Dramatischer Wiedereintritt der SpaceX-Rakete weckt neue Sorgen über Verschmutzung der Atmosphäre
Im Februar letzten Jahres trat eine SpaceX-Rakete wieder in die Erdatmosphäre ein und sorgte für Schlagzeilen, nachdem der Feuerball über Europa gesichtet und Teile davon hinter einem Lagerhaus in Polen entdeckt worden waren.
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That same rocket is in the news again because researchers at the Leibniz Institute of Atmospheric Physics in Germany managed to measure the pollution the rocket emitted in the upper atmosphere.
What they found was a tenfold increase in lithium levels caused by the rocket exploding at an altitude of nearly 90 kilometres above Earth.
This was the first time researchers were able to measure pollutants from space debris re-entering the atmosphere. And according to Robin Wing, a researcher from the Leibniz Institute of Atmospheric Physics, this form of pollution has been easy to ignore.
“When we imagine industrial pollution, we see a river with dead animals and plants,” he said.
“It's an emotional response that we can get, and we say we have to clean up this environment. There's no visible evidence of pollution in the upper atmosphere.”
A new space race
This information is vital as companies and organisations are racing to launch more satellites in the coming years.
According to NASA, around 31,000 human-made objects are orbiting Earth.
Around 14,000 of those are active satellites orbiting at heights up to 35,000 kilometres above Earth.
The rest are broken-down pieces of old technology, known as space debris, some of which date back to the first space race.
China recently announced plans to launch around 200,000 satellites. SpaceX also applied to launch one million more.
The problem is that each satellite is only designed to last about five years.
This means that they are eventually lowered tens of thousands of kilometres to burn up in the middle atmosphere, which contains the stratosphere and mesosphere.
These objects then release pollutants as they plummet, including lithium, but also copper, titanium and lead.
Scientists know that these materials are there, but they are much harder to track with a technology called LIDAR, which uses laser pulses to measure pollutants.
Unknown consequences
According to the researchers at the Leibniz Institute, the consequences of these metals accumulating in the atmosphere are unknown.
But one theory with a positive outcome is that they could reflect solar radiation back into space, slightly cooling the planet and offsetting some climate change.
The second is that they could contribute to ozone loss in the stratosphere and an increased rate of skin cancer and eye diseases.
Regardless of the outcome, this pollution is hard to address because satellites are vital to daily activity.
“We all need it,” Gerd Baumgarten, a researcher from the Leibniz Institute of Atmospheric Physics, said.
“It's really hard for us to imagine that we go to work without a map or without information about the traffic jam, things like this, we need it, so (more satellites) will be coming.”
The researchers behind this discovery hope that their work will eventually help policymakers and companies make better choices — from alternative fuels to different spacecraft materials.
The goal is simple: make this rapidly growing industry less environmentally damaging.
By Kal Berjikian