GPS Satellite Launch Coming October 30, 2015

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jimh
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GPS Satellite Launch Coming October 30, 2015

Postby jimh » Thu Oct 15, 2015 2:02 pm

October 30, 2015 is the scheduled date for the launch of the U.S. Air Force NAVSTAR GPS satellite GPS IIF-11. This will be the second to last of the Block IIF-series of satellites. GPS IIF-11 is the eleventh in the Block IIF series. These satellites feature improvements and enhancements over previous generations of GPS satellites. The most notable of these is the addition of more civilian signals which will provide users with a much enhanced position fix accuracy by being able to adjust for real-time variations in the speed of signal propagation through the ionosphere. Of course, users will need more sophisticated GPS receivers to obtain this improvement. The situation is much like the classic cart-and-horse problem. Before there can be GPS receivers to use the improved signals there must be satellites in orbit to provide them.

Assuming all goes well for GPS IIF-11, the GPS constellation will then have 11 of the newer satellites in orbit, in a total constellation of 32 active satellites. That means about one-third of the GPS constellation will be of the modern Block IIF design, and there should be a high probability that one of the Block IIF satellites will always be overhead for any user.

The launch vehicle will be an Atlas V-401 from United Launch Alliance (ULA). As usual, the ULA website will have a live broadcast of the launch.

For more details, see:

http://www.ulalaunch.com/

http://continuouswave.com/ubb/Forum6/HTML/003777.html

https://en.wikipedia.org/wiki/List_of_GPS_satellites

jimh
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Re: GPS Satellite Launch Coming October 30, 2015

Postby jimh » Thu Oct 29, 2015 8:13 am

This launch is still scheduled for October 30--that's tomorrow. Don't forget to watch the webcast. The launch window opens at 12:17 p.m. EDT.

jimh
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Re: GPS Satellite Launch Coming October 30, 2015

Postby jimh » Fri Oct 30, 2015 10:25 am

Due to some problems with ground equipment at the launch pad, the GPS IIF-11 launch has now been postponed to Saturday, October 31, 2015. The launch window opens at 12:13 p.m.

jimh
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Re: GPS Satellite Launch Coming October 30, 2015

Postby jimh » Sat Oct 31, 2015 12:40 pm

The launch of GPS IIF-11 was successfully accomplished on schedule today. I watched the live broadcast. The close-up long-range camera views of the rocket booster engine in flight were spectacular, the best I've ever seen.

It was fun to watch our government launch $1-billion into space.

A good video replay is available from

https://www.youtube.com/watch?v=MkRZeEtumNE

jimh
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Re: GPS Satellite Launch Coming October 30, 2015

Postby jimh » Tue Nov 03, 2015 1:40 pm

Perhaps the most significant difference between the Block IIF GPS satellites and the earlier designs is found in the lack of a rocket propulsion motor as part of the satellite. The Block IIF satellites are launched directly into their final orbits by their rocket launch vehicle, while in earlier GPS satellite designs the satellites had their own rocket motor. These earlier satellites propelled themselves into their final operational orbit after having been launched by a rocket booster into a transfer orbit.

Typically the GPS satellite operational orbit is a nearly circular orbit with a height of 12,500-miles. The typical method for deployment is to initially launch the satellite into an elliptical transfer orbit, with widely different apogee and perigee heights. As the satellite transfer orbit approaches apogee around 12,500-miles, a further rocket burn propels it into a circular orbit at that altitude.

To get an idea of the size of a satellite, here is an image with some men working on a GPS IIF satellite in the foreground:

http://www.insidegnss.com/auto/popupimage/GPSIIF_photo_lo.jpg

Plans for GPS IIF-11 (SVN73) are to orbit in Slot 2 of Plane E, and to broadcast its GPS signals with PRN 10.

If your thirst for information on GPS IIF-11 is not slackened, then read more at NASASPACEFLIGHT.COM

As always, good sources of up-to-date information on GPS satellites are

http://gpsworld.com/the-almanac/

and

http://www.nstb.tc.faa.gov/rt_waassatellitestatus.htm