50 free GPS trivia questions with answers — technology quiz, new questions added Aug 2026.
This GPS trivia quiz covers the satellite navigation system that went from a Cold War tool for missile submarines to the thing that finds your ride home. The easy questions cover what the letters stand for, who owns it, how many satellites make a full constellation, how many you need to fix a position and what your phone can do with it. From there the quiz moves through the story: the Johns Hopkins physicists who tracked Sputnik by its Doppler shift, Transit and Timation, the Labor Day 1973 meeting at the Pentagon, the first Block I launch in 1978, the Korean airliner that pushed Reagan to open the system to civilians and the 100-metre fuzz called Selective Availability. The hard end covers the engineering and the politics: the six orbital planes, the 20,200 km altitude and twelve-hour orbits, Einstein's 38 microseconds a day, Gladys West's Earth model, Schriever Space Force Base, the Gulf War jamming, the day in May 2000 accuracy jumped from 100 metres to five, the week-number rollover, GLONASS, Galileo and BeiDou, and the $5 billion price tag. Every answer was checked against the encyclopaedia entry for the Global Positioning System before publishing and the supporting sentence is stored with each question. Our space exploration, satellites and technology quizzes are natural next stops.
30 of 50 questions with answers and explanations. Play the quiz
Q 01What do the letters GPS stand for?
Global Positioning System
It is one of several global navigation satellite systems, or GNSS.
Q 02Which country's government owns and operates GPS?
The United States
It is treated as a national resource but is freely accessible to anyone with a receiver.
Q 03Which branch of the US military has owned GPS since 2019?
The Space Force
Mission Delta 31 operates it from Schriever Space Force Base near Colorado Springs.
Q 04How many satellites make up a full GPS constellation?
24
Between 24 and 32 are usually flying, so several are visible from any point with a clear horizon.
Q 05What is the minimum number of satellites a receiver needs in view to compute a normal position fix?
Four
Three for the position coordinates and one more to solve for the receiver's clock error.
Q 06At roughly what altitude do GPS satellites orbit?
20,200 km
Each completes two orbits per sidereal day, repeating the same ground track daily.
Q 07How long does one GPS satellite take to orbit the Earth?
About 12 hours
Precisely half a sidereal day, 11 hours 58 minutes.
Q 08How many orbital planes are the GPS satellites arranged in?
Six
The original plan was three planes of eight; it became six planes tilted about 55 degrees.
Q 09In what year was the GPS project started by the US Department of Defense?
1973
About twelve military officers met at the Pentagon over Labor Day weekend to discuss a Defense Navigation Satellite System.
Q 10In what year was the first experimental Block I GPS satellite launched?
1978
Ten Block I prototypes flew between 1978 and 1985, and one more was lost in a launch failure.
Q 11In which year did GPS achieve initial operational capability with a full 24-satellite constellation?
1993
Full Operational Capability for the military's secure service was declared in April 1995.
Q 12What was the name given to the individual GPS satellites?
Navstar
Two Navy predecessor systems shared the same naming habit; GPS combined their ideas.
Q 13Which 1957 event led two Johns Hopkins physicists to realise satellites could be tracked, and users located, by the Doppler effect?
The launch of Sputnik 1
William Guier and George Weiffenbach's work led to the Navy's first satellite navigation system for Polaris submarines.
Q 21Which mathematician's geodetic Earth model was instrumental to GPS and earned her a place in the Air Force Space and Missile Pioneers Hall of Fame in 2018?
Gladys West
She worked at the Dahlgren Naval Proving Ground in Virginia.
Q 22Which two men, of The Aerospace Corporation and the Applied Physics Laboratory, are usually credited with inventing GPS and shared the 2003 Draper Prize?
Ivan Getting and Bradford Parkinson
Roger Easton of the Naval Research Laboratory received the National Medal of Technology in 2006.
Q 23Which award did four GPS founders, including Bradford Parkinson, receive on 12 February 2019?
Q 14Which Naval Research Laboratory satellite carried the first atomic clock into orbit in 1974?
Timation
Proving that accurate clocks could work in space was essential to the GPS concept.
Q 15The shooting down of which airliner in 1983 prompted President Reagan to promise GPS to civilians?
Korean Air Lines Flight 007
The 747 had strayed into Soviet airspace through navigational error and all 269 aboard died.
Q 16What was the name of the policy that deliberately degraded the civilian GPS signal to roughly the length of a football field?
Selective Availability
It limited accuracy to about 100 metres and was temporarily switched off during the Gulf War because troops were using civilian units sent from home.
Q 17Which US president ordered the deliberate civilian signal degradation switched off, effective 1 May 2000?
Bill Clinton
Civilian accuracy improved roughly twentyfold overnight.
Q 18How accurate was GPS for civilians once the deliberate degradation was discontinued in 2000?
About 5 metres
Modern L5-band receivers reach 30 centimetres, and survey gear can hit sub-millimetre over time.
Q 19By how much do the clocks on GPS satellites run fast each day, as predicted by relativity and corrected in the design?
38 microseconds
Friedwardt Winterberg had proposed testing general relativity with orbiting atomic clocks back in 1955.
Q 20Which was the first war in which the US military widely used GPS?
The Gulf War of 1990-91
Iraqi forces also demonstrated its vulnerability by installing radio jammers on likely targets.
The Queen Elizabeth Prize for Engineering
Hugo Fruehauf, James Spilker and Richard Schwartz shared it; the citation called engineering the foundation of civilisation.
Q 24Where is the GPS master control station?
Schriever Space Force Base, Colorado
Command moved there from Onizuka Air Force Station in California in 1988; dedicated ground antennas sit at Kwajalein, Ascension, Diego Garcia and Cape Canaveral.
Q 25What is Russia's equivalent of GPS called?
GLONASS
Developed at the same time as GPS, it lacked full global coverage until the mid-2000s.
Q 26What is the European Union's global navigation satellite system called?
Galileo
It began operation in 2016 and was fully deployed by 2020; the FCC approved its use in the US in 2018.
Q 27Which country's BeiDou system began global services in 2018?
China
Japan's QZSS is a regional augmentation system for Asia-Oceania.
Q 28How accurate can a smartphone's GPS be when helped by services like Wi-Fi positioning?
About 4.9 metres or better
High-quality standard receivers managed better than 3.5 metres horizontally by 2015.
Q 29How much did the GPS programme cost, including launches but not user equipment, according to the estimate cited?
US$5 billion
That is about $11 billion in 2025 dollars; only the Cold War nuclear threat was thought to justify it.
Q 30How often does the ten-bit GPS week number roll over to zero?
Every 1,024 weeks
That is about 19.6 years; the second rollover happened on 6 April 2019.