Mars exploration program analysis group goal one: determine if life ever arose on Mars

The Mars Exploration Program Analysis Group (MEPAG) maintains a standing document that articulates scientific community goals, objectives, and priorities for mission-enabled Mars science. Each of the goals articulated within the document is periodically revisited and updated. The astrobiology-related Goal One, "Determine if life ever arose on Mars," has recently undergone such revision. The finalized revision, which appears in the version of the MEPAG Goals Document posted on September 24, 2010, is presented here.     

Special regions in Mars exploration: Problems and potential

“Special regions” on Mars are areas designated in the COSPAR planetary protection policy as areas that may support Earth microbes inadvertently introduced to Mars, or that may have a high probability of supporting indigenous martian life. Since absolutely nothing is known about martian life, the operational definition of a special region is a place that may allow the formation and maintenance of liquid water, on or under the surface of Mars. This paper will review the special-regions concept, the implications of recent recommendations on avoiding them, and the work of the Mars science community in providing an operational definition of those areas on Mars that are “non-special.”     

Preservation of martian organic and environmental records: final report of the Mars biosignature working group

The Mars Science Laboratory (MSL) has an instrument package capable of making measurements of past and present environmental conditions. The data generated may tell us if Mars is, or ever was, able to support life. However, the knowledge of Mars' past history and the geological processes most likely to preserve a record of that history remain sparse and, in some instances, ambiguous. Physical, chemical, and geological processes relevant to biosignature preservation on Earth, especially under conditions early in its history when microbial life predominated, are also imperfectly known. Here, we present the report of a working group chartered by the Co-Chairs of NASA's MSL Project Science Group, John P. Grotzinger and Michael A. Meyer, to review and evaluate potential for biosignature formation and preservation on Mars. Orbital images confirm that layered rocks achieved kilometer-scale thicknesses in some regions of ancient Mars. Clearly, interplays of sedimentation and erosional processes govern present-day exposures, and our understanding of these processes is incomplete. MSL can document and evaluate patterns of stratigraphic development as well as the sources of layered materials and their subsequent diagenesis. It can also document other potential biosignature repositories such as hydrothermal environments. These capabilities offer an unprecedented opportunity to decipher key aspects of the environmental evolution of Mars' early surface and aspects of the diagenetic processes that have operated since that time. Considering the MSL instrument payload package, we identified the following classes of biosignatures as within the MSL detection window: organism morphologies (cells, body fossils, casts), biofabrics (including microbial mats), diagnostic organic molecules, isotopic signatures, evidence of biomineralization and bioalteration, spatial patterns in chemistry, and biogenic gases. Of these, biogenic organic molecules and biogenic atmospheric gases are considered the most definitive and most readily detectable by MSL.     

Subcritical water extractor for Mars analog soil analysis

Abstract Technologies that enable rapid and efficient extraction of biomarker compounds from various solid matrices are a critical requirement for the successful implementation of in situ chemical analysis of the martian regolith. Here, we describe a portable subcritical water extractor that mimics multiple organic solvent polarities by tuning the dielectric constant of liquid water through adjustment of temperature and pressure. Soil samples, collected from the Yungay region of the Atacama Desert (martian regolith analogue) in the summer of 2005, were used to test the instrument's performance. The total organic carbon was extracted from the samples at concentrations of 0.2-55.4 parts per million. The extraction data were compared to the total organic carbon content in the bulk soil, which was determined via a standard analytical procedure. The instrument's performance was examined over the temperature range of 25-250 degrees C at a fixed pressure of 20.7 MPa. Under these conditions, water remains in a subcritical fluid state with a dielectric constant varying between approximately 80 (at 25 degrees C) and approximately 30 (at 250 degrees C).     

Humans to Mars: a feasibility and cost-benefit analysis

Mars is a compelling astrobiological target, and a human mission would provide an opportunity to collect immense amounts of scientific data. Exploration alone, however, cannot justify the increased risk. Instead, three factors drive a human mission: economics, education, and exploration. A human mission has a unique potential to inspire the next generation of young people to enter critically needed science and engineering disciplines. A mission is economically feasible, and the research and development program put in place for a human mission would propel growth in related high-technology industries. The main hurdles are human physiological responses to 1–2 years of radiation and microgravity exposure. However, enabling technologies are sufficiently mature in these areas that they can be developed within a few decade timescale. Hence, the decision of whether or not to undertake a human mission to Mars is a political decision, and thus, educational and economic benefits are the crucial factors.     

Mars through the looking glass: an interdisciplinary analysis of forward and backward contamination

The exploration of the planet Mars represents a significant milestone in humanity's exploration of the Universe. In the quest to better explore and understand Mars, issues of forward and backward contamination are particularly pertinent. This paper provides an interdisciplinary analysis of forward and backward contamination. Its substantive material reflects the scientific and technical concerns through the looking glass of legal and policy issues, and vice versa. The paper critically surveys contamination issues of current, nascent and proposed Mars missions from a scientific viewpoint. It then makes a comparative review of legal and policy mechanisms designed to protect against such contamination. It draws cross-linkages between the sciences and the law in this area. The paper then delineates a suggested interdisciplinary framework to protect against forward and backward contamination. This framework is based on co-operation between the various nations undertaking Mars missions, as well as between the various fields of expertise. It highlights the importance of an interdisciplinary overview in the implementation of measures protecting against forward and backward contamination. Strategies on the implementation of these measures are also outlined.     

Application of hyperspectral infrared analysis of hydrothermal alteration on Earth and Mars

An integrated analysis of both airborne and field short-wave infrared hyperspectral measurements was used in conjunction with conventional field mapping techniques to map hydrothermal alteration in the central portion of the Mount Painter Inlier in the Flinders Ranges, South Australia. The airborne hyperspectral data show the spatial distribution of spectrally distinct minerals occurring as primary minerals and as weathering and alteration products. Field spectral measurements, taken with a portable infrared mineral analyzer spectrometer and supported by thin-section analyses, were used to verify the mineral maps and enhance the level of information obtainable from the airborne data. Hydrothermal alteration zones were identified and mapped separately from the background weathering signals. A main zone of alteration, coinciding with the Paralana Fault zone, was recognized, and found to contain kaolinite, muscovite, biotite, and K-feldspar. A small spectral variation associated with a ring-like feature around Mount Painter was tentatively determined to be halloysite and interpreted to represent a separate hydrothermal fluid and fluid source, and probably a separate system. The older parts of the alteration system are tentatively dated as Permo-Carboniferous. The remote sensing of alteration at Mount Painter confirms that hyperspectral imaging techniques can produce accurate mineralogical maps with significant details that can be used to identify and map hydrothermal activity. Application of hyperspectral surveys such as that conducted at Mount Painter would be likely to provide similar detail about putative hydrothermal deposits on Mars.     

Astrobiology through the ages of Mars: the study of terrestrial analogues to understand the habitability of Mars

Mars has undergone three main climatic stages throughout its geological history, beginning with a water-rich epoch, followed by a cold and semi-arid era, and transitioning into present-day arid and very cold desert conditions. These global climatic eras also represent three different stages of planetary habitability: an early, potentially habitable stage when the basic requisites for life as we know it were present (liquid water and energy); an intermediate extreme stage, when liquid solutions became scarce or very challenging for life; and the most recent stage during which conditions on the surface have been largely uninhabitable, except perhaps in some isolated niches. Our understanding of the evolution of Mars is now sufficient to assign specific terrestrial environments to each of these periods. Through the study of Mars terrestrial analogues, we have assessed and constrained the habitability conditions for each of these stages, the geochemistry of the surface, and the likelihood for the preservation of organic and inorganic biosignatures. The study of these analog environments provides important information to better understand past and current mission results as well as to support the design and selection of instruments and the planning for future exploratory missions to Mars.     

From Halley's Comet to solar terrestrial science : The evolution of the Inter-Agency consultative group

The Inter-Agency Consultative Group (IACG) is an organization which seeks to maximize scientific returns from focused areas of space science through international cooperation. In its 11-year history the IACG has experienced both monumental success (with the collaborative exploration of Comet Halley) and, more recently, some serious growing pains in its second phase of operation, which focuses on solar terrestrial science. In this post-Cold War period, with increased interaction between countries offering greater opportunities for cooperation, the lessons to be learned from the IACG's experience will be valuable ones.     

随“MAVEN”一起呼吸火星大气

美国“火星大气与挥发演化”（MAVEN）探测器于2014年9月22日进入火星轨道,开始了其为期1年的科学探测任务。MAVEN的主要使命是调查火星大气失踪之谜,并寻找火星上早期拥有的水源及二氧化碳消失的原因。为完成使命,MAVEN的研制者在充分继承之前火星探测器的研制经验基础上,为其精心打造了各项独具功能的探测设备。     

"火星快车"轨道器简介

“火星快车”选在今年5月底或6月份发射,考虑的是这时火星和地球的相对位置。此时发射可使探测器的飞行路线最短,而这样的机会每26个月才出现一次。探测器脱离地球踏上飞往火星的旅程后,将以相对于地球10800公里/小时的速度进行6个月的行星际巡航飞行。2003年12月抵达火星前5天,它将把“猎兔犬”2弹射出去,由其自己飞向火星表面上的正确着陆场。轨道器则将通过机动进入一条大椭圆轨道,使之能由此进入其近极工作轨道。“火星快车”项目经理鲁迪·施密特称:“这次任务是一项令人激动的挑战。‘火星快车’将先在太空中长时间飞行,然后完成关键…     

Key science questions from the second conference on early Mars: geologic, hydrologic, and climatic evolution and the implications for life

In October 2004, more than 130 terrestrial and planetary scientists met in Jackson Hole, WY, to discuss early Mars. The first billion years of martian geologic history is of particular interest because it is a period during which the planet was most active, after which a less dynamic period ensued that extends to the present day. The early activity left a fascinating geological record, which we are only beginning to unravel through direct observation and modeling. In considering this time period, questions outnumber answers, and one of the purposes of the meeting was to gather some of the best experts in the field to consider the current state of knowledge, ascertain which questions remain to be addressed, and identify the most promising approaches to addressing those questions. The purpose of this report is to document that discussion. Throughout the planet's first billion years, planetary-scale processes-including differentiation, hydrodynamic escape, volcanism, large impacts, erosion, and sedimentation-rapidly modified the atmosphere and crust. How did these processes operate, and what were their rates and interdependencies? The early environment was also characterized by both abundant liquid water and plentiful sources of energy, two of the most important conditions considered necessary for the origin of life. Where and when did the most habitable environments occur? Did life actually occupy them, and if so, has life persisted on Mars to the present? Our understanding of early Mars is critical to understanding how the planet we see today came to be.     

Human exploration of Mars

The human exploration of Mars has the potential to return a rich harvest of scientific information about that planet, its possible past biological history and the prospects for future habitation by Earthly life. The realization of that potential will require new approaches and new technologies--a whole new paradigm in space exploration. Picture yourself exploring the surface of Mars, where your task involves conducting a detailed investigation of features larger than the United States in order to uncover a record of planetary history spanning over four billion years.     

火星常识知多少

为什么火星看上去是红色的?人们都知道,火星看上去就像是一个大大的红色火球,火星似火一般在夜空发出火红色的光芒。从望远镜中看去,火星宛若一团燃烧的火球。这一现象曾一直使古人迷惑难解,因此在中国古代,人们把这颗火红的星星称为荧惑,莹就是莹莹似火的意思。那么火星为什么会呈火红色呢?对于这个疑问,答案也是众说纷纭。一直以来,     

"火星探测漫游者"降落伞的研制

概述了“火星探测漫游者”探测器的降落伞系统,并介绍了降落伞系统的组成和性能,以及降落伞的研制过程的主要工作,尤其是设计人员解决和处理的一些细节问题。     

Public perceptions of the Mars sample return program

In 2014 NASA may bring back a sample of Mars rocks, soil and atmosphere to Earth. The most likely location for returning this sample will be somewhere in the central USA. The purpose of the project is to understand the history of Mars; the samples may also reveal evidence of previous or existing life on Mars. Confirmation of this possibility would rank as one of the most profound discoveries in human history, yet to date it is unclear how the public in the USA actually views the mission. This study addresses this issue by examining the views of 70 residents of Cincinnati, OH. These perceptions are examined in light of the conceptual ideas and theories presented in the risk perception and communication literatures. While respondents were generally favourable towards a Mars sample return mission, and largely unworried by possible risks, they did have concerns about the use of plutonium for electrical propulsion and were somewhat ill-informed about the issues.