Washington, May 9: In a bid to show its seriousness about taking its “flying car” concept off the ground, ride hailing company Uber has signed a second space act agreement with NASA. The pact aims to further explore concepts and technologies related to urban air mobility (UAM) to ensure a safe and efficient system for future air transportation in populated areas. Under this agreement, Uber will share its plans for implementing an urban aviation rideshare network, NASA said in a statement on Tuesday.