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| Titel |
Time-Dependent dust accumulation on the Telltale fibres of the Phoenix mission |
| VerfasserIn |
H. P. Gunnlaugsson, C. Holstein-Rathlou, J. P. Merrison, M. D. Ellehøj, M. T. Lemmon, Phoenix Science Team |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250034199
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| Zusammenfassung |
| The NASA Mars Mission Phoenix lasted 152 sols corresponding to LS = 76° to 148° [1].
During this time wind speeds and directions were measured with the so–called Telltale wind
indicator [2, 3]. The Telltale is a mechanical anemometer containing a lightweight Kapton
tube suspended in Kevlar fibres. Wind speeds and directions were determined by analyzing
the position of the Kapton cylinder in pictures taken with the Surface Stereo Imager
(SSI).
Time dependent dust accumulation on the Telltale fibres was observed during the
Phoenix mission. The amount of dust on the fibres was estimated by calculating a dust
factor assuming exponential absorption through the dust loaded fibres with the sun
almost in the line of sight of the Telltale. Alternatively, and in the laboratory, the
dust load can be monitored using light source behind the camera system. On Mars,
however, this situation was only reached at 3 AM, where very little Telltale data was
obtained.
At the start of the mission (LS ~ 78º) the dust load is minor. The dust load increased at a
steady rate until LS ~ 114º. On later sols, the fibres appear thinner, indicating that they have
been partially cleared of dust. The removal of dust seems coupled with dust devil passing at
the Phoenix landing site. The first major dust-devil days [4], were at LS ~ 112º and LS ~
120º, correlate with the removal of dust of the fibres. The behaviour appears to be more
erratic hereafter, but there are clear indications of periods with accumulation and
removal.
In this contribution we will present the data from Mars and compare with on-going
simulation experiments performed at the Aarhus wind tunnel facilities [5].
References: [1] Smith, P. H., et al., (2009) Science, 325, 58. [2] Gunnlaugsson, H. P., et
al., (2008) JGR, 113, E00A04 [3] Holstein-Rathlou, C., et al., (2010) JGR in press. [4]
Ellehoj, M. D., et al., (2010) JGR in press. [5] Merrison, J. P., et al., (2007) Icarus, 191,
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