The Air Force launched its latest GPS satellite in March to join about 30 others in Earth's orbit to provide positioning, directions and locations to both the military and civilians.
While one of the newest Block IIF satellites, it's likely to be one of the last few launched before the Air Force tries to upgrade the Global Positioning System to the next generation, dubbed GPS III.
Here's what you need to know:
1. History. The first GPS satellite launched in 1978, but the system wasn't considered fully operational until 1995. Roger Easton, a physicist at the U.S. Naval Research Laboratory, is considered to be the father of GPS after he got the idea for multiple satellites that could track time and location. He died in 2014. President Reagan was the first to make GPS available to the public, following an incident where a South Korean passenger jet wandered into Soviet airspace and was shot down.
Capability has always been split into military and civilian uses, with the civilian side originally using degraded signals. But President Clinton ended the practice, allowing civilian GPS to operate on the clearer, more exact satellite signals originally only used by the military.
2. How it works. GPS relies on a network of about 30 satellites that orbit the Earth and broadcast their location and the exact time. A navigational device — like a cellphone or GPS unit in a car — then collects those signals and can calculate how far it is from each satellite.
Once the device is receiving signals from four or more satellites, it can calculate its location on the planet, as well as get a good sense of direction, movement and speed.
3. GPS III. Lockheed Martin won the Pentagon contract to provide eight of the next-generation satellites that are estimated to begin launching in 2017.
The GPS III satellites and systems are expected to add additional navigational signals, which will lead to more accurate directions for drivers, provide greater bandwidth for use by first responders and other emergency personnel, and integrate better with European and Asian navigational systems.
The military, meanwhile, will have a separate GPS signal to use. The satellites are also expected to survive longer than previous models, with an operational life estimated at 15 years.
4. Jamming concerns. GPS jamming is an increasing concern among military leaders, Defense News reported June 1. Devices that can block a GPS signal are increasingly more common and cheaper to build, and they could easily be acquired by groups such as the Islamic State, military leaders said. Jammers can be used not only to disrupt military operations on the ground, but also to scramble the guidance systems of smart missiles or remotely piloted aircraft.
Lockheed Martin claims the new GPS III satellites will provide anti-jamming capabilities more than eight times greater than previous models. Part of that comes from focusing the GPS signals. The satellites broadcast all over the world, and therefore the signal can be weak when it reaches a navigational device.
The military hopes that by focusing some GPS signals in specific areas, it can boost the signal strength and break through some of the jamming.
5. Down on the farm. The use of GPS technology is spreading beyond the military and civilian drivers. The Agriculture Department reports that GPS is increasingly being used for farming and land management. It's been used for farm planning, tracking soil samples and crop yields, and helping farmers navigate tractors in bad weather.
