GPS has become an essential instrument in the more than 35 years that it has been open to the civilian population. Thanks to him, we can go to any part of the world with the certainty that we will not get lost. However, the GPS has many uses beyond positioning us, and they go beyond positioning us with error margins less than one meter.
Currently there are dozens of satellites that send their signal to the Earth’s surface. Our mobile needs the signal from at least three satellites to triangulate our position by pooling the areas where it thinks we may be. The more satellites there are, the more precise the positioning with accuracies of up to a few centimeters in the case of Galileo.
In addition to positioning, scientists use GPS for many purposes thanks to multiple receivers on earth (including a mobile one), such as measuring natural disasters, volcanic eruptions, or simply to measure the density of snow at different points on earth. So, these are all the things that GPS is used for in addition to locating us on the planet:
Quickly measure the effects of an earthquake
Seismographs have traditionally been used to measure earthquakes, as they are connected directly to the ground and measure their vibrations. However, the GPS can measure plate tectonics, being able to know the speed at which the faults are moving. Initially it was not believed that GPS could be so precise as to measure those signals, but there are two types of information that can be measured with them.
The first are ones and zeros that each satellite transmits, which is the code. The second is the carrier signals that transmit the code from the satellite. These carrier signals have a shorter wavelength (only 20 cm) unlike the code, which can be tens or hundreds of meters of wavelength. Therefore, the carrier signal offers more precision to locate specific points on the earth.
In addition, GPS receivers have been improving, and are now updated up to 20 times per second. With this, they have been able to measure the effects of earthquakes for years, such as the fact that the 2011 earthquake of 9.1 on the Richter scale of Japan caused the sea floor to move 60 meters. And although it does not help in prediction, it is possible to know if it will have devastating effects or what will be its scale in less than 10 seconds after it occurs.
Probing the snow
GPS signals are better received on our mobile when we have direct vision of the satellite outdoors. However, you may have noticed applications like GPS Status that can position you even if you have no sky in sight. This is because GPS signals bounce off surfaces such as the ground or glass. Until now, it was believed that these signals did not provide additional data for scientific purposes, but they began to see that the frequencies of the bounced signals changed depending on the surface with respect to those coming directly from the satellite.
Thanks to this, information can be obtained on the surface under the GPS receiver , being able to know how much accumulated snow there is. The more snow there is, the shorter the distance between the echo generated by the signal and the receiver. This system is currently used to measure Antarctic ice.
Monitor a volcano
On earth there are many active volcanoes . Many of the observatories around them have a network of GPS receivers that, as soon as there is movement underneath, begin to notice vibrations. By knowing the precise changes in height that these sensors undergo, you can know where the magma goes and if it will go out. With this, they can know which zones are more convenient to evacuate first.
This movement can also cause the signals to become distorted, and in 2013 in Alaska changes in the signal were detected as soon as the eruption began.
Save your life
The Galileo satellite network includes an SOS help system that was activated in early 2020. Thanks to this, it is possible to transmit distress signals, and receive responses that this request has been received and that someone is already going to rescue us. For this, it is necessary to have a system capable of communicating with the satellites, which unfortunately current mobile phones do not yet do.
Know if the earth sinks
The riverbanks, and the rivers themselves, are constantly changing depth due to the accumulation of sediment. Depending on the depth of the rivers, they can facilitate floods because they cannot cope with the flow. With GPS receivers, you can measure the distance each one is from each other and, through the echoes of the signal, know if there have been changes in height where the ground level has sunk or risen.
Analyze the atmosphere
GPS can also provide a lot of data about the atmosphere. In addition to the fact that meteorological satellites use signals at various frequencies to detect the density of clouds and know the amount of water they carry to know whether it is going to rain or not, GPS signals that travel through the atmosphere also provide a lot of information about the amount of water vapor in the clouds.
Tsunamis also cause changes in the atmosphere that can reach the ionosphere, and measuring changes in it can give data on how tsunamis will evolve. A smaller number of electrons have also been measured in upper layers of the atmosphere during lunar eclipses.
As we can see, GPS has many more applications than just positioning us, and satellites become the future of communications thanks to networks like Starlink , which will offer satellite Internet .
