Iffy forecast for 4th try to launch Atlas V, spy satellite

An Atlas V rocket returned to its pad Thursday morning for a fourth attempt to launch a classified national security mission from Cape Canaveral Air Force Station, planned before dawn Saturday.

Launch of the National Reconnaissance Office's NROL-52 mission is scheduled for 3:31 a.m. Saturday.

Weather, which scrubbed the first two launch attempts last Thursday and Friday, again looks iffy.

The threat of showers, thunderstorms and lightning combine for a 40 percent chance of conditions meeting launch rules during the window, whose length was not disclosed but based on previous countdowns is expected to last about a half-hour. 

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The outlook improves to 60 percent favorable if the launch slips to Sunday, according to the Air Force's 45th Weather Squadron.

After the two weather scrubs, a third launch countdown was cut short last Saturday by a faulty telemetry transmitter on the rocket.

On Monday, United Launch Alliance rolled the rocket from its pad back to a processing tower called the Vertical Integration Facility, or VIF. There crews installed and tested a replacement transmitter.

The mission then had to wait for a SpaceX mission to take flight, which it did on its first attempt at sunset Wednesday.

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ULA is trying to launch its seventh mission of the year — and last of 2017 from Cape Canaveral.

The satellite on top of the nearly 200-foot rocket is speculated to be a communications relay bird, part of a system that routes intelligence collected by spacecraft in lower orbits to analysts on the ground.

Atlas V set to launch secret U.S. spy satellite early Thursday

The mission is ULA's 26th for the NRO, the  U.S. agency responsible for fielding and operating spy satellites, and third of those this year.

Contact Dean at 321-242-3668 or jdean@floridatoday.com. And follow on Twitter at @flatoday_jdean and on Facebook at facebook.com/jamesdeanspace.

Launch Saturday

Rocket: United Launch Alliance Atlas V (421 configuration)

Mission: Classified NROL-52 for National Reconnaissance Office

Launch Time: 3:31 a.m. EDT

Launch Window: Not disclosed

Launch Complex: 41 at Cape Canaveral Air Force Station

Weather: 40 percent “go”

Join floridatoday.com at 3 a.m. Saturday for countdown chat and updates, including streaming of ULA’s launch webcast starting at 3:11 a.m.