Contestants from around the world met in Pomona, California, this month to test their skills at things like driving a car, walking down stairs, and opening doors. Sounds easy, right? But the competitors weren't people--they were robots! The bots were participating in  the final round of the US's DARPA(Defense Advanced Research Projects Agency) Robotics Challenge. This event, which took place on June 5-6, tested robots on how well they could respond during a disaster and the winning team finally took home a $2 million grand prize. The DARPA challenge was created after the 2011 Fukushima nuclear disaster in Japan. An earthquake caused a tsunami, which damaged a nuclear power plant. Workers at the plant needed to shut off an important valve , but it was too dangerous for humans to reach it. The US scientists at DARPA wondered whether the disaster could have been avoided if a robot had been sent to do _ . So they set up the robotics competition. Turning a valve was just one task a robot might have to perform when entering a disaster zone. In addition to doing this, robots participating in the challenge had to navigate a course containing several other tasks: driving and exiting a vehicle, opening a door, walking over or clearing objects, cutting a hole in a wall, plus climbing a flight of stairs. Teams had to complete the challenge in one hour, and points were awarded based on how quickly the robots completed a task. They didn't have to attempt all the tasks. To make things even more realistic, challenge organizers caused short computer-system blackouts  that prevented robots and the human operators controlling them from communicating. That means teams had to program their robots to be partially autonomous . Robots also couldn't be attached to anything that could keep them from falling down, which happened a lot. What is the text mainly about?
A nuclear disaster. A research program. A robotics competition. A scientific organization.