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GPS III Scheduled for Launch December 2018

Posted: Wed Dec 05, 2018 8:51 am
by jimh
The United States Air Force, the operators of the NAVSTAR Global Positioning System widely know as just GPS, are on the verge of deploying the next generation GPS III satellites. At the moment there are ten GPS III-series satellites in production. Launch of the first GPS III satellite by a SpaceX Falcon 9 rocket is scheduled for December 2018--that is this month. The tentative launch date and time are Tuesday, December 18, 2018 at 9:10 AM EST, less than two weeks away.

As the previous GPS IIF-series was being completed, nine satellites were launched from 2013 to 2016 in a steady pace of launches. The last of the GPS IIF-series satellites was launched in February 2016, two years and ten months ago, and we have had a rather long pause in GPS satellite launches since then. One reason for the delay in deployment of GPS III satellites was the longer-than-expected service life of the GPS II series satellites, as well as delays in preparation of the ground segment to support the new GPS III series satellites.

The launch with a SpaceX Falcon 9 rocket will also be a first. Previously the Air Force used United Launch Alliance rockets for GPS satellites, either Delta IV or Atlas boosters.

The first eight GPS III series satellites will have a total estimated cost of about $4.4-billion, or an average cost of about $550-million per satellite.

The GPS III series satellites will provide a new civilian signal, the L1C, which will enable increased accuracy in position fixing for civilian receivers capable of using both L1 C/A (CoarseAcquisition) and L1C signals.

The new GPS III-series satellites will also carry receiver-relay transponders for the SARSAT rescue beacons, a global international cooperative system for search and rescue. (Read more about EPIRP and SARSAT next-generation systems in my article from December 2016.)

To control and manage these new satellites, a next-generation Operational Control Segment called OCX has also been developed. OCX is now in Block 0 status, ready to begin to work with the first GPS III satellites in orbit.

Most current marine GPS receivers will not be able to use the new L1C signal. A new generation of receiver modules will need to be brought to market.

A short promotional presentation from Lockheed-Martin, the builder of the GPS III satellites, gives a rapid overview of their capability and size:

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 05, 2018 11:29 am
by Dutchman
Does [GPS Modernizaton] mean we need to get new [GPS receivers] in the next couple of years?

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 05, 2018 3:00 pm
by jimh
The GPS will likely continue to provide the L1 C/A signal for years and years to come. More than a billion people use it globally.

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 05, 2018 9:00 pm
by jimh
Re improved accuracy available with GPS III: for marine navigation, extreme accuracy is generally not a necessity. First of all, marine navigation is really only in one plane. Ships already know their elevation: sea level. Second, nautical charts are generally not extraordinarily precise. Often the charted location of a marine chart object is based on surveys done decades ago, when precision position location was not possible. It does not make much sense to be able to know your position with a resolution to less than six-inches of error if you then plot your position on a chart with errors of maybe as much as 200-feet or in some cases 2,000-feet. For these reasons, marine GNSS receivers have so far not been able to use the highest possible accuracy available in GNSS systems. That said, the L1C signal, when used in conjunction with the L1 C/A signal, will deliver improved accuracy over just using the L1 C/A signal, the signal now used by civilian users in GPS.

At one time, maritime users of GPS were a significant portion of the user base, but now, with billions of land-based users, maritime users are just a small segment of GPS users. For land-based users, the improved position accuracy provided by the L1C signal in GPS III-series satellites will mean that GPS receivers will be able to know in what lane on a multi-lane highway a vehicle is travelling.

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 05, 2018 9:14 pm
by jimh
By the way, SpaceX launched a Falcon 9 rocket today on a successful mission to re-supply the International Space Station. I watched a live broadcast (via youTube streaming) of the launch. The main booster of the Falcon 9 was intended to return to Cape Canaveral and land on the SpaceX landing pad there. SpaceX had a perfect record going of successful land-based landing and recovery of the first stage rocket booster.

Today there was a malfunction in the rocket's grid fins--control surfaces that help steer the rocket as it descends at high speed--and the rocket began a rather rapid roll during descent. The autonomous controls recovered from the roll just before the rocket landed, but the on-board safety system prevented the rocket from heading to land. Instead the Falcon 9 landed in shallow water just off Cape Canaveral. It was a nice landing, but the sea bottom could not support the rocket in a vertical position, and it gently tipped over into the sea. SpaceX will recover the rocket. They described the cause of the grid fin failure as a stalled hydraulic pump.

The mission for the GPS III launch is denoted as a non-recoverable-booster mission. This may be due to the weight of the payload and the height of the orbit insertion for the GPS III mission. In order for the booster to be able to land itself, the rocket has to reserve some propellant for that function. For launches where the payload is heavier and the orbit is higher, the rocket may have to use more propellant for the launch mission, and there may not be enough left for a safe landing.

I am looking forward to watching the GPS III launch on December 18, 2018. It should be a very interesting mission, the first time a GPS satellite will be launched on a SpaceX Falcon 9 rocket.

Re: GPS III Scheduled for Launch December 2018

Posted: Fri Dec 14, 2018 2:32 pm
by jimh
There are just a few days to go before the GPS-III SV-01 launch. The SpaceX Falcon 9 booster will be launching in the expendable mode, meaning there will not be any attempt to recover the first stage. There is speculation that the contract with the Air Force for this mission calls for that provision. The Falcon 9 must retain some rocket propellant if it is to be recovered, but for this mission the Air Force appears to want all available propellant to be dedicated to the launch mission. I can't blame them: the payload is worth more than a half-billion dollars.

Be sure to watch on Tuesday, December 18. I expect the live-broadcast via streaming will be available from

Re: GPS III Scheduled for Launch December 2018

Posted: Mon Dec 17, 2018 3:21 pm
by jimh
The launch time is now scheduled for about 9 a.m. EST on Tuesday. Don't miss the live coverage.

Re: GPS III Scheduled for Launch December 2018

Posted: Tue Dec 18, 2018 10:16 am
by jimh
OOPS--at T-minus seven minutes a problem with an onboard computer on the Falcon 9 rocket caused a hold. The hold duration caused the launch window to expire for today. Another window is available on Wednesday morning, again around 9 a.m. The launch has been postponed until then. Tune in tomorrow.

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 19, 2018 10:19 am
by jimh
This morning, Wednesday, December 19, 2018, the re-scheduled launch of the GPS III SV-01 by the SpaceX Falcon 9 rocket was again scrubbed. SpaceX is said to be conducting more investigation into the cause of the problem that scrubbed the initial launch attempt on Tuesday, December 18, 2018. There has been no date given for the next attempt to launch.

SpaceX Twitter Feed wrote:Standing down from today’s launch attempt of GPS III SV01 to further evaluate out of family reading on first stage sensors; will confirm a new launch date once complete.

3:32 AM - 19 Dec 2018

"Out-of-family reading" probably means that some parameter being monitored by more than one sensor was showing different values on different sensors.

Space X Website wrote:SpaceX is standing down from today's launch attempt of the United States Air Force’s first Global Positioning System III space vehicle (SV) from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station, Florida to further evaluate an out of out of family reading on first stage sensors. A new launch date will be confirmed once this evaluation is complete.

The SpaceX Falcon 9 rocket has previously flown successfully with many payloads, but this mission is its first attempt to carry a large GPS satellite into a medium-earth orbit for the U.S. Air Force.

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 19, 2018 5:48 pm
by jimh
I was very disappointed that the launch of GPS III SV-01 was delayed again for a second day, but to make up for that lack of live web streaming of big rocket launches, I turned to ArianeSpace and their launch TODAY of the French military reconnaissance satellite OCS-1 from the Ariane SpacePort in French Guyana with a Russian Soyuz booster. As usual, the broadcast was hosted and narrated by Katy Haswell, a fantastic presenter who speaks marvelously in both English and French. The replay is available on youTube and is very enjoyable. The Soyuz booster and Frigate final stage appear to have delivered the payload to a perfect insertion orbit. Bravo.

Re: GPS III Scheduled for Launch December 2018

Posted: Wed Dec 19, 2018 10:37 pm
by jimh
SpaceX Website wrote:SpaceX is now targeting Thursday, December 20 for launch of the United States Air Force’s first Global Positioning System III space vehicle (SV) from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station, Florida. Weather remains a challenge, currently forecasted at 20% favorable during the 26 minute launch window, which opens at 9:03 a.m. EST, or 14:03 UTC.

Launch is re-scheduled, but the weather looks unfavorable.

Re: GPS III Scheduled for Launch December 2018

Posted: Thu Dec 20, 2018 9:06 am
by jimh
Thursday launch was scrubbed due to weather. They can’t launch in rain and high winds.

Re: GPS III Scheduled for Launch December 2018

Posted: Fri Dec 21, 2018 9:53 am
by hauptjm
Looks like they will try again tomorrow (12-22-2018) at 8:55am EST

Re: GPS III Scheduled for Launch December 2018

Posted: Sat Dec 22, 2018 9:26 am
by jimh
Saturday's launch has been scrubbed due to upper level winds being too high. The launch is now rescheduled for Sunday, December 23, 2018, at about 8:51 a.m.

This mission is having a hard time getting off the ground. I hope Sunday's weather is a go-for-launch situation.

Re: GPS III Scheduled for Launch December 2018

Posted: Sun Dec 23, 2018 4:31 pm
by jimh
Here is good news: the GPS III SV-01 satellite was lifted into orbit successfully this morning, and separated from its booster rocket. That completed SpaceX's part of the mission. (And I watched the whole thing live via SpaceX's streaming--very enjoyable to see this mission go well.)

Lockheed-Martin, the builder of the satellite, is reporting that GPS III SV-01 has been acquired by ground control and is responding to command signals. That may sound a bit blasé, but this operation is critically important. The spacecraft is running on limited internal power. Ground control must establish communication to begin further operation and control of the spacecraft; deployment of the solar panels is necessary to get power going for further operation.

Here a portion of the press release:

    DENVER, Dec. 23, 2018

    GPS III Space Vehicle 01 (GPS III SV01) is now receiving and responding to commands from Lockheed Martin's Launch and Checkout Center at the company's Denver facility. Air Force and company engineers declared satellite control signal acquisition and rocket booster separation about 119 minutes after GPS III SV01's launch. The satellite lifted off from Cape Canaveral Air Force Station, Florida aboard a SpaceX Falcon 9 rocket at 8:51 a.m. EST.

    GPS III SV01 is the first of an entirely new, next generation GPS satellite designed to modernize the GPS constellation. GPS III has three times better accuracy and up to eight times improved anti-jamming capabilities. Spacecraft life will extend to 15 years, 25 percent longer than any of the GPS satellites on-orbit today. GPS III's new L1C civil signal will also make it the first GPS satellite broadcasting a compatible signal with other international global navigation satellite systems, like Europe's Galileo, improving connectivity for civilian users.

    Once declared operational, GPS III SV01 is expected to take its place in today's 31 satellite strong GPS constellation, which provides positioning, navigation and timing services to more than four billion civil, commercial and military users. The Air Force nicknamed the satellite "Vespucci" after Italian explorer Amerigo Vespucci.

    "In the coming days, GPS III SV01 will use its liquid apogee engines to climb into its operational orbit about 12,550 miles above the earth. We will then send it commands to deploy its solar arrays and antennas, and begin on-orbit checkout and tests, including extensive signals testing with our advanced navigation payload provided by Harris Corporation," said Johnathon Caldwell, Lockheed Martin's Vice President for Navigation Systems.

    Air Force and Lockheed Martin engineers are controlling GPS III SV01's launch and checkout test using elements of the GPS Next Generation Operational Control System (OCX) Block 0. Satellite control and operations are expected to shift to the Air Force's current Operational Control Segment when GPS III Contingency Operations upgrades are fully implemented later this year.

    "This is the Air Force's first GPS III, so we are excited to begin on-orbit test and demonstrate its capabilities," Caldwell said. "By this time next year, we expect to also have a second GPS III on orbit and users should be receiving signals from this first satellite."

    Lockheed Martin developed GPS III and manufactured GPS III SV01 at its advanced $128-million GPS III Processing Facility near Denver. In September 2017, the Air Force declared the satellite "Available for Launch" (AFL) and had the company place it into storage. Last summer the Air Force "called up" the satellite for launch and Lockheed Martin delivered it to Florida on Aug. 20. On Dec. 8, GPS III SV01 completed pre-launch processing, fueling and encapsulation at Astrotech Space Operations, in Titusville, Florida.

    GPS III SV01 is the first of 10 GPS III satellites originally ordered by the Air Force. GPS III SV03-08 are now in various stages of assembly and test. In August, the Air Force declared the second GPS III "AFL" and, in November, called GPS III SV02 up for a 2019 launch.

    In September, the Air Force selected Lockheed Martin for the GPS III Follow On (GPS IIIF) program, an estimated $7.2 billion opportunity to build up to 22 additional GPS IIIF satellites with additional capabilities. GPS IIIF builds off Lockheed Martin's existing modular GPS III, which was designed to evolve with new technology and changing mission needs. On Sept. 26, the Air Force awarded Lockheed Martin a $1.4 billion contract for support to start up the program and to contract the 11th and 12th GPS III satellite.

    Lockheed Martin is proud to be a part of the Air Force's GPS III team. The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center. Air Force Space Command's 2nd Space Operations Squadron (2SOPS), based at Schriever Air Force Base, Colorado, manages and operates the GPS constellation for both civil and military users.

    For additional GPS III information, photos and video visit: .

Re: GPS III SAR-SAT Payloads

Posted: Mon Dec 24, 2018 11:41 am
by jimh
Earlier in this thread, I wrote:

jimh wrote:The new GPS III-series satellites will also carry receiver-relay transponders for the SARSAT rescue beacons, a global international cooperative system for search and rescue.

While that statement is true, I just came across some information that suggest the SAR-SAT payloads won't be on the first ten satellites. (See a public presentation on GPS III). An illustration showing evolution of GPS satellites indicates that the Search & Rescue or SARSAT payload won't be added to the GPS III satellites until the second phase (or follow-on phase) of production, which will occur with the 11th satellite in the GPS III series. See below:

Fig. 1. Illustration from public release presentation for GPS III modernization, page 6 of original.
schaub-6.png (70.53 KiB) Viewed 9302 times

According to that same presentation, GPS III SV-11 is not planned to be available for launch (AFL) until fiscal-year-2025 ends, or about October 2025.
Fig. 2. Portion of illustration from public release presentation for GPS III modernization, page 9 of original.
schaub-9.png (9.06 KiB) Viewed 9299 times

The delay for the SAR until SV-11 in the GPS III series is also mentioned in a Wikipedia article.

In contrast, there are 15 GALILEO satellites now in orbit with an operational SAR receiver-relay payload. (More information on GALILEO SAR capabilities and general SAR-SAT status available.) Also, there are 20 present GPS II-series satellites with SAR-SAT transponders, but they are using a different downlink, S-band. More information on those 20 GPS II-series satellites is in a separate article. The GPS III follow-on satellites will have an L-band downlink for SAR-SAT. The L-band downlink is the SAR-SAT standard for ground stations to receive emergency beacon data relayed from satellites.

Re: GPS III Scheduled for Launch December 2018

Posted: Tue Dec 25, 2018 1:03 am
by jimh
The GPS III F (follow-on or second phase) satellites will have some other enhancements, in addition to the SAR-SAT L-band downlink transponders.

Regional Military Protection capability will allow the GPS III F series to deliver increased anti-jamming capabilities by using a spot-beam antenna to concentrate signal power to a smaller footprint.

The GPS III F series will also have laser reflector targets to allow for ultra-precise measurement of their actual range from ground stations with lasers.

And improved nuclear detonation detectors will be on board the GPS III F satellites.

The S-band uplink/downlink for telemetry and control will also be improved.