Triboelectric, or frictional, charging is a ubiquitous yet poorly understood phenomenon in granular flows. Recognized in terrestrial volcanic plumes and sand storms, such electrification mechanisms are possibly present on Titan. There, dunes and plains of low-density organic particles blanket extensive regions of the surface. Unlike Earth, Titan hosts granular reservoirs whose physical and chemical properties possibly enhance the effects of charging on particle motion. Here we demonstrate in laboratory tumbler experiments under atmospheric conditions and using organic materials analogous to Titan that Titan sands can readily charge triboelectrically. We suggest that the resulting electrostatic forces are strong enough to promote aggregation of granular materials and affect sediment transport on Titan. Indeed, our experiments show that electrostatic forces may increase the saltation threshold for grains by up to an order of magnitude. Efficient electrification may explain puzzling observations on Titan such as the mismatch between dune orientations and inferred wind fields. We conclude that, unlike other Solar System bodies, nanometre-scale electrostatic processes may shape the geomorphological features of Titan across the moon’s surface.
At a glance
- Triboelectrification of identical insulators. I. An experimental investigation. J. Phys. Appl. Phys. 19, 1273–1280 (1986). &
- Triboelectrification of identical insulators. II. Theory and further experiments. J. Phys. Appl. Phys. 19, 1281–1298 (1986). &
- Triboelectric charging of powders: a review. Chem. Eng. Sci. 65, 5781–5807 (2010). , , &
- Characterisation of electrostatic properties of powder coatings in relation with their industrial application. Powder Technol. 190, 230–235 (2009). , , &
- Contact electrification of insulating materials. J. Phys. Appl. Phys. 44, 453001 (2011). &
- Electrostatics and gas phase fluidized bed polymerization reactor wall sheeting. Chem. Eng. Sci. 61, 1041–1064 (2006).
- Ash aggregation in explosive volcanic eruptions. Geophys. Res. Lett. 40, 2355–2360 (2013). , &
- Experimental investigation of volcanic particle aggregation in the absence of a liquid phase. J. Geophys. Res. 107, 2191 (2002). , &
- Electrostatics in wind-blown sand. Phys. Rev. Lett. 100, 014501 (2008). &
- An experimental evaluation of ash aggregation in explosive volcanic eruptions. J. Volcanol. Geotherm. Res. 209–210, 1–8 (2012). &
- Direct observation of particle interactions and clustering in charged granular streams. Nat. Phys. 11, 733–737 (2015). , , &
- Cassini SAR, radiometry, scatterometry and altimetry observations of Titan’s dune fields. Icarus 213, 608–624 (2011). et al.
- The sand seas of Titan: Cassini RADAR observations of longitudinal dunes. Science 312, 724–727 (2006). et al.
- Dunes on Titan observed by Cassini Radar. Icarus 194, 690–703 (2008). et al.
- Global mapping and characterization of Titan’s dune fields with Cassini: correlation between RADAR and VIMS observations. Icarus 230, 168–179 (2014). et al.
- Nature, distribution, and origin of Titan’s undifferentiated plains. Icarus 270, 162–182 (2016). et al.
- Material transport map of Titan: the fate of dunes. Icarus 270, 183–196 (2016). et al.
- Correlations between Cassini VIMS spectra and RADAR SAR images: implications for Titan’s surface composition and the character of the Huygens probe landing site. Planet. Space Sci. 55, 2025–2036 (2007). et al.
- Spectroscopy, morphometry, and photoclinometry of Titan’s dunefields from Cassini/VIMS. Icarus 195, 400–414 (2008). et al.
- Geomorphological map of the Afekan Crater region, Titan: terrain relationships in the equatorial and mid-latitude regions. Icarus 270, 130–161 (2016). et al.
- 2011). Gas Discharge Physics (Springer,
- Ueber die zum Funkenübergang in Luft, Wasserstoff und Kohlensäure bei verschiedenen Drucken erforderliche Potentialdifferenz. Ann. Phys. 273, 69–96 (1889).
- Electric discharge in the Martian atmosphere, Paschen curves and implications for future missions. Adv. Space Res. 46, 1334–1340 (2010). , , &
- Physics of saltation and sand transport on Titan: a brief review. Icarus 230, 162–167 (2014). ,
- Low Level Measurements Handbook 6th edn (Keithley, 2004).
- Friction, tribochemistry and triboelectricity: recent progress and perspectives. RSC Adv. 4, 64280–64298 (2014). et al.
- Investigation of a test methodology for triboelectrification. J. Electrost. 49, 245–256 (2000).
- The electrical properties of Titan’s surface at the Huygens landing site measured with the PWA–HASI mutual impedance probe. New approach and new findings. Icarus 270, 272–290 (2016). et al.
- Global pattern of Titan’s dunes: radar survey from the Cassini prime mission. Geophys. Res. Lett. 36, L03202 (2009). &
- Relevance of fast westerlies at equinox for the eastward elongation of Titan’s dunes. Aeolian Res. 2, 113–127 (2010).
- GCM simulations of Titan’s middle and lower atmosphere and comparison to observations. Icarus 250, 516–528 (2015). , &
- Growth mechanisms and dune orientation on Titan. Geophys. Res. Lett. 41, 6093–6100 (2014). et al.
- Methane storms as a driver of Titan’s dune orientation. Nat. Geosci. 8, 362–366 (2015). et al.
- Variations in Titan’s dune orientations as a result of orbital forcing. Icarus 270, 197–210 (2016). et al.
- Higher-than-predicted saltation threshold wind speeds on Titan. Nature 517, 60–63 (2015). et al.
- Multiple origins of linear dunes on Earth and Titan. Nat. Geosci. 2, 653–658 (2009). &
- Saltation threshold on Earth, Mars and Venus. Sedimentology 29, 111–119 (1982). &
- The process of tholin formation in Titan’s upper atmosphere. Science 316, 870–875 (2007). et al.
- The photochemical products of benzene in Titan’s upper atmosphere. Icarus 207, 477–484 (2010). &
- A simple expression for wind erosion threshold friction velocity. J. Geophys. Res. 105, 22437–22443 (2000). &
- The effects of dynamics on the triboelectrification of volcanic ash. J. Geophys. Res. 121, 8209–8228 (2016). &
- Charge-to-mass ratio of saltating particles in wind-blown sand. Sci. Rep. 4, 5590 (2014). , &
- Electrostatic analysis of the interactions between charged particles of dielectric materials. J. Chem. Phys. 133, 024105 (2010). , , &
- The relationship between attractive interparticle forces and bulk behaviour in dry and uncharged fine powders. Adv. Phys. 54, 263–376 (2005).
- Electrostatic self-assembly of macroscopic crystals using contact electrification. Nat. Mater. 2, 241–245 (2003). , , , &
- Two modes for dune orientation. Geology 42, 743–746 (2014). , &
- Controls on and effects of armoring and vertical sorting in aeolian dune fields: a numerical simulation study. Geophys. Res. Lett. 43, GL068416 (2016). , &
- Sediment flux from the morphodynamics of elongating linear dunes. Geology 43, 1027–1030 (2015). et al.
- Investigation of electrostatic charge distribution in gas–solid fluidized beds. Chem. Eng. Sci. 65, 2771–2781 (2010). , &
- Compositional and spatial variations in Titan dune and interdune regions from Cassini VIMS and RADAR. Icarus 270, 222–237 (2016). et al.
- Composition of Titan’s lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment. J. Geophys. Res. 115, E12006 (2010). et al.
- Effect of particle size distribution on the polarity of triboelectric charging in granular insulator systems. J. Electrost. 65, 107–112 (2007). &
- Charge segregation depends on particle size in triboelectrically charged granular materials. Phys. Rev. Lett. 102, 028001 (2009). , &
- The electrification of volcanic particles during the brittle fragmentation of the magma column. In Proc ESA Annu. Meet. Electrost. 2015 (Electrostatics Society of America, 2015). , &
- Fractoemission from fused silica and sodium silicate glasses. J. Vac. Sci. Technol. A 6, 1084–1089 (1988). et al.
- Why like-charged particles of dielectric materials can be attracted to one another. J. Colloid Interface Sci. 354, 417–420 (2011). , , &
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