How does satellite communication work in space

Missing Link: Space dump - how sustainable is satellite communication?

A man is sawing a branch on which he is sitting himself - centuries ago bailiff singers amused their audience with this picture. The stupidity it describes has persisted to this day. A striking example of this has recently been provided by the US company Swarm Technologies, which wants to build a satellite-based global communication network for the Internet of Things.

When she put her first four satellites into orbit on January 12, 2018, aboard an Indian PSLV rocket, it did so despite an express ban by the US regulator FCC (Federal Communications Commission). Swarm is responsible for the first unauthorized launch of a commercial satellite at all - and first of all gave the branch, which is supposed to support not only the company, but an entire industry, a strong blow with the ax.

Orbits could become unusable

The FCC refused to give permission because the satellites were about 10 x 10 x 2.8 centimeters (about ¼ U, the standard size of 10x10x10 cm for cubesats) too small to be able to track them continuously. According to the FCC, this means that it is not possible to warn other satellite operators of possible collisions. The launch of the “Spacebee” satellites by Swarm Technologies is therefore “not in the public interest”.

With its gruff behavior, the company based in California's Silicon Valley has ignored the limits of growth in near-earth space that have been known for over 40 years: As early as 1978, the astronomer and NASA employee Donald J. Kessler published his now famous study, which showed that Collisions between artificial satellites in Earth orbit, similar to a chain reaction, inevitably lead to a cascading increase in the number of debris. In the long term, according to his prediction at the time, particularly polluted orbits could become completely unusable as a result.

"Cemetery orbit" cheaper than controlled crash

This is no longer a prognosis, but a tangible reality. Measures against the threat of space debris already account for around 5 to 10 percent of the total costs of satellites in geostationary orbit, writes the Directorate for Science, Technology and Innovation (STI) of the OECD in a report from April this year.

For near-earth orbits, the authors of the study suspect, the costs are likely to be significantly higher. The operators of such satellites were reluctant to publish reliable figures. Technologically, however, in relation to the total costs, it is more complex and therefore more expensive to deliberately crash a satellite from an altitude of more than 650 km than to lift it from the geostationary orbit at an altitude of 36,000 km into the "cemetery orbit" several hundred kilometers higher. This is not the only reason why the operators of geostationary satellites are more willing to adhere to the rules for avoiding space debris. The investments in the individual satellites are usually many times higher than for their lower-flying siblings, as is their lifespan. Together with the high profits that can still be achieved with it, there is a common interest of all companies and authorities active here in keeping the orbit clean.