Jack Taylor/Photo Editor
Millions of people around the world enjoy the benefits of Global Positioning System (GPS) satellites every day. From the American soldier finding the coordinates of his location in the battlefield, to the college student using Google Maps to find the nearest Starbucks, GPS plays an import role in all of our lives.
These quiet heroes orbit the earth twice a day, 12,400 miles above the earth. For comparison, the ISS orbits nearly 16 times a day at a low 250 miles above earth. GPS satellites are categorized into “Blocks”. The original Block I satellites were developed by Rockwell International in 1978. Twelve were built and eleven were successfully launched into orbit. They served mostly as proof on concept and were continually being developed. They had an operational life expectancy of five years, however the last satellite, launched in 1985, lasted far longer and was decommissioned 10 years later in 1995.
Rockwell International launched the second generation of GPS in 1989 with the fully operational Block II satellites. Some of the improvements included 3-axis stabilization and the ability to point and track at the earth’s surface with reaction wheels. Larger solar panels and batteries allowed the satellite to operate through the earth’s shadow. The operational lifespan was extended to seven and a half years, and most importantly, two L Band signals and atomic clocks were added. These additions allowed for fully functional GPS service. The last of the nine Block IIs was launched in 1990 and was decommissioned in 2007. Nineteen upgrades, called Block IIA satellites, were launched from 1990 to 1997. The Block IIA satellites could operate 180 days without ground control communication.
Lockheed Martin took the reins of GPS satellite production with the Block IIR “replenishment” satellites. The first of twenty-one Block IIRs was destroyed just 12 seconds into launch, when the Atlas II that was carrying it exploded after a solid booster failed. Twelve additional Block IIRs were carried to space safely from 1997 until 2004, and all remain in operation today. From 2005-2009, Lockheed Martin upgraded eight of the existing Block IIR to the Block IIR-M GPS satellites. These units carried an improved civilian signal as well as a specialized military grade signal. Eight were launched and seven remain in service today.
Beginning in 2010, Boeing built a series of twelve “Follow Up” satellites called Block IIF. These satellites included vastly improved civilian signals, more accurate atomic clocks, and an extended twelve-year lifespan. Six years later, the conclusion of the Block II satellites has finally been reached. The launch of GPS IIF-12 marks the end of over twenty-five years of GPS development.
Lockheed Martin will be back in the saddle with the newest generation of GPS satellites. The Block III GPS satellites will have a fifteen-year life expectancy and improved military and civilian signals. Arguably the most important change is the development of anti-hacking technology that will make the satellites more secure from cyber attacks.
GPS satellites will continue to play a larger and larger role in the daily lives of civilians and military personnel around the globe. From the convenience of everyday navigation to life-saving search and rescue missions, the Global Positioning System improves quality of life of all who live on earth. As GPS technology advances, society and mankind will advance with it. Who knows what the next twenty-five years will have in store.