Though they were originally supposed to launch on Thursday, August 23, the twin Radiation Belt Storm Probes (RBSP) are now scheduled for takeoff on Sunday, August 25. The window of opportunity opens at 04:07 am EDT (0807 GMT), and lasts for 20 minutes.
The previous two delays were all caused by technical glitches, but this early morning's was brought on by several weather violations. The NASA
Weather Office had announced less than 50 percent chance of favorable weather for today.
After the 20-minute launch window closed this morning, mission managers decided to reschedule for tomorrow. However, forecasts indicate only a 40 percent chance of favorable weather on Sunday.
Once in orbit, RBSP will study the Earth two Van Allen radiation belts. The goal is to learn more about the factors that influence space weather.