[Thanks Jon!]

GPS Modernization
50th Space Wing Completes GPS 24+3 Constellation Expansion

June 15, 2011



SCHRIEVER AIR FORCE BASE, Colorado — The 50th Space Wing successfully
completed a two phase Global Positioning System constellation expansion,
known as “Expandable 24” or 24+3, on June 15. This expansion increased
global GPS coverage and is now providing civil, military, and commercial
GPS users with a more robust signal and a higher probability of signal
acquisition in terrain challenged environments.

The GPS constellation consists of 24 operational slots positioned within
six equally-spaced orbital planes surrounding the earth. This plane/slot
scheme and enhanced satellite placement ensure GPS users receive the
most accurate navigation data at any time, at any place around the
world, the Air Force said.

“This marks another successful milestone in our continued commitment to
modernize our weapon system,” said Lt. Col. Jennifer Grant, 2nd Space
Operations Squadron commander. “We take great pride in providing GPS
performance that exceeds our requirements for the system, which we have
been doing since 1995.”

Expandable 24 is a U.S. Strategic Command commander directed initiative,
executed by the 2nd Space Operations Squadron, to reposition six
satellites in the current GPS constellation. Given the strength and
number of satellites in the current constellation, Air Force Space
Command was in a unique position to enact this revolutionary strategy to
benefit global users. AFSPC acted on this opportunity to increase the
robustness of satellite availability and overall signal-in-space
performance by expanding three of the baseline 24 constellation slots.

Phase one of Expandable 24 began in January 2010 when 2 SOPS performed
maneuvers to reposition three GPS satellites, one of which took 351 days
to maneuver. The last of the satellites completed repositioning on
January 18, 2011. Phase two began in August 2010 when 2 SOPS maneuvered
the final three satellites to their new locations, and was completed
today when the last satellite arrived at its new location.

“From the planning phases in the fall of 2009 to its completion today, 2
SOPS operators, engineers, analysts and support personnel have done an
incredible job in making the Expandable 24 GPS initiative a reality,”
said Maj. Benjamin Barbour, assistant director of operations. “It’s an
exciting time to be a part of GPS. This is a huge milestone and everyone
in the squadron is excited about the accomplishment and proud to have
played a part in continuing GPS’s position as the gold standard for
global navigation space systems.”

The GPS constellation has now attained the most optimal geometry in its
42 year history, maximizing GPS coverage for all users worldwide.

On Jun 22, 8:04*pm, Sam Wormley <sworml...@gmail.com> wrote:
> [Thanks Jon!]
>
> GPS Modernization
> 50th Space Wing Completes GPS 24+3 Constellation Expansion
>
> June 15, 2011
>
> SCHRIEVER AIR FORCE BASE, Colorado The 50th Space Wing successfully
> completed a two phase Global Positioning System constellation expansion,
> known as Expandable 24 or 24+3, on June 15. This expansion increased
> global GPS coverage and is now providing civil, military, and commercial
> GPS users with a more robust signal and a higher probability of signal
> acquisition in terrain challenged environments.
>
> The GPS constellation consists of 24 operational slots positioned within
> six equally-spaced orbital planes surrounding the earth. This plane/slot
> scheme and enhanced satellite placement ensure GPS users receive the
> most accurate navigation data at any time, at any place around the
> world, the Air Force said.
>
> This marks another successful milestone in our continued commitment to
> modernize our weapon system, said Lt. Col. Jennifer Grant, 2nd Space
> Operations Squadron commander. We take great pride in providing GPS
> performance that exceeds our requirements for the system, which we have
> been doing since 1995.
>
> Expandable 24 is a U.S. Strategic Command commander directed initiative,
> executed by the 2nd Space Operations Squadron, to reposition six
> satellites in the current GPS constellation. Given the strength and
> number of satellites in the current constellation, Air Force Space
> Command was in a unique position to enact this revolutionary strategy to
> benefit global users. AFSPC acted on this opportunity to increase the
> robustness of satellite availability and overall signal-in-space
> performance by expanding three of the baseline 24 constellation slots.
>
> Phase one of Expandable 24 began in January 2010 when 2 SOPS performed
> maneuvers to reposition three GPS satellites, one of which took 351 days
> to maneuver. The last of the satellites completed repositioning on
> January 18, 2011. Phase two began in August 2010 when 2 SOPS maneuvered
> the final three satellites to their new locations, and was completed
> today when the last satellite arrived at its new location.
>
> From the planning phases in the fall of 2009 to its completion today, 2
> SOPS operators, engineers, analysts and support personnel have done an
> incredible job in making the Expandable 24 GPS initiative a reality,
> said Maj. Benjamin Barbour, assistant director of operations. It s an
> exciting time to be a part of GPS. This is a huge milestone and everyone
> in the squadron is excited about the accomplishment and proud to have
> played a part in continuing GPS s position as the gold standard for
> global navigation space systems.
>
> The GPS constellation has now attained the most optimal geometry in its
> 42 year history, maximizing GPS coverage for all users worldwide.

I'm not impressed with the expandable 24 GPS initiative so far. Too
much hoopla for too little improvement. So much left to be desired.
However really disappointing is the apparent choice to use PRN30 for
IIF-2 (I'll call it SVN63).
Unless PRN30 is showing signs of imminent failure, I would recommend
using PRN3 for SVN63. The reason is PRN3 (SVN33) is strictly a backup
of a backup. It sits between PRN19 and PRN6 in an extra inefficient
satellite triplet (too close to PRN6 to improve PDOP whether PRN3 is
operational or residual). Set PRN3 as a residual, and should PRN6 or
PRN19 fail, then reactivate it using the failed PRN. If 2 SOPS is
afraid PRN30 has a high chance of failing, launch SVN63 with PRN3
forming a wide triplet with PRN30 and PRN16, as long as its a wide
triplet, the resulting constellation PDOP levels will be better than
replacing PRN30. Otherwise, launch SVN63 to form a wide pair with the
oldest IIR GPS satellite out there (all IIA birds already have
operational backup pairs).
Obviously using PRN1 for SVN63 would be an even better idea. No
explanation was given to say why that might be undesirable or
impossible. If the issue is something to do with troubles with 32
healthy PRNs, then use PRN1 for SVN63 and shutdown PRN3 L-band
transponder or set it unhealthy until it's actually needed.
If SVN63 can use PRN1, then re-use PRN3 for SVN64 (IIF-3).
GPS satellites are living far longer than originally expected. And
constellation positioning is based more on the extremely unlikely risk
of a mass failure of older GPS satellites than on maintaining maximum
constellation geometry during planned Delta V and Cs Clock pumping
outages that impact the constellation for hundreds of hours yearly.
Finally, spreading the PRN11/PRN24, PRN9/PRN27 and PRN20/PRN32 pairs
would improve worst case constellation PDOPs substantially, both
during normal times and during planned GPS bird outages.
Just my 2 cents 2 weeks from the planned launch of GPS IIF-2.

Marcelo Pacheco

On 2011-06-29 19:49 , macpacheco wrote:

> I'm not impressed with the expandable 24 GPS initiative so far. Too

Considering the cost to you is absolutely 0, you don't have much to
gripe about. You don't pay taxes in the US.

And when Europe puts up another 24 or so satellites, you'll be getting
the benefit of both without paying a cent.

--
gmail originated posts filtered due to spam.

On Jun 29, 9:45*pm, Alan Browne <alan.bro...@FreelunchVideotron.ca>
wrote:
> On 2011-06-29 19:49 , macpacheco wrote:
>
> > I'm not impressed with the expandable 24 GPS initiative so far. Too
>
> Considering the cost to you is absolutely 0, you don't have much to
> gripe about. *You don't pay taxes in the US.
>
> And when Europe puts up another 24 or so satellites, you'll be getting
> the benefit of both without paying a cent.
>
> --
> gmail originated posts filtered due to spam.

Launching new satellites has a cost. Repositioning them has no cost,
and as long as the repositioning starts and ends with an already
scheduled Delta V, fuel consumption is minimized.
I lived in the US for 7 years, with an H1B visa, paying all sort of
taxes, and all payroll taxes I paid I won't be able to use towards
retirement. So I can't really be called a total freeloader.
The GPS program is a tiny percentage of the US military budget, and an
even smaller percentage of the total US budget. The US financial
problem is driven primarily by the cost of the Afghanistan/Iraq war,
the cost importing oil like there's no tomorrow, the artificially low
taxes on petrol, and the very high level of social benefits afforded
to the population. The GPS program costs like 1% of the F-35 program !
That's one big wasteful program. USAF should have gone 100% UCAV
instead of having the F-35 program.
The problem with Democracy is it works. If the population in a
democracy wants the impossible, somehow, they will get it. Be careful
what you wish for. That's the real problem (actually both for the US
and for Brazil). Although we don't have a mamoth armed forces, we have
social programs we can't afford, and rampant corruption, and 99% of
the politicians say all is well ! But if Brazil had the debt / GDP
ratio the US has, we would be broke, going to the IMF for money !

Marcelo Pacheco