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posted by martyb on Wednesday March 07 2018, @10:31AM   Printer-friendly
from the here-be-dragons dept.

World-first firing of air-breathing electric thruster

In a world-first, an ESA-led team has built and fired an electric thruster to ingest scarce air molecules from the top of the atmosphere for propellant, opening the way to satellites flying in very low orbits for years on end.

[...] Replacing onboard propellant with atmospheric molecules would create a new class of satellites able to operate in very low orbits for long periods. Air-breathing electric thrusters could also be used at the outer fringes of atmospheres of other planets, drawing on the carbon dioxide of Mars, for instance.

"This project began with a novel design to scoop up air molecules as propellant from the top of Earth's atmosphere at around 200 km altitude with a typical speed of 7.8 km/s," explains ESA's Louis Walpot.

A complete thruster was developed for testing the concept by Sitael in Italy, which was performed in a vacuum chamber in their test facilities, simulating the environment at 200 km altitude.


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  • (Score: 2) by bob_super on Wednesday March 07 2018, @05:30PM (2 children)

    by bob_super (1357) on Wednesday March 07 2018, @05:30PM (#649083)

    The better analogy would be an air-breathing cannonball using a ramjet to expend reach, but without any control surfaces.

    > drag is a function of the square of velocity (does that hold in ultra-low densities?)

    That is a very good question, and I'm really curious what the answer could be. Obviously, moving the molecules out of the way is the same effect on the surface they bounce on, but the fact that they don't have neighbors preventing them from bouncing off has to account for some reduction. Does a spaceship traveling extremely fast in very-low density atmosphere create a spaceship-shaped tunnel that is temporarily a true void?

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  • (Score: 2) by JoeMerchant on Wednesday March 07 2018, @06:09PM

    by JoeMerchant (3937) on Wednesday March 07 2018, @06:09PM (#649100)

    I'm really curious what the answer could be.

    If you're really curious, that paper I referenced above probably tell you in a roundabout fashion how they calculated drag... Seems like more attention span and time than I possess at the moment, especially compared to how curious I really am.

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  • (Score: 2) by JoeMerchant on Wednesday March 07 2018, @06:12PM

    by JoeMerchant (3937) on Wednesday March 07 2018, @06:12PM (#649101)

    The thing that a spaceship has that your average pirate-era cannon ball doesn't is gyro control of orientation...

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