Constraining the atmospheric influx of anthropogenic materials using in situ micro-debris composition measurements

The number of launches and objects in space has been growing fast in the last few years, particularly due to the growth of satellite mega-constellations. Defunct satellites and other space junk products collide and create a collisional cascade of smaller space debris. Space debris ablates and burns up in the atmosphere upon re-entry and thereby metals and rare materials are injected, some of which already exceed the natural input of exogenous material today.

Quantifying the influx of these anthropogenic materials into the atmosphere is essential to address the possible environmental consequences, through constraining the physico-chemical atmospheric models. This quantification can be done using catalogs of spacecraft being launched, but not all manufacturers provide these data. Small micro-debris can be used as tracers of their larger counterparts through the collisional cascade, which would complement these existing catalogs, for the inventory of elemental compositions of human-made materials in Low EarthOrbit that will re-enter in the atmosphere.

We propose in situ measurements of sub-micrometer and micrometer sized particles as tracers of the larger space debris, using in situ mass spectrometers with a velocity grid, that were originally designed for cosmic dust measurements.

These instruments can measure the elemental composition (impact-speed dependent), mass distribution, surface charge, impact velocity vector, and time-resolved fluxes of dust and debris particles. Moreover, measuring the natural cosmic dust flux itself is necessary as a benchmark for the debris.

In this talk we introduce in situ cosmic dust measurements in the past, the different measurement methods, and measurements of micrometer-sized space debris so far with “active” (time-resolved) and “passive” (sample return) methods. We elaborate on the particles we can expect to measure in orbit, and the science goals to be achieved through such measurements that are useful for both the assessment of the anthropogenic influx into the atmosphere and for space debris research in Low Earth Orbit.  

Elemental composition measurements of these micro-debris particles, combined with orbital velocity and location data, offer a new avenue for quantifying the chemical influx of anthropogenic material into Earth’s atmosphere, and for assessing more thoroughly the broader space debris populations.