[Infowarrior] - GPS Satellite Glitches Fuel Concern on Next Generation

[Richard Forno]

GPS Satellite Glitches Fuel Concern on Next Generation
By ANDY PASZTOR

http://online.wsj.com/article/SB124520702464422059.html

Technical problems are degrading the accuracy of signals from the last  
GPS satellite launched by the Pentagon, sparking concerns among U.S.  
military and aerospace industry officials that the next generation of  
the widely used satellites could face similar troubles.

The Air Force's Southern California space acquisition center on  
Tuesday announced that a Global Positioning System satellite,  
manufactured by Lockheed Martin Corp. and launched in March, is  
experiencing performance problems in orbit. It hasn't become part of  
the "operational constellation" of more than two dozen other GPS  
satellites, and is slated to undergo a battery of tests expected to  
stretch through October to try to resolve the problems, according to  
an Air Force news release.

The GPS system, which serves both military and civilian users,  
provides precise time and location coordinates for everything from  
military missile launches and "smart" bombs to automated bank-teller  
machines to aircraft, ships and everyday vehicles. The Lockheed  
satellite is the first to include a new civilian frequency -- dubbed  
L5 -- designed for, among other things, use by future nationwide air- 
traffic control systems. But that signal, part of test package,  
apparently is interfering with other signals from the satellite and  
reducing their accuracy, according to industry and Air Force  
officials. The degraded signals are accurate only to about 20 feet,  
versus about two feet for typical GPS signals, industry officials said.

The issue is significant, according to these officials, because it  
could complicate deployment of a new family of Boeing Co. GPS  
satellites currently being built that also feature the L5 signal.  
Already years behind schedule and hundreds of millions of dollars over  
budget, the 12 satellites, which are scheduled to replace satellites  
currently in orbit, could face further testing and delays to ensure  
that they are free of interference problems. The Boeing satellites  
have a history of quality-control and manufacturing problems unrelated  
to the latest concerns.

While the Air Force said it has "high confidence there is no related  
concern" with other Lockheed satellites in orbit or waiting for  
launch, Air Force brass have begun examining whether Boeing versions  
of GPS satellites require additional tests and analysis to eliminate  
concerns, according to industry officials familiar with the details. A  
spokeswoman for Boeing declined to comment. A Lockheed Martin  
spokesman said the company is working with the Air Force "to fully  
evaluate the issue and to ensure the satellite meets GPS requirements."

In its release, the Air Force said the routine in-orbit checkout of  
the suspect Lockheed satellite revealed that some signals "were  
inconsistent" with comparable GPS satellites. The Air Force also said  
upcoming tests will include simulations and "testing of real-life GPS  
receiver equipment to the greatest extent possible" to prevent  
"inadvertent impacts to GPS users."

The first of Boeing's GPS IIF satellites, incorporating the new  
civilian signal, is slated to launch late this year or early 2010,  
delayed from the summer.

In May 2008, Lockheed bested Boeing to win a contract worth at least  
$1.8 billion to build the most-advanced navigation satellites yet,  
dubbed GPS III, scheduled to go into operation around the middle of  
the next decade.

Concerns over signal quality come barely weeks after a Congressionally- 
ordered study raised a red flag about potential erosion of GPS  
accuracy in the next few years due to launch delays and other  
challenges. If certain launches get delayed up to two years, the  
General Accountability Office report predicted, the Pentagon could  
have trouble maintaining the desired fleet of 24 fully-functional GPS  
satellites in operation.

The Pentagon responded by minimizing the potential risk, arguing that  
significant spare capacity remains on orbit and on the ground to  
handle unexpected problems. Gen. Robert Kehler, head of Air Force  
Space Command, said in an interview earlier this month that the GAO  
conclusions were overly pessimistic partly because they failed to take  
into account strategies the Air Force could use to extend the life of  
existing satellites. For example, Gen Kehler said, managing power  
output could give solar arrays longer life.

Despite some continuing quality-control issues with Boeing's IIF  
versions, Gen. Kehler said, "we're not going to have an issue"  
maintaining the current robust constellation.

Write to Andy Pasztor at andy.pasztor at wsj.com