Why are Elon Musk’s Starlink satellites burning up in the skies?

As many as 62 fireballs lit up the skies over the US states of Wisconsin, Michigan and Illinois on January 29 as a satellite burned and blew to smithereens without ever hitting the ground.

It was far from an isolated incident. In January alone, 120 satellites crashed and re-entered the Earth’s atmosphere in the shape of spectacular fireballs.

Most of these crashing satellites belong to Elon Musk-owned company Starlink, which uses a global satellite network to provide low-cost internet worldwide.

The reason for the unusually high crash-and-burn rate of satellites is that Starlink is retiring approximately four to five space capsules every day, according to astronomer Jonathan McDowell.

Starlink satellites are designed in a way that they fully disintegrate upon crashing and pose no physical threat to public safety. However, the massive surge in satellite crash incidents is causing atmospheric pollution and possible orbital debris.

What do Starlink satellites do?

Most satellite internet services use single geo-stationary spacecraft. These are planet-orbiting satellites that appear to be stationary in the sky above a fixed point on the Earth’s surface.

Using this technique to provide internet connectivity results in considerably high latency, which means the round-trip data time between the user and the satellite is long enough to slow down streaming, online gaming, video calls and other activities that consume heavy data.

In contrast to single geo-stationary spacecraft, Starlink operates a “constellation” consisting of thousands of satellites orbiting the planet 24/7.

Starlink’s constellation orbits closer to Earth. This means the round-trip data time - milliseconds that a data packet takes to travel from a computer to the satellite and back - is 24 times shorter than the conventional alternative.

The lifespan of a Starlink satellite is approximately five years. There are currently 5,999 Starlink satellites orbiting the planet. Its constellation of satellites ensures the internet is accessible in war zones and even the remotest parts of the oceans.

Yet many countries like India, China, and Russia, as well as most countries in Africa, have been reluctant to allow the company to use their spectrums for different reasons.

Eventually, the company expects to have as many as 42,000 satellites in its constellation. The company plans to replace its constellation every five years with satellites fitted with newer technology.

This mass retirement of the first-generation or Gen1 Starlink satellites to make way for newer models is resulting in the spike in the number of crashing spacecraft.

The Starlink network is designed, owned and operated by SpaceX, Musk’s rocket-launching company that became the first private firm to deliver astronauts to and from the International Space Station.

Polluting the atmosphere

The steady rate of crashing spacecraft has raised concerns among environmentalists about atmospheric pollution.

The current V2 Starlink satellite version weighs approximately 800 kilograms at launch, almost three times heavier than the older generation satellites that weighed 260 kilograms each.

Each Gen1 Starlink satellite produces, during its incineration, about 30 kilograms of aluminium oxide, a compound known to deplete the ozone layer, an atmospheric shield that protects life on Earth from the sun’s harmful ultraviolet radiation.

The disintegration of satellites is also known to create “metallic vapours” in the atmosphere. The chance of debris hitting an aircraft is “very low”, even though the possibility of uncontrolled space rocket junk disrupting flights cannot be ruled out.

A 2023 study found that 10 percent of aerosols - small particles suspended in the atmosphere - collected 60,000 feet over Alaska contained aluminium and other metals produced by the satellite burn-up.

The presence of these compounds increased eightfold between 2016 and 2022, with the recent surge further exacerbating the level of pollution.

The study proved for the first time that stratospheric pollution is “unquestionably linked to (the) re-entry of space debris” into the atmosphere.

The aerosols contained niobium and hafnium - which do not exist as free elements in nature - that are used in semiconductors and superalloys.

In addition to these two unusual elements, a significant number of particles also contained copper, lithium and aluminium at concentrations “far exceeding” the abundance found in meteorics or space dust, the study showed.