An approaching storm threatens to delay NASA’s next launch attempt for the New Moon rocket, already grounded for weeks by fuel leaks. A tropical depression in the southern Caribbean is moving toward Florida and could become a major hurricane. Managers said Friday that the rocket is ready to launch Tuesday on its first unmanned test flight after overcoming more hydrogen leaks during a fueling test earlier in the week. NASA said it would continue to monitor the forecast and decide by Saturday whether to not only delay the launch, but withdraw the rocket from the pad and return it to the hangar. Officials said it was unclear when the next launch attempt would be — whether in October or even November — if the missile had to be sheltered indoors. It takes three days of preparation to return the rocket to Kennedy Space Center’s mammoth Vehicle Assembly Building, four miles away. “I don’t think we’re limiting it,” said NASA’s Tom Whitmeyer, deputy associate administrator for exploration systems. “We’re just taking it one step at a time.” This would be the third launch attempt for the Space Launch System rocket, the most powerful ever built by NASA. Fuel leaks and other technical problems scuttled the first two attempts. The 322-foot (98-meter) rocket can withstand gusts of 85 mph (137 km/h) on the pad, but only 46 mph (74 km/h) once underway.