Problems with GPS WAAS satellite 48

[DougPaul]

There have been some recent problems with WAAS satellite #48--the transponders are still working, but it does not respond to commands. It is possible that it will soon cease WAAS transmissions. (I can receive it right now.) http://www.insidegnss.com/node/2030

This satellite covers mostly the west coast and the Pacific. (Intelsat GXV, at 133W, shown in red)

Here in the NE, I mostly see WAAS satellite #51 (Telesat F1R, at 107W, shown in green)--I can also receive it right now. (Inmarsat 4F3, at 98W, #46, shown in yellow, is still under test.)


Fear not, your GPSes will still work perfectly well for hiking without the use of WAAS (error reduction). FWIW, I generally have WAAS turned off on mine...

Doug

 

[DougPaul]

Another report: http://www.gpsworld.com/gps/news/waas-broadcasting-satellite-having-problems-9810?print=1

Doug

 

[Little Rickie]

Who's seen the movie "Independence Day"?

Has anyone looked for a countdown sequence?

 

[DougPaul]

The WAAS satellite is expected to drift out of usable orbit in two to four weeks. Plans are being investigated to switch to another satellite or replace it.
http://www.gpsworld.com/gnss-system...news/failure-imminent-waas-geo-satellite-9841

PRN 133 = sat #46
PRN 135 = sat #48
PRN 138 = sat #51
(subtract 87 from the PRN # to get the sat #)

Doug

 

[Little Rickie]

The WAAS satellite is expected to drift out of usable orbit in two to four weeks. Doug

How can that happen?

 

[DougPaul]

How can that happen?

The WAAS satellites are in geosynchronous orbits. Minor perturbations cause them to drift away from the desired locations. The ground-based controllers track the satellites and command them to fire thrusters to keep them on station. In this case, the loss of control prevents the controllers from sending the orbit modification commands.

The useful lifetime of satellites is often limited by the amount of fuel on board. The final steering act for many satellites is a movement from its design orbit to an out-of-the-way parking orbit. (The satellite itself may remain in orbit for hundreds of years--higher orbits last longer due to less atmospheric resistance.) Such a move to a parking orbit may not be possible here...

Doug

 

[WinterWarlock]

How can that happen?

The earthquake in Chile did move the earth off it's axis...maybe the satellite got lost when that happened.