The US Space Force, United states space force (USSF), has been part of the United States military since 2019 and focuses on missions in space. The USSF is part of the United States Air Force Department and a separate defense branch alongside the Air Force.

Recently, the space force conducted a training mission called Black Skies to practice jamming satellite signals. Other countries, such as China and Russia, already has such technology in use. The exercise is the first in a series to provide the US defense with competencies in electronic warfare.

Satellite jamming is attacks that disrupt and block signals to and from satellites in Earth orbit without destroying the satellites themselves. The US military’s exercise included signal jamming of communications from and to satellites hired by private companies.

Satellites play an important role in war

In the ongoing war in Ukraine, Russia has attacked several of Ukraine’s infrastructures. According to the USSF Russia has also targeted the satellite system Navstar owned by the US and used to deliver GPS data. Satellites play a major role in modern warfare and are used, among other things, for navigation and for coordinating troops.

Navstar consists of 24 main satellites which circles the earth in 12 hours. The satellites are time-synchronized and as they move in different directions, a user receives signals from them at slightly different times. If, for example, a mobile phone is reachable by at least four satellites, its position can be calculated from the time differences.

GPS data from Navstar is used by several countries around the world. Russia, on the other hand, has its own independent system called Glonass. The Russian satellite system has one higher inclination than Navstar which improves the coverage at northern latitudes a little. A satellite’s inclination or orbital inclination is the angle between the orbit and the Earth’s equatorial plane.

Russia has been jamming satellite signals in Ukraine since 2014

According to a report of Center for strategic and international studies (CSIS) Russia has been actively trying to jam GPS signals in Ukraine since 2014 when the Crimean peninsula was invaded. Equipment to block satellite signals, which are believed to be in large trucks which has been seen on satellite images, was taken as troops gathered outside the Ukrainian border ahead of the invasion on February 24 this year.

Navstar, which the Russian army is focused on disrupting, uses radio frequencies typical of GPS receivers in cars or mobile phones. A possible way to get around the interference could be to vary or widen the frequency bands used by the satellites.

A typical satellite jammer works by a very large radio transmitter or satellite dish sending out its own radio signals that act as noise. If the radio signals reach the right frequency, the satellite’s signals can be interfered enough to become difficult to read.

In 2007, China blew up a weather satellite

Another way to stop satellite data is to permanently destroy and blow up satellites in orbit around the Earth. On January 11, 2007, China blew up one of its own weather satellites in a test of an anti-satellite missile. The satellite orbiting the earth at a distance of 865 kilometers and weighing 750 kilograms was destroyed by the missile traveling at 8 km/s straight towards the satellite.

The Chinese missile test was the first known and successful since 1985 when the US blew up a P78-1 satellite. To destroy satellites with kinetic kill vehiclesi.e. direct collisions, create large amounts of space debris and strongly affect the space environment.

Also India has blown up a satellite in orbit when they tested a new missile in 2019. The Indian satellite was in a lower orbit than the Chinese one but still created a lot of space junk that posed a danger to other satellites and the astronauts aboard the International Space Station ISS.

The US Space Force’s satellite jamming does not create any space junk, but only temporarily impedes the satellites’ function. The exercise Black Skies to be followed up by Red Skies and Blue Skies which will focus on orbital warfare and cyber warfare.