METAL proposal for ESA mini-F mission: How do natural and anthropogenic metallic ions access the geospace?

METAL is one of 11 proposals that have passed the preliminary evaluation in the "test call" of ESA mini-F (only 50 Meur with 10-20 kg payload at LEO).  The METAL mission aims to measure metallic (non-volatile) ions in the upper ionosphere of the Earth, both below and above the exobase, to address the overlooked basic questions for the first time:
(Q1) How are metallic ions, the best tracer in the ionosphere, lifted up in various conditions?
(Q2) How much is the ionosphere polluted by ablated anthropogenic metallic ions originating from space waste?
Only one or two ion instruments (ion mass spectrometer covering m>70, and mass-resolving ion energy spectrometer covering up to 100 eV) on board high-inclination LEO (<300 km times >500 km, ideally 1000 km) are needed, making the mission cost very low.  The required specification of the mass spectrometer is already available, by which more sciences such as
(q3) How localized is the ionization chemistry in latitude?
can be performed.  

While Q1 and q3 are related to basic ionospheric science (both physics and chemistry), Q2 is related to anthropogenic environmental issue that requires prompt measurements rather than comprehensive measurements: pollution of the upper atmosphere by re-entering space waste (launch vehicle, used satellites, and space debris).  Since a substantial fraction of the re-entering space waste burn up (=ablated) in the upper atmosphere, and since the composition of the space waste is quite different from those of meteoroids, some elements (Li, Al, Cu, Ge, Pb) are already fully polluted compared to the natural origin.

Some of these ablated atoms are expected to be accumulated near the ionopause (metallic layer) in the same mechanism as natural process through meteor ablation, and some (although small fraction) of accumulated metals are lifted up (after ionization) to the ionosphere and magnetosphere, as are the natural metallic ions.  Considering the difficulty of regular measurement in the mesosphere and lower ionosphere (to high for balloons and too low for satellites), in-situ measurement by satellites, even about 300 km altitude, is one of the best method to diagnose the anthropogenic contamination of the mesosphere.