<Tr> <Th> Manufacturer </Th> <Td> Lockheed Martin </Td> </Tr> <Tr> <Th> Status </Th> <Td> Design proposal </Td> </Tr> <P> The Lockheed Martin SR - 72 is a conceptualized hypersonic UAV intended for intelligence, surveillance and reconnaissance proposed by American company Lockheed Martin to succeed the retired Lockheed SR - 71 Blackbird . </P> <P> The SR - 71 Blackbird retired in 1998, leaving what is considered a coverage gap between surveillance satellites, manned aircraft, and unmanned aerial vehicles for intelligence, surveillance and reconnaissance (ISR) and strike missions . With the growth of anti-satellite weapons, anti-access / area denial tactics, and counter-stealth technologies, a high - speed aircraft could penetrate protected airspace and observe or strike a target before enemies could detect or intercept it . The proposed reliance on extremely high speed to penetrate defended airspace is considered a significant conceptual departure from the emphasis on stealth in fifth - generation jet fighter programs and projected drone developments . </P>

What took the place of the sr-71 blackbird