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Lava tubes on Mars hold exciting potential for the preservation of biosignatures, which may survive on geological timescales in these isolated, stable environments. To support the development of future astrobiological mission concepts, we turn to terrestrial lava tubes, host to a variety of microbial communities and secondary minerals. Following a multidisciplinary sampling protocol, we retrieved biological, molecular, and mineralogical data from several lava tubes in Iceland. We report on blue-colored copper-rich secondary minerals and their associated bacterial communities using a multi-method approach, and an amalgam of 16S rRNA gene sequencing, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy data sets. We found numerous bacterial genera known for their high metal resistance and ability to survive in low-nutrient environments. Both are characteristics to be expected for any potential life in Martian lava tubes, and should be considered when checking for contaminants in Mars mission preparations. Associated with the microbial mats, we identified several types of copper-rich secondary minerals, indicating localized copper enrichments in the groundwater, possibly stemming from overlying ash deposits and nearby hyaloclastite formations. Molecular analysis revealed carotenoid signals preserved within the copper speleothems. If found in Martian lava tubes, blue copper-rich mineral precipitates would be deserving of astrobiological investigation, as they have potential to preserve biosignatures and harbor life.

Energy from active serpentinization processes potentially fuelled the origin of life on Earth, thus, if serpentinite-impacted sites facilitate microbial habitability, it is important to understand the source and retention of biological signatures in serpentine rocks. Investigating biological signatures in terrestrial analogues of serpentinite-impacted environments is also essential for interpreting molecular signature preservation on extra-terrestrial bodies. To expand knowledge on the types of biological signatures directly derived from living microorganisms (intact polar lipids, IPLs), and both living and dead microorganisms (core lipids), mass spectrometry analysis was performed on Chimaera serpentinite rocks from Antalya Province, Turkey. Brucite rocks were dominated by IPLs from fungal, eukaryotic origin but in contrast, travertine samples had IPL profiles consistent with a mixed fungal, archaeal and bacterial community. The abundance and diversity of archaeal IPLs was significantly higher in the travertine compared to the brucite, and the abundance of archaeal IPLs inside the travertine rock was highest. Archaeal specific core lipids identified inside the brucite rock were not observed as IPL counterparts, suggesting the presence of a non-viable or fossil archaeal community. Comparing IPL profiles with core lipids can discriminate between living microbial communities, necromass, and fossils to combine as a promising molecular tool for identification and interpretation of bio-signatures in serpentinite-impacted sites. Continuing survey of serpentinization samples on Earth can act as analogue environments and provide valuable insight into microbial habitability on Mars and other planetary objects.

Polycyclic aromatic hydrocarbons (PAHs) represent ~20% of cosmically available carbon [1, 2]. The further photochemical evolution of PAHs on planetary surfaces is of interest to early Earth origin-of-life studies and Mars origin-of-life speculations. Much of the literature has focused on small molecules contained in meteorites, such as amino acids and nucleic acid bases, and their potential as a carbon source for prebiotic chemistry on early Earth. However, 75% of extraterrestrial organic matter in meteorites is in aromatic form [3], and is more likely to survive the journey to a planetary surface, during which much of the small molecules can be destroyed. These stable carbon compounds could later be broken down into smaller, more biologically relevant molecules by photocatalysis on clay mineral surfaces in the ultraviolet radiation regime of early Earth and Mars. Here we experimentally test whether PAHs degrade when adsorbed to nontronite clay and exposed to ultraviolet radiation. Experiments were performed at the INAF Observatory of Arcetri and in the PALLAS chamber at Utrecht University and were monitored with in-situ diffuse reflectance infrared spectrometry (DRIFTS) measurements. PAHs and any degradation products were extracted post-irradiation and analyzed with nuclear magnetic resonance (NMR). [1] Allamandola, L. J., Tielens, A. G. G. M., & Barker, J. R. (1989). The Astrophysical Journal Supplement Series, 71, 733-775. [2] Puget, J. L., & Léger, A. (1989). Annual review of astronomy and astrophysics, 27(1), 161-198. [3] Sephton, M. A. (2002). Natural product reports, 19(3), 292-311.

Understanding how to catalytically break the C-H bond of aromatic molecules, such as polycyclic aromatic hydrocarbons (PAHs), is currently a big challenge and a subject of study in catalysis, astrochemistry, and planetary science. In the latter, the study of the breakdown reaction of PAHs on mineral surfaces is important to understand if PAHs are linked to prebiotic molecules in regions of star and planet formation. In this work, we employed a periodic density functional theory along with Grimme's D4 (DFT-D4) approach for studying the adsorption of a sample of PAHs (naphthalene, anthracene, fluoranthene, pyrene, coronene, and benzocoronene) and fullerene on the [010] forsterite surface and its defective surfaces (Fe-doped and Ni-doped surfaces and a MgO-Schottky vacancy) for their implications in catalysis and astrochemistry. On the basis of structural and binding energy analysis, large PAHs and fullerene present stronger adsorption on the pristine, Fe-doped, and Ni-doped forsterite surfaces than small PAHs. On a MgO-Schottky vacancy, parallel adsorption of the PAH leads to the chemisorption process (C-Si and/or C-O bonds), whereas perpendicular orientation of the PAH leads to the catalytic breaking of the aromatic C-H bond via a barrierless reaction. Spin density and charge analysis show that C-H dissociation is promoted by electron donation from the vacancy to the PAH. As a result of the undercoordinated Si and O atoms, the vacancy acts as a Frustrated Lewis Pair (FLP) catalyst. Therefore, a MgO-Schottky vacancy [010] forsterite surface proved to have potential catalytic activity for the activation of C-H bond in aromatic molecules.

Prebiotic chemistry has dominated the origins of life (OoL) field to such an extent that often these terms have been used interchangeably. While prebiotic chemistry has benefited from cross-seeding with other disciplines (e.g., biochemistry, biophysics, computational sciences, geosciences), the OoL problem is still primarily a chemical one. The range of possible non-enzymatic pathways provisioning important biomolecules is becoming clearer, and the problem can now be cast in terms of understanding how the constructive interplay between such pathways is underlying the mechanisms controlling their self-organization into systems. Those systems must be capable of producing their constituent parts and reproducing as a result, with a degree of maintaining and transferring their information content. This chapter provides a concise historical overview of the research field, presents a comprehensive panorama of the possible synthesis pathways for each biomolecular domain, discusses the homochirality conundrum, argues a case for experimentation using non-classical materials, and models, and finally considers current and future trends.

Lava tubes have been detected on Mars and because of their subsurface nature are shielded from the harsh conditions at the surface. If water intersects with the Martian lava tubes, a life nurturing environment may exist locally in these tubes. Lava tubes on Iceland and the Azores may support similar conditions as lava tubes on Mars and have been shown to contain a wide variety of microbes. [Planetary Analogues and Lava Tube ] (PELE) field expeditions have been setup to understand the relationship between microbes and susbtrate and the preservation of microbes in deeptime within these systems. Within such systems biogenic and hydrothermal alteration processes are not necessarily mutually exclusive and a good understanding of the mineralogy helps distinguish one from the other. Here, I have performed an analytical study analysing basalt mineralogy from recent lava flows from Iceland and Azores islands, attempting to distinguish between biogenic and hydrothermal signatures. I used a workflow of semi quantitative analysis using viewing thin sections under a light microscope to understand textural information. This was supplemented by ImageJ software and using SEM+EDX for point analysis of regions of interest to shed light on our areas of interest. My results showed some ambiguous features linked to alteration in a sample in the north of Iceland related to clays or spherulites, in the Azores vesicle infill of clays or devitrified glass were seen with potential bio signatures including carbon,calcum and phosphorous. These results may indicate environmental factors leading to location specific alteration or related to lava rock mineralogy. Contamination effects cannot be ignored and must be taken into consideration when reviewing these results. Overall these analyses will contribute to the larger PELE outcome by providing a complimentary workflow that can be used to assess biosignatures and specific regions of interest within lava tube rocks.

Laboratory simulations of Martian conditions are essential to develop quantitative models for the survival of organic biomarkers for future Mars exploration missions. In this work, we report the results of ultraviolet (UV) irradiation processing of biomarkers adsorbed on minerals under Martian-like conditions. Specifically, we prepared Mars soil analogues by doping forsterite, lizardite, antigorite, labradorite, natrolite, apatite and hematite minerals with organic compounds considered as potential biomarkers of extant terrestrial life such as the nucleotides adenosine monophosphate (AMP) and uridine monophosphate (UMP). We characterized such Mars soil analogues by means of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Confocal Raman Imaging Spectroscopy (CRIS), in order to get insights into the specific molecule-mineral interactions and explore the capabilities of different techniques to reveal diagnostic features of these biomarkers. Then, we performed irradiation experiments in the mid-UV spectral region under simulated Martian conditions and under terrestrial ambient conditions for comparison, monitoring the degradation process through DRIFTS. We observed that degradation under Martian-like conditions occurs much slower than in terrestrial ambient conditions. The minerals labradorite and natrolite mainly promote photodegradation of nucleotides, hematite and forsterite exhibit an intermediate degrading effect, while apatite, lizardite and antigorite do not show any significant catalytic effect on the degradation of the target organic species.

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.

Within the framework of the International Lunar Surface Operation - In-Situ Resource Utilization Analogue Test held on January 27 - February 11, 2010 on the Mauna Kea volcano in Hawaii, a number of scientific instrument teams collaborated to characterize the field site and test instrument capabilities outside laboratory environments. In this paper, we provide a geological setting for this new field-test site, a description of the instruments that were tested during the 2010 ILSO-ISRU field campaign, and a short discussion for each instrument about the validity and use of the results obtained during the test. These results will form a catalogue that may serve as reference for future test campaigns. In this paper we provide a description and regional geological setting for a new field analogue test site for lunar resource exploration, and discuss results obtained from the 2010 ILSO-ISRU field campaign as a reference for future field-testing at this site. The following instruments were tested: a multispectral microscopic imager, MMI, a Mossbauer spectrometer, an evolved gas analyzer, VAPoR, and an oxygen and volatile extractor called RESOLVE. Preliminary results show that the sediments change from dry, organic-poor, poorly-sorted volcaniclastic sand on the surface, containing basalt, iron oxides and clays, to more water- and organic-rich, fine grained, well-sorted volcaniclastic sand, primarily consisting of iron oxides and depleted of basalt and clays. Furthermore, drilling experiments showed a very close correlation between drilling on the Moon and drilling at the test site. The ILSO-ISRU test site was an ideal location for testing strategies for in situ resource exploration at the lunar or martian surface.

Low power, robust technologies are appealing for in situ planetary science throughout the Solar System. The VAPoR (Volatile Analysis by Pyrolysis of Regolith) instrument is under development toward studying soil composition, volatiles, and trapped noble gases in the polar regions of the Moon and on the surface of other airless bodies. VAPoR will ingest a soil sample and conduct analysis by pyrolysis and time-of-flight mass spectrometry (ToF-MS). Two components of the system have been characterized in parallel development: a field-tested sample heater design and a laboratory-based time-of-flight mass spectrometer that emphasizes reduced mass and power through the use of micro- and nanotechnology. The pyrolysis field unit, vacuum-coupled to a commercial residual gas analyzer, has been used in Hawaii to analyze Mauna Kea soils. Water was detected, as were key inorganic pyrolysis products, including CO2 and SO2, and organic volatiles, including methane, benzene, toluene, and various hydrocarbon fragments. In parallel development, a laboratory reflectron time-of-flight mass spectrometer has been designed, assembled, and tested using electron impact ionization from a carbon nanotube electron gun. Preliminary testing reveals a mass resolution of 270.

We have investigated the native amino acid composition of two analogs of Martian soil, JSC Mars-1 and Salten Skov. A Mars simulation chamber has been built and used to expose samples of these analogs to temperature and lighting conditions similar to those found at low latitudes on the Martian surface. The effects of the simulated conditions have been examined using high-performance liquid chromatography (HPLC). Exposure to energetic ultraviolet (UV) light in vacuum appears to cause a modest increase in the concentration of certain amino acids within the materials, which is interpreted as resulting from the degradation of microorganisms. The influence of low temperatures shows that the accretion of condensed water on the soils leads to the destruction of amino acids, supporting the idea that reactive chemical processes involving H2O are at work within the Martian soil. We discuss the influence of UV radiation, low temperatures, and gaseous CO2 on the intrinsic amino acid composition of Martian soil analogs and describe, with the help of a simple model, how these studies fit within the framework of life detection on Mars and the practical tasks of choosing and using Martian regolith analogs in planetary research.

In order to understand the complex multi-parameter system of destruction of organic material on the surface of Mars, step-by-step laboratory simulations of processes occurring on the surface of Mars are necessary. This paper describes the measured effects of two parameters, a CO2 atmosphere and low temperature, on the destruction rate of amino acids when irradiated with Mars-like ultraviolet light (UV). The results show that the presence of a 7 mbar CO2 atmosphere does not affect the destruction rate of glycine, and that cooling the sample to 210 K (average Mars temperature) lowers the destruction rate by a factor of 7. The decrease in the destruction rate of glycine by cooling the sample is thought to be predominantly caused by the slower reaction kinetics. When these results are scaled to Martian lighting conditions, cold thin films of glycine are assumed to have half-lives of 250 h under noontime peak illumination. It has been hypothesised that the absence of detectable native organic material in the Martian regolith points to the presence of oxidising agents. Some of these agents might form via the interaction of UV with compounds in the atmosphere. Water, although a trace component of Mars’ atmosphere, is suggested to be a significant source of oxidising species. However, gaseous CO2 or adsorbed H2O layers do not influence the photodestruction of amino acids significantly in the absence of reactive soil. Other mechanisms such as chemical processes in the Martian regolith need to be effective for rapid organic destruction.

In the framework of international planetary exploration programs, several space missions are planned to search for organics and bio-signatures on Mars. Previous attempts have not detected any organic compounds in the Martian regolith. It is therefore critical to investigate the processes that may affect organic molecules on and below the planet's surface. Laboratory simulations can provide useful data about the reaction pathways of organic material at Mars' surface. We have studied the stability of amino acid thin films against ultraviolet (UV) irradiation and use those data to predict the survival time of these compounds on and in the Martian regolith. We show that thin films of glycine and D-alanine are expected to have half-lives of 22 ± 5 hr and of 3 ± 1 hr, respectively, when irradiated with Mars-like UV flux levels. Modelling shows that the half-lives of the amino acids are extended to the order of 10 7 years when embedded in regolith. These data suggest that subsurface sampling must be a key component of future missions to Mars dedicated to organic detection.

International audience; The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.

International audience; The Radiation Assessment Detector (RAD) on the Mars Science Laboratory's Curiosity rover began making detailed measurements of the cosmic ray and energetic particle radiation environment on the surface of Mars on 7 August 2012. We report and discuss measurements of the absorbed dose and dose equivalent from galactic cosmic rays and solar energetic particles on the martian surface for similar to 300 days of observations during the current solar maximum. These measurements provide insight into the radiation hazards associated with a human mission to the surface of Mars and provide an anchor point with which to model the subsurface radiation environment, with implications for microbial survival times of any possible extant or past life, as well as for the preservation of potential organic biosignatures of the ancient martian environment.

The extraction and identification of volatile resources that could be utilized by humans including water, oxygen, noble gases, and hydrocarbons on the Moon, Mars, and small planetary bodies will be critical for future long-term human exploration of these objects. Vacuum pyrolysis at elevated temperatures has been shown to be an efficient way to release volatiles trapped inside solid samples. In order to maximize the extraction of volatiles, including oxygen and noble gases from the breakdown of minerals, a pyrolysis temperature of 1400°C or higher is required, which greatly exceeds the maximum temperatures of current state-of-the-art flight pyrolysis instruments. Here we report on the recent optimization and field testing results of a high temperature pyrolysis oven and sample manipulation system coupled to a mass spectrometer instrument called Volatile Analysis by Pyrolysis of Regolith (VAPoR). VAPoR is capable of heating solid samples under vacuum to temperatures above 1300°C and determining the composition of volatiles released as a function of temperature.

We discuss the development of a miniature near-infrared point spectrometer, operating in the 1.7–4 mm region, based on acousto-optic tunable filter (AOTF) technology. This instrument may be used to screen and corroborate analyses of samples containing organic biomarkers or mineralogical signatures suggestive of extant or extinct organic material collected in situ from planetary surfaces. The AOTF point spectrometer will be paired with a laser desorption time-of-flight (LDTOF) mass spectrometer and will prescreen samples for evidence of volatile or refractory organics before the laser desorption step and subsequent mass spectrometer measurement. 1 2 We describe the prototype AOTF point spectrometer instrument and present laboratory analysis of geological samples of known astrobiological importance. An initial mineral and rock sample suite of planetary relevance was used in the laboratory for baseline testing. To this, we will add a complement of astrobiologically relevant biosignatures from a variety of well-characterized geomicrobial study sites. We also describe LDTOF analysis of kaolinite and serpentine specimens, which are both highly relevant to the Martian surface mineralogy and the aqueous history of the planet. The AOTF-LDTOF instrument pairing offers the powerful advantage of cross-checked chemical analyses of individual samples, which can reduce chemical and biological interpretation ambiguities.

This roundtable discussion was convened to discuss the ongoingplanning process in planetary sciences and its relationship toAstrobiology goals. The participants were selected to represent arange of interests and backgrounds in Astrobiology and all of themhave been involved in planetary missions and the use of data fromplanetary missions. Three questions were sent to the panel beforethe roundtable discussion to provide a context of initiating thediscussion. These questions were:1. What would you list as the most important opportu-nity for Astrobiology in planetary missions in the nextdecade?2. What is the right balance between directly searching for lifeand investigations that focus on the physical environmentproviding a context for life? Does the current program strikethe right balance?3. The Decadal Survey process mirrors the organizationalstructure of NASA Headquarters (HQ). Hence, Astrobiologyis included in the Planetary Decadal Survey because Astro-biology is programmatically part of the Planetary program atNASA HQ. Is this the right approach? What are otherpossible approaches? Does the Astrobiology Roadmap (pro-mulgated by the NASA Astrobiology Institute) provide animportant alternative? How effectively do these two processescapture real community input?Christopher P. McKay: Dirk, what would you list as themost important opportunity for astrobiology and planetarymissions in the next decade?Dirk Schulze-Makuch: Well, there would be severalpossibilities, but…we are at a point where we have a verygood idea about the environmental conditions on Mars and Ithink that we are now ready to both design and then launcha life detection mission to Mars.CPMcK: That’s interesting because in a recent forum ar-ticle, you point to Titan as being a priority; so, if you were tolist one thing, would it be a Mars mission, rather than, say, aTitan mission?DSM: I feel Mars is more pressing and we are ready for aMars life detection mission. I would like to see a Titan mis-sion as well, but there is probably still a bit more develop-ment needed, and we have to think exactly how we want todo it. We are not at that exciting juncture with Titan wherewe can look for life. We first have to characterize the envi-ronment. A life detection mission for Mars is on the firstplace for me, and second, an elaborate Titan mission char-acterizing its environment.CPMcK: Penny, how about you next?Penelope Jane Boston: I have a two-part answer to that.On one hand there is a methodological issue and I would liketo see us shift our astrobiological attention—and the missionprogram in general—to a better balance of landed missionsversus orbital missions. While orbital missions have greatvalue for a number of different things, pushing forward thescience relevant to life detection will require landed missionswith increasingly sophisticated in situ measurements. So thatis a philosophical orientation in terms of how you design themissions.Then if I were picking my favorite body to go to—I wouldnot necessarily couch it in those terms—I have become in-creasingly interested in the issue of ices in the solar systemand their potential for preserving biological signals. So thatactually applies to the icy terrains on Mars. It applies to icymoons around at least Jupiter and Saturn as well.So I have started to do some work on Antarctic materialsthat are promising, we think, in terms of trapping microor-ganisms and preserving their signals. Other people, of course,are working on permafrost and so forth. Ices are an arena inwhich I would like to see us really aggressively advance.CPMcK: Everett, how about you?Everett Shock: I would like to comment that one problemwe face in general is that on most planets, the surface is not avery hospitable place, and yet, of course, the surface is theeasiest thing for us to collect data from, either from a vast

Organics are expected to exist on Mars based on meteorite infall, in situ production, and any possible biological sources. Yet they have not been detected on the martian surface; are they there, or are we not capable enough to detect them? The Viking gas chromatograph-mass spectrometer did not detect organics in the headspace of heated soil samples with a detection limit of parts per billion. This null result strongly influenced the interpretation of the reactivity seen in the Viking biology experiments and led to the conclusion that life was not present and, instead, that there was some chemical reactivity in the soil. The detection of perchlorates in the martian soil by instruments on the Phoenix lander and the reports of methane in the martian atmosphere suggest that it may be time to reconsider the question of organics. The high-temperature oxidizing properties of perchlorate will promote combustion of organics in pyrolytic experiments and may have affected the ability of both Phoenix's organic analysis experiment and the Viking mass spectrometer experiments to detect organics. So the question of organics on Mars remains open. A primary focus of the upcoming Mars Science Laboratory will be the detection and identification of organic molecules by means of thermal volatilization, followed by gas chromatography-mass spectrometry--as was done on Viking. However, to enhance organic detectability, some of the samples will be processed with liquid derivatization agents that will dissolve organics from the soil before pyrolysis, which may separate them from the soil perchlorates. Nonetheless, the problem of organics on Mars is not solved, and for future missions other organic detection techniques should therefore be considered as well.

The objective of the 2009 Mars Science Laboratory (MSL), which is planned to follow the Mars Exploration Rovers and the Phoenix lander to the surface of Mars, is to explore and assess quantitatively a site on Mars as a potential habitat for present or past life. Specific goals include an assessment of the past or present biological potential of the target environment and a characterization of its geology and geochemistry. Included in the 10 investigations of the MSL rover is the Sample Analysis at Mars (SAM) instrument suite, which is designed to obtain trace organic measurements, measure water and other volatiles, and measure several light isotopes with experiment sequences designed for both atmospheric and solid-phase samples. SAM integrates a gas chromatograph, a mass spectrometer, and a tunable laser spectrometer supported by sample manipulation tools both within and external to the suite. The sub-part-per-billion sensitivity of the suite for trace species, particularly organic molecules, along with a mobile platform that will contain many kilograms of organic materials, presents a considerable challenge due to the potential for terrestrial contamination to mask the signal of martian organics. We describe the effort presently underway to understand and mitigate, wherever possible within the resource constraints of the mission, terrestrial contamination in MSL and SAM measurements.

Given rapid photodissociation and photodegradation, the recently discovered organics in the Martian subsurface and atmosphere were probably delivered in geologically recent times. Possible parent bodies are C-type asteroids, comets, and interplanetary dust particles (IDPs). The dust infall rate was estimated, using different methods, to be between $0.71$ and $2.96 \times 10^6$ kg/yr (Nesvorny et al., 2011, Borin et al., 2017, Crismani et al., 2017); assuming a carbon content of 10% (Flynn, 1996), this implies an IDP carbon flux of $0.07 - 0.3 \times 10^6$ kg/yr. We calculate for the first time the carbon flux from impacts of asteroids and comets. To this end, we perform dynamical simulations of impact rates on Mars. We use the N-body integrator RMVS/Swifter to propagate the Sun and the eight planets from their current positions. We separately add comets and asteroids to the simulations as massless test particles, based on their current orbital elements, yielding Mars impact rates of $4.34\times10^{-3}$ comets/Myr and 3.3 asteroids/Myr. We estimate the global carbon flux on Mars from cometary impacts to be $\sim 0.013 \times 10^{6}$~kg/yr within an order of magnitude, while asteroids deliver $\sim 0.05 \times 10^6$~kg/yr. These values correspond to $\sim 4-19 \%$ and $\sim 17-71 \%$, respectively, of the IDP-borne carbon flux estimated by Nesvorny et al. 2011, Borin et al. 2017 and Crismani et al. 2017. Unlike the spatially homogeneous IDP infall, impact ejecta are distributed locally, concentrated around the impact site. We find organics from asteroids and comets to dominate over IDP-borne organics at distances up to 150~km from the crater center. Our results may be important for the interpretation of in situ detections of organics on Mars., Comment: 30 pages, 5 figures, accepted for publication in Icarus