Researchers developed an atmosphere-breathing electric propulsion system for Very Low Earth Orbit (VLEO) that ingests the thin upper-atmosphere gas causing drag and uses it as reaction mass instead of carrying xenon. The work addresses key VLEO advantages - sharper imagery and lower communications power - while tackling critical challenges such as corrosive atomic oxygen and variable atmospheric density. Three intake geometries were tested in wind-tunnel conditions: an enhanced funnel, a diffuse hexagonal intake, and a specular parabolic mirror. The specular design, coated with graphite or silicon dioxide, trapped about 94.3% of incoming particles and retained most efficiency under misalignment, solving the problem of collecting widely spaced gas molecules in VLEO flows.
The propulsion concept pairs that intake with a contactless RF helicon plasma thruster driven by a birdcage-style antenna and a surrounding solenoid to expel a quasi-neutral plasma jet, eliminating the need for a conventional cathode neutralizer that atomic oxygen would rapidly degrade. Lab vacuum tests sustained plasma streams using 50-60 W of RF power; system-level modeling applied to historical missions like GOCE indicates continuous operation between roughly 190-250 km on less than 1.6 kW of electrical power, and similar principles could work around Mars at 120-160 km. The approach is unproven in orbit and requires further de-risking, but shows a practical path to indefinite VLEO operations without onboard propellant.
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