December 14, 2017

Preview: Atlas 5 rocket goes for its third launch of October

Credit: ULA
Credit: ULA

CAPE CANAVERAL — The penultimate satellite in the current generation of Global Positioning System spacecraft will be deployed Friday, capping a hectic four weeks with three launches from two coasts for the Atlas 5 rocket fleet.

The GPS replenishment mission comes on the heels of the Oct. 2 commercial launch of the Mexican Morelos 3 telecommunications satellite from Florida’s Cape Canaveral and the Oct. 8 classified flight for the National Reconnaissance Office from California’s Vandenberg Air Force Base.

It’s the busiest month in Atlas 5 rocket history.

“With 100 launches under your belt, half of those being Atlas, you have a lot of data of what you can do and can’t do,” said Tory Bruno, United Launch Alliance president and CEO.

“We have basically, since the beginning of ULA, shortened the span to integrate and launch in half, and we are now going to cut that in half again.”

Carrying the $245 million GPS 2F-11 navigation satellite, liftoff of the United Launch Alliance rocket is planned Friday during a 19-minute window of 12:17 to 12:36 p.m. EDT (1617-1636 GMT).

An artist's concept of GPS 2F. Credit: Boeing
An artist’s concept of GPS 2F. Credit: Boeing

As its name implies, this is the 11th spacecraft in the dozen built by Boeing for the Air Force under the Block 2F program. The craft have featured improved accuracy, better anti-jamming and longer design lives than previous designs.

“As we reach the final stages of the GPS 2F series, we stand ready to launch the next GPS 2F space vehicle,” said Col. Steve Whitney, director of the Global Positioning Systems Directorate.

“The 2F satellites provide improved accuracy through better clocks, longer design life and a third civil signal for aviation and safety-of-life applications. It also includes a more robust military signal that started with the GPS 2R-M family of satellites.”

The new craft will replace the GPS 2R-10 launched aboard Delta 302 on Dec. 21, 2003 in Plane E, Slot 2 of the constellation. The old craft moves to an alternate role in the network once the fresh GPS 2F-11 enters service.

The 12-satellite Block 2F project began launching in 2010 to form the backbone of the GPS fleet for the next 15 years.

GPS 2F-1: May 27, 2010 (Delta 4) Plane B, Slot 2
GPS 2F-2: July 16, 2011 (Delta 4) Plane D, Slot 2A
GPS 2F-3: Oct. 4, 2012 (Delta 4) Plane A, Slot 1
GPS 2F-4: May 15, 2013 (Atlas 5) Plane C, Slot 2
GPS 2F-5: Feb. 20, 2014 (Delta 4) Plane A, Slot 3
GPS 2F-6: May 16, 2014 (Delta 4) Plane D, Slot 4
GPS 2F-7: Aug. 1, 2014 (Atlas 5) Plane F, Slot 3
GPS 2F-8: Oct. 29, 2014 (Atlas 5) Plane E, Slot 1
GPS 2F-9: March 25, 2015 (Delta 4) Plane B, Slot 1F
GPS 2F-10: July 15, 2015 (Atlas 5) Plane C, Slot 3

GPS 2F-11: Friday (Atlas 5) Plane E, Slot 2
GPS 2F-12: February (Atlas 5)

This will be the 71st GPS satellite launch since 1978, the 16th to use an Atlas rocket and the fifth Block 2F on Atlas 5.

There are 31 satellites in operation today — two GPS 2As, 12 GPS 2Rs, 7 GPS 2R-Ms and 10 GPS 2Fs.

The continuous navigation signals emitted by GPS satellites allow users to find their position in latitude, longitude and altitude and measure time. A GPS user receiver measures the time delay for the signal to reach the receiver, which is the direct measure of the apparent range to the satellite.

Measurements collected simultaneously from four satellites are processed to solve for the three dimensions of position, velocity and time.

ULA mission poster. Credit: ULA
ULA mission poster. Credit: ULA

The launch marks the 59th Atlas 5 rocket since 2002 and the 23rd for the Air Force since 2007. For United Launch Alliance, it is the company’s 102nd launch overall since 2006 and the 11th this year.

The rocket will be flying in its 401-configuration, which is powered by the RD-180 main engine burning kerosene and liquid oxygen on the first stage and an Aerojet Rocketdyne RL10C cryogenic liquid hydrogen and liquid oxygen upper stage. The payload is shrouded in an aluminum fairing 14 feet in diameter and 39 feet long.

As the most-used Atlas 5 variant, the 401 has flown on 28 previous missions. It will mark the 65th flight of the RD-180 engine, the 463rd production RL10 engine to be launched and the 8th RL10C-1.

The Launch Readiness Review is scheduled for Wednesday to grant authority to proceed with rollout of the rocket to the pad. That transfer occurs Thursday morning.

Countdown clocks will begin ticking a little after 5 a.m. EDT on Friday as the vehicle stages are powered up and the launch day regiment begins. Fueling will get underway shortly after 10 a.m. EDT.

An artist's concept of the rocket's initial flight path. Credit: ULA
An artist’s concept of the rocket’s initial flight path. Credit: ULA

Weather forecasters are projecting a 90 percent chance of favorable launch conditions.

“On launch day, high pressure begins to establish itself across the Space Coast giving way to partly cloudy skies and a minimal shower threat during the count. Winds will be north-northeast gusting into the mid-teens,” Air Force meteorologists say.

The ascent profile for AV-060 follows an initial flight azimuth of 45.8 degrees to the northeast and features two burns by the Centaur upper stage, separated by a three-hour coast period, to insert the payload into a circular 11,047 nautical mile orbit at 55 degrees inclination. Deployment of GPS 2F-11 is expected at T+plus 3 hours and 23 minutes, or 3:40 p.m. EDT (1940 GMT) given an on-time liftoff.

See earlier GPS 2F-11 coverage.

Our Atlas archive.

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