Pilot Study Data Products and Results


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DISCLAIMER! Mapping results presented herein are PRELIMINARY and could change substantially as work progresses toward the conclusion of the SWIM study. Please check back frequently or follow us on Twitter @RedPlanetSWIM for SWIM news and product release information.
Welcome to the 2018 SWIM Pilot Study!

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Arcadia: Composite
Product Name
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Description PNG TIFF GeoTIFF Anc. Data
Combined Ice Consistency

Last Updated: 2019-01-08 11:41:43

The ice consistency map is generated by combining all the individual consistency maps through the "SWIM Equation", i.e. Neutron; Thermal; Radar Surface Power; Geomorphology and Radar Dielectric Estimates. The ice consistency map is designed to show where all data sets are consistent or inconsistent with the presence of ice over a combined sensing depth of ~5m, indicating the likely presence of ice or lack thereof in that location.
Arcadia: Individual Data Sets
Product Name
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Description PNG TIFF GeoTIFF Anc. Data
Geomorphology

Last Updated: 2019-01-08 11:41:43

The geomorphology map was created using previous and new mapping of periglacial and glacial features. First, the southernmost boundary of latitude dependent mantle was estimated and mapped using the SHARAD roughness and surface reflectivity properties that are consistent with previously mapped mantle. The outlines of glacial features, including lobate debris aprons (LDA), lineated valley fill (LVF), and concentric crater fill (CCF) were also mapped. Areas of mantle were assigned a value of 0, while glacial features were assigned a value of 1. All areas equatorward of the mantle boundary were assigned a value of -1.
Radar Surface Power Return

Last Updated: 2019-01-08 11:41:43

The SHARAD surface power was measured and corrected for surface topography using a combination of MOLA and SHARAD surface roughness data. Low power values provide a proxy for the bulk density of the upper ~ 5m. Due to the low density of ice relative to other martian near surface materials, lower power returns are assumed to be consistent with the presence of ice. Consistency values were assigned according to the global power distribution: < -1σ = 1; -1σ - -0.5σ = 0.5; -0.5σ - 0.5σ = 0; 0.5σ = 1σ = 0.5; >1σ = -1
Thermal Analysis

Last Updated: 2019-01-08 11:41:43

The TES map is generated by matching modeled to apparent variations in thermal inertia. Matches to models of low thermal inertia units over high thermal inertia units are assigned values of 1, when no good match to models is found a value of 0 is assigned, and matches to high thermal inertia units over low thermal inertia units are assigned values of -1.
MONS Analysis

Last Updated: 2019-01-08 11:41:43

Pathare et al. [2018] produced the most definitive global maps to date of near-surface water-equivalent hydrogen in an upper layer (W_up), lower layer (W_dn), and depth (D) to the lower layer. They refined the cross-over technique developed by Feldman et al. [2011] to produce the first maps of self-consistent W_up, W_dn, and D. These W_dn results (expressed in terms of WEH as percentages) were then scaled to fit into the SWIM equation. If W_dn ≥ 25% -> 1, 10% ≤ W_dn < 25% scaled between 0 and 1, 5% ≤ W_dn < 10% scaled between -1 and 0, and W_dn < 5% -> -1.
Est. Dielectric Properties

Last Updated: 2019-01-08 11:41:43

At locations where of rapid surface elevation change associated with subsurface reflector approaching the surface reflection tell the two are indistinguishable we can estimate the real dielectric permittivity (ε’) of the unit above the reflector. By doing this at numerous locations across a region and interpolating between the points we can estimate ε’ from the whole region. To generate the estimated dielectric properties ice consistency map we applied equation C_rd = ε’x-0.5+2.5 to all the point on the interpolated dielectric map.
Deep Radar Reflectors

Last Updated: 2019-01-08 11:41:43

In the subsurface radar map we map all shallow reflectors (>2 µs from the surface return) in SHARAD radargrams in areas where shallow reflectors are present we assign value of 1. We excluded reflectors previously mapped to be lava flows or linked to clutter mapping them as 0 along with regions where no reflector is found.