircraft would have a more leaf-like descent rather than a strict nose-dive like many other aircraft. The large wings may have slowed the vehicle and allowed it to land relatively unscathed.
Until more research has been done, how the UAV got into Iranian hands is unknown. Let's hope this was a rare mistake by the DoD and that no critical information can be gleaned from the UAV's surviving electronics.