[[File:NE Syrtis Context.png|thumb|The yellow rectangle indicates the location of Northeast [[Syrtis Major quadrangle|Syrtis Major. Syrtis Major is]] one of the largest volcanic provinces on Mars. The west part is the ancient and huge impact basin—Isidis, about 1500&nbsp;km in diameter.]] '''Northeast Syrtis''' is a region of [[Mars]] once considered by [[NASA]] as a landing site for the [[Mars 2020|Mars 2020 rover mission]].<ref>{{Cite web|url=https://mars.nasa.gov/mars2020/|title=Mars 2020 Rover|publisher=[[NASA]]|access-date=9 October 2018}}</ref> This landing site failed in the competition with [[Jezero (crater)|Jezero crater]], another landing site dozens of kilometers away from Northeast Syrtis.<ref name="Hautaluoma 2018">{{Cite news|url=https://www.nasa.gov/press-release/nasa-announces-landing-site-for-mars-2020-rover|title=NASA Announces Landing Site for Mars 2020 Rover|last=Hautaluoma|first=Grey|date=19 November 2018|work=NASA|access-date=2018-11-20|language=en}}</ref> It is located in the northern hemisphere of Mars at coordinates 18°N,77°E in the northeastern part of the [[Syrtis Major quadrangle|Syrtis Major]] volcanic province, within the ring structure of [[Isidis Planitia|Isidis impact basin]] as well. This region contains diverse morphological features and minerals, indicating that water once flowed here.<ref name="Ehlmann 2012">{{cite journal|last1=Ehlmann|first1=Bethany L.|author2-link=John F. Mustard|last2=Mustard|first2=John F.|date=June 2012|title=An in-situ record of major environmental transitions on early Mars at Northeast Syrtis Major|journal=Geophysical Research Letters|volume=39|issue=11|pages=n/a|doi=10.1029/2012GL051594|bibcode=2012GeoRL..3911202E|doi-access=free}}</ref><ref>{{Cite journal|last1=Mangold|first1=N.|last2=Ansan|first2=V.|last3=Baratoux|first3=D.|last4=Costard|first4=F.|last5=Dupeyrat|first5=L.|last6=Hiesinger|first6=H.|last7=Masson|first7=Ph.|last8=Neukum|first8=G.|last9=Pinet|first9=P.|date=May 2008|title=Identification of a new outflow channel on Mars in Syrtis Major Planum using HRSC/MEx data|journal=Planetary and Space Science|volume=56|issue=7|pages=1030–1042|doi=10.1016/j.pss.2008.01.011|bibcode=2008P&SS...56.1030M|issn=0032-0633}}</ref><ref name="Mustard 2009">{{cite journal|last1=Mustard|first1=J. F.|last2=Ehlmann|first2=B. L.|last3=Murchie|first3=S. L.|last4=Poulet|first4=F.|last5=Mangold|first5=N.|last6=Head|first6=J. W.|last7=Bibring|first7=J.-P.|last8=Roach|first8=L. H.|date=12 December 2009|title=Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis basin|journal=Journal of Geophysical Research|volume=114|issue=7|doi=10.1029/2009JE003349|bibcode=2009JGRE..114.0D12M|s2cid=17913229|doi-access=free}}</ref><ref name="Ehlmann 2009">{{cite journal|last1=Ehlmann|first1=Bethany L.|last2=Mustard|first2=John F.|last3=Swayze|first3=Gregg A.|last4=Clark|first4=Roger N.|last5=Bishop|first5=Janice L.|author-link5=Janice Bishop|last6=Poulet|first6=Francois|last7=Des Marais|first7=David J.|last8=Roach|first8=Leah H.|last9=Milliken|first9=Ralph E.|date=23 October 2009|title=Identification of hydrated silicate minerals on Mars using MRO-CRISM: Geologic context near Nili Fossae and implications for aqueous alteration|journal=Journal of Geophysical Research|volume=114|doi=10.1029/2009JE003339|last10=Wray|first10=James J.|last11=Barnouin-Jha|first11=Olivier|last12=Murchie|first12=Scott L.|issue=53|bibcode=2009JGRE..114.0D08E|url=https://authors.library.caltech.edu/34910/1/2009JE003339.pdf|doi-access=free}}</ref><ref name="Bramble 2017">{{Cite journal|last1=Bramble|first1=Michael S.|last2=Mustard|first2=John F.|last3=Salvatore|first3=Mark R.|date=September 2017|title=The geological history of Northeast Syrtis Major, Mars|journal=Icarus|volume=293|pages=66–93|doi=10.1016/j.icarus.2017.03.030|bibcode=2017Icar..293...66B|issn=0019-1035}}</ref><ref>{{Cite journal|last1=Ehlmann|first1=Bethany L.|last2=Mustard|first2=John F.|date=June 2012|title=An in-situ record of major environmental transitions on early Mars at Northeast Syrtis Major|journal=Geophysical Research Letters|language=en|volume=39|issue=11|pages=n/a|doi=10.1029/2012gl051594|bibcode=2012GeoRL..3911202E|issn=0094-8276|citeseerx=10.1.1.656.7596|s2cid=3174336 }}</ref> It may be an ancient habitable environment; microbes could have developed and thrived here.

The layered terrain of Northeast Syrtis is unique on the surface of Mars, containing diverse aqueous minerals such as like [[Clay minerals|clay]], [[carbonate]], [[Serpentine soil|serpentine]] and [[sulfate]],<ref name="Ehlmann 2009" /><ref>{{Cite journal|last1=Murchie|first1=Scott L.|last2=Mustard|first2=John F.|last3=Ehlmann|first3=Bethany L.|last4=Milliken|first4=Ralph E.|last5=Bishop|first5=Janice L.|author-link5=Janice Bishop|last6=McKeown|first6=Nancy K.|last7=Noe Dobrea|first7=Eldar Z.|last8=Seelos|first8=Frank P.|last9=Buczkowski|first9=Debra L.|date=22 September 2009|title=A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter|journal=Journal of Geophysical Research|language=en|volume=114|issue=E2|doi=10.1029/2009je003342|bibcode=2009JGRE..114.0D06M|issn=0148-0227|url=https://authors.library.caltech.edu/43957/1/jgre2648.pdf}}</ref> as well as igneous minerals such as [[olivine]] and high-calcium and low-calcium [[pyroxene]]. Clay minerals form in the interaction between water and rock<ref>{{Cite journal|last1=Poulet|first1=F.|last2=Bibring|first2=J.-P.|last3=Mustard|first3=J. F.|last4=Gendrin|first4=A.|last5=Mangold|first5=N.|last6=Langevin|first6=Y.|last7=Arvidson|first7=R. E.|last8=Gondet|first8=B.|last9=Gomez|first9=C.|date=December 2005|title=Phyllosilicates on Mars and implications for early martian climate|journal=Nature|language=En|volume=438|issue=7068|pages=623–627|doi=10.1038/nature04274|pmid=16319882|bibcode=2005Natur.438..623P|s2cid=7465822|issn=0028-0836}}</ref> and [[sulfate minerals]] usually form through intense evaporation on Earth. Similar processes may happen on Mars forming these minerals, which strongly suggests a history of water and rock interaction. In addition, [[megabreccia]], possibly the oldest material throughout this region (some blocks are over 100&nbsp;m in diameter), could give an insight into the primary crust when Mars first formed.<ref name="Mustard 2009" /> The location is an ideal site for studying the timing and evolution of the surface processes of Mars, such as huge [[impact basin]] formation, fluvial activity ([[valley network]]s, small [[outflow channels]]), [[groundwater]] activity, history of [[Glaciers on Mars|glaciation]], and [[volcanic activity]].<ref name="Ehlmann 2012" />

==Regional stratigraphy == [[File:StratigraphicColumn of Northeast Syrtis.png|thumb|The stratigraphic column of Northeast Syrtis. The thickness of each unit is hard to estimate. after <ref>{{Cite web|url=https://marsnext.jpl.nasa.gov/workshops/2018-10/PRESENTATIONS/m2020_lsw_day2_09_ehlmann.pdf|title=Mapping the Decadal Survey Drivers for Sample Return to Geologic Units Accessible in the Primary and Extended Missions from NE Syrtis and Midway|last=Bethany|first=Ehlmann|website=Fourth landing site workshop for the Mars 2020 rover mission}}</ref>]] The regional [[stratigraphy]] of Northeast Syrtis has been studied in detail.<ref name="Ehlmann 2012" /><ref name="Bramble 2017" /> This area is sandwiched between a huge [[shield volcano]]—Syrtis Major—and one of largest impact basins in the [[Solar System]], and therefore could provide a key constraint of the timing of key events in the history of Mars. The stratigraphy can be divided into four major units, from young to old:<ref name=nta>{{cite web |last1=Quantin-Nataf |first1=C. |last2=Dromart |first2=G. |last3=Mandon |first3=L. |title=NOACHIAN TO AMAZONIAN VOLCANIC ACTIVITY IN NE SYRTIS REGION |url=https://www.hou.usra.edu/meetings/lpsc2018/pdf/2591.pdf |website=www.hou.usra.edu |accessdate=13 December 2018 |date=2018}}</ref>

#Syrtis Major lavas unit contains high-calcium pyroxene bearing material; #Layered sulfate-bearing unit, include poly-hydrated sulfates and [[jarosite]]; #Olivine unit, olivine-enriched unit variably altered to carbonate and serpentine; #Basement unit: The mixture of iron/magnesium (Fe/Mg) [[smectite]] and low-calcium pyroxene-bearing unit variably altered to Aluminium-clay bearing materials.<ref name=nta/>

The basement unit is one of newest units on Mars, recording early-stage evolution history of terrestrial planets. The change from carbonate to sulfate indicates a transition from alkaline-neutral to acid aqueous environments.<ref name="Ehlmann 2012" />

== Mars 2020 mission == The Mars 2020 rover launched in July 2020 with [[Atlas V]] rocket to reach Mars in February 2021. This rover inherits from the [[Curiosity (rover)|Mars Science Laboratory Curiosity]], with similar entry, descent, and landing systems, and the sky crane. Besides exploring a likely habitable site and searching for signs of past life, collecting scientifically compelling samples (rock and [[regolith]]) which could address fundamental scientific questions if returned to Earth, is the main goal of the Mars 2020 mission.<ref>{{Cite journal|last=Witze|first=Alexandra|date=18 January 2017|title=The $2.4-billion plan to steal a rock from Mars|journal=Nature|language=en|volume=541|issue=7637|pages=274–278|doi=10.1038/541274a|pmid=28102284|bibcode=2017Natur.541..274W|issn=0028-0836|doi-access=free}}</ref> The landing site's selection is the key part of this mission's success.<ref>{{cite web |last1=Skok |first1=J. R. |title=NASA Prepares to Select Landing Site for Mars Life Detection Mission {{!}} SETI Institute |url=https://www.seti.org/nasa-prepares-select-landing-site-mars-life-detection-mission |website=www.seti.org |accessdate=13 December 2018 |date=18 October 2018}}</ref>

Although Northeast Syrtis survived the cut in third Mars 2020 Landing Site Workshops, it failed final completion. The landing ellipse of Northeast Syrtis is 16 x 14&nbsp;km and the smaller ellipse is 13.3 × 7.8&nbsp;km with the help of advanced technologyTerrain-Relative Navigation (TRN).<ref name="Hautaluoma 2018" /><ref>{{Cite journal|last=Witze|first=Alexandra|date=11 December 2017|title=Three sites where NASA might retrieve its first Mars rock|journal=Nature|language=en|volume=542|issue=7641|pages=279–280|doi=10.1038/nature.2017.21470|pmid=28202980|bibcode=2017Natur.542..279W|issn=0028-0836|doi-access=free}}</ref> [[File:NE Syrtis Ellipse.png|thumb|Landing ellipse of NE Syrtis, Mars. The blue oval is Northeast Syrtis landing ellipse. The white oval is the smaller anding ellipse with Terrain-Relative Navigation technique. The yellow oval is another potential landing site, Jezero landing ellipse. The context image is CTX (Context Camera) onboard Mars Reconnaissance Orbiter.]]

=== Region of interest === [[File:Mesa of Northeast Syrtis.png|alt=|thumb|Mesa unit in Northeast Syrtis, Mars.]]

==== Mesa unit ==== [[File:Megaberica.png|thumb|Megabreccia in Northeast Syrtis.]] The mesa is one of the interesting locations. It consists of five subunits: crater-retaining cap, boulder-shedding slopes exposing lightened blocks, olivine-carbonate unit, Fe/Mg-phyllosilicate, allowing easy to access diverse rocks.<ref name="Carter 2015" /><ref name=bis/>

On the top of the mesa is a dark toned cap unit, composed of meter-scale boulders. It was interpreted as [[Hesperian]] Syrtis Major lava flows or lithified ash. These igneous rocks are suitable samples for acquiring the age of Martian geologic events, which could calibrate the planet dating method. Unlike Earth, planet dating mainly relies on [[crater count]]ing, a method based on the assumption that the number of impact craters on a planet surface increases with the length of time that the surface has been exposed to space cratering, calibrated using the ages obtained by radiometric dating of samples of Luna and [[Apollo mission]]s. The samples of this mission returned to Earth will be analyzed by state of the art equipment in laboratories. Igneous samples from Northeast Syrtis could provide four key time for Martian geology history, including (1) the timing of [[Isidis Planitia|Isidis]] impact event, (2) the timing of emplacement of olivine-rich unit, (3) the timing of dark-toned mafic cap rock, (4) the timing of Syrtis lava flows, which would fundamentally improve human knowledge of early Mars and the early history of solar system, such as the [[Late Heavy Bombardment|late-heavy bombardment]].<ref name="Carter 2015" /><ref name=bis/>

This region exposes the largest high-olivine abundance rocks on Mars.<ref>{{Cite journal|last1=Christensen|first1=Philip R.|last2=Pearl|first2=John C.|last3=Smith|first3=Michael D.|last4=Bandfield|first4=Joshua L.|last5=Clark|first5=Roger N.|last6=Hoefen|first6=Todd M.|date=2003-10-24|title=Discovery of Olivine in the Nili Fossae Region of Mars|journal=Science|language=en|volume=302|issue=5645|pages=627–630|doi=10.1126/science.1089647|issn=1095-9203|pmid=14576430|bibcode=2003Sci...302..627H|s2cid=20122017|url=https://zenodo.org/record/1230836}}</ref> The origin of high-olivine rock is still in debate. Impact cumulates<ref name="Mustard 2009" /> or olivine-rich lava<ref>{{Cite journal|last1=Hamilton|first1=Victoria E.|last2=Christensen|first2=Philip R.|year=2005|title=Evidence for extensive, olivine-rich bedrock on Mars|journal=Geology|language=en|volume=33|issue=6|pages=433|doi=10.1130/g21258.1|bibcode=2005Geo....33..433H|issn=0091-7613}}</ref><ref>{{Cite journal|last1=Tornabene|first1=Livio L.|last2=Moersch|first2=Jeffrey E.|last3=McSween|first3=Harry Y.|last4=Hamilton|first4=Victoria E.|last5=Piatek|first5=Jennifer L.|last6=Christensen|first6=Phillip R.|date=2 October 2008|title=Surface and crater-exposed lithologic units of the Isidis Basin as mapped by coanalysis of THEMIS and TES derived data products|journal=Journal of Geophysical Research|language=en|volume=113|issue=E10|doi=10.1029/2007je002988|bibcode=2008JGRE..11310001T|issn=0148-0227|doi-access=free}}</ref> are two leading hypotheses. A portion of olivine rock was altered to carbonate. Many hypotheses have been proposed to explain the origin of carbonate, including a serpentine springs system.<ref>{{Cite journal|last1=Brown|first1=Adrian J.|last2=Hook|first2=Simon J.|last3=Baldridge|first3=Alice M.|last4=Crowley|first4=James K.|last5=Bridges|first5=Nathan T.|last6=Thomson|first6=Bradley J.|last7=Marion|first7=Giles M.|last8=de Souza Filho|first8=Carlos R.|last9=Bishop|first9=Janice L.|author-link9=Janice Bishop|date=August 2010|title=Hydrothermal formation of Clay-Carbonate alteration assemblages in the Nili Fossae region of Mars|journal=Earth and Planetary Science Letters|volume=297|issue=1–2|pages=174–182|doi=10.1016/j.epsl.2010.06.018|issn=0012-821X|arxiv=1402.1150|bibcode=2010E&PSL.297..174B|s2cid=54496871}}</ref><ref>{{Cite journal|last1=Viviano|first1=Christina E.|last2=Moersch|first2=Jeffrey E.|last3=McSween|first3=Harry Y.|date=September 2013|title=Implications for early hydrothermal environments on Mars through the spectral evidence for carbonation and chloritization reactions in the Nili Fossae region|journal=Journal of Geophysical Research: Planets|language=en|volume=118|issue=9|pages=1858–1872|doi=10.1002/jgre.20141|bibcode=2013JGRE..118.1858V|issn=2169-9097|doi-access=free}}</ref> Carbonate is important [[Carbon sink|sink of carbon]], and is a crucial part of understanding the [[carbon cycle]] of Mars. Future sample return could shed light on the environmental conditions of carbonate. As well, the isotopic composition of carbonate through time, records the atmosphere loss, and it also reveals whether life once emerged on Mars.<ref name="Carter 2015" /><ref name=bis/>

The lower part of mesa unit is the basement unit of the Northeast Syrtis region, consisting of Fe/Mg smectites and low calcium pyroxene. The basement unit was partially altered to form kaolinite. The kaolinite (Al-clay) usually overlying the Fe/Mg smectites across the Martian surface.<ref name="Carter 2015">{{Cite journal|last1=Carter|first1=John|last2=Loizeau|first2=Damien|last3=Mangold|first3=Nicolas|last4=Poulet|first4=François|last5=Bibring|first5=Jean-Pierre|date=March 2015|title=Widespread surface weathering on early Mars: A case for a warmer and wetter climate|journal=Icarus|volume=248|pages=373–382|doi=10.1016/j.icarus.2014.11.011|bibcode=2015Icar..248..373C|issn=0019-1035}}</ref> Weathering in a warm climate or acid leaching are two domain interpretations of kaolinite formation.<ref name="Carter 2015" /><ref name=bis>{{Cite journal|last1=Bishop|first1=Janice L.|author-link1=Janice Bishop|last2=Dobrea|first2=Eldar Z. Noe|last3=McKeown|first3=Nancy K.|last4=Parente|first4=Mario|last5=Ehlmann|first5=Bethany L.|last6=Michalski|first6=Joseph R.|last7=Milliken|first7=Ralph E.|last8=Poulet|first8=Francois|last9=Swayze|first9=Gregg A.|date=8 August 2008|title=Phyllosilicate Diversity and Past Aqueous Activity Revealed at Mawrth Vallis, Mars|journal=Science|language=en|volume=321|issue=5890|pages=830–833|doi=10.1126/science.1159699|issn=0036-8075|pmid=18687963|pmc=7007808|bibcode=2008Sci...321..830B}}</ref>

===== Megabreccia ===== [[File:Layersulfate.png|thumb|Layer sulfate unit in Northeast Syrtis.]] Megabreccia occurs throughout the basement unit of Northeast Syrtis. The composition of these megabreccias is complex, including altered or mafic material.<ref name="Mustard 2009" /> These megabreccias may be uplifted and exposed by the [[Isidis Planitia|Isidis Basin]] forming event. The megabreccia could reveal the nature of the remnant of Mars's primary crust or the Noachian-aged low-calcium [[pyroxene]] lavas. It also could constrain the timing of Martian [[dynamo]] activity.

==== Layer sulfate unit ==== Further to the south of the landing ellipse, there is a {{convert|500|m|adj=on}} thick sequence of [[sulfate]] deposits capped by lava flows from the later [[Syrtis Major Planum|Syrtis Major]] volcanic formation. The layer of sulfates include poly-hydrated sulphates and [[jarosite]]. [[Jarosite]] usually indicate oxidizing and acid (pH<4) environments. The occurrence of jarosite indicates that the environment changed from neutral/alkaline (as suggested by extensive Fe/Mg smectites and carbonate) to acid.<ref name="Ehlmann 2012" /> The detection of sulfate adds more complexity to Martian geologic history.

== See also == {{Portal|Astronomy|Biology|Solar System}} {{Div col|colwidth=30em}} * [[Astrobiology]] * [[Climate of Mars]] * [[Composition of Mars]] * [[Exploration of Mars]] * [[Geology of Mars]] * [[Impact crater]] * [[Inverted relief]] * [[Lakes on Mars]] * [[List of craters on Mars]] * [[Water on Mars]] *[[Mars lander]] {{div col end}}

==References== {{Reflist}}

==External links== * [https://mars.nasa.gov/mars2020/ Mars 2020 Rover official site] * [https://marsnext.jpl.nasa.gov/ Mars 2020 Rover Landing sites selection]

{{Mars 2020}} {{Geography of Mars}}

[[Category:Mars 2020]] [[Category:Syrtis Major quadrangle]]