New radar technique lets scientists probe invisible ice sheet region on
Earth and icy worlds

Date:
July 12, 2023
Source:
University of Texas at Austin
Summary:
A new radar technique developed by a graduate student allows
imaging of the upper few feet of ice sheets on Earth and icy
worlds. The technique uses instruments on airplanes or satellites
to survey large regions quickly. The upper few feet of ice sheets
are important for measuring melt on Earth or looking for habitable
environments on icy worlds.

Previous airborne or satellite techniques could not image this
narrow region in detail.


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FULL STORY ========================================================================== Scientists at the University of Texas Institute for Geophysics (UTIG) have developed a radar technique that lets them image hidden features within
the upper few feet of ice sheets. The researchers behind the technique
said that it can be used to investigate melting glaciers on Earth as well
as detect potentially habitable environments on Jupiter's moon Europa.

The near-surface layers of ice sheets are difficult to study with airborne
or satellite ice-penetrating radar because much of what's scientifically important happens too close to the surface to be accurately imaged. That
has left scientists relying on ground instruments that give only limited coverage, or extracting ice cores -- a difficult and time-consuming
operation currently impossible to do on other planets.

The new radar technique combines two different radar bandwidths and
looks for discrepancies as a way of boosting the resolution. Because
the instruments are carried on airplanes or satellites, scientists can
quickly survey vast regions of ice.

To test the new technique, the team flew radar surveys over the Devon
Ice Cap in the Canadian Arctic where they mapped a slab-like layer of impermeable ice near the surface. Further analysis suggested that the
ice layer is redirecting surface melt from the ice cap's snow-packed
surface into water channels downhill. The research was published May,
2023, in the journal The Cryosphere.

According to Kristian Chan, a graduate student at the UT Jackson School
of Geosciences who devised the technique, the study's findings about
the ice slab layer could help scientists predict the future of the ice
cap and its contribution to sea level rise.

"If you have only relatively thin ice layers then the firn [snow-packed
surface layers] has the ability to absorb and retain surface meltwater,"
Chan said.

"But if these impermeable slabs are widespread then the contribution of
surface melt to sea level rise is enhanced." Surface melt is normal on
ice sheets during summer months. As the top of the previous winter's
snow warms up, meltwater sinks in and refreezes deeper in the snow,
forming thin ice layers.

Most of the ice layers on Devon Ice Cap, however, are much thicker
than expected, some forming slabs as much as 16 feet thick over several
miles. That makes them very effective at redirecting meltwater, which
the researchers confirmed when they matched the location of the thickest
ice slabs with that of meltwater rivers.

Chan said the findings demonstrate what scientists can accomplish with
the new technique.

"We used an airborne radar to find ice slabs on Devon Ice Cap, but
the same thing applies for detecting layers with an orbiting radar at ice-covered 'ocean' worlds like Jupiter's moon Europa," he said.

Chan is part of a UTIG group, led by Senior Research Scientist Don
Blankenship, that is developing a radar instrument called REASON, which
will launch aboard NASA's Europa Clipper in 2024. Along with a European
Space Agency spacecraft that launched this year, scientists will soon have
two ice-penetrating radar instruments investigating Jupiter's moons Europa
and Ganymede. Both radar systems are compatible with Chan's technique.

With the new technique, scientists will be able to peer into the upper few
feet of the icy shells where they might find frozen brine, cryovolcanic remnants or even plume fallout deposits. All are either potential
habitats or clues about habitable environments in the subsurface, said
coauthor Cyril Grima, a UTIG research associate who is also part of the
REASON team.

"Kristian has given us the ability to see things in this hidden part
just beneath the surface that is potentially accessible to future
landers," Grima said. "It's really improved the reconnaissance ability
of those radars." The research was supported by the NASA Texas Space
Grant Consortium at UTIG, and the G. Unger Vetlesen Foundation. UTIG is
a research unit of the UT Jackson School of Geosciences.

* RELATED_TOPICS
o Space_&_Time
# Moon # Jupiter # Uranus # Space_Probes
o Earth_&_Climate
# Global_Warming # Snow_and_Avalanches # Ice_Ages #
Climate
* RELATED_TERMS
o Ice_age o Ice_sheet o Antarctic_ice_sheet o Solar_system o
Meteor o Glacier o Phoenix_(spacecraft) o Larsen_Ice_Shelf

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Story Source: Materials provided by University_of_Texas_at_Austin. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Kristian Chan, Cyril Grima, Anja Rutishauser, Duncan A. Young, Riley
Culberg, Donald D. Blankenship. Spatial characterization of
near-surface structure and meltwater runoff conditions across
the Devon Ice Cap from dual-frequency radar reflectivity. The
Cryosphere, 2023; 17 (5): 1839 DOI: 10.5194/tc-17-1839-2023 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/07/230712124607.htm

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