1/26/2011: First public appearance of TurtleBot, at Homebrew Robotics Club 2/15/2011: Introduction of ROS Answers[28] 4/18/2011: Willow Garage announces TurtleBot[29] 5/11/2011: First pure Java implementation of ROS announced at Google I/O 5/5/2011: ROS surpasses 100 repositories[30] 100th repository is rl-texplore-ros-pkg from the University of Texas at Austin 11/8/2011: 4th anniversary of ROS and video compilation published