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Image credit: NOAA Graphic/Chelsea Thompson

Scientists have linked exotic metal particles in the upper atmosphere to re-entering rockets and satellite leftovers.

The just-issued findings come from work by the National Oceanic and Atmospheric Administration (NOAA).

Measurements show that about 10% of the aerosol particles in the stratosphere contain aluminum and other metals that originated from the “burn-up” of satellites and rocket stages during reentry, according to the NOAA work.

While direct health or environmental impacts at ground level are seen as unlikely, these measurements have broad implications for the stratosphere and higher altitudes.

Research plane

The new NOAA work explains that, with many more launches planned in the coming decades, metals from spacecraft reentry could induce changes in the stratospheric aerosol layer.

NOAA researchers made use of data collected by a high-altitude research plane over the Arctic during a NOAA Chemical Science Laboratory mission called Stratospheric Aerosol processes, Budget and Radiative Effects or SABRE.

Chemical Science Laboratory’s Mike Lawler installs the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument into the nose of the WB-57. Photo: Chelsea Thompson, NOAA

This NASA WB-57 research aircraft found aluminum and exotic metals embedded in about 10 percent of sulfuric acid particles, which comprise the large majority of particles in the stratosphere. Researchers were able to match the ratio of rare elements they measured to special alloys used in rockets and satellites.

That sealed the deal, confirming their source as metal vaporized from spacecraft reentering Earth’s atmosphere.

Distinct elements

“This discovery by NOAA scientists represents the first time that stratospheric pollution has been unquestionably linked to reentry of space debris,” reported NOAA in a statement.

For example, NOAA stated that Niobium and hafnium do not occur as free elements in nature, but are refined from mineral ores. They are used in semiconductors and superalloys.

Credit: ESA

“In addition to these two unusual elements,” the NOAA statement adds, “a significant number of particles contained copper, lithium and aluminum at concentrations far exceeding the abundance found in meteorics, or ‘space dust.’”

“The combination of aluminum and copper, plus niobium and hafnium, which are used in heat-resistant, high-performance alloys, pointed us to the aerospace industry,’’ said Dan Murphy, a NOAA scientist and leader of the appraisal.

All in all, scientists identified over 20 distinct elements from spacecraft and satellite reentry in particles sampled during SABRE, including, silver, iron, lead, magnesium, titanium, beryllium, chromium, nickel, zinc and lithium.

To view the research results, go to – “Metals from spacecraft reentry in stratospheric aerosol particles” – at: https://www.pnas.org/doi/full/10.1073/pnas.2313374120