About
The Global Positioning System (GPS) is a network of 31 US military satellites in medium Earth orbit (20,200 km altitude) that continuously broadcast precise timing signals. A GPS receiver calculates its position by measuring the time delay from at least 4 satellites — triangulating position to within 3 meters (consumer) or 30 cm (military/professional). GPS was developed by the US Department of Defense (1973-1995) and made fully available for civilian use (previously degraded by 'Selective Availability') in 2000.
GPS underpins modern civilization: navigation (3.6 billion GPS users); precision timing for financial transactions, telecommunications, and power grids; precision agriculture (1 cm accuracy for automated tractors); first-responder dispatch; aviation approach guidance; and tsunami warning systems. Russia (GLONASS), Europe (Galileo), China (BeiDou), and others operate their own GNSS systems. A GPS failure would immediately disable the US economy.
# Top 10 GPS facts
- 131 satellites
- 2Einstein relativity corrections required
- 3military origin (1973)
- 4civilian access free (2000)
- 53.6B users
- 6precision farming
- 7financial timing
- 8GLONASS/Galileo/BeiDou alternatives
- 9spoofing and jamming as threats
- 10$1.4 trillion US economic value
Fascinating Facts
- ◆GPS satellites must correct for Einstein's relativity — clocks on GPS satellites tick 38 microseconds faster per day due to general and special relativity, and without correction, GPS would drift by 10 km per day
- ◆GPS was classified US military technology until 2000 — civilian users previously received deliberately degraded signals; President Clinton removed the degradation after a civilian airliner was shot down using GPS
- ◆The economic value of GPS to the US economy is estimated at $1.4 trillion — it has generated $1.4 trillion in benefits since 1983, making it the best return on government investment in history
More in Technology4 related
1
Technology
The Internet
The global network that connected all of humanity.
Interest98/100
34
Technology
Artificial Intelligence
Teaching machines to think — the technology reshaping every aspect of human civilization.
Interest92/100
12
Technology
CRISPR Gene Editing
The molecular scissors that let scientists rewrite the code of life.
Interest81/100
18
Technology
Quantum Computing
Computing that harnesses quantum mechanics to solve problems impossible for classical computers.
Interest79/100