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.

Abstract-Ultra wideband (UWB) radio technology for wireless implants has gained significant attention. UWB enables the fabrication of faster and smaller transceivers with ultra low power consumption, which may be integrated into more sophisticated implantable biomedical sensors and actuators. Nevertheless, the large path loss suffered by UWB signals propagating through inhomogeneous layers of biological tissues is a major hindering factor. For the optimal design of implantable transceivers, the accurate characterization of the UWB radio propagation in living biological tissues is indispensable. Channel measurements in phantoms and numerical simulations with digital anatomical models provide good initial insight into the expected path loss in complex propagation media like the human body, but they often fail to capture the effects of blood circulation, respiration, and temperature gradients of a living subject. Therefore, we performed UWB channel measurements within 1-6 GHz on two living porcine subjects because of the anatomical resemblance with an average human torso. We present for the first time a path loss model derived from these invivo measurements, which includes the frequency-dependent attenuation. The use of multiple on-body receiving antennas to combat the high propagation losses in implant radio channels was also investigated. Index Terms-channel model, implant, in-body, in-vivo, path lossThis work is part of the MELODY Project-Phase II (Contract no. 225885), which is financially sponsored by the Research Council of Norway.

The Radar Imager for Mars’ Subsurface Experiment (RIMFAX) is a Ground Penetrating Radar on the Mars 2020 mission’s Perseverance rover, which is planned to land near a deltaic landform in Jezero crater. RIMFAX will add a new dimension to rover investigations of Mars by providing the capability to image the shallow subsurface beneath the rover. The principal goals of the RIMFAX investigation are to image subsurface structure, and to provide information regarding subsurface composition. Data provided by RIMFAX will aid Perseverance’s mission to explore the ancient habitability of its field area and to select a set of promising geologic samples for analysis, caching, and eventual return to Earth. RIMFAX is a Frequency Modulated Continuous Wave (FMCW) radar, which transmits a signal swept through a range of frequencies, rather than a single wide-band pulse. The operating frequency range of 150–1200 MHz covers the typical frequencies of GPR used in geology. In general, the full bandwidth (with effective center frequency of 675 MHz) will be used for shallow imaging down to several meters, and a reduced bandwidth of the lower frequencies (center frequency 375 MHz) will be used for imaging deeper structures. The majority of data will be collected at regular distance intervals whenever the rover is driving, in each of the deep, shallow, and surface modes. Stationary measurements with extended integration times will improve depth range and SNR at select locations. The RIMFAX instrument consists of an electronic unit housed inside the rover body and an antenna mounted externally at the rear of the rover. Several instrument prototypes have been field tested in different geological settings, including glaciers, permafrost sediments, bioherme mound structures in limestone, and sedimentary features in sand dunes. Numerical modelling has provided a first assessment of RIMFAX’s imaging potential using parameters simulated for the Jezero crater landing site.

There has been research interest in using radar for contactless measurements of the human heartbeat for several years. While many systems have been demonstrated, not much attention have been given to the actual physical causes of why this work. The consensus seems to be that the radar senses small body movements correlated with heartbeats, but whether only the movements of the body surface or reflections from internal organs are also monitored have not been answered definitely. There has recently been proposed another theory that blood perfusion in the skin could be the main reason radars are able to detect heartbeats. In this paper, an experimental approach is given to determine the physical causes. The measurement results show that it is the body surface reflections that dominate radar measurements of human heartbeats.

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