Planning for the Scientific Exploration of Mars by Humans By the mepag human Exploration of Mars Science Analysis Group (hem-sag)
|
|  Yüklə 13.93 Mb.
|
Early Atmospheric EvolutionThe early evolution of the Mars atmosphere, as discussed here, refers to the first 1-2 billion years of coupled exchanges among Mars interior, surface, and atmospheric volatile inventories and subsequent loss of these volatiles to space. Key measurement objectives, as developed in MEPAG 2006 Goals IIB, are gas and ice isotopic ratios, current atmospheric escape processes and rates, and surface morphological and chemical records of early Mars climate. A number of these objectives will have been substantially addressed prior to HEM activities. However, HEM in situ measurements should play an especially important role in the study of the early Mars atmospheric environment, given the Archean-Hesperian ages presented over much of the current Mars surface. Impact BrecciasSample return might target impact breccias of different ages, which are good sources of fluid inclusions. Inferring the Paleoclimatic Conditions of Mars: the Geological Record of the Ancient Atmospheric StateThe paleoclimatic — paleoatmospheric (this would be quite much complicated) — conditions that reigned during earlier atmospheric episodes of Mars can be inferred through several types of geological evidence ranging from planetary/regional to molecular scale. As on Earth, wet climate episodes, under interplay with geological processes, produced different geomorphic and sedimentological imprints that are related to the occurrence of quiet or running water bodies. Fan-shaped structures or meandering to braiding channels, but also fluvial-like terrace deposits or fine-grained continuous deposits are evidence for an active and stable hydrosphere. Some other sedimentary record as evaporites (i.e. Mars sulfates are a good example) can be used to determine the thermal regime of the paleoclimate, whereas some fine-grained deposits–mainly composed by phyllosilicates- can denote wet and temperate ancient climates. Stratigraphy and geochemical analysis of very peculiar materials formed in-situ or deposited as paleosoils, gossans/laterites, sulfide orebodies –sedimentary or hydrothermal- and red beds are geological markers of the chemical state of Mars ancient atmosphere. Oxygen and silicon stable isotopes of chemical sediments — e.g. silica-rich, sulfates, carbonates — can be used to estimate the temperature of waters that generated them. Moreover, other chemical tracers of sediments have a great importance to the evaluation of the redox state of the waters interplaying the ancient Mars atmosphere – bearing in mind that an oxidizing atmosphere does not mean in this case an O2 -enriched atmosphere. On Earth several trace elements (U, Ce, Mo), but also isotopes of Fe and S (mass independent fractionation) are been used to determine the oxidizing potential of solutions in contact with the atmosphere, as well as of the atmosphere directly. Desired precursor measurements
Investigations for the Human Era of Exploration
Appendix C. The Human Exploration of Mars: Lessons Learned from Apollo (Written by James W. Head)Born from international competition with the Soviet Union at the height of the Cold War, the Apollo Lunar Exploration Program accomplished the first significant and sustained scientific exploration of another planetary body by human explorers. Following the precursor missions Apollo 7-10, Apollo 11 touched down at Tranquility Base on July 20th, 1969, accomplishing for all humankind U.S. President John F. Kennedy's goal of sending humans to the Moon and returning them safely by the end of the decade. Why did human exploration of the Moon continue past this major milestone? U.S. national political, scientific and engineering leadership understood that this huge investment in exploration infrastructure could pay fundamental dividends in terms of inspiration, scientific results, technological and economic competitiveness, and international leadership. Having understood this from the outset, participants ensured that the capabilities built into the exploration architecture and engineering infrastructure were much more than what was simply required to place humans on the Moon and return them safely. Thus, with each successive Apollo mission, expanding confidence in rendezvous and docking, landing site accuracy, astronaut mobility, human capability, and systems engineering of a hugely complex task, led to increased capabilities and ever more profound scientific results. Apollo 12 was targeted to the western lunar nearside to make a pinpoint landing near the Surveyor III spacecraft and performed an additional EVA. Apollo 13/14 were targeted to rough terrain of the Fra Mauro Formation in order to sample the ejecta of the Imbrium Basin. Astronauts carried a wheelbarrow-like Mobile Equipment Transporter (MET) to the top of the ridges. Apollo 15 was targeted to high latitudes at the edge of Hadley Rille nestled in the Apennine Mountains, undertook three EVAs and a SEVA (Standup EVA; involved suiting up, depressurization of the LM, opening of top hatch, and regional description of the landing site), and deployed a satellite in lunar orbit. A Lunar Roving Vehicle (LRV) provided access to important scientific sites separated by almost 15 kilometers. Apollo 16 was targeted to the rough and varied lunar highlands and revealed the mysteries and complexities of the lunar crust and the processes that shaped it. Apollo 17 carried the first geologist to another planetary body and landed in a narrow box canyon at the edge of the Serenitatis Basin, unlocking many of the secrets of impact basin formation and subsequent lava filling. Apollo 18-22 were to involve ever more complex and capable exploration capabilities, and development of the human-robotic partnership. Such efforts included DM-LRVs (Dual-Mode Lunar Roving Vehicles) that the astronauts, at the end of their mission, would set to automated mode. Controllers and scientists in Houston would then undertake scientific exploration traverses hundreds of kilometers in length, ending at the next human landing site, to provide scientific interpolation between different key regions explored in detail by human. Loss of national will and the financial burdens of the Viet Nam war resulted in the termination of the Apollo Lunar Exploration Program following Apollo 17. There are several important lessons to be learned from these events relevant to the human exploration of Mars. First, landing humans on the Moon was a fundamental accomplishment that brought tremendous pride and prestige to the United States. The lasting legacy, however, was not just this historical event, but what humans actually accomplished during this period of exploration. Wise leaders ensured that the capability was built into the system so that what was learned along each step of the way could be folded back into the system to improve its capability. Apollo was an Exploration Program, not just a single landing. And exploration was not just "flags and footprints", but indeed was fundamental scientific exploration. The true and lasting legacy of the Apollo Exploration Program is the wealth of scientific observations made by the astronaut explorers, the materials that they collected and the instruments that they deployed. The results of this exploration fundamentally changed, and continues to change to this day, the way in which we view Earth, our own Home Planet, and its place in the Solar System. Therefore, when humans explore Mars, it would be prudent to follow our experience in the first great wave of the human exploration of other planetary bodies, the Apollo Lunar Exploration Program. We should plan for a program, not a single landing. We should build in broad capabilities from the start, to take advantage of what we learn at each step along the way. We should understand that the true lasting legacy is not just going to Mars, but what can actually be accomplished by humans when they are there, and the scientific results that they can obtain. Using these simple guidelines as a broad compass will lead us to a successful human exploration of Mars, and a legacy that will outlast us all. In addition to these broad guidelines, a host of individual lessons were learned from the Apollo Lunar Exploration Program that provide guidance for the task of visualizing and planning for the human exploration of Mars. These lessons are documented in numerous publications, some of which are referenced below. For landing site selection, it would be important to develop science and engineering synergism, so that scientific goals and crew safety can be optimized. Single landing sites should provide the capability to access multiple broad scientific objectives, in order to optimize the scientific return. System engineering concepts should be applied to the planning of surface exploration activities, in order to optimize the wide range of human surface exploration capabilities. Astronauts should be trained in fundamental scientific exploration capabilities (e.g., geological observations), so that they are prepared for both the expected, and can deal intelligently with the unexpected. Astronauts should be involved in planning at all steps in the process. Infrastructure should be developed to take advantage of the human capability for in situ analysis and on-site decision making and scientific traverse planning adjustments. The human-robotic partnership should be explored to its fullest, with robotic capabilities providing for scouting and scientific interpolation, as well as performance of analysis tasks in order to optimize the utility of human insight, analysis and decision-making. There should be sufficient payload capability to return abundant samples and related materials from Mars to undertake measurements that would always be more capable on Earth than in situ analyses. Returning astronauts should be involved in the post-mission analysis of the data at all stages. These guidelines, together with more detailed operational experience, provide a basis for successful planning for the human exploration of Mars. Sample Reference:Heiken, G. et al., eds., Lunar Sourcebook, Cambridge University Press, 736 p. (1991). Heiken, G. and Jones, E., On the Moon, The Apollo Journals, Springer, 492 p. (2007). Jolliff, B. et al., eds., New Views of the Moon, Min. Soc. Am., 60, 721 p. (2006).
|