M2P2: Mini Magnetosphere Plasma Propulsion

1. M2P2: �Mini Magnetosphere Plasma Propulsion� Kelly Wallenstein May 10, 2007 22.012 Additional notes: This is to expand on the talk a few weeks ago, �Space Propulsion with Plasma�Additional notes: This is to expand on the talk a few weeks ago, �Space Propulsion with Plasma�

2. M2P2 = �Mini-Magnetosphere Plasma Propulsion� Also known as a �plasma sail� Concept proposed by geophysicist Robert Winglee (U. Wash.) Has been successfully tested on Earth, but not deployed in space.

3. Inspiration: Magnetic Sail Deploy a large loop of superconducting wire to generate a magnetic field Field deflects charged particles radiated by the Sun, which provides momentum to accelerate the spacecraft After first bullet: (and auxiliary loops for steering)After first bullet: (and auxiliary loops for steering)

4. M2P2 Use smaller loops + plasma to get the effect of bigger loops

5. Mechanism Solar Cells power solenoid coils on spacecraft Inject a cloud of plasma (~ pickle jar sized) Mag. field causes plasma to become dense/magnetized Plasma is trapped in field lines

6. Mechanism, cont�d. Plasma cloud is conductive ? induced current Field is inflated by plasma, similar to the way a balloon is inflated by hot air Field lines are dragged outward to a radius of 18-36 miles around the spacecraft Interaction with the solar wind is greatly increased

8. Solar wind (stream of charged particles) would act on field as with a magnetic sail Solar wind is deflected Wind is made of protons moving at a speed of 350 to 800 km/s Protons have mass ? Momentum is transferred to spacecraft, craft accelerates

12. If the electric current through the solenoid drops, the plasma can deionize and escape This shrinks the large �sail� field Gas must be stored to replace ions that leak from the plasma

13. The Plasma Argon or helium? Prototype uses argon More massive, so ions move more slowly ?Easier to contain Helium more likely for the future Less massive, so ions move more quickly ?Harder to contain / more leakage BUT might give more velocity per kilogram

14. What makes this concept better than others? A) Maintains thrust as distance from Sun increases Efficiencies of (normal) magnetic and solar sails decrease with square of distance from Sun M2P2 field expands as solar wind density decreases

15. B) No erosion of components Plasma rocket components (e.g. nozzle) come in contact with hot plasma In M2P2, plasma is confined by a magnetic field C) Suitable for long distances Plasma rockets require lots of electric power, which is limited in space In M2P2: 3 kW electricity to run solenoid would come from solar cells; 3 kg helium ? 3 months

16. D) Reduced Mass Solar sails are large and need to be deployed Normal magnetic sails would need huge coils for comparable power M2P2: Field is made by electromagnetic processes and lies outside the craft

17. Comparisons Theoretically 10X faster than space shuttle (4.3 million miles/day vs. 430,000 miles/day) �Specific Impulse,� or thrust/propellant is 200X better (200 kN�s/kg) than space shuttle main engine Could overtake Pioneers 10 & 11 and Voyagers 1 & 2 (launched in the 1970s) to be first manmade object to leave solar system

20. Sources http://www.space.com/scienceastronomy/solarsystem/m2p2_propulsion_817.html http://www.space.com/businesstechnology/technology/advanced_propulsion_020522-1.html http://www.ess.washington.edu/Space/M2P2/ http://science.nasa.gov/newhome/headlines/prop19aug99_1.htm