Newswise — Researchers at the University of Texas Institute for Geophysics (UTIG) have devised a radar method enabling them to visualize concealed attributes within the uppermost layers of ice sheets. The scientists leading this innovation noted its applicability in studying thawing glaciers on our planet and identifying potentially livable habitats on Jupiter's moon Europa.
Airborne or satellite ice-penetrating radar encounters challenges when studying the shallow layers of ice sheets, as crucial scientific phenomena occur too close to the surface to be precisely captured. Consequently, scientists have heavily relied on ground-based instruments, which offer restricted coverage, or on extracting ice cores—a laborious and time-consuming task that remains unfeasible on celestial bodies beyond our planet.
By integrating two distinct radar bandwidths and exploiting discrepancies between them, the novel radar technique enhances resolution significantly. This advancement allows scientists to swiftly survey extensive ice-covered regions using instruments mounted on airplanes or satellites.
In order to validate the efficacy of the new technique, the research team conducted radar surveys over the Devon Ice Cap located in the Canadian Arctic. Through these surveys, they successfully mapped a solid and impenetrable layer of ice situated close to the surface. Subsequent analysis indicated that this ice layer redirects the surface melt from the snow-covered top of the ice cap into downhill water channels. The findings from this research were published in the scientific journal The Cryosphere in May 2023.
Kristian Chan, a graduate student at the UT Jackson School of Geosciences and the innovator behind the technique, emphasized that the study's discoveries regarding the presence of the ice slab layer hold significant implications for predicting the future behavior of the ice cap and its potential impact on sea level rise. This newfound understanding can provide valuable insights for scientists studying climate change and its consequences.
Kristian Chan explained that when the ice layers are relatively thin, the snow-packed surface layers, known as firn, can effectively absorb and retain surface meltwater. However, if these impermeable slabs are prevalent and widespread, they can significantly amplify the contribution of surface melt to the rise of sea levels. This underscores the importance of understanding the distribution and characteristics of such ice slabs in accurately assessing the impacts of climate change on our planet's water levels.
Surface thaw is typical on ice sheets throughout summer months. As the uppermost part of the preceding winter's snow heats up, the thawed water infiltrates and solidifies further within the snow, creating slender layers of ice.
The majority of the ice layers found on Devon Ice Cap, nevertheless, exceed anticipated thickness, with certain slabs spanning up to 16 feet over considerable distances. This substantial thickness proves highly efficient in diverting meltwater, as confirmed by researchers who correlated the densest ice slabs' positions with those of the rivers formed by the melted water.
Chan said the findings demonstrate what scientists can accomplish with the new technique.
"The utilization of an airborne radar enabled us to locate ice slabs on Devon Ice Cap, and the same principle can be applied to detect layers using an orbiting radar on icy celestial bodies such as Europa, one of Jupiter's moons," he stated.
Chan, as a member of a UTIG group led by Senior Research Scientist Don Blankenship, is actively involved in the development of a radar instrument known as REASON. This instrument is scheduled to be launched aboard NASA's Europa Clipper in 2024. Additionally, in conjunction with a European Space Agency spacecraft that was launched earlier this year, scientists will soon have the advantage of two ice-penetrating radar instruments dedicated to exploring the moons Europa and Ganymede of Jupiter. It is worth noting that both radar systems are compatible with Chan's technique.
By employing the new technique, scientists will gain the capability to observe the upper layers of the icy shells, delving into a depth of a few feet. Within these layers, they may discover frozen brine, remnants of cryovolcanoes, or even deposits from plume fallout. These findings hold great significance as they provide potential habitats or valuable clues regarding habitable environments existing beneath the surface. Cyril Grima, a UTIG research associate and member of the REASON team, emphasized the importance of these discoveries in understanding subsurface habitats and their characteristics.
"Grima highlighted that Kristian has granted us the remarkable capability to perceive the concealed realm lying just below the surface, which could be potentially explored by forthcoming landers. This breakthrough has significantly enhanced the reconnaissance prowess of the 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.
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