SpaceX on Wednesday plans a third attempt to launch a space weather satellite from Cape Canaveral Air Force Station.
Liftoff of a Falcon 9 with the $340 million Deep Space Climate Observatory mission is scheduled for an instantaneous window at 6:03 p.m.
The forecast is excellent, with less than a 10 percent chance of weather violating launch rules.
Conditions looked good Tuesday, but high-altitude winds proved too strong for the rocket to fly through safely, resulting in the countdown being scrubbed a little over 10 minutes before a planned 6:05 p.m. liftoff.
"Safety prevails," said NASA TV commentator Mike Curie.
In a Twitter message earlier, SpaceX CEO Elon Musk noted "extreme wind shear" over the Cape that could push the rocket off course or stress it beyond levels it was designed to withstand at high speed.
"Feels like a sledgehammer when supersonic in the vertical," Musk explained.
Those upper-level winds are expected to be weaker on Wednesday.
The mission's first launch attempt on Sunday scrubbed when an Air Force tracking radar went down.
No launch attempt was made Monday because of a poor weather forecast, a smart call as it was raining heavily at launch time.
If the mission nicknamed DSCOVR can't launch by Wednesday, teams would stand down for more than a week, to Feb. 20. During that period, the moon's position would exert a gravitational pull on the flight that would require more propellant to overcome, NASA said.
Once it gets off the ground, the mission will send a satellite to a neutral orbit between the Earth and the sun, a million miles from Earth.
From there, the National Oceanic and Atmospheric Administration will monitor solar storms and use the data to provide alerts if blasts of magnetic field and charged particles could threaten satellites, power grids and other infrastructure.
The mission was first proposed in 1998 by then-Vice President Al Gore as an opportunity to transmit inspiring pictures of Earth over the Internet by the year 2000, and to perform climate research.
The spacecraft's two NASA science instruments are now considered a secondary part of the mission. Gore attended Sunday's countdown and was expected to attend Tuesday's as well.
NOAA currently relies on a 17-year-old NASA research satellite for that data. The agency partnered with NASA and the Air Force to revive the mission Gore and NASA originally called Triana.
The Triana mission faced political opposition and additional reviews that bumped it from a planned shuttle launch in 2000. Then it was canceled and placed in storage for a decade before emerging with a new name and focus.
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