Fifty years ago, on 14 December 1962, the Mariner 2 spacecraft flew by Venus and inaugurated the modern era of planetary exploration. Since that first Venus flyby, roughly 80 spacecraft have successfully probed, orbited, flown by, landed on, or roved on other planets, satellites, asteroids, and comets. As Carl Sagan used to say, only one generation of humankind can be the first explorers of the solar system, and we are that generation.

AstrobiologyVol. 12, No. 3 News & ViewsPlanning for Mars Returned Sample Science: Final Report of the MSR End-to-End International Science Analysis Group (E2E-iSAG)Published Online:2 Apr 2012https://doi.org/10.1089/ast.2011.0805AboutSectionsView articleView Full TextPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View articleAbstractExecutive Summary1. Introduction1.1. A proposed MSR implementation architecture2. MSR Campaign Scientific Aims and Objectives2.1. Introduction2.2. Specific proposed science aims and objectives for Mars returned sample science (organized by topic)2.2.1. Aim A. Life2.2.2. Aim B. Surface2.2.3. Aim C. Planetary evolution2.2.4. Aim D. Prepare for human exploration2.3. Prioritization of scientific objectives3. Achieving the Scientific Objectives—Some Considerations Involving Collecting Samples from a Field Area3.1. Relationship between field and sample science3.2. Information hierarchy3.3. Collect early, exchange later3.4. The importance of rock and soil sample suites4. Achieving the Proposed Scientific Objectives—Samples Required/Desired4.1. Integrated priorities for rock samples4.1.1. Considerations in designing the suites of rock samples4.1.2. Possible/probable variations in rock we need to be prepared to detect and sample4.1.3. Scientific value of a subsurface rock sample4.1.4. Number of rock samples desired/required4.2. Considerations related to the number and type of regolith samples4.2.2. Regolith—sampling implications4.3. Considerations related to the number and type of gas samples4.3.1. Integrated priorities for gas samples4.3.2. Atmospheric gas—sampling implications4.3.3. The importance of rock/mineral samples with fluid or melt inclusions5. Where on Mars Might It Be Possible to Obtain the Samples Needed to Achieve the Proposed Objectives of MSR?5.1. Establishing a reference landing site set5.2. Brief descriptions of the reference landing sites5.3. Implications of the reference landing set for the major EDL and mobility parameters6. Measurements on Returned Samples Required to Achieve the Proposed Objectives6.1. Analysis flow for rock and regolith samples6.1.1. Preliminary examination6.1.2. Planetary protection6.1.3. Scientific research6.1.4. Requirement for replicate analyses6.1.5. Reserve samples for future research6.2. Implications for sample sizing: rock samples6.3. Implications for sample sizing: regolith samples6.4. Implications for sample sizing: atmospheric gas samples7. Capabilities on Mars Needed to Select, Acquire, and Preserve the Samples7.1. Observations required to understand geological context7.1.1. Scale of required field observations7.2. The Pasteur payload7.2.1. Potential use of the instruments of the Pasteur payload to support the objectives of the MSR Campaign7.3. Measurement needs of the proposed 2018 joint rover in addition to those of Pasteur7.3.1. Mast-mounted instruments7.3.2. Arm-mounted instruments7.3.3. Summary of on-Mars measurement needs in excess of Pasteur7.4. Sample collection and preservation system7.4.1. Sizing the sample cache7.4.2. Sample packing7.4.3. Organic blanks and calibration standards7.4.4. Sample sealing and preservation7.4.5. Sealing concepts and materials8. Conclusions8.1. Summary8.2. Recommendation for future work8.2.1. MEPAG-related tasks8.2.2. Programmatic issues (NASA and ESA)8.2.3. Research work (NASA and ESA)8.2.4. Engineering development (NASA and ESA)A. AppendicesA1. GlossaryA2. Charter of This StudyA2.1. Charter assumptionsA2.2. Methodology and approachA2.2.1. Requested tasksA2.2.2. MethodsA2.2.3. Deliverables, scheduleA3. Scientific Risk for the MSR CampaignA4. Planetary Protection Issues/OpportunitiesA5. Reference Landing SitesAcknowledgmentsAbbreviationsReferencesFiguresReferencesRelatedDetailsCited byRegolith of the Crater Floor Units, Jezero Crater, Mars: Textures, Composition, and Implications for Provenance12 March 2023 | Journal of Geophysical Research: Planets, Vol. 128, No. 3A Deep Ultraviolet Raman and Fluorescence Spectral Library of 51 Organic Compounds for the SHERLOC Instrument Onboard Mars 2020 Joseph Razzell Hollis, Sunanda Sharma, William Abbey, Rohit Bhartia, Luther Beegle, Marc Fries, Jeffrey D. Hein, Brian Monacelli, and Austin D. Nordman30 December 2022 | Astrobiology, Vol. 23, No. 1Identifying Shocked Feldspar on Mars Using Perseverance Spectroscopic Instruments: Implications for Geochronology Studies on Returned Samples3 May 2022 | Earth, Moon, and Planets, Vol. 126, No. 2Preliminary Planning for Mars Sample Return (MSR) Curation Activities in a Sample Receiving Facility (SRF) Kimberly T. Tait, Francis M. McCubbin, Caroline L. Smith, Carl B. Agee, Henner Busemann, Barbara Cavalazzi, Vinciane Debaille, Aurore Hutzler, Tomohiro Usui, Gerhard Kminek, Michael A. Meyer, David W. Beaty, Brandi L. Carrier, Timothy Haltigin, Lindsay E. Hays, Charles S. Cockell, Daniel P. Glavin, Monica M. Grady, Ernst Hauber, Bernard Marty, Lisa M. Pratt, Aaron B. Regberg, Alvin L. Smith, Roger E. Summons, Timothy D. Swindle, Nicholas J. Tosca, Arya Udry, Michael A. Velbel, Meenakshi Wadhwa, Frances Westall, and Maria-Paz Zorzano2 June 2022 | Astrobiology, Vol. 22, No. S1Scientific Value of Including an Atmospheric Sample as Part of Mars Sample Return (MSR) Timothy D. Swindle, Sushil Atreya, Henner Busemann, Julia A. Cartwright, Paul Mahaffy, Bernard Marty, Andreas Pack, and Susanne P. Schwenzer2 June 2022 | Astrobiology, Vol. 22, No. S1Science and Curation Considerations for the Design of a Mars Sample Return (MSR) Sample Receiving Facility (SRF) Brandi L. Carrier, David W. Beaty, Aurore Hutzler, Alvin L. Smith, Gerhard Kminek, Michael A. Meyer, Timothy Haltigin, Lindsay E. Hays, Carl B. Agee, Henner Busemann, Barbara Cavalazzi, Charles S. Cockell, Vinciane Debaille, Daniel P. Glavin, Monica M. Grady, Ernst Hauber, Bernard Marty, Francis M. McCubbin, Lisa M. Pratt, Aaron B. Regberg, Caroline L. Smith, Roger E. Summons, Timothy D. Swindle, Kimberly T. Tait, Nicholas J. Tosca, Arya Udry, Tomohiro Usui, Michael A. Velbel, Meenakshi Wadhwa, Frances Westall, and Maria-Paz Zorzano2 June 2022 | Astrobiology, Vol. 22, No. S1The Scientific Importance of Returning Airfall Dust as a Part of Mars Sample Return (MSR) Monica M. Grady, Roger E. Summons, Timothy D. Swindle, Frances Westall, Gerhard Kminek, Michael A. Meyer, David W. Beaty, Brandi L. Carrier, Timothy Haltigin, Lindsay E. Hays, Carl B. Agee, Henner Busemann, Barbara Cavalazzi, Charles S. Cockell, Vinciane Debaille, Daniel P. Glavin, Ernst Hauber, Aurore Hutzler, Bernard Marty, Francis M. McCubbin, Lisa M. Pratt, Aaron B. Regberg, Alvin L. Smith, Caroline L. Smith, Kimberly T. Tait, Nicholas J. Tosca, Arya Udry, Tomohiro Usui, Michael A. Velbel, Meenakshi Wadhwa, and Maria-Paz Zorzano2 June 2022 | Astrobiology, Vol. 22, No. S1Balancing Predictive and Reactive Science Planning for Mars 2020 PerseveranceComposition of planetary crusts and planetary differentiationPerseverance rover reveals an ancient delta-lake system and flood deposits at Jezero crater, MarsScience, Vol. 374, No. 6568Machine Vision based Sample-Tube Localization for Mars Sample ReturnDefinition and use of functional analogues in planetary explorationPlanetary and Space Science, Vol. 197Mars 2020 Mission Overview3 December 2020 | Space Science Reviews, Vol. 216, No. 8What is the Oxygen Isotope Composition of Venus? The Scientific Case for Sample Return from Earth’s “Sister” Planet11 May 2020 | Space Science Reviews, Vol. 216, No. 4The Limits, Capabilities, and Potential for Life Detection with MinION Sequencing in a Paleochannel Mars Analog Catherine Maggiori, Jessica Stromberg, Yolanda Blanco, Jacqueline Goordial, Edward Cloutis, Miriam García-Villadangos, Victor Parro, and Lyle Whyte2 March 2020 | Astrobiology, Vol. 20, No. 3Field and laboratory validation of remote rover operations Science Team findings: The CanMars Mars Sample Return analogue missionPlanetary and Space Science, Vol. 176How Will the Emerging Plurality of Lives Change How We Conceive of and Relate to Life?18 June 2019 | Challenges, Vol. 10, No. 1The Sedimentary Cycle on Early MarsAnnual Review of Earth and Planetary Sciences, Vol. 47, No. 1The potential science and engineering value of samples delivered to Earth by Mars sample return5 March 2019 | Meteoritics & Planetary Science, Vol. 54The CanMars Mars Sample Return analogue missionPlanetary and Space Science, Vol. 166Sulfur on Mars from the Atmosphere to the CoreTEMMI, a Three-dimensional Exploration Multispectral Microscope Imager for planetary exploration missionsPlanetary and Space Science, Vol. 165Earth and Space Science, Vol. 6, No. 8The science process for selecting the landing site for the 2020 Mars roverPlanetary and Space Science, Vol. 164Computer‐Aided Exploration of the Martian Geology31 August 2018 | Earth and Space Science, Vol. 5, No. 8Spatial Spectroscopic Models for Remote Exploration David R. Thompson, Alberto Candela, David S. Wettergreen, Eldar Noe Dobrea, Gregg A. Swayze, Roger N. Clark, and Rebecca Greenberger1 July 2018 | Astrobiology, Vol. 18, No. 7A Method for Choosing the Best Samples for Mars Sample Return Peter R. Gordon and Mark A. Sephton1 May 2018 | Astrobiology, Vol. 18, No. 5Selecting Mars samples to return to EarthAstronomy & Geophysics, Vol. 59, No. 1Exploration Tools23 August 2017Ground Truth23 August 2017Microbialite Biosignature Analysis by Mesoscale X-ray Fluorescence (μXRF) Mapping Michael M. Tice, Kimbra Quezergue, and Michael C. Pope1 November 2017 | Astrobiology, Vol. 17, No. 11Organism-substrate interactions and astrobiology: Potential, models and methodsEarth-Science Reviews, Vol. 171Organic Matter Detection on Mars by Pyrolysis-FTIR: An Analysis of Sensitivity and Mineral Matrix Effects Peter R. Gordon and Mark A. Sephton1 November 2016 | Astrobiology, Vol. 16, No. 11Rapid habitability assessment of Mars samples by pyrolysis-FTIRPlanetary and Space Science, Vol. 121A Hierarchical System for Evaluating the Biogenicity of Metavolcanic- and Ultramafic-Hosted Microalteration Textures in the Search for Extraterrestrial Life Nicola McLoughlin and Eugene G. Grosch23 October 2015 | Astrobiology, Vol. 15, No. 10Ultrastructural Heterogeneity of Carbonaceous Material in Ancient Cherts: Investigating Biosignature Origin and Preservation Yuangao Qu, Anders Engdahl, Shixing Zhu, Vivi Vajda, and Nicola McLoughlin23 October 2015 | Astrobiology, Vol. 15, No. 10The chances of detecting life on MarsPlanetary and Space Science, Vol. 112Synchronous in-field application of life-detection techniques in planetary analog missionsPlanetary and Space Science, Vol. 106Planning Considerations Related to the Organic Contamination of Martian Samples and Implications for the Mars 2020 Rover, R.E. Summons, A.L. Sessions, , A.C. Allwood, H.A. Barton, D.W. Beaty, B. Blakkolb, J. Canham, B.C. Clark, J.P. Dworkin, Y. Lin, R. Mathies, S.M. Milkovich, and A. Steele15 December 2014 | Astrobiology, Vol. 14, No. 12Statistics Provide Guidance for Indigenous Organic Carbon Detection on Mars Missions Mark A. Sephton and Jonathan N. Carter7 August 2014 | Astrobiology, Vol. 14, No. 8Astrobiology can help space science, education and the economySpace Policy, Vol. 30, No. 3Report of the workshop for life detection in samples from MarsLife Sciences in Space Research, Vol. 2Microscale Mapping of Alteration Conditions and Potential Biosignatures in Basaltic-Ultramafic Rocks on Early Earth and Beyond Eugene G. Grosch, Nicola McLoughlin, Pierre Lanari, Muriel Erambert, and Olivier Vidal12 March 2014 | Astrobiology, Vol. 14, No. 3MarsThe effect of artificial seawater on SERS spectra of amino acids-Ag colloids: An experiment of prebiotic chemistrySpectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Vol. 118On the chronology of lunar origin and evolution12 November 2013 | The Astronomy and Astrophysics Review, Vol. 21, No. 1Searching for biomolecules on Mars: Considerations for operation of a life marker chip instrumentPlanetary and Space Science, Vol. 86Selecting samples for Mars sample return: Triage by pyrolysis–FTIRPlanetary and Space Science, Vol. 78Conference Summary: Life Detection in Extraterrestrial Samples Abigail Allwood, David Beaty, Deborah Bass, Cassie Conley, Gerhard Kminek, Margaret Race, Steve Vance, and Frances Westall19 February 2013 | Astrobiology, Vol. 13, No. 2The Role of Terrestrial Analogs in the Exploration of the Habitability of Martian Evaporitic Environments6 May 2013 Volume 12Issue 3Mar 2012 InformationCopyright 2012, Mary Ann Liebert, Inc.To cite this article:Planning for Mars Returned Sample Science: Final Report of the MSR End-to-End International Science Analysis Group (E2E-iSAG).Astrobiology.Mar 2012.175-230.http://doi.org/10.1089/ast.2011.0805Published in Volume: 12 Issue 3: April 2, 2012PDF download

The Mars canal controversy is a reminder to be cautious when interpreting alien worlds, notes Michael Carr.

You have accessJournal of UrologyPediatrics: Imaging Genital & Urinary Tract/Infections and Vesicoureteral Reflux/Andrology - Cryptorchidism & Varicoceles1 Apr 20101261 TOTAL BUT NOT DIFFERENTIAL TESTICULAR VOLUMES CORRELATE WITH SPERM COUNTS IN ADOLESCENT VARICOCELE PATIENTS Thomas Kolon, Angela Kalmus, Aileen Schast, Pasquale Casale, Michael Carr, Howard Snyder, Douglas Canning, and Stephen Zderic Thomas KolonThomas Kolon More articles by this author , Angela KalmusAngela Kalmus More articles by this author , Aileen SchastAileen Schast More articles by this author , Pasquale CasalePasquale Casale More articles by this author , Michael CarrMichael Carr More articles by this author , Howard SnyderHoward Snyder More articles by this author , Douglas CanningDouglas Canning More articles by this author , and Stephen ZdericStephen Zderic More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.806AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Management of the adolescent with a varicocele remains controversial. While some have argued for surgical correction if the affected testicular volume is 20% less than that of its contralateral mate, we have noted that 80% of these volume discrepancies correct over time without surgery. In this study, we correlate differential and total testicular volumes with semen analyses obtained once the patients had reached 18 years of age. METHODS Records of patients followed nonsurgically for a diagnosis of varicocele were reviewed after patients returned with a completed semen analysis. Testicular volumes were determined by ultrasound using the Lambert formula at 1 year intervals. Differential testicular volume was calculated as affected testis/total testicular volume x 100. The best and worst volume differential for each patient was used for this analysis (t-test). RESULTS 48 patients were followed for an average of 3.2 ± 1.6 years and underwent an average of 4.2 ± 2.5 ultrasound studies, For all 48 patients the mean total sperm count was 43 million ± 44 (range 0-240). The worst testicular differential volume recorded for each patient was 43.6 cc ± 4.1 (range 43-66); the best was 51.7 cc ± 5 (range 34-50). The best and worst testicular differential volumes were then analyzed for total sperm counts above and below 40, 30, 20, and 10 million. For each of these categories, the testicular differential volumes did not differ (p=NS). However the mean sum of the total testicular volumes (right and left) taken at the last ultrasound differed substantially for those patients with a total sperm count less than 40 million (35.1 ± 10.9) versus those with a count above 40 million (43.5 ± 10) (p= 0.02). CONCLUSIONS From these data we conclude that: i)differential testicular volume is not predictive of future total sperm count. ii) the diminished bilateral testicular volume observed in those patients with the worst semen parameters supports a possible underlying endocrinopathy. Philadelphia, PA© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e488 Peer Review Report Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Thomas Kolon More articles by this author Angela Kalmus More articles by this author Aileen Schast More articles by this author Pasquale Casale More articles by this author Michael Carr More articles by this author Howard Snyder More articles by this author Douglas Canning More articles by this author Stephen Zderic More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

In Schor's (1993) book, she claimed that American's were overworked. With hindsight, this turns out to be only half right. What has happened is an increase in the dispersion of labor supply, with more individuals working long or short hours, respectively, now than in 1980. Simultaneously, wage inequality has also increased. Recent research suggests that the widening income distribution plays an important causal role in determining labor supply patterns. Using a sensitive version of the Panel Study on Income Dynamics linked to the Current Population Survey, this claim is tested. Little support is found for the claim that either inequality in the workplace or inequality in the community increases labor supply. The results are robust to dierent measures of inequality, dierent specication of the reference group, and dierent panel data estimation techniques. The conclusion is that the positive correlation between work hours and inequality at the occupational level found by previous researchers is capturing variations in the underlying institutional structure of occupations.

Sedimentary rocks exposed in the Meridiani Planum region of Mars record aqueous and eolian deposition in ancient dune and interdune playa-like environments that were arid, acidic, and oxidizing. On Earth, microbial populations have repeatedly adapted to low pH and both episodic and chronic water limitation, suggesting that, to a first approximation, the Meridiani plain may have been habitable during at least part of the interval when deposition and early diagenesis took place. On the other hand, the environmental conditions inferred for Meridiani deposition would have posed a challenge for prebiotic chemical reactions thought to have played a role in the origin of life on Earth. Orbital observations suggest that the combination of sulfate minerals and hematite found in Meridiani rocks may be unusual on the martian surface; however, there is reason to believe that acidity, aridity, and oxidizing conditions were broadly distributed on ancient Mars. When these conditions were established and how much environmental heterogeneity existed on early Mars remain to be determined. Because sulfates and iron oxides can preserve detailed geochemical records of environmental history as well as chemical, textural and microfossil signatures of biological activity, Meridiani Planum is an attractive candidate for Mars sample return.

Abstract The relationship between inequality and labor supply has gained an increasing amount of attention in recent years. This is due, in no small part, to the rise in both work hours and inequality overtime within the U.S. and relative to other developed countries. This paper investigates the possibility of a causal relationship running from inequality to labor supply. After controlling for individual, industrial, and occupational characteristics it is found that inequality has an overall positive effect on work hours. This result changes along the income distribution with both high and low relative wages being associated with higher levels of labor supply, but wages in the middle being associated with less. Results are robust to alternative definitions of inequality as well as to changes in the specific sample of individuals.

This paper summarizes our work designing optimal shaped pupils for high-contrast imaging. We show how any effective apodization can be created using shaped pupils and present a variety of both one-dimensional and azimuthally symmetric pupil shapes. Each pupil has its own performance advantage and we discuss the tradeoffs among various designs. Optimizations are typically performed by maximizing a measure of system throughput under constraints on contrast and inner working angle. We mention the question of sensitivity to aberrations. Controlling aberrations will be critical for any implementation of a planet-finding coronagraph. Finally, we present our first laboratory results testing a shaped pupil coronagraph.

The NASA Mars Exploration Rover (MER) Project has been considering a landing‐site ellipse designated EP78B2 in southeastern Utopia Planitia, southwest of Elysium Mons. The site appears to be relatively safe for a MER landing site because of its predicted low wind velocities in mesoscale atmospheric circulation models and its low surface roughness at various scales as indicated by topographic and imaging data sets. Previously, the site's surface rocks have been interpreted to be marine sediments or lava flows. In addition, we suggest that Late Noachian to Early Hesperian collapse and mass wasting of Noachian highland rocks contributed to the deposition of detritus in the area of the ellipse. Furthermore, we document partial Late Hesperian to Early Amazonian resurfacing of the ellipse by flows and vents that may be of mud or silicate volcanic origin. A rover investigation of the Utopia landing site using the MER Athena instrument package might address some fundamental aspects of Martian geologic evolution, such as climate change, hydrologic evolution, and magmatic and tectonic history.

The NASA Mars Exploration Rover (MER) Project has been considering a landing-site ellipse designated EP78B2 in southeastern Utopia Planitia, southwest of Elysium Mons. The site appears to be relatively safe for a MER landing site because of its predicted low wind velocities in mesoscale atmospheric circulation models and its low surface roughness at various scales as indicated by topographic and imaging data sets. Previously, the site's surface rocks have been interpreted to be marine sediments or lava flows. In addition, we suggest that Late Noachian to Early Hesperian collapse and mass wasting of Noachian highland rocks contributed to the deposition of detritus in the area of the ellipse. Furthermore, we document partial Late Hesperian to Early Amazonian resurfacing of the ellipse by flows and vents that may be of mud or silicate volcanic origin. A rover investigation of the Utopia landing site using the MER Athena instrument package might address some fundamental aspects of Martian geologic evolution, such as climate change, hydrologic evolution, and magmatic and tectonic history.

[1] The selection of Meridiani Planum and Gusev crater as the Mars Exploration Rover landing sites took over 2 years, involved broad participation of the science community via four open workshops, and narrowed an initial ∼155 potential sites (80–300 × 30 km) to four finalists based on science and safety. Engineering constraints important to the selection included (1) latitude (10°N–15°S) for maximum solar power, (2) elevation (less than −1.3 km) for sufficient atmosphere to slow the lander, (3) low horizontal winds, shear, and turbulence in the last few kilometers to minimize horizontal velocity, (4) low 10-m-scale slopes to reduce airbag spin-up and bounce, (5) moderate rock abundance to reduce abrasion or strokeout of the airbags, and (6) a radar-reflective, load-bearing, and trafficable surface safe for landing and roving that is not dominated by fine-grained dust. The evaluation of sites utilized existing as well as targeted orbital information acquired from the Mars Global Surveyor and Mars Odyssey. Three of the final four landing sites show strong evidence for surface processes involving water and appear capable of addressing the science objectives of the missions, which are to determine the aqueous, climatic, and geologic history of sites on Mars where conditions may have been favorable to the preservation of evidence of possible prebiotic or biotic processes. The evaluation of science criteria placed Meridiani and Gusev as the highest-priority sites. The evaluation of the three most critical safety criteria (10-m-scale slopes, rocks, and winds) and landing simulation results indicated that Meridiani and Elysium Planitia are the safest sites, followed by Gusev and Isidis Planitia.

[1] Gusev Crater was selected as the landing site for the Mars Exploration Rover (MER) Spirit mission. Located at the outlet of Ma'adim Vallis and 250 km south of the volcano Apollinaris Patera, Gusev is an outstanding site to achieve the goals of the MER mission. The crater could have collected sediments from a variety of sources during its 3.9 Ga history, including fluvial, lacustrine, volcanic, glacial, impact, regional and local aeolian, and global air falls. It is a unique site to investigate the past history of water on Mars, climate and geological changes, and the potential habitability of the planet, which are central science objectives of the MER mission. Because of its complex history and potential diversity, Gusev will allow the testing of a large spectrum of hypotheses with the complete suite of MER instruments. Evidence consistent with long-lived lake episodes exist in the landing ellipse area. They might offer a unique opportunity to study, for the first time, Martian aqueous sediments and minerals formed in situ in their geological context. We review the geological history and diversity of the landing site, the science hypotheses that can be tested during the MER mission, and the relevance of Gusev to the MER mission objectives and payload.

A major oceanographic event preserved in the Cocos plate sedimentary column survived subduction and is recorded in the changing composition of Nicaraguan magmas. A uranium increase in these magmas since the latest Miocene (after 7 Ma) resulted from the "carbonate crash" at 10 Ma and the ensuing high organic carbon burial in the sediments. The response of the arc to this paleoceanographic event requires near steady-state sediment recycling at this margin since 20 Ma. This relative stability in sediment subduction invites one of the first attempts to balance sedimentary input and arc output across a subduction zone. Calculations based on Th indicate that as much as 75% of the sedimentary column was subducted beneath the are. The Nicaraguan margin is one of the few places to observe such strong links between the oceans and the solid earth.