Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 107
OCR for page 108
This page in the original is blank.
OCR for page 109
Appendix A The NASA Mars Exploration Program A summary of active and planned missions of NASA’s Mars Exploration Program is presented in Table A.1 pn pages 110 and 111. Foreign as well as NASA missions are included so that the totality of Mars research can be evaluated. The section that follows on pages 112 through 117, written by Orlando Figueroa, director, and James B. Garvin, lead scientist, of the Mars Exploration Program, Office of Space Science, NASA Headquarters, enlarges upon details of the missions and the overall strategy of the program. It should be stressed that the presence of an integrated Mars program at NASA, as opposed to a series of isolated missions to Mars, is a relatively new development.
OCR for page 110
TABLE A.1 Active and Planned Missions to Mars, by NASA and Foreign Space Agencies Launch Date Mission Instrument Complement Science Objectives and Other Comments 1996 NASA Mars Global Surveyor (MGS) Mars Orbiter Camera Thermal Emission Spectrometer Mars Orbital Laser Altimeter Radio Science Magnetic Fields Investigation Recovering some of the Mars Observer (MO) objectives; acquiring systematic global data sets. High-resolution imaging. One orbiting spacecraft, polar orbit. 1998 NASDA (Japan) Nozomi Mars Imaging Camera Neutral Mass Spectrometer Thermal Plasma Analyzer Mars Dust Counter Radio Science Experiment Plasma Waves and Sounder Low Frequency Plasma Wave Analyzer Ion Mass Imager Magnetic Field Investigation Probes for Electron Temperature Measurements Ultraviolet Imaging Photometer Electron Spectrum Analyzer Energetic Ion Spectrometer Extreme Ultraviolet Spectrometer Space physics; motion and structure of upper atmosphere and ionosphere. Intended to arrive at Mars in 1999, but technical problems have delayed arrival until 2004. One spacecraft in elliptical orbit. 2001 NASA Mars Odyssey Orbiter (MO 2001) Mars Radiation Environment Experiment Thermal Emission Imaging System Gamma Ray Spectrometer Recovering some of the Mars Observer objectives; systematic global measurement of chemical elements, H, and minerals. One orbiting spacecraft, polar orbit. 2003 NASA Mars Exploration Rover (MER) Panoramic Camera Miniature Thermal Infrared Spectrometer Microscopic Camera Mössbauer Spectrometer Alpha Particle-X-Ray Spectrometer Determining the aqueous, climatic, and geologic history of two sites where conditions may have been favorable for the preservation of biotic or prebiotic processes. Two landed rovers. 2003 ESA Mars Express (ME) High Resolution Stereo Color Imager IR Mineralogical Mapping Spectrometer Planetary Fourier Spectrometer UV and IR Atmospheric Spectrometer Energetic Neutral Atoms Analyzer Subsurface Sounding Radar/Altimeter Radio Science Experiment Global mineralogic and high-resolution stereo mapping, subsurface sounding, atmospheric dynamics. One orbiting spacecraft, polar elliptical orbit. 2003 U.K. Beagle 2 Gas Chromatograph-Mass Spectrometer Microscope Camera Panoramic and Wide Angle Cameras Mössbauer Spectrometer Alpha Proton X-Ray Spectrometer Environmental Package Sensors Investigating the geology, geochemistry, and exobiology of a landing site. One lander. 2005 NASA Mars Reconnaissance Orbiter (MRO) Recommended: Pressure-Modulator Infrared Radiometer Mars Color Imager Wide Angle Camera Mars Color Imager Medium Angle Camera Visible near-IR imaging spectrometer Visible imaging camera Radar sounder Radio science investigations Recovering the MO and MCO atmosphere and climate science objectives; searching for sites showing evidence of aqueous and/or hydrothermal activity; exploring in detail hundreds of targeted, globally distributed sites; searching for liquid or frozen water in the near surface. One orbiting spacecraft, polar orbit.
OCR for page 111
Launch Date Mission Instrument Complement Science Objectives and Other Comments 2007 ASI (Italy)/ NASA Orbiter (To be determined) Telecommunication relay 2007 Orbiter, CNES (To be determined) Prototype orbiter; orbital science and NetLander transport, demonstration of aerocapture and orbital rendezvous, telecommunication relay for NetLander mission. One orbiting spacecraft. 2007 NetLander, European consortium (CNES, DLR, FMI, ASI, Belgium and others) Some of these experiments: Surface Meteorology Package Electric Field Ground Penetrating Radar Magnetometer NetLander Ionosphere and Geodesy Experiment (plus Total Electron Content) Panoramic Camera Seismometer Soil Properties, Thermal Inertia and Cohesion Experiment Mars Microphone Objective is to perform simultaneous measurements in order to study the internal structure of Mars, its subsurface and its atmosphere. Network of four stationary landers. 2007 NASA Mars Scout (To be determined) Discovery-class competed mission opportunities, $300 million cost cap, PI-led; expected to meet science goals and opportunities not covered by other missions. 2007 NASA Mars Science Laboratory (MSL) (To be determined) Long-range, long-duration advanced science laboratory. A pathfinding mission for sample return to demonstrate “smart landers” technology, including accurate landing and hazard avoidance. One landed rover. Delayed to 2009 to allow for the inclusion of an advanced radioisotope power system. 2009 ASI (Italy)/ NASA Orbiter (To be determined) Possible synthetic aperture radar system. 2011 NASA Mars Sample-Return mission (MSR) (To be determined)
OCR for page 112
THE MARS EXPLORATION PROGRAM: A HIGH-LEVEL DESCRIPTIONa James B. Garvin and Orlando FigueroaOffice of Space Science, NASA Headquarters The newly restructured Mars Exploration Program (MEP) is fundamentally a science-driven program whose focus is on understanding Mars as a dynamic “system” and ultimately addressing whether life is or was ever a part of that system. It further embraces the challenges associated with the development of a predictive capability for martian climate and how the role of water, obliquity variations and other factors may have influenced the environmental history of Mars. This white paper outlines in a high-level sense the scientific strategy of the new Mars Exploration Program. As the MEP will continuously evolve in the context of the scientific discoveries achieved and the changing character of the scientific drivers provided by the broad scientific community to NASA, it is important to recognize that the present strategy is a living one. The foundation of the present strategy is often referred to as “Follow the water” and this serves to connect fundamental program goals pertaining to biological potential, climate, the evolution of the solid planet, and preparations for eventual human exploration. Balance is recognized as important within the present MEP, given the challenges associated with assessing the biological potential and climate record of a distant object such as Mars. On the basis of the knowledge gained from the Mariner, Viking, and Mars Global Surveyor missions, we know that Mars, like Earth, has experienced dynamic interactions between its atmosphere, surface, and interior that are, at least in part, related to water. As NASA embarks upon an intensive program of scientific exploration of Mars, following the pathways and cycles of water has emerged as a strategy that may lead to a possibly preserved ancient record of biological processes, as well as to an understanding of the character of paleoenvironments on Mars. In humanity’s exploration of extreme environments on Earth (the deep ocean, ice fields, geothermal sites, and so on), wherever there is liquid water below the boiling point, evidence of life has been identified. The presence of liquid water sometime and somewhere in the martian past, coupled with other key variables (temperature, pressure, soil chemistry, and atmospheric chemistry) makes Mars an attractive target in expanding the scientific understanding of life, its origins, and diversity within the Universe. In addition, other scientific drivers have emerged, including the use of Mars as a location from which to provide absolute calibration of the timing of major Solar System events. One example of the difficulties associated with understanding a planet as complex as Mars is associated with the assessment of its biological potential. Searching for evidence of existing or ancient life on Mars is fraught with seemingly insurmountable challenges. There is a tremendous surface area within which to search—150 million square kilometers of martian surface, roughly equivalent to the continental land mass of Earth. In addition, even after five major missions to Mars, comparatively little is known about the characteristics of the upper surface layer, and of the impact of ultraviolet and cosmic radiation upon the surface environment. Thus, evidence of potential life may lie tens or even hundreds of meters below within the naturally shielded shallow subsurface. Our existing knowledge of the martian shallow subsurface remains purely inferential, yet predictive models indicate that liquid water could be stored in subsurface reservoirs. Such environments may be compelling localities for in situ exploration. The Viking missions of the 1970s searched for answers to the “life question” by directly seeking evidence of biological activity in the upper 10 cm of the surface at two widely separated landing sites. In effect, the Vikings sought to hit a scientific “home run” on our first attempt at bat. The life detection experiments on Viking were arguably the best available, given 1970’s technology and the limited understanding of how to detect life in general in extreme environments. Unfortunately, the results of the Viking in situ life detection experiments were inconclusive. Given our then limited knowledge of Mars, the two Viking landing sites selected were reasonable starting places, but we now know that Mars is a remarkably diverse and dynamic planet, with many distinct regions that may differ significantly in their potential for harboring records of existing or ancient life. In retrospect, in spite of the bold approach adopted by the Vikings in the 1970s, Mars was not quick to yield its secrets, and in the ensuing 25 years NASA and the scientific community have developed an improved framework for examining Mars, just as has been done for Earth. What we have found is a planet exceedingly rich in landscape diversity, with what appears to be a preserved record of sediments that may be an indication of a major role of liquid water in its earliest epoch. a The program description, a “living document” that is updated periodically, is reprinted here as received at the time of the study.
OCR for page 113
As an example, the search for life or life-generating environments on Mars requires a systematic approach through which we can begin to understand the complex systems of geology, climate, and biological potential that constitute the “Mars System.” In order to understand Mars as a dynamic system, we must first establish a global context of information about the planet, and then validate and expand that knowledge by increasingly narrowing our focus through surface investigations, ground-truthing, and targeted reconnaissance. With a strong foundation of orbital and surface reconnaissance and directed investigations, we can then make a well-informed selection of the most-promising local sites from which to obtain samples for return to Earth for comprehensive analysis. We refer to this approach as “Seek, In-situ, Sample”—increasingly narrowed cycles of “seeking,” first from orbit, then on the surface, followed by collection of well-selected samples for return to Earth. This approach parallels that used in exploration for minerals and other natural resources here on Earth. Petrochemical companies use satellite imagery of Earth to identify regions where there are chemical indicators of processes that concentrate valuable materials in certain geologic settings. They then follow up with localized analysis of those regions, before sending in the “wildcat” crews to drill for resources beneath the surface. The difference in our exploration of Mars is that rather than prospecting for oil or natural gas, we are prospecting for water, signatures of life, or ancient environments conducive to life as we currently understand it. In attempting to understand the “real” Mars, it is first necessary to inventory the key constituents of the Mars system. This step is needed to establish the foundation or context within which particularly difficult questions (i.e., such as “Was there ever life on Mars?”) can be addressed. Thanks to Viking and the ongoing Mars Global Surveyor (MGS) mission, we now know Mars has experienced wide swings in its climate, potentially extensive periods in its past when liquid water was persistent at the surface in localized depressions, and that it may harbor an active subsurface hydrological system even today. In spite of the failures of the Viking surface laboratories to detect any signs of past or present life in the 1970s, we can refine the approach and continue the quest with real prospects of making major strides during the current decade. Global Mapping—The Foundation for Context How will we attack the mysteries of Mars in order to determine whether it ever harbored life or had experienced climate oscillations that mimic those of Earth? These questions have puzzled planetary scientists for 25 years and today, thanks to the global mapping of the MGS, a refined and robust strategy has emerged. For example, in order to most aggressively address whether life ever existed within the Mars system, it is first necessary to have a systematically increasing body of knowledge about the global surface, atmosphere, hydrosphere (although it may be entirely frozen into a cryosphere), and interior. A comprehensive global inventory of the martian surface (and shallow interior) then enables detection of localized “anomalies”—places that are different in terms of chemistry, temperature, venting of important gases, or other factors. This “prospecting” step is a key initial part of our strategy. We must seek the most promising places on the surface of Mars to continue intensive local reconnaissance in the context of a global picture of Mars. Thus, the first step in our Mars exploration strategy is to acquire adequate global reconnaissance using orbital remote sensing tools that not only define Mars in a global context but also tell us where to look in our refined search for localized “hot spots”—places where the action of liquid water and possibly temperature have provided “fingerprints” that we can identify from orbit. The MGS mission currently mapping Mars in combination with the Mars Odyssey orbiter constitutes the first wave of systematic orbital reconnaissance of Mars. The aim is to continuously refine our search for areas on Mars where higher-resolution and landed investigations can best continue the exploration for those materials that offer the most promising prospects for resolving issues related to life, timing of events, and climate history. At issue is what percentage of Mars today might be identifiable as “hot spots.” Recent findings from the imaging systems and spectrometers aboard the Mars Global Surveyor suggest that there may be a few hundred to perhaps a thousand “hot spots” worthy of near-term intensive investigation at the surface. Isolating the handful of the most scientifically compelling poses a challenge to the reconnaissance elements of our unfolding Mars Exploration Program. Data from Viking and MGS suggest that certain landscapes on Mars were likely sculpted by the action of liquid water. However, those same formations might also have been formed as a consequence of exotic processes associat-
OCR for page 114
ed with wind, or even explosive volcanism. We cannot discriminate between the possibilities until we can go to those identified regions and study them at “sample scales”—both at the appropriate scale for definitive process identification, as well as at microscopic scales for provenance studies. Therefore, the next step in refining our global understanding of Mars from this first wave of orbital reconnaissance is to conduct surface investigations at some of the most scientifically compelling sites. Such surface-based investigations will validate and calibrate our global remote sensing data and demonstrate that the mapping from orbit matches the reality of the surface. Data from MGS and Odyssey will identify hundreds to thousands of the most promising regions for these intensive surface investigations. Surface Investigation and Ground-Truthing The 2003 Mars Exploration Rovers (MERs) will take those next steps in making the discoveries that could lead in the future to determining whether or not life ever arose on Mars. The mission of the MERs is to find conclusive evidence of water-affected materials on the surface. They are designed to effectively serve as robotic field geologists, and they will provide the first microscopic study of rocks and soils on Mars. The Mars Pathfinder Sojourner rover analyzed eight rocks and soil patches with one inadequately calibrated instrument (APXS) in 83 days of surface operation. The twin MERs will study dozens of rocks with at least three different calibrated instruments, as well as capturing spectacular context images together with mineralogy (from hyperspectral middle-IR imaging). The twin MERs will also have the mobility to wander up to 1,000 meters across the martian landscape, measuring the chemical character of the soils, rocks, and even the previously inaccessible interiors of rocks where unaltered materials may lurk. Just as human field geologists study Earth by using a hammer to break open rocks, the MERs will employ a rock abrasion tool to scratch beneath the outer covering of Mars rocks and look inside with microscopic resolution. Evidence from martian meteorites indicates that carbonates existed on Mars at one time in its past, at least at microscopic scales. What we don’t know is whether carbonates existed at or near the surface, or whether they were produced in association with biological processes. The MER robotic geologists will help answer this question. Finally, the MER perspective will allow for quantified calibration and validation of orbital remote sensing data at the surface that will hopefully yield the capacity to extrapolate to other places on Mars that are similar to the MER landing sites. By studying the rocks and soils in a “hot spot” region chosen from the MGS and Odyssey reconnaissance data, the MERs will tell us whether what we see from orbit is what we anticipate, and if not, what it may represent instead at least chemically. The MERs will link the surface chemistry and mineralogy at the surface with that surmised from orbital observations and facilitate extrapolation across many different places on Mars. Armed with this new knowledge and characterization of water-related geologic regions on Mars, we are ready to climb to the next level of reconnaissance and in-situ investigations—including the search for life-bearing environments within those water-related regions as well as the surface record of climate. Targeted Reconnaissance and Landing Site Characterization The 2005 Mars Reconnaissance Orbiter (MRO) is the ultimate reconnaissance tool in the Seek, In Situ, Sample strategy. Following the surface validation and investigations of the 2003 MER twin rovers, the MRO will narrow the focus into the localities identified from MGS and Odyssey to search for the most compelling environmental indicators suitable for bearing life (warm, wet, chemically benign, etc.) or recording aspects of climate. The MRO will use its new observational tools, some of which could resolve beachball-sized objects and their mineralogies, to search for clues within the martian landscape of telltale layers and materials associated with the action of liquid water. Recent evidence suggests that water-related mineral indicators may be detectable from orbit at certain specific infrared wavelengths provided high enough spatial resolution is adopted. While debate lingers within the science community about resolution thresholds, imaging thousands of promising sites at ~30-cm resolution would allow discrimination of water-related sedimentation from that associated with explosive volcanism (layers of cemented ash), wind, or global dust settling. Thus, the MRO seeks to develop a globally-distributed set of panchromatic and hyperspectral images that isolate the dozen or so most compelling sites for intensive surface-based exploration and sample return. When coupled with the first in-situ examination of two different water-related sites on Mars as
OCR for page 115
provided by our twin MERs, our approach allows us to build confidence we can predict how Mars operates under certain conditions, as well as to demonstrate the past action of water in the otherwise hyper-arid desert that characterizes the modern Mars of today. In addition, the MRO will seek to develop the first understanding of modern water as it behaves within the present martian atmosphere and how climatology operates on annual basis. The MRO will also attempt to characterize the shallow subsurface of Mars in search of water-related layers or deposits and other stratigraphic indicators of ancient water-related environments. While MGS and Odyssey may identify hundreds to thousands of interesting places on Mars, only two can be visited and evaluated by the twin MERs, in part because of their landing precision (50 km at best). The MRO is designed to evaluate the most compelling places identified previously and to measure their prospects at new scales, wavelengths, and with tools that measure the shallow subsurface vertical structure. The “hottest” places for intensive surface reconnaissance and exploration identified from MGS and Odyssey will be exhaustively targeted by MRO so that by 2006, a set of compelling localities will be established within a global scientific framework. Of these, the top two or three in terms of their potential as martian biomarker sites will serve as the bridge into the second phase of our strategy. Of course, scientifically compelling sites may include localities where the climate record is best exposed in a physical and chemical sense. In Situ Analysis and Returning Samples to Earth The final part of phase one of our Mars Exploration strategy begins after MRO has “fingered” where to go. If all goes as planned, in 2007b we will launch a precision landed mobile surface laboratory—the Mars Science Laboratory (MSL)—to the most promising of the targeted sites that will operate on the martian surface for at least half a year. Planned development of a new suite of miniature analytical instruments for this mobile laboratory, which are tuned to questions of geochemistry and biological processes, will measure aspects of the surface and subsurface materials potentially linked with ancient life and climate. Plans include a laser Raman spectrometer to focus our surface search for carbonates, a micron-resolution optical microscope to assess patterns of micro-scale features, and an instrumented drill that could reach 2 to 3 m beneath the surface in search of buried ice or other “shielded” substances. MSL—also known as the Mobile Science Laboratory or the Mars Smart Lander—could also explore the shallow (~100-m) subsurface using ground penetrating radar or other electromagnetic sounding approaches. With some cooperation from Mars, the MSL could confirm the surface presence of water-related minerals and carbonates and their formational histories. MSL will also have the benefit of the investment in continuous refinement of how orbital remote sensing can be used as a pathfinder to those surface localities that offer the highest probability of harboring martian “fossils” or other forms of indicators of past life. It will serve as both a scientific and technological pathfinder for the robotic sample return campaign that forms the ultimate step in our Mars Exploration Program. This phase of in situ analysis will incorporate technological advances that permit mobile surface laboratories to be landed within a few kilometers or less of any interesting spot on Mars. By precision landing near to a telling site and having the longevity and mobility to explore as if we (humans) were there, we can extend our search for life-signs and other scientific indicators on Mars to horizontal scales on the surface that will be measured in multiple kilometers, and not football fields. MSL will serve as the bridge to the next phase of Mars exploration: a future series of missions that will endeavor to bring preserved samples of the most interesting materials back to Earth, in context, and with real prospects for harboring bio-signs or chemical indicators of warmer and wetter past environments. Clearly a campaign of sample returns will be needed to tie major Mars system events to the absolute chronology of the solar system. When Mars may have been more biologically hospitable and what the global planetary state of evolution was at that time are vital if understanding is to be achieved. Thus, our refined strategy seeks to establish a suite of the most promising places for intensive surface analysis prior to the technological leap of returning samples to Earth for analysis. Once we have identified the hottest prospects, a program of long-duration, and reasonably long-range mobile surface laboratory(ies) must be sent to Mars to unravel what is in the rocks, soils, ices, and atmospheric constituents that could be linked to favorable environments for biology and for its preservation or other driving questions. Under this strategy, with good fortune, by the end of b Editor’s Note: Following the completion of this study, NASA announced that it was delaying the launch of MSL until 2009 to allow time to develop an advanced, radioisotope power system for this mission.
OCR for page 116
2008 we could be receiving images of martian microscopic features not unlike those identified by D. McKay and E. Gibson from the Allan Hills meteorite, ALH84001. The overarching science thrust of the Mars Exploration Program is to examine the diversity of Mars by investigating multiple sites with mobile surface laboratories. However, this would require additional budget resources; a more aggressive program with additional budget increments would allow the development of more than one mobile surface lab and enable the exploration of multiple “hot spots” identified by the MRO and its forerunners. It would also facilitate the earliest possible implementation of sample-return missions. In addition, with the addition of reliable, long-lived power, it could enable direct access to regions up to 20 m deep within the subsurface. One means of providing balance, innovation, and adaptability in our MEP is the Mars Scout Program. This program, currently planned for inception with the 2007 launch opportunity, will solicit principal-investigator-led missions to explore Mars in focused ways not currently baselined in the core MEP program of flight missions. The aim is to promote scientific innovation within the MEP by allowing the broad community to compete for a “Discovery class” mission every other launch opportunity. Given the somewhat limited breadth of the core MEP flight program, and the recommendations of the Mars Exploration Payload Assessment Group (MEPAG), there is plenty of room for additional, high-science-value missions, within the overall Mars Exploration Program. The 2007 Scout competition is expected to engage the Mars scientific and engineering community and deliver an innovative mission with a specific focus not emphasized or treated within the core program. It is possible that the first Mars Scout Mission will involve an array of small surface stations to explore the surface diversity of the planet, or an orbiter to map aspects of the global Mars that cannot be implemented on the 2005 MRO mission. A preliminary set of 10 Scout Mission concepts were selected for 6-month study as of June of 2001. Finally, the first of several “informed” Mars sample-return missions (MSRs) is planned for a late 2011 launch, with return of ~1 kg of sample materials by 2014. The specific scientific scope of the first MSR mission remains in the hands of science definition teams, but the intent is to build upon the technologies utilized in 2007 for the mart mobile surface laboratory to selectively screen samples at a surface site selected to provide the best sedimentary record of water-related materials indicative of perhaps hospitable paleo-environments. Given the material diversity of Mars and the challenges presented by sampling one scientifically-compelling locality to provide definitive answers to the driving scientific questions about Mars, it is unlikely that a single MSR mission to a sedimentary site will fulfill the scientific requirements and needs. Thus, NASA plans to implement a campaign of MSR missions in the next decade (2011–2020) that will involve long-lived surface exploration with subsurface access to provide the most diagnostic materials for analytical investigations in terrestrial laboratories. Summary Finding the right places to go on Mars’s vast surface to pursue the search for origins of life, the record of climate, and ultimately our place as humans within the cosmos is the first step required in the new Mars exploration strategy. A natural extension of this progressive strategy of orbital, surface, and ultimately sample-based reconnaissance is to visit two or more sites with precision-landed mobile surface laboratories by the end of the decade. Such a strategy, when combined with small, totally competed missions in 2007 and beyond, will extend our ability to search for elusive clues to the possibilities of life or at least for evidence of ancient, warm, wet environments. Ultimately the surface-based search, in the context of orbital “foundation” data sets, will yield Mars’s secrets and allow us to return samples safely to Earth for unprecedented analytical scrutiny. The new Mars Exploration Program delivers a continuously refined view of Mars with the excitement of discovery at every step. What might we find as we move along the roadmap of mission events this decade? MGS has already discovered possible clues to a source, however small, of modern liquid water. Odyssey could discover carbonates at the surface or regions of enrichment in hydrogen, as well as evidence of possible martian geothermal vents. The twin MERs may discover local evidence for how water once persisted at the surface and what ultimately to search for from orbit. The MRO may discover ancient martian “oases”—localities where chemical and morphological evidence of past warmer and wetter environments is preserved. Alternately, MRO could uncover the shallow subsurface of Mars and voluminous repositories of buried water ice. In 2008, the first of potentially several mobile surface laboratories could find specific materials indicative of locally warm, wet paleo-environments and possibly the first in situ detection of martian organics. A Mars Scout mission in 2007 could sample martian atmospheric dust or probe the workings of martian meteorology. Ultimately the first martian samples of rocks, soils, dust, and perhaps vola-
OCR for page 117
tiles, will arrive on Earth by 2014, isolated to preclude contamination. These first samples, collected in careful context, will open the door for human missions to Mars sometime in the future. NASA has fashioned a strategy that is risk attentive, including a natural responsivity to science challenges that will emerge as discoveries are made. It is linked to our experience exploring the deep ocean here on Earth, as well as part of a strategy that uses Mars as a natural laboratory for understanding life and climate on Earth-like planets other than our own.
Representative terms from entire chapter: