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USAF To Launch GPS IIF2 Satellite Early Thursday Morning

Article by: Mike Barrett
Date: 12 Jul 2011

A GPS satellite is to be launched into orbit early thursday morning from Cape Canaveral Airforce Station in Florida. This will be the GPS IIF-2 satellite the second in a new family of GPS spacecraft which are designed to increase GPS signal accuracy, provide more robust signals for Civilian and Commercial Aviation and improve the military signals to provide better resistance to jamming.

The GPS IIF-2 satellite is scheduled to blast off at 6:49 GMT ( 2:49am EST or 7:49am UK time). PocketGPSWorld.com will be at Cape Canaveral to cover the launch. The launch window is 18 minutes allowing the rocket to lift off at any time between 6:49 and 7:08 GMT. The exact launch time will be determined on the day and may be affected by a number of things such as the weather, or technical issues.

Florida has entered the tropical summer weather pattern now where there is a build up of cloud throughout the day resulting in some interesting thunder storms mid to late afternoon, then the weather settles down again. The forecast for Wednesday night and Thursday morning is favourable: partly cloudy (50% reducing to 30% overnight) with a 30% chance of rain.

The GPS 2F satelliteThe Launch Commit Criteria for a non-human rocket launch is less stringent than that for the Space Shuttle so the GPS Rocket can be launched with quite a lot of cloud cover. Obviously the main concern would be lightning, but any thunderstorms in the area will be long gone at launch time.

The GPS IIF satellite will be launched from Launch Complex 37B at Cape Canaveral Air Force Station by United Launch Alliance (ULA). This Launch Complex is dedicated to launching Delta IV rockets.

The GPS IIF-1 satellite was the first GPS to be launched on the Delta IV Launch Vehicle, all the previous GPS Satellites were launched on Delta II rockets. This rocket is flying in the Delta IV Medium+ configuration with 2 'small' solid rocket boosters to help the rocket get off the launch pad.

Delta 4 GPS 2F rocket detailThe rocket itself consist 2 stages and the Payload. The first stage booster is Oxygen and Hydrogen fuelled and is know as the Common Booster Core. To give it a good start it has 2 solid rocket boosters attached at the bottom. The solid rocket boosters burn for just over 1.5 minutes and are ejected a few seconds after burning out. The Common Booster Core will continue lifting the rocket until 4 minutes into the flight, at which point it will cut off and will separate from the second stage and the payload.

The second stage will fire three times to raise the GPS satellite into the correct orbit. This will occur about 3.5 hours after launch when the second stage will perform an "End Evasive Manoeuvre" to ensure it does not collide with the satellite. After that the GPS Satellite is on its own and will undergo a series of tests before being inserted into the operational GPS Constellation.

To keep abreast of what is happening you can follow @mikepgps on twitter, there will also be live coverage of the launch on ULA's website. Coverage starts at 1:53am EDT or 6:53am BST.

Posted by alanwalker on Wed Jul 13, 2011 5:48 am Reply with quote

Are we as Sat Nav users, likely to notice any improvement in our GPS signal performance?

Posted by davemcwish on Wed Jul 13, 2011 8:31 am Reply with quote

alanwalker Wrote:
Are we as Sat Nav users, likely to notice any improvement in our GPS signal performance?

According to this accuracy could get down to ~1m (from the currect ~3m. Whether this will fully be available for all non-military uses is open to question. From what I've read on the Geocaching forum, to get this accuracy you'd also need new device(s) that can receive the additional signal that's generated.

TomTom 940 GO Live
Garmin Oregon 650
Apple iPhone 5S

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