Using DAS-Fibres for Lunar Seismic Imaging

A set of major mission themes has emerged from the 2020 ESA Call for Ideas, "Exploring the Moon with a large European lander", with a polar ice prospecting mission identified and currently being studied as a candidate EL3 science mission. A combination of Ground-Penetrating Radar (GPR), Magnetic Induc-tion Spectroscopy (MIS) and Distributed Acoustic Sensing (DAS) has been proposed to localize and 3D-map water ice and volatiles in the subsurface. In 2020 CGF (Centre for Geophysical Forecasting at NTNU) conducted a DAS field test using one DAS (Distributed Acoustic Sensing) interrogator located in Longyearbyen. An interrogator is a laser instru-ment that sends light into a fiber optic cable to perform real-time measurements of strain. This operation was a cooperation between CGF/NTNU, and industry. 40 days of continuous DAS recording was successfully completed, and the results demonstrate the huge potential of using telecommunication fibre cables for underwater sensing. We recorded more than 800 whale soundings, several earthquakes, ship passing and long distance Atlantic storms in 2020. In another field test in 2021 CGF established a field station in a quick clay area in Rissa, Norway for the purpose of acoustic monitoring of the clay proper-ties. Both these experiments were successful and proved that good DAS-data can be acquired using the newly developed high-energy interrogator

Isotopic and geochemical investigation of two distinct Mars analog environments using evolved gas techniques in Svalbard, Norway

The 2010 Arctic Mars Analog Svalbard Expedition (AMASE) investigated two distinct geologic settings on Svalbard, using methodologies and techniques to be deployed on Mars Science Laboratory (MSL). AMASE-related research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions. The Sample Analysis at Mars (SAM) instrument suite on MSL includes pyrolysis ovens, a gas-processing manifold, a quadrupole mass spectrometer (QMS), several gas chromatography columns, and a Tunable Laser Spectrometer (TLS). An integral part of SAM development is the deployment of SAM-like instrumentation in the field. During AMASE 2010, two parts of SAM participated as stand-alone instruments. A Hiden Evolved Gas Analysis-Mass Spectrometer (EGA-QMS) system represented the EGA-QMS component of SAM, and a Picarro Cavity Ring Down Spectrometer (EGA-CRDS), represented the EGA-TLS component of SAM. A field analog of CheMin, the XRD/XRF on MSL, was also deployed as part of this field campaign. Carbon isotopic measurements of CO2 evolved during thermal decomposition of carbonates were used together with EGA-QMS geochemical data, mineral composition information and contextual observations made during sample collection to distinguish carbonates formation associated with chemosynthetic activity at a fossil methane seep from abiotic processes forming carbonates associated with subglacial basaltic eruptions. Carbon and oxygen isotopes of the basalt-hosted carbonates suggest cryogenic carbonate formation, though more research is necessary to clarify the history of these rocks

Visiting a fresh crater in Jezero with the Mars 2020 Perseverance Rover

Fresh craters provide an opportunity for close examination into the subsurface for landed missions. Adziilii crater is one of many fresh craters with extant ejecta within Jezero crater, the field site for the Mars 2020 Perseverance rover, formed in the unit termed Crater Floor- Fractured Rough (CF-Fr) which comprises much of the Jezero crater floor. This ~80x70 m elliptical crater has a depth/diameter ratio of 0.05 consistent with a low-angle secondary impact. Considering two similar appearing elongated impact craters lying to the southwest and southeast of the landing site, Adziilii crater is probably part of a secondary crater cluster. Meter scale-sized blocks line the Adziilii crater rim out to one crater radii to the north and south. Such asymmetric ejecta distribution is also related to shallow impact angles. Several sharp-rimmed kilometer diameter craters, for example the 2 km diameter Dacono crater east of Adziilii, are close enough to have been the source for ejecta blocks traveling at sub-hypervelocity. In the case of Dacono, a mere 320-350 m/s initial velocity at an ejection angle ranging from 30-45 degrees can loft an ejecta block the ~28 km distance to form Adziilii crater. Excavation depths of a crater this size are approximately 3-5 meters. Some larger ejecta blocks seen in Mastcam-Z images exhibit unique vesicular, sometimes ropey, textures different from the surrounding dusty low-lying rocks nearby and appear rougher than similar dark toned, smooth textured blocks examined by the Perseverance rover. Observations from the rover’s ground penetrating radar system (RIMFAX) reveal at least one higher density subsurface transition at about 3-5 m depth. Given the unique textures and excavation depths, there’s potential these blocks represent a unique buried surface. While the ejecta block textures are consistent with a geologic unit with a volcanic origin, as are several subsurface structures, the pattern is also consistent with aeolian erosion as seen in Gale Crater rocks at Rocknest. It is also possible the unique lithologic characteristics hint at impactor fragment survivability, more likely in a low velocity impact. However, if the source crater is local, the differences in lithology may be small or unobservable. Future observations of fresh impact craters along the rover's traverse should help elucidate more subsurface stratigraphy of the crater floor and other buried units examined by Perseverance at the surface

Isotopic and geochemical investigation of two distinct Mars analog environments using evolved gas techniques in Svalbard, Norway

The 2010 Arctic Mars Analog Svalbard Expedition (AMASE) investigated two distinct geologic settings on Svalbard, using methodologies and techniques to be deployed on Mars Science Laboratory (MSL). AMASE-related research comprises both analyses conducted during the expedition and further analyses of collected samples using laboratory facilities at a variety of institutions. The Sample Analysis at Mars (SAM) instrument suite on MSL includes pyrolysis ovens, a gas-processing manifold, a quadrupole mass spectrometer (QMS), several gas chromatography columns, and a Tunable Laser Spectrometer (TLS). An integral part of SAM development is the deployment of SAM-like instrumentation in the field. During AMASE 2010, two parts of SAM participated as stand-alone instruments. A Hiden Evolved Gas Analysis-Mass Spectrometer (EGA-QMS) system represented the EGA-QMS component of SAM, and a Picarro Cavity Ring Down Spectrometer (EGA-CRDS), represented the EGA-TLS component of SAM. A field analog of CheMin, the XRD/XRF on MSL, was also deployed as part of this field campaign. Carbon isotopic measurements of CO2 evolved during thermal decomposition of carbonates were used together with EGA-QMS geochemical data, mineral composition information and contextual observations made during sample collection to distinguish carbonates formation associated with chemosynthetic activity at a fossil methane seep from abiotic processes forming carbonates associated with subglacial basaltic eruptions. Carbon and oxygen isotopes of the basalt-hosted carbonates suggest cryogenic carbonate formation, though more research is necessary to clarify the history of these rocks

Ground penetrating radar observations of the contact between the western delta and the crater floor of Jezero crater, Mars

The delta deposits in Jezero crater contain sedimentary records of potentially habitable conditions on Mars. NASA's Perseverance rover is exploring the Jezero western delta with a suite of instruments that include the RIMFAX ground penetrating radar, which provides continuous subsurface images that probe up to 20 meters below the rover. As Perseverance traversed across the contact between the Jezero crater floor and the delta, RIMFAX detected a distinct discontinuity in the subsurface layer structure. Below the contact boundary are older crater floor units exhibiting discontinuous inclined layering. Above the contact boundary are younger basal delta units exhibiting regular horizontal layering. At one location, there is a clear unconformity between the crater floor and delta layers, which implies that the crater floor experienced a period of erosion before the deposition of the overlying delta strata. The regularity and horizontality of the basal delta sediments observed in the radar cross sections indicate that they were deposited in a low-energy lake environment.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Ground penetrating radar observations of subsurface structures in the floor of Jezero crater, Mars

The Radar Imager for Mars Subsurface Experiment instrument has conducted the first rover-mounted ground-penetrating radar survey of the Martian subsurface. A continuous radar image acquired over the Perseverance rover's initial ~3-kilometer traverse reveals electromagnetic properties and bedrock stratigraphy of the Jezero crater floor to depths of ~15 meters below the surface. The radar image reveals the presence of ubiquitous strongly reflecting layered sequences that dip downward at angles of up to 15 degrees from horizontal in directions normal to the curvilinear boundary of and away from the exposed section of the Séitah formation. The observed slopes, thicknesses, and internal morphology of the inclined stratigraphic sections can be interpreted either as magmatic layering formed in a differentiated igneous body or as sedimentary layering commonly formed in aqueous environments on Earth. The discovery of buried structures on the Jezero crater floor is potentially compatible with a history of igneous activity and a history of multiple aqueous episodes.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]