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Radiation-induced reactions in comet analogues 类似彗星的辐射诱发反应
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-12-01 DOI: 10.1017/s1473550422000416
A. López-Islas, A. Negrón-Mendoza
Comets are a source of prebiotic molecules that likely enriched the early Earth during the Late Heavy Bombardment period. Laboratory experiments that replicate cometary conditions may facilitate understanding of the chemical reactions and supplement observational studies of these icy bodies. Prebiotic compounds, such as formic acid and formaldehyde, have been observed in comets. Furthermore, these compounds can easily be formed in experimental models using a variety of gas combinations and energy sources. We conducted experimental cometary simulations using radiation chemistry tools to obtain insight into the possible fate of formic acid and formaldehyde. The main results suggest a redundant system, signifying that the irradiation of formic acid forms formaldehyde molecules and vice versa. This phenomenon ensures the permanence of prebiotic molecules in high-radiation environments. Additionally, the potential role of forsterite and graphite was explored in cometary simulations. Our experimental results show the differential formation of aldehydes and other carbonyl-containing compounds dependent on the mineral phase present.
彗星是生命前分子的来源,可能在晚期重轰炸时期丰富了早期地球。复制彗星条件的实验室实验可能有助于理解化学反应,并补充对这些冰体的观测研究。益生元化合物,如甲酸和甲醛,已经在彗星中被观察到。此外,这些化合物可以很容易地在使用各种气体组合和能源的实验模型中形成。我们使用辐射化学工具进行了彗星模拟实验,以深入了解甲酸和甲醛的可能命运。主要结果表明一个冗余系统,表明甲酸辐照形成甲醛分子,反之亦然。这种现象保证了益生元分子在高辐射环境中的持久性。此外,在彗星模拟中还探索了橄榄石和石墨的潜在作用。我们的实验结果表明,醛和其他含羰基化合物的不同形成取决于存在的矿物相。
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引用次数: 0
Extraterrestrial nature reserves (ETNRs) 地外自然保护区
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-11-24 DOI: 10.1017/s1473550422000398
Paul L. Smith
If human population growth is not controlled, natural areas must be sacrificed. An alternative is to create more habitat, terraforming Mars. However, this requires establishment of essential, ecosystem services on a planet currently unamenable to Terran species. Shorter term, assembling Terran-type ecosystems within contained environments is conceivable if mutually supportive species complements are determined. Accepting this, an assemblage of organisms that might form an early, forest environment is proposed, with rationale for its selection. A case is made for developing a contained facsimile, old growth forest on Mars, providing an oasis, proffering vital ecosystem functions (a forest bubble). It would serve as an extraterrestrial nature reserve (ETNR), psychological refuge and utilitarian botanic garden, supporting species of value to colonists for secondary metabolites (vitamins, flavours, perfumes, medicines, colours and mood enhancers). The design presented includes organisms that might tolerate local environmental variance and be assembled into a novel, bioregenerative forest ecosystem. This would differ from Earthly forests due to potential impact of local abiotic parameters on ecosystem functions, but it is argued that biotic support for space travel and colonization requires such developments. Consideration of the necessary species complement of an ETNR supports a view that it is not humanity alone that is reaching out to space, it is life, with all its diverse capabilities for colonization and establishment. Humans cannot, and will not, explore space alone because they did not evolve in isolation, being shaped over aeons by other species. Space will be travelled by a mutually supportive system of Terran organisms amongst which humans fit, exchanging metabolites and products of photosynthesis as they have always done.
如果不控制人口增长,就必须牺牲自然区域。另一种选择是创造更多的栖息地,将火星地形化。然而,这需要在地球上建立基本的生态系统服务,目前地球上还没有人族物种。在短期内,如果确定了相互支持的物种互补性,那么在封闭的环境中组装人族类型的生态系统是可以想象的。接受了这一点,提出了一个可能形成早期森林环境的生物群落,并提出了其选择的理由。一个案例是在火星上开发一个封闭的、古老的森林,提供绿洲,提供重要的生态系统功能(森林泡沫)。它将作为地外自然保护区(ETNR)、心理避难所和实用植物园,为殖民者提供有价值的次生代谢产物(维生素、香料、香水、药物、色素和情绪增强剂)。所提出的设计包括可能耐受当地环境变化的生物,并将其组装成一个新的生物再生森林生态系统。由于当地非生物参数对生态系统功能的潜在影响,这与地球森林不同,但有人认为,对太空旅行和殖民的生物支持需要这样的发展。考虑到ETNR的必要物种补充,支持了这样一种观点,即并非只有人类在探索太空,而是生命,具有殖民和建立的各种能力。人类不能,也不会独自探索太空,因为它们不是孤立地进化的,是由其他物种长期塑造的。人类将通过一个相互支持的人族生物系统进入太空,像往常一样交换代谢产物和光合作用产物。
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引用次数: 1
Brief review about history of astrobiology 简述天体生物学的历史
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-10-19 DOI: 10.1017/s1473550422000386
B. Nascimento-Dias, J. Martínez-Frías
The main idea of this work is to develop a chronological and descriptive historical review in a summarized form about content on astrobiology, which is a research area considered as an emerging science. This is exploratory research that was developed from document review from scientific articles and books, that related to the themes of astrobiology, exobiology and the search for life outside the Earth were used. Based on the research developed, it was possible to collect data related to the vision of other worlds beyond Earth from the ancient Greeks to the present day. Finally, it was possible to conclude that although astrobiology is a recent area of scientific research, the concept and search for life outside the Earth already existed long before the development of modern science.
这项工作的主要思想是以总结的形式对天体生物学的内容进行时间和描述性的历史回顾,天体生物学是一个被认为是新兴科学的研究领域。这是一项探索性研究,是根据科学文章和书籍的文件审查发展起来的,与天体生物学、外生物学和寻找地球以外生命的主题有关。根据所开展的研究,有可能收集从古希腊人到今天与地球以外其他世界的景象有关的数据。最后,可以得出这样的结论:尽管天体生物学是最近的科学研究领域,但在现代科学发展之前很久就已经存在了对地球以外生命的概念和探索。
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引用次数: 1
Formalizing the Fermi paradox and combining consistent explanatory hypotheses 将费米悖论形式化并结合一致的解释假设
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-10-18 DOI: 10.1017/s1473550422000374
Alexandre Costa-Leite
A formalization of Fermi paradox inside the environment of classical propositional logic is proposed. The notion of Silentium Universi set is launched in order to establish that the Fermi paradox is truly paradoxical. Combining consistent explanatory hypotheses is taken into consideration and discussed inside this framework explaining what would count as a solution to the paradox. By the end, it is argued that Fermi paradox is an unsolvable problem in the domain of science.
提出了经典命题逻辑环境下费米悖论的形式化。寂静宇宙集的概念是为了证明费米悖论是真正的悖论而提出的。结合一致的解释性假设,在这个框架内进行了考虑和讨论,解释了什么可以算作悖论的解决方案。最后,论述了费米悖论是科学领域中一个无法解决的问题。
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引用次数: 0
Solid grains ejected from terrestrial exoplanets as a probe of the abundance of life in the Milky Way 从类地系外行星喷出的固体颗粒,作为探测银河系中生命丰富程度的一种手段
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-10-13 DOI: 10.1017/S147355042300006X
T. Totani
Searching for extrasolar biosignatures is important to understand life on Earth and its origin. Astronomical observations of exoplanets may find such signatures, but it is difficult and may be impossible to claim unambiguous detection of life by remote sensing of exoplanet atmospheres. Here, another approach is considered: collecting grains ejected by asteroid impacts from exoplanets in the Milky Way and then travelling to the Solar System. The optimal grain size for this purpose is around 1 μm, and though uncertainty is large, about 105 such grains are expected to be accreting on Earth every year, which may contain biosignatures of life that existed on their home planets. These grains may be collected by detectors placed in space, or extracted from Antarctic ice or deep-sea sediments, depending on future technological developments.
寻找太阳系外的生物特征对于了解地球上的生命及其起源非常重要。对系外行星的天文观测可能会发现这样的特征,但通过遥感系外行星大气层来明确探测生命是困难的,也可能是不可能的。在这里,考虑了另一种方法:收集小行星撞击银河系外行星喷出的颗粒,然后前往太阳系。为此目的,最佳晶粒尺寸约为1μm,尽管不确定性很大,但预计每年约有105个这样的晶粒在地球上堆积,其中可能包含其母行星上存在的生命的生物特征。这些颗粒可以由放置在太空中的探测器收集,也可以从南极冰或深海沉积物中提取,这取决于未来的技术发展。
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引用次数: 0
Special issue: Open questions and next steps in astrobiology in Europe – celebrating 20 years of EANA 特刊:欧洲天体生物学的开放问题和下一步——庆祝EANA成立20周年
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-10-01 DOI: 10.1017/S1473550422000362
B. Cavalazzi, F. Westall, L. Noack, R. Taubner, T. Milojevic, K. Finster
(origin and evolution of planetary systems; origins of organic compounds in space; rock – water – carbon interactions, as on the surface of Mars and of about 13 million years at 2 metres depth. In addition, they highlight that chitin may also be included in the list of robust biosignature molecules for which one could search for during life-seeking missions.
(行星系统的起源和演化;有机化合物在太空中的起源;岩石-水-碳的相互作用,如在火星表面和大约1300万年的2米深处。此外,他们还强调,几丁质也可能被列入强大的生物特征分子清单中,人们可以在寻找生命的任务中寻找这些分子。
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引用次数: 0
Microbial protocols for spacecraft: 2. Biocidal effects of Delrin and nylon in sealed compartments may enhance bioburden reductions in planetary spacecraft 航天器微生物方案:2。Delrin和尼龙在密封舱中的生物杀灭作用可能会增强行星航天器中生物负载的减少
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-09-29 DOI: 10.1017/s1473550422000349
A. Schuerger, P. Schwendner, R. Tucker
Interplanetary spacecraft are assembled with thousands of parts composed of many diverse materials. Little is known on whether any of the spacecraft materials are biocidal to the typical microbiomes that develop on spacecraft during pre-launch processing. During ongoing experiments to examine the interactive effects of solar UV irradiation, solar heating, ionizing radiation, and vacuum, we observed that bacterial spores of three Bacillus spp. were killed when incubated within small vacuum chambers for 5 days – without exposure to the aforementioned factors. Eight potential spacecraft materials were tested within the vacuum chambers for biocidal activities against spores of B. atrophaeus ATCC 9372, B. pumilus SAFR-032 and B. subtilis 168. All three species were fully inactivated (i.e., no survivors detected) by machined parts manufactured from Delrin®; a thermoplastic polyacetal polymer. Although not tested here, it is known that Delrin can off-gas formaldehyde, and thus, we hypothesize that this volatile organic compound (VOC) was responsible for the biocidal activity of the material. Knowledge of the biocidal nature of routinely used spacecraft materials might offer diverse methods to inactivate deeply embedded or shielded microbiota within spacecraft via the release of biocidal VOCs.
行星间航天器由数千个零件组装而成,这些零件由多种不同的材料组成。目前尚不清楚航天器材料是否对发射前处理过程中在航天器上形成的典型微生物群具有生物杀灭作用。在正在进行的研究太阳紫外线照射、太阳加热、电离辐射和真空相互作用的实验中,我们观察到三种芽孢杆菌的细菌孢子在小真空室内培养5天时被杀死,而不暴露于上述因素。在真空室内测试了八种潜在的航天器材料对B.atrophaeus ATCC 9372、B.pumilus SAFR-32和B.subtilis 168孢子的杀生物活性。所有三个物种都被Delrin®制造的机械加工零件完全灭活(即未检测到幸存者);一种热塑性聚缩醛聚合物。虽然这里没有测试,但已知Delrin可以释放甲醛气体,因此,我们假设这种挥发性有机化合物(VOC)是该材料的杀生物活性的原因。了解常规使用的航天器材料的杀生物性质可能会提供多种方法,通过释放杀生物挥发性有机物来灭活航天器内深埋或屏蔽的微生物群。
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引用次数: 0
Abiogenesis: the Carter argument reconsidered 自然发生论:对卡特论点的重新思考
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-09-23 DOI: 10.1017/s1473550422000350
D. Whitmire
The observation of life on Earth is commonly believed to be uninformative regarding the probability of abiogenesis on other Earth-like planets. This belief is based on the selection effect of our existence. We necessarily had to find ourselves on a planet where abiogenesis occurred, thus nothing can be inferred about the probability of abiogenesis from this observation alone. This argument was first formalized in a Bayesian framework by Brandon Carter. Though we definitely had to find ourselves on a planet where abiogenesis occurred, I argue here that (1) the Carter conclusion is based on what is known as the ‘Old Evidence Problem’ in Bayesian Confirmation Theory and that (2) taking this into account, the observation of life on Earth is not neutral but evidence that abiogenesis on Earth-like planets is relatively easy. I then give an independent timescale argument that quantifies the prior probabilities, leading to the inference that the timescale for abiogenesis is less than the planetary habitability timescale and therefore the occurrence of abiogenesis on Earth-like planets is not rare.
对地球上生命的观察通常被认为对其他类地行星上自然发生的可能性没有提供信息。这种信念是基于我们存在的选择效应。我们必须在一个发生自然发生的星球上找到自己,因此,仅从这一观察无法推断出自然发生的可能性。这个论点首先由布兰登·卡特在贝叶斯框架中形式化。虽然我们必须找到一个发生自然发生的行星,但我在这里认为:(1)卡特的结论是基于贝叶斯确认理论中所谓的“旧证据问题”,(2)考虑到这一点,对地球上生命的观察不是中立的,但证据表明,类地行星上的自然发生相对容易。然后,我给出了一个独立的时间尺度论证,量化了先验概率,从而得出结论:自然发生的时间尺度小于行星可居住的时间尺度,因此,在类地行星上发生自然发生并不罕见。
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引用次数: 0
Stromatolite photomorphogenesis: lighting up their shape 叠层石的光形态发生:照亮它们的形状
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-09-06 DOI: 10.1017/s1473550422000313
G. Ojakangas, S. Awramik, M. Storrie-Lombardi
Most stromatolites are built by photosynthetic organisms, for which sunlight is a driving factor. We examine stromatolite morphogenesis with modelling that incorporates the growth rate of cyanobacteria (the dominant stromatolite-builder today, and presumably through much of the past), as a function of the amount of irradiance received. This function is known to be non-monotonic, with a maximum beyond which growth rate decreases. We define optimal irradiance as that which generates maximal growth, and we find fundamentally different morphologies are predicted under suboptimal and superoptimal direct irradiance. When the direct irradiance is suboptimal, narrow widely spaced columns are predicted, with sharp apices resembling conical stromatolites. When it is superoptimal, broad, closely spaced, flattened domical forms appear. Such disparate morphologies could also occur as a result of other vector-flux-dependent growth factors (e.g. currents). A differential equation is developed that describes the rate of change of the radius of curvature R at the apex of a growing stromatolite column, allowing simple simulations of the time evolution of R for model stromatolites. The term photomorphism is proposed to describe the disparate morphologies that may arise due to the effects described here (and photomorphogenesis as the process). Model results appear to explain, at least qualitatively, the morphologies of a number of stromatolites. If stromatolites are encountered on Mars, our model suggests that they are quite likely to be conical in form, owing to likely suboptimal irradiance since Mars has always received less irradiance than Earth.
大多数叠层石是由光合生物建造的,阳光是其驱动因素。我们通过建模来研究叠层石的形态发生,该建模结合了蓝细菌(当今占主导地位的叠层石建设者,可能在过去的大部分时间里都是如此)的生长速度,作为接收到的辐照度的函数。已知该函数是非单调的,具有最大值,超过该最大值增长率下降。我们将最佳辐照度定义为产生最大生长的辐照度,我们发现在次优和超优直接辐照度下预测的形态有根本不同。当直接辐照度次优时,预测窄而宽的柱状物,其尖锐的顶点类似于圆锥形叠层石。当它是超优的,宽,紧密间隔,扁平的圆顶形式出现。这种不同的形态也可能是其他矢量通量相关生长因子(例如电流)的结果。建立了一个微分方程,描述了生长中的叠层石柱顶点曲率半径R的变化率,从而可以简单地模拟模型叠层石的R的时间演变。光形态一词被提出来描述由于本文所述的效应(以及光形态发生过程)而可能出现的不同形态。模型结果似乎至少在定性上解释了一些叠层石的形态。如果在火星上遇到叠层石,我们的模型表明,它们很可能是圆锥形的,因为火星的辐照度总是比地球低,所以可能是次优的。
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引用次数: 0
Extraterrestrial intelligence and moral standing 外星智慧和道德地位
IF 1.7 4区 物理与天体物理 Q2 Physics and Astronomy Pub Date : 2022-09-01 DOI: 10.1017/s1473550422000337
M. Ćirković, Ana Katić
We consider the Search for ExtraTerrestrial Intelligence (SETI) activities from a bioethical standpoint. In particular, we argue that there is a moral duty to search for other intelligent beings in the Universe. Some of them could – and are likely to be – morally enhanced in the sense that they are not only capable of unmistakable moral reasoning but are also capable of consistently acting upon the results of such deliberations. Even if the probability of finding such morally superior beings is small, it is higher than zero in any case; in fact, our astrobiological knowledge suggests that this probability is significant. Hence, there are both deductive and inductive arguments for the proposition that our duty is to search for such morally superior extraterrestrial beings. In other words, there is a duty to undertake and support our SETI efforts. The argument to that effect runs parallel to some of the arguments deployed in current debates on human moral enhancement.
我们从生物伦理的角度考虑搜寻地外智慧生物(SETI)活动。特别是,我们认为在宇宙中寻找其他智慧生物是一种道德责任。他们中的一些人可以——而且很可能——在道德上得到加强,因为他们不仅能够进行准确无误的道德推理,而且还能够始终如一地根据这种审议的结果采取行动。即使找到道德上优越的人的概率很小,但在任何情况下都大于零;事实上,我们的天体生物学知识表明,这种可能性是显著的。因此,对于我们的责任是寻找道德上优越的外星生物这一命题,有演绎和归纳两种论证。换句话说,我们有责任承担并支持我们的SETI努力。这种观点与当前关于人类道德提升的辩论中的一些观点如出一辙。
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引用次数: 0
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International Journal of Astrobiology
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