NASA radiation mission awaits third launch attempt. Photo: NASA- TV.
Efforts to launch NASA's twin Radiation Belt Storm Probe mission spacecraft were scrubbed for a second time early Saturday by the threat of off shore thunderstorms.
A third attempt to launch the United Launch Alliance Atlas 5 401 rocket carrying the two 1,400 pound probes from Space Launch Complex-41 at Cape Canaveral Air Force Station, Fla., was re-scheduled for Sunday at 4:07 a.m., EDT, the start of a 20 minute window.
Forecasters offered a 40 percent chance of favorable weather for the attempt. Stormy conditions to the south and east of Cape Canaveral on Saturday violated launch weather rules for lightning and flight through cumulus clouds. Wind gusts associated with Tropical Storm Isaac and cloud cover will be a concern on Sunday.
The first attempt to start the two-year $686 million mission for studies of high energy particle fluctuations in the Earth's twin Van Allen radiation belts was scrubbed on Friday by a drift in frequency noted in the C-band transponder on the Atlas 5. Mission managers elected to proceed with the defective hardware but activated additional ground-based C-band radar tracking assets for the ascent.
Saturday's countdown reached a prolonged four-minute hold without technical issues. The scrub was called as the 20 minute launch period expired.