NASA have conducted research with helicopters since its foundation. Since the beginning participated in partnership with the Armed Forces, the Defense Advanced Research Projects Agency (DARPA) and others in advanced projects like the XV-3, the S-72 or the GL-10.
Many crash tests have help make helicopters safer with new materials that can keep passengers safe in the event of helicopter crashes and with wind tunnel tests investigates how to make quieter, bigger and faster helicopters. More recently NASA has even studied how helicopters could be flown on Mars. A mission to the red planet carrying a small drone helicopter is scheduled for 2020