It is the news space enthusiasts had been hoping for. Next week, NASA is to make another attempt to launch the shuttle Discovery. July 26 is the designated date for lift-off, now that engineers have found the likely causes of the fuel sensor problem that foiled the first launch attempt last week. Time is running out for a successful link-up with the International Space Station, which must be in the right position in orbit. If Discovery’s astronauts do not get airborne before the end of the month, they will have to wait until September.The flight will be NASA’s first since the loss of the shuttle Columbia and its crew in February 2003.