Physical properties of Titan’s surface at the Huygens landing site from the surface science package acoustic properties sensor (API-S)
Physical properties of Titan’s surface at the Huygens landing site from the surface science package acoustic properties sensor (API-S)
We present the results from the first sonar to be deployed outside of Earth, and the first active acoustic instrument on Titan, onboard the Huygens probe, and the implications of its data for the geomorphology and characteristics of the Huygens landing site. Signals were recorded from 90 m downwards until impact, with a maximum sensor footprint diameter at the ground of 39.2 m. Probe impact speed was measured to be 4.67 m s?1. Derivation of terrain topography in a transect beneath the probe may indicate a ridge-trough terrain with an amplitude of about 1 m and a wavelength of about 10 m, although a flat surface is also consistent with the results. Modelling of the returned signal indicates that the surface acoustic properties at the landing site must be specular in nature, which may have two possible (not incompatible) causes—the surface may consist of sorted interlocking grains, smooth on the centimetre scale, which would imply either fluvial sorting or the infill of small particles interstitial to the larger particles (similar to a terrestrial playa). Alternatively, specularity may indicate the presence of methane as an interstitial liquid or as very small pools. Due to mission constraints, tens of metres around the landing site were not well-imaged by Huygens' cameras except for the narrow azimuth observed after impact (the camera did not look straight down, and was not in imaging mode during the last few hundred metres of descent). Thus the data presented are among the few direct observations of the landing site surroundings.
Titan, geological processes
457-465
Towner, M.C.
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Garry, J.R.C.
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Lorenz, R.D.
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Hagermann, A.
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Hathi, B.
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Svedhem, H.
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Clark, B.C.
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Leese, M.R.
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Zarneck, J.C.
6e88551c-e592-4903-b17c-d2f14d124ebd
2006
Towner, M.C.
fa155635-c752-4641-9c73-0613c2c88d34
Garry, J.R.C.
aa5a8ae6-0640-459a-aee7-68d7673afbb4
Lorenz, R.D.
467768cc-8516-4049-a206-937e829012e2
Hagermann, A.
37a7cf14-d170-41ed-a528-5a5f7756f966
Hathi, B.
86a0d55e-707f-48e9-a043-cb8c88908a06
Svedhem, H.
4a080daa-4a1a-48c4-a4ee-ac2038b5a06e
Clark, B.C.
28e8d464-5de5-49d2-b5ed-18ac52ed9ef5
Leese, M.R.
d3eed510-ef9f-42d5-b359-e418847ba2e8
Zarneck, J.C.
6e88551c-e592-4903-b17c-d2f14d124ebd
Towner, M.C., Garry, J.R.C., Lorenz, R.D., Hagermann, A., Hathi, B., Svedhem, H., Clark, B.C., Leese, M.R. and Zarneck, J.C.
(2006)
Physical properties of Titan’s surface at the Huygens landing site from the surface science package acoustic properties sensor (API-S).
Icarus, 185 (2), .
(doi:10.1016/j.icarus.2006.07.013).
Abstract
We present the results from the first sonar to be deployed outside of Earth, and the first active acoustic instrument on Titan, onboard the Huygens probe, and the implications of its data for the geomorphology and characteristics of the Huygens landing site. Signals were recorded from 90 m downwards until impact, with a maximum sensor footprint diameter at the ground of 39.2 m. Probe impact speed was measured to be 4.67 m s?1. Derivation of terrain topography in a transect beneath the probe may indicate a ridge-trough terrain with an amplitude of about 1 m and a wavelength of about 10 m, although a flat surface is also consistent with the results. Modelling of the returned signal indicates that the surface acoustic properties at the landing site must be specular in nature, which may have two possible (not incompatible) causes—the surface may consist of sorted interlocking grains, smooth on the centimetre scale, which would imply either fluvial sorting or the infill of small particles interstitial to the larger particles (similar to a terrestrial playa). Alternatively, specularity may indicate the presence of methane as an interstitial liquid or as very small pools. Due to mission constraints, tens of metres around the landing site were not well-imaged by Huygens' cameras except for the narrow azimuth observed after impact (the camera did not look straight down, and was not in imaging mode during the last few hundred metres of descent). Thus the data presented are among the few direct observations of the landing site surroundings.
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Published date: 2006
Keywords:
Titan, geological processes
Identifiers
Local EPrints ID: 46060
URI: http://eprints.soton.ac.uk/id/eprint/46060
ISSN: 0019-1035
PURE UUID: 70dd9055-cf6f-42a3-8648-186df708b1d4
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Date deposited: 18 Oct 2007
Last modified: 15 Mar 2024 09:16
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Contributors
Author:
M.C. Towner
Author:
J.R.C. Garry
Author:
R.D. Lorenz
Author:
A. Hagermann
Author:
B. Hathi
Author:
H. Svedhem
Author:
B.C. Clark
Author:
M.R. Leese
Author:
J.C. Zarneck
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