If I take my cell phone into Earth orbit, will I be able to make calls? | By Space | December 2023

I recently received another interesting question from one of my subscribers.

If I take my cell phone into Earth orbit, will I be able to make calls?

The concept of Earth’s orbit is flexible, allowing celestial bodies to orbit the planet at distances ranging from 120 km to 36,000 km above the Earth’s surface. However, since people most often travel to the International Space Station (ISS), whose orbit varies between 337 and 430 km, we consider the possibility of calling from the height of the ISS’s orbit.

Astronauts on the ISS use special radio transmitters to maintain constant communication with Earth, but can they make calls from there using regular cell phones? The short answer is, no, you can’t make phone calls to orbit in the standard mode of the cell network. The system is configured to work with devices on Earth’s surface, but a relatively simple change in settings could allow astronauts to use their phones. To understand how it is done, we need to consider some principles of cell communication.

Base stations and mobile phones operate in the 890-960 MHz frequency range. Waves in this range pass through the ionosphere well and easily reach instruments in orbit, unlike longer waves that are reflected by the ionosphere. Stations send data in packets. After each packet, it waits for a response signal for a certain period of time, and if it does not receive a response signal, it starts working with another phone. In flat terrain, this latency limits the base station’s range, but it is adjustable and, with proper configuration, is sufficient for the signal to reach the phone in orbit and back. is.

Large base stations on Earth have enough power to transmit a stable signal over 70 miles (120 km) on clear skies. To increase the efficiency of the network, its operating range is artificially limited. Also, the curvature of the earth’s surface makes it pointless to send more signals. The exact characteristics of a base station depend on…