Level 1 — Absolute Beginner

An engineer named Francesco Romano built a new kind of engine for satellites. The engine does not need normal fuel.

Instead, the engine uses air. It collects tiny gas particles from high in the sky and turns them into fuel.

This new engine is for satellites that fly very close to Earth, much closer than most satellites. Flying that low usually needs a lot of fuel because of air resistance.

In tests, the engine worked well. It used only a small amount of electricity, about 50 to 60 watts, which is similar to a light bulb.

engineer

a person who designs and builds machines, structures or systems

satellite

a machine sent into space that orbits Earth or another planet

engine

a machine that produces power to make something move

fuel

a substance burned or used to produce energy or power

particle

a very small piece of matter

orbit

the curved path an object follows around a planet or star

resistance

a force that slows down or opposes movement

electricity

a form of energy used to power machines and lights

Level 2 — Elementary

As part of his doctoral research at the University of Stuttgart in Germany, engineer Francesco Romano has designed a plasma thruster that uses the thin atmosphere itself as fuel, potentially letting satellites stay aloft indefinitely without carrying heavy tanks of propellant.

The design targets very low Earth orbit, a band between about 100 and 450 kilometers above the surface, which offers advantages for sharper remote sensing and faster communications but comes at a cost: air molecules at that altitude create enough friction to drag satellites down unless an engine constantly fires to keep them up.

Traditionally, satellites in this zone carry costly gases such as xenon to power their engines, which eventually run out. Romano's system instead collects passing air molecules, uses radio frequency energy to turn them into charged plasma, and expels that plasma to generate thrust, all without needing an onboard fuel supply.

Laboratory testing in a vacuum chamber simulating the atmospheric conditions of very low orbit showed the engine could generate steady plasma using just 50 to 60 watts of power, while its intake system captured about 94.3 percent of incoming particles, an efficiency milestone that researchers say makes fuel free satellite propulsion viable, at least in theory.

doctoral research

advanced academic study leading to a doctorate degree

thruster

a device that produces thrust to propel a vehicle, especially a spacecraft

propellant

a substance used to provide the force that propels something, such as a rocket

altitude

the height of an object above sea level or the ground

friction

the resistance that one surface or object encounters when moving over another

xenon

a rare, heavy gas sometimes used as a propellant in ion engines

radio frequency

electromagnetic waves used to transmit energy or signals, such as in radio

thrust

the forward force produced by an engine that propels a vehicle

Level 3 — Intermediate

A doctoral thesis at the University of Stuttgart has produced a working laboratory design for an atmosphere breathing electric propulsion system, a plasma thruster engineered to draw its working fluid directly from the thin gases of very low Earth orbit rather than from an onboard propellant tank, a distinction that could fundamentally alter the economics of operating satellites at extremely low altitudes.

Very low Earth orbit, generally defined as the band between roughly 100 and 450 kilometers, has long been attractive for its proximity to the surface, which sharpens imaging resolution and reduces communication latency, but the same thin atmosphere that makes the zone useful also generates persistent aerodynamic drag, forcing conventional satellites to fire thrusters almost continuously and burn through finite supplies of costly propellants such as xenon far faster than satellites in higher, less turbulent orbits.

Romano's design circumvents that constraint by using an intake structure to collect ambient air molecules ahead of the spacecraft, ionizing them with radio frequency fields into a plasma, and expelling that plasma to generate thrust, effectively converting the very drag that threatens the satellite's altitude into the raw material for counteracting it.

Vacuum chamber testing that replicated the atmospheric composition and density of very low orbit demonstrated the thruster could sustain stable plasma generation on just 50 to 60 watts, a strikingly modest power budget, while its specular intake captured roughly 94.3 percent of incoming particles, an efficiency figure researchers regard as the key threshold separating a theoretical concept from a system with genuine mission potential, even as engineers caution that atomic oxygen's corrosive effect on electrodes and grids remains an unresolved durability challenge.

propulsion

the process or means of driving or pushing something forward

working fluid

a substance used within a system to transfer or generate energy or force

latency

the delay before a transfer of data begins following an instruction

drag

a force that opposes an object's motion through a fluid, such as air

circumvent

to find a way around an obstacle or restriction

ionize

to convert an atom or molecule into an ion by adding or removing charged particles

specular

relating to or having the properties of a mirror, reflecting in a particular direction

corrosive

causing gradual damage or destruction to a material through chemical action

Level 4 — Advanced

A doctoral thesis emerging from the University of Stuttgart has advanced atmosphere breathing electric propulsion from a theoretical curiosity toward a laboratory validated concept, demonstrating a plasma thruster that metabolizes the very rarefied gases responsible for orbital decay into the reaction mass required to counteract it, a conceptual inversion that, if it survives the transition from bench test to flight hardware, could reshape the economics of very low Earth orbit operations.

The appeal of that orbital regime, roughly 100 to 450 kilometers above the surface, has always been offset by a stubborn physical penalty: the same residual atmosphere that sharpens imaging resolution and shrinks communication latency imposes aerodynamic drag severe enough that conventional satellites must fire onboard thrusters almost continuously, exhausting finite reserves of costly propellants such as xenon at a rate that has historically confined missions there to relatively short operational lifespans.

By positioning an intake structure to harvest ambient air molecules ahead of the spacecraft, ionizing them via radio frequency fields into plasma, and expelling that plasma as thrust, the design effectively closes a loop in which the drag threatening the satellite's altitude becomes, itself, the resource sustaining it, a reframing that laboratory results lend real credibility to: stable plasma generation on a mere 50 to 60 watts, alongside an intake efficiency of roughly 94.3 percent of incoming particles, a figure researchers treat as the decisive threshold between an elegant proof of concept and a system plausibly durable enough for genuine mission use.

That credibility remains provisional, however, since the same upper atmospheric environment that supplies the thruster's fuel also subjects its electrodes, acceleration grids and cathodes to atomic oxygen, a highly reactive byproduct of ultraviolet radiation splitting ordinary oxygen molecules, whose corrosive potential over months or years of continuous operation has yet to be demonstrated in orbit, leaving the design's ultimate viability contingent on hardware durability that no vacuum chamber can fully replicate.

metabolize

to process or convert a substance into a usable form, often used metaphorically here

reaction mass

the mass expelled from a propulsion system to generate thrust in the opposite direction

orbital decay

the gradual reduction of a satellite's orbital altitude due to drag or other forces

regime

a particular system, order or set of conditions under which something operates

residual

remaining after most has been removed or has decayed

harvest

to gather or collect something, often a resource, for use

provisional

arranged or existing for the present, possibly to be changed in the future