Navstar, the official U.S. Air Force program moniker for the constellation of satellites most of us refer to simply as GPS, has undergone a multitude of technical changes and upgrades in the nearly 30 years since a group of military and civil engineers first sat down in the Pentagon to talk about the far-reaching precision navigation concept.
The FAA’s original plan to transition to sole-means GPS is no longer practical and some form of backup will be required for the foreseeable future, according to speakers at a recent Navigation Industry Day. This event was sponsored by the DOT, FAA and Civil Aviation Advanced Systems Development (CAASD), which is a component of the federally-funded MITRE research and development center and a key FAA think-tank resource.
Speakers from Eurocontrol and the European Space Agency last month informed attendees at a meeting of the FAA’s Satellite Operational Implementation Team (SOIT) that their organizations would accept liability for system failures when the Galileo satnav system was used in critical applications requiring high-accuracy guidance, such as approach and landing operations.
Concerned about attempts by adversaries to jam global positioning satellite system signals–as occurred with only limited success during the recent Iraq conflict–the U.S. Air Force is moving ahead with plans to field a new-generation constellation of satellites, called GPS III. After a months-long logjam, the Air Force next month will begin accepting requests for proposals to develop and deploy the satellites sometime between 2010 and 2013.
In 1997 the President’s Commission on Critical Infrastructure Protection, which was charged with examining threats to our national security, recommended an assessment be made of the vulnerability of the U.S. transportation infrastructure if it had to rely on GPS.
The DOD’s Navstar GPS reached a new performance level this year, with 30 satellites in orbit versus its minimum required civil complement of 24. Four more satellites add signal coverage and reduce the number of occasional “holes,” or gaps where fix geometry can sometimes fall below navigation standards.
The U.S. Air Force last month reiterated its intention to choose a single contractor for a new constellation of global positioning satellites known as GPS III. Teams led by Lockheed Martin and Boeing are competing for the contract to launch eight Block A GPS III satellites by 2013. The Air Force invited bids last month for these first satellites, the foundation for an enhanced system scheduled to start operating in 2018.
A solar flare 10 times stronger than anything researchers had previously observed or predicted surprised scientists last December, not only because of its size and strength, but because of the effect it had on GPS receivers and other communications systems. Now scientists are looking at previous data and trying to understand how these flares affect satellite signals, in the hope that they can one day prevent further disruptions.
Boeing has formed an international industry team to compete for the contract to build and deploy the next generation of GPS satellites.
The Air Force plans to award the contract in early 2006 for the new GPS III satellites that will replace the ones currently in orbit and those scheduled for launch between now and when the GPS III satellites are ready.
GPS Satellite SVN-15 will celebrate its 16th birthday in space this month, and by next spring it will have circled the earth 12,000 times (roughly twice a day), continuously transmitting navigation signals to us. That’s amazing performance, especially considering that its original orbital life was expected to be 7.5 years.