Dust Mitigation Technologies for Lunar Exploration

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1 Dust Mitigation Technologies for Lunar Exploration Carlos I. Calle, Ph.D., NASA Kennedy Space Center J.M. McFall, ASRC Aerospace, Kennedy Space Center C.R. Buhler, Ph.D. ASRC Aerospace, Kennedy Space Center A. Chen, Ph.D., Oklahoma Baptist University J.S. Clements, Ph.D., Appalachian State University S. Trigwell, Ph.D., ASRC Aerospace, Kennedy Space Center J.G. Mantovani, NASA Kennedy Space Center J. Quinn, NASA Kennedy Space Center E.E. Arens, NASA Kennedy Space Center M.L. Ritz, ASRC Aerospace, Kennedy Space Center Electrostatics and Surface Physics Laboratory NASA Kennedy Space Center International Conference on Exploration and Utilization of the Moon, Sorrento, Italy, October 22-26, 2007

were spent on the lunar surface before the LM ascent engine fired for liftoff Lunar dust tracked into the LM became a

2 Lunar Dust Environment Top layer of the lunar regolith is comprised of dust Lunar dust is an abrasive powder that clings to space suits, robots, and virtually all machinery Apollo 12, November 1969: A total of 31 hours, 31 minutes were spent on the lunar surface before the LM ascent engine fired for liftoff Lunar dust tracked into the LM became a problem Since the dust became weightless after liftoff from the Moon, the astronauts had trouble breathing without their helmets.

electric field to electrodes that are embedded in the surface Electrodes: Thin wires on

3 Dust Mitigation Dust Shield technology removes dust particles and prevents dust accumulation on surfaces Particles are removed by applying a multi-phase traveling electric field to electrodes that are embedded in the surface Electrodes: Thin wires on opaque surfaces Transparent, flexible electrodes on transparent surfaces for optical devices, windows, visors

4 Controlled Dust Motion + dust particle motion + dust particle motion Single-phase electrode pattern with phase 1 electrodes at V1>0V and phase 2 electrodes at V2=0V Charged particles tend to oscillate instead of being transported in any particular direction. Three-phase electrode pattern with phase 1 electrodes at V1>0V, phase 2 electrodes at V2=0V, and phase 3 electrodes at V3= -V1. Charged particles will move in a particular direction.

5 Electrokinetics F r + v F = q Re r [ ] ( ) E + Re p E The time-averaged force <F> acting on a dust particle of charge q having an effective electric dipole moment p due to an external electric field E. (Ref: Electromechanics of Particles, T.B. Jones, 1995). 1 2 r r r

6 Dust Shields Copper electrodes on opaque board Transparent electrodes on flexible PET over solar panel Before activation After activation

4 μa current from each of three high-voltage amplifiers for a combined total current of 88.2 μa.

7 Experimental Setup Experimental setup. A 1200 V amplitude Moesner-Higuchi waveform applied to the dust screen draws 29.4 μa current from each of three high-voltage amplifiers for a combined total current of 88.2 μa. Moesner-Higuchi timing diagram with voltage along the vertical axis and time along the horizontal axis. Each color represents one of the three-phases applied to sets of line-electrodes. The voltages for each phase are different at any given time.

8 Shield Optimization

Simulated Lunar Conditions Experiments with JSC 1af simulant ~20 μm Vacuum chamber at 10-6 kpa Shields were driven with a Mosener & Higuchi waveform (maximum

9 Simulated Lunar Conditions Experiments with JSC 1af simulant ~20 μm Vacuum chamber at 10-6 kpa Shields were driven with a Mosener & Higuchi waveform (maximum amplitude of 1,200 V) The shields had trace spacings of 0.5 to 1.0 mm Aerosolized simulant dust was deposited on the shields under very low relative humidity conditions

10 Numerical Modeling Kennedy Space Center Sine wave Square wave Green circles show the particles initial positions

11 E-field Contours E-field contour plot with a 900 V three-phase sinusoidal signal. Three-phase Square Signal, E-field plot (900 V)

12 Potential Contours V-field plot for 900 V, threephase sine signal. The different phases caused the voltage to vary among the electrodes. Three-phase square wave signal, 900 V

13 Martian Simulant Removal

14 Transparent Screen

15 Optical Window

16 Optical Window

17 Metal Backed Glass Shield

18 Apollo XIV Sample

Paper Session II-A - Electrodynamic Shield to Remove Dust from Solar Panels on Mars

The Space Congress Proceedings 2004 (41st) Space Congress Proceedings Apr 30th, 8:00 AM Paper Session II-A - Electrodynamic Shield to Remove Dust from Solar Panels on Mars C. I. Calle NASA, Kennedy Space