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The effects of radiation on the survivability of key biosignatures are a driving factor in exploration strategies throughout the solar system. Ultraviolet (UV) radiation, especially shorter wavelength UVC radiation, is known to be damaging to organisms and to potential organic biosignatures; however, the interaction of UV radiation with minerals and rocks is not well understood. Constraining the survivability of organics and generation of habitable zones requires assessment of physical parameters such as penetration depth of UV photons. This type of information helps to identify to what extent rocks and minerals can provide effective shielding against UV radiation and is especially important on Mars, where the surface chemistry is more oxidizing, and the radiation environment is more extreme than on Earth. Using pressed pellets of natural gypsum, kaolinite, Mars simulant basalt, and welded tuff, we measured the spectral transmittance of each in the wavelength range of 220–400 nm. Although transmittance drops off quickly with depth, detectable levels of UV can penetrate >500 μm in each material. Each substrate allowed higher transmittance of UVC radiation than of longer wavelength UVA/B radiation, possibly as a result of surface reflectance and internal scattering properties. This could result in increased subsurface photolysis of organic compounds and biosignatures. We have used the transmittance data collected herein to constrain the lifetimes of several organic molecules in the Martian subsurface. These results will also have implications for organic analyses to be conducted by Mars 2020 and could be used to better constrain the SHERLOC/Mars 2020 interrogation volume. Some types of radiation, including ultraviolet (UV) radiation, can be damaging to organisms and to organic molecules which could potentially be used as evidence of life. For this reason it is important to understand how rocks and minerals can provide protection against these types of radiation. In this study we prepared pellets of varying thickness made of different types of rocks and minerals relevant to Mars exploration and measured the amount of UV light that was able to pass through them. These data were used in combination with knowledge of the UV environment on Mars in order to determine what the UV radiation dosage would be under various thicknesses of the rocks and minerals we had analyzed. The percentage of UV radiation that was able to pass through the rock and mineral pellets was found to be higher than we expected, which suggests that this type of damaging radiation would be able to penetrate further into rock and mineral environments. This information was then used to determine approximately how long different types of organic molecules could be expected to survive if buried under different depths in rock and mineral materials. The interaction of UV photons with rocks and minerals has implications for habitability as well as organic biosignature preservation and detectionTransmittance of UV radiation has been determined for four types of natural rocks and minerals that are relevant for Mars explorationUV photons can penetrate to depths greater than anticipated, resulting in a large effective radiation dosage over geological timescales

Measuring the physical properties of geological materials is important for understanding geologic history. Yet there has never been an instrument with the purpose of measuring mechanical properties of rocks sent to another planet. The Mars Science Laboratory (MSL) rover employs the Powder Acquisition Drill System (PADS), which provides direct mechanical interaction with Martian outcrops. While the objective of the drill system is not to make scientific measurements, the drill's performance is directly influenced by the mechanical properties of the rocks it drills into. We have developed a methodology that uses the drill to indicate the uniaxial compressive strengths of rocks through comparison with performance of an identically assembled drill system in terrestrial samples of comparable sedimentary class. During this investigation, we utilize engineering data collected on Mars to calculate the percussive energy needed to maintain a prescribed rate of penetration and correlate that to rock strength. The one tool that personifies the field geologist is a rock hammer. The field geologist will use his/her hammer to expose fresh rock surfaces allowing examination of unweathered rock. He/she will also use it to determine qualitative rock strengths in the field. While Curiosity does not carry a traditional rock hammer, it does have a drill system. The ability to fail rock with a hammering mechanism and the ability to use the performance data from the drill system presented the authors with an innovative concept. The drill could be used as an instrument to indicate the strength of rocks, except that the drill's measurement is better. Where the field geologist has only his/her tactile senses, Curiosity is instrumented with sensors that measure rates of penetration, percussive energy, and weight on bit allowing a quantifiable measurement of rock strength. The article describes the methodologies that allow the drill system aboard the Mars Science Laboratory rover to also serve as a scientific instrument and reports the compressive strength of the rocks drilled on Mars using these methods. A nonstandard method was employed to provide a scientific measurement on the surface of MarsSedimentary structure matters when determining rock strengthStrengthwise, the sedimentary rocks at Gale crater are more akin to younger sedimentary rock on Earth

The first samples collected by the Mars 2020 mission represent units exposed on the Jezero Crater floor, from the potentially oldest Séítah formation outcrops to the potentially youngest rocks of the heavily cratered Máaz formation. Surface investigations reveal landscape‐to‐microscopic textural, mineralogical, and geochemical evidence for igneous lithologies, some possibly emplaced as lava flows. The samples contain major rock‐forming minerals such as pyroxene, olivine, and feldspar, accessory minerals including oxides and phosphates, and evidence for various degrees of aqueous activity in the form of water‐soluble salt, carbonate, sulfate, iron oxide, and iron silicate minerals. Following sample return, the compositions and ages of these variably altered igneous rocks are expected to reveal the geophysical and geochemical nature of the planet's interior at the time of emplacement, characterize martian magmatism, and place timing constraints on geologic processes, both in Jezero Crater and more widely on Mars. Petrographic observations and geochemical analyses, coupled with geochronology of secondary minerals, can also reveal the timing of aqueous activity as well as constrain the chemical and physical conditions of the environments in which these minerals precipitated, and the nature and composition of organic compounds preserved in association with these phases. Returned samples from these units will help constrain the crater chronology of Mars and the global evolution of the planet's interior, for understanding the processes that formed Jezero Crater floor units, and for constraining the style and duration of aqueous activity in Jezero Crater, past habitability, and cycling of organic elements in Jezero Crater. Here we provide a narrative of sample collection and associated in situ rover observations for the rocks collected by the Perseverance rover to provide a preliminary description of the first samples of the Mars 2020 mission. These rocks collected in Jezero Crater represent the first samples from Mars with a known geologic context, the first collected with the potential to be returned to Earth for laboratory analysis, and the first cores from rock outcrops on another planet. Remote and proximal analyses indicate that all crater floor outcrops investigated are igneous in origin. Laboratory analyses of these rocks will be useful to study the planet's interior at the time of emplacement, characterize martian magmatism, and place timing constraints on geologic processes, both in Jezero Crater and more widely on Mars. All collected rocks have interacted with water and contain secondary geochemical and mineralogical evidence that can be used to understand aqueous environments in the crater and the potential conditions of habitability for ancient life on Mars. Nine samples, consisting of four pairs of rock cores and a tube of atmospheric gas, were collected from the floor of Jezero Crater, MarsIn situ observations of crater floor outcrops, used as proxies for the samples, reveal aqueously altered igneous lithologiesPerseverance will leave one sample from each pair at the Three Forks depot and retain a second to be cached with future samples Nine samples, consisting of four pairs of rock cores and a tube of atmospheric gas, were collected from the floor of Jezero Crater, Mars In situ observations of crater floor outcrops, used as proxies for the samples, reveal aqueously altered igneous lithologies Perseverance will leave one sample from each pair at the Three Forks depot and retain a second to be cached with future samples