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  • Writer's pictureMatt Russell

Zubrin's Propellant-less Propulsion

I shuddered when I saw a crimson flame through the porthole instead of the usual starry sky at the night horizon of the planet. Vast pillars of light were bursting into the sky, melting into it, and flooding over with all the colors of the rainbow. An area of red luminescence merged smoothly into the black of the cosmos. The intense and dynamic changes in the colors and forms of the pillars and garlands made me think of visual music. Finally, we saw that we had entered directly into the aurora borealis.

Aleksandr Ivanchenkov (40 years since 15 June 1978 Soyuz flight)

Robert Zubrin and his propellant-less Dipole Drive.

The dipole drive is a new propulsion system which uses ambient space plasma as propellant, thereby avoiding the need to carry any of its own. The dipole drive remedies two shortcomings of the classic electric sail in that it can generate thrust within planetary magnetosphere and it can generate thrust in any direction in interplanetary space. In contrast to the single positively charged screen employed by the electric sail, the dipole drive is constructed from two parallel screens, one charged positive, the other negative, creating an electric field between them with no significant field outside. Ambient solar wind protons entering the dipole drive field from the negative screen side are reflected out, with the angle of incidence equaling the angle of reflection, thereby providing lift if the screen is placed at an angle to the plasma wind. If the screen is perpendicular to the solar wind, only drag is generated but the amount is double that of an electric sail of the same area. To accelerate within a magnetosphere, the positive screen is positioned forward in the direction of orbital motion. Ions entering are then propelled from the positive to the negative screen and then out beyond, while electrons are reflected. There are thus two exhausts, but because the protons are much more massive than the electrons, the thrust of the ion current is more than 42 times greater than the opposing electron thrust, providing net thrust. To deorbit, the negative screen is positioned forward, turning the screen into an ion reflector. The dipole drive can achieve more than 6 mN/kWe in interplanetary space and better than 20 mN/kWe in Earth, Venus, Mars, or Jupiter orbit. In contrast to the electric sail, the ultimate velocity of the dipole drive is not limited by the speed of the solar wind. It therefore offers potential as a means of achieving ultra-high velocities necessary for interstellar flight.

Previous concepts

  • Solar Sail

  • Electrodynamic Tether

  • Bussard Ramjet

  • Magnetic Sail

  • Electric Sail

  • EM Drive

  • Ionospheric ramjet

Dipole Drive

In Planetary Orbit

Dipole Drive in Interplanetary Space

Thrust and Diameter of Dipole Drive in Solar Wind

Use of the Dipole Drive for Interstellar Flight

Ultra High Speed Dipole Drive Performance

Dipole Drive Designs

For more details contact

Pioneer Astronautics 11111 W. 8th Ave. unit A Lakewood, CO 80215 303-980-0890 (phone) 303-980-0753 (fax)


Space word of the week: Apoapsis

Apoapsis: That point in an orbit which is farthest from the primary. Apogee: That point in a terrestrial orbit which is farthest from the Earth. Apolune: That point in a lunar orbit which is farthest from the Moon. Apoapsis and periapsis are the generic terms for describing the farthest and closest points of an orbit to the body being orbited. Ge comes from the Greek for Earth, so apogee and perigee are indeed simply other names for the apoapsis and periapsis of an item orbiting the Earth

Aphelion: That point in a solar orbit which is farthest from the Sun.


The Crew Interactive MObile companioN (CIMON)


  • GRACE-FO microwave ranging instruments allow distance measurements with a precision better than one micron—less than the diameter of a blood cell, or a tenth the width of a human hair.

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