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LIVE: Atlas V 401 - GPS IIF-7 - August 01, 2014
by
beidou
on 21 Feb, 2014 18:08
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#1
by
russianhalo117
on 21 Feb, 2014 19:23
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This is going to be the third GPS launch in just half a year 
do we know the SVN number GPS IIF-7 yet.
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#2
by
beidou
on 21 Feb, 2014 19:29
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This is going to be the third GPS launch in just half a year
do we know the SVN number GPS IIF-7 yet.
As GPS IIF-5 is SVN 64, and SVN 65 and 66 were already taken by GPS IIF-3 and 4, so GPS IIF-6 should be SVN 67 and GPS IIF-7 should be SVN 68, which is just a wild guess.
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#3
by
beidou
on 28 Apr, 2014 18:34
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#4
by
beidou
on 21 May, 2014 20:06
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Predict PRN3, secondary possibility PRN8.
There is also possibility for PRN4, which was assumed to be take by GPS IIF-6; but the just launched IIF-6 already took PRN6.
"04/34 D4 Rb1 IIA Rephase out of slot D4...will be replaced by upcoming SVN67"
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#5
by
macpacheco
on 21 May, 2014 21:59
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Predict PRN3, secondary possibility PRN8.
There is also possibility for PRN4, which was assumed to be take by GPS IIF-6; but the just launched IIF-6 already took PRN6.
"04/34 D4 Rb1 IIA Rephase out of slot D4...will be replaced by upcoming SVN67"
Removed the first post, my logic was incomplete and likely wrong.
PRN 3 / SVN 33 will likely be shutdown to free up almanac space.
Once PRN 3 is shutdown, PRN 3 and PRN 9 will be available for assignment.
Based on past behavior, PRN 9 will be assigned (the one that has been offline the longest).
My real bet is on what GPS IIA will be shutdown to free up almanac space.
There is almost zero chance PRN 4 or PRN 8 will be decommissioned instead, since they are replaced by IIF-5 and IIF-6 both of which are still in checkout, and they typically wait until it's operational for a good time (say 6 months) before becoming first choices for shutting down the satellite it replaced.
Even if IIF-7 gets delayed by as much as two months, the prediction stays the same.
It has been common to keep 3 satellites doing the job of 2 paired orbital slots.
PRN 3 replacement SVN 66 / PRN 27 has been operational since 06/21/2013.
The comment from NGA doesn't make much sense, since IIF-6 is replacing PRN 4 / SVN 34. But PRN 4 should stay online until IIF-6 completes its checkout and is set healthy for a while before SVN 34 gets shutdown (probably for IIF-9 or IIF-10)
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#6
by
beidou
on 22 May, 2014 20:19
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The comment from NGA doesn't make much sense, since IIF-6 is replacing PRN 4 / SVN 34. But PRN 4 should stay online until IIF-6 completes its checkout and is set healthy for a while before SVN 34 gets shutdown (probably for IIF-9 or IIF-10)
NGA is probably more authoritative than most of people in this forum. Your statement on GPS IIF-6 uses PRN 6 is definitely wrong - it is using PRN 6 and its signals have been tracked by many receivers around the world.
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#7
by
macpacheco
on 22 May, 2014 21:42
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The comment from NGA doesn't make much sense, since IIF-6 is replacing PRN 4 / SVN 34. But PRN 4 should stay online until IIF-6 completes its checkout and is set healthy for a while before SVN 34 gets shutdown (probably for IIF-9 or IIF-10)
NGA is probably more authoritative than most of people in this forum. Your statement on GPS IIF-6 uses PRN 6 is definitely wrong - it is using PRN 6 and its signals have been tracked by many receivers around the world.
Yes IIF-6 is broadcasting using PRN6, that's correct. But what you don't get is that its broadcasting an
unhealthy signal, and it will take at least about a month its checkout period testing to be completed, only after the checkout is complete the satellite will start broadcasting a healthy signal. Until healthy, the satellite should only be used for the express purpose of testing the satellite.
Even after IIF-6 is set healthy, the observed procedure is to keep the new and the old satellite broadcasting for many months (over a year when possible).
PRN 30 (SVN 64) replaces PRN 8 / SVN 38 and PRN 9 / SVN 39. The latter is already decommissioned, but the former should stay online for many months AFTER SVN 64 is set healthy (USABINIT NANU).
PRN 06 (SVN 67) replaces PRN 4 / SVN 34. As I explaned, SVN 34 should be kept operational for many months after SVN 67 is set healthy (USABINIT NANU).
I my lingo, a GPS satellite is not operational until it's set HEALTHY, right now SVN 64 and SVN 67 are broadcasting an unhealthy signal, so it's not operational (only special receivers set to track unhealthy signals are even capable of tracking those signals).
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#8
by
jacqmans
on 04 Jun, 2014 10:35
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From L2:
SLC-41 – Atlas V / GPS IIF-07
Launch scheduled > 8/1/14 (Range Approved)
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#9
by
gwiz
on 04 Jun, 2014 10:41
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I my lingo, a GPS satellite is not operational until it's set HEALTHY, right now SVN 64 and SVN 67 are broadcasting an unhealthy signal, so it's not operational...
SVN 64 was set healthy on May 30.
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#10
by
Targeteer
on 05 Jun, 2014 07:54
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Since it hasn't been stated yet, I'll pick a fight and start the arrows headed my way... Here's the first launch of what we now know may now turn out to be a finite number of Atlas 5/RD-180 cores with a payload that is ALREADY Delta IV qualified. In several years a payload requiring an Atlas 541 or 551 may be seriously delayed because the RD-180 was "wasted" on a GPS satellite fully capable of riding an RS-68...
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#11
by
beidou
on 27 Jun, 2014 23:18
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Count down on gps.gov website.
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#12
by
jacqmans
on 30 Jun, 2014 09:48
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From L2:
SLC-41 – Atlas V / GPS IIF-07
· Launch scheduled > 8/1/14, window: 2327L-2345L. (Range Approved)
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#13
by
BabaORileyUSA
on 01 Jul, 2014 16:46
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"...the first launch of what we now know may now turn out to be a finite number of Atlas 5/RD-180 cores with a payload that is ALREADY Delta IV qualified..."
I would call this the second. GPS_IIF-04 (a.k.a. Navstar-066, a.k.a. USA-0242, a.k.a. Vega) was launched on an Atlas-V(401) after three consecutive successful flights of the GPS_IIF on Delta-IVs. The number of RD-180s has always been, and will continue to remain, finite! :-)
-BabaORileyUSA
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#14
by
Targeteer
on 02 Jul, 2014 00:00
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"...the first launch of what we now know may now turn out to be a finite number of Atlas 5/RD-180 cores with a payload that is ALREADY Delta IV qualified..."
I would call this the second. GPS_IIF-04 (a.k.a. Navstar-066, a.k.a. USA-0242, a.k.a. Vega) was launched on an Atlas-V(401) after three consecutive successful flights of the GPS_IIF on Delta-IVs. The number of RD-180s has always been, and will continue to remain, finite! :-)
-BabaORileyUSA
USA-242 was launched on 15 May 2013, long before there was threat of the RD-180 supply being cut off and ULA could blissfully "waste" an awesome, cheap engine to launch a payload that didn't require it because there was an endless supply.
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#15
by
macpacheco
on 18 Jul, 2014 00:36
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Since it hasn't been stated yet, I'll pick a fight and start the arrows headed my way... Here's the first launch of what we now know may now turn out to be a finite number of Atlas 5/RD-180 cores with a payload that is ALREADY Delta IV qualified. In several years a payload requiring an Atlas 541 or 551 may be seriously delayed because the RD-180 was "wasted" on a GPS satellite fully capable of riding an RS-68...
The real issue should be: Is this launch needed right now for constellation sustainment ?
The answer is not really. The GPS constellation as of right now is better than ever.
Another question, would the cost of storing those satellites on the ground be higher than launching them: Perhaps
Launching IIF-7 and IIF-8 makes some technical sense as they clean up the way to launching IIIA-1 when its ready (fulfilling the 24+3 orbital layout even with all GPS IIA birds retired).
But launching IIF-9/10/11/12 as scheduled makes increasingly less sense (regardless of which booster is used). While ground storage costs money, latter launch would extend the service life of those satellites.
All GPS IIF satellites should still be serving us past 2030, with most of the lasting past 2040 and some all the way into 2050.
What if there is a major problem with IIIA satellites ? Having a few IIF on ground storage gives flexibility to launch them on more pressing orbital slots in the future should anything unplanned happen.
GPS satellites don't die sequentially. Although they provide quite a bit of early warning, having a strategic reserve of IIF satellites on the ground until the first IIIA is fully tested is a wise move (that isn't contemplated in the current GPS launch planning).
There is a lot of bureaucratic inertia in the GPS constellation sustainment process.
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#16
by
Jim
on 18 Jul, 2014 00:43
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Another question, would the cost of storing those satellites on the ground be higher than launching them: Perhaps
Not perhaps, but it is.
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#17
by
baldusi
on 18 Jul, 2014 01:30
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Macpacheco, weren't you the one saying that they were not replenishing fast enough and should increase the rate?
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#18
by
Lar
on 18 Jul, 2014 03:25
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Another question, would the cost of storing those satellites on the ground be higher than launching them: Perhaps
Not perhaps, but it is.
I think clearly the cost of X years of storage plus a launch in year X+1 is higher than a launch in year 1, unless the cost of launch in year X+1 is enough lower than the cost in year 1 that it covers the storage cost. So Jim is likely right, because launch costs are not likely to come down. Ever. No matter what happens.
But I don't think that's the right question. The right question is to ask what is the total cost of ownership of the entire GPS constellation (as birds die and get replaced) over the next N (where N is some large number, say 50) years. And I think there the argument can be made that IF you have sufficient on orbit spares already, why launch another spare now? Assuming the on orbit life is not diminished by storage, launching way more birds now than you need means you need replacement birds sooner and your TCO goes up.
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#19
by
baldusi
on 18 Jul, 2014 04:35
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IIF has the new signals. This is also about accelerating service improvements.
