View source for Astronomy:Trace Gas Orbiter

{{Short description|A Mars orbiter, part of ExoMars programme}}
{{Infobox spaceflight
| name                  = Trace Gas Orbiter

<!--image of the spacecraft/mission-->
| image                 = ExoMars 2016 TGO and EDM trans-small.png
| image_caption         = Artist's illustration of ExoMars 2016
| image_size            = 300px

<!--Basic details-->
| mission_type          = [[Astronomy:List of Mars orbiters|Mars orbiter]]
| operator              = [[Organization:European Space Agency|ESA]]{{dot}}Roscosmos
| COSPAR_ID             = 2016-017A
| SATCAT                = 41388
| website               = http://exploration.esa.int/jump.cfm?oid=46475
| mission_duration      = Planned: 7 years<ref name="esaOverview">{{cite web |url=http://exploration.esa.int/mars/46124-mission-overview/ |title=ExoMars Trace Gas Orbiter and Schiaparelli Mission (2016) |publisher=European Space Agency |date=16 October 2016 |accessdate=24 October 2016}}</ref><ref name="june2011">{{cite conference |title=2016 ESA/NASA ExoMARS/Trace Gas Orbiter |conference=Mars Exploration Program Assessment Group. 15–16 June 2011. Lisbon, Portugal. |first1=Mark A. |last1=Allen |first2=Olivier |last2=Witasse |date=2011|hdl = 2014/42148}}</ref> <br /> Elapsed: {{time interval|14 March 2016 09:31|show=ymd|sep=,}}

<!--Spacecraft properties-->
| manufacturer          = [[Company:Thales Alenia Space|Thales Alenia Space]]
| launch_mass           = {{convert|3755|kg|lb|abbr=on}}<ref name="trace-gas-orbiter">{{cite web |url=http://exploration.esa.int/jump.cfm?oid=46475 |title=ExoMars Trace Gas Orbiter (TGO) |publisher=European Space Agency |date=12 July 2012 |accessdate=8 March 2014}}</ref>
| dry_mass              = 
| payload_mass          = Instruments: {{convert|113.8|kg|lb|abbr=on}}<ref name="trace-gas-orbiter" /> <br /> ''Schiaparelli'': {{convert|577|kg|lb|abbr=on}}<ref name="trace-gas-orbiter" />
| dimensions            = {{convert|3.2|xx|2|xx|2|m|ft|abbr=on}}<ref name="trace-gas-orbiter" />
| power                 = ~2000&nbsp;W<ref name="trace-gas-orbiter" />

<!--Launch details-->
| launch_date           = {{start-date|14 March 2016, 09:31}}&nbsp;[[UTC]]<ref name="bbcnews20160314" />
| launch_rocket         = [[Engineering:Proton-M|Proton-M]]/Briz-M
| launch_site           = Baikonur 200/39
| launch_contractor     = [[Company:Khrunichev State Research and Production Space Center|Khrunichev]]

<!--orbit parameters-->
| orbit_reference       = [[Astronomy:Areocentric orbit|Areocentric]]
| orbit_regime          = [[Astronomy:Circular orbit|Circular]]
| orbit_semimajor       = <!--semimajor axis-->
| orbit_eccentricity    = 0
| orbit_periapsis       = {{convert|400|km|mi|abbr=on}}
| orbit_apoapsis        = {{convert|400|km|mi|abbr=on}}
| orbit_inclination     = 74&nbsp;degrees
| orbit_period          = 2&nbsp;hours
| orbit_epoch           = Planned
| apsis                 = areion

| interplanetary        = {{Infobox spaceflight/IP
 | type                 = orbiter
 | object               = Mars
 | arrival_date         = 19 October 2016, 15:24&nbsp;UTC<ref>{{cite news |url=http://www.spaceflightinsider.com/missions/solar-system/lost-mars-schiaparelli-lander-falls-silent-shortly-touchdown/ |title=Lost on Mars: Schiaparelli lander falls silent shortly before touchdown |work=Spaceflight Insider |first=Tomasz |last=Nowakowski |date=20 October 2016 |accessdate=24 October 2016}}</ref>
 }}

| instruments_list      = {{Infobox spaceflight/Instruments
  | acronym1 = NOMAD  | name1 = [[Engineering:Nadir and Occultation for Mars Discovery|Nadir and Occultation for Mars Discovery]]
  | acronym2 = ACS    | name2 = Atmospheric Chemistry Suite
  | acronym3 = CaSSIS | name3 = Colour and Stereo Surface Imaging System
  | acronym4 = FREND  | name4 = Fine-Resolution Epithermal Neutron Detector
 }}

<!--mission insignia or patch-->
| insignia              = File:ExoMars 2016 insignia.png
| insignia_caption      = ESA mission insignia for the ''ExoMars 2016'' launch, featuring the ''Trace Gas Orbiter'' (left) and ''Schiaparelli'' (right).
| insignia_alt          = 
| insignia_size         = 80px

<!--transponder parameters-->
| trans_band            = [[Physics:X band|X band]]<br />[[Engineering:Electra (radio)|UHF band]]
| trans_frequency       = 390–450 [[Hertz|MHz]]
| trans_bandwidth       = <!--bandwidth-->
| trans_capacity        = <!--capacity of the transponders-->
| trans_coverage        = <!--area covered-->
| trans_TWTA            = 65 W
| trans_EIRP            = <!--equivalent isotropic power-->
| trans_HPBW            = <!--half-power beam width-->

<!--Only use where a spacecraft/mission is part of a clear programme of sequential missions.
If in doubt, leave it out-->
| programme             = [[Astronomy:ExoMars|ExoMars]] programme
| previous_mission      =
| next_mission          = [[Engineering:Rosalind Franklin (rover)|''Rosalind Franklin'' rover]] <br /> and [[Astronomy:Kazachok|''Kazachok'' lander]]
}}

The '''ExoMars Trace Gas Orbiter''' ('''TGO''' or '''ExoMars Orbiter''') is a collaborative project between the [[Organization:European Space Agency|European Space Agency]] (ESA) and [[Company:Roscosmos|Roscosmos]] that sent an [[Physics:Atmospheric science|atmospheric research]] [[Engineering:Orbiter|orbiter]] and the [[Engineering:Schiaparelli EDM|''Schiaparelli'']] demonstration lander to [[Astronomy:Mars|Mars]] in 2016 as part of the European-led [[Astronomy:ExoMars|ExoMars]] programme.<ref name="NYT-20161019">{{cite news |last=Chang |first=Kenneth |title=ExoMars Mission to Join Crowd of Spacecraft at Mars |url=https://www.nytimes.com/2016/10/20/science/esa-mars-lander.html |date=19 October 2016 |work={{wipe|The New York Times}} |accessdate=19 October 2016}}</ref><ref name="tbthStatus">{{Citation |first=J. L. |last=Vago |contribution=Mars Panel Meeting |title=Planetary Science Decadal Survey |publisher=[[Organization:European Space Agency|European Space Agency]] |place=Arizona State University, Tempe (US) |date=10 September 2009 |contribution-url=http://www.marspages.eu/media/archive4/exomars/statusbericht/StatusberichtSep2009.pdf|contribution-format=PDF}}</ref><ref name="Mustard">{{cite web |url=http://www.lpi.usra.edu/pss/july2009/presentations/05MEPAG.pdf |title=MEPAG Report to the Planetary Science Subcommittee |publisher=Mars Exploration Program Analysis Group |first=Jack |last=Mustard |page=3 |date=9 July 2009}}</ref>

The Trace Gas Orbiter delivered the ''Schiaparelli'' lander on 16 October 2016, which crashed on the surface.<ref name=BBC_20_Oct_2016>{{cite news |url=https://www.bbc.co.uk/news/science-environment-37707776 |title=Fears grow for European Schiaparelli Mars lander |first=Jonathan |last=Amos |work=BBC News |date=19 October 2016 |accessdate=20 October 2016}}</ref>

The orbiter began [[Astronomy:Aerobraking|aerobraking]] in March 2017 to lower its initial orbit of {{convert|200|by|98000|km|mi|abbr=on}}. Aerobraking concluded on 20 February 2018 when a final thruster firing resulted in an orbit of {{convert|200|by|1050|km|mi|abbr=on}}.<ref name="esa_Done">{{cite web |url=http://www.esa.int/Our_Activities/Operations/Surfing_complete |title=Surfing complete |publisher=European Space Agency |date=21 February 2018 |accessdate=1 May 2018 |archiveurl=https://web.archive.org/web/20180222072551/http://www.esa.int/Our_Activities/Operations/Surfing_complete |archivedate=22 February 2018}}</ref> Additional thruster firings every few days raised the orbiter to a circular "science" orbit of {{convert|400|km|mi|abbr=on}}, which was achieved on 9 April 2018.<ref name="esa20180409">{{cite web |url=http://www.esa.int/Our_Activities/Space_Science/ExoMars/ExoMars_poised_to_start_science_mission |title=ExoMars poised to start science mission |publisher=European Space Agency |first1=Pia |last1=Mitschdoerfer |first2=Håkan |last2=Svedhem |first3=Markus |last3=Bauer |display-authors=1 |date=9 April 2018 |accessdate=18 June 2018}}</ref>

A key goal is to gain a better understanding of [[Astronomy:Methane on Mars|methane]] ({{chem2|CH4}}) and other trace gases present in the [[Astronomy:Atmosphere of Mars|Martian atmosphere]] that could be evidence for possible biological activity. The programme will follow with the [[Astronomy:Kazachok|''Kazachok'' lander]] and the [[Engineering:Rosalind Franklin (rover)|''Rosalind Franklin'' rover]] in 2020,<ref name="LaunchMoved2020">{{cite press release |url=http://www.esa.int/For_Media/Press_Releases/Second_ExoMars_mission_moves_to_next_launch_opportunity_in_2020 |title=Second ExoMars mission moves to next launch opportunity in 2020 |publisher=[[Organization:European Space Agency|European Space Agency]] |date=2 May 2016 |accessdate=2 May 2016}}</ref> which will search for [[Physics:Biomolecule|biomolecule]]s and [[Astronomy:Biosignature|biosignature]]s; the TGO will operate as the communication link for the ExoMars lander and rover and provide communication for other Mars surface probes with Earth.

== History ==
Investigations with space and Earth-based observatories have demonstrated the presence of a small amount of [[Astronomy:Methane on Mars|methane]] on the atmosphere of Mars that seems to vary with location and time.<ref>{{cite web |url=http://mepag.jpl.nasa.gov/decadal/TGM_Mars_Panel-cleared-9-4-09.ppt |title=Mars Trace Gas Mission |publisher=MEPAG |date=10 September 2009 |url-status=dead |archiveurl=https://web.archive.org/web/20110721052957/http://mepag.jpl.nasa.gov/decadal/TGM_Mars_Panel-cleared-9-4-09.ppt |archivedate=21 July 2011 |df=dmy-all}}</ref><ref name="plumes">{{Cite journal |title=Strong Release of Methane on Mars in Northern Summer 2003 |journal=Science |date=20 February 2009 |first=Michael J. |last=Mumma |last2=Villanueva |first2=Gerónimo L. |volume=323 |issue=5917 |pages=1041–1045 |doi=10.1126/science.1165243 |url=http://images.spaceref.com/news/2009/Mumma_et_al_Methane_Mars_wSOM_accepted2.pdf |pmid=19150811 |bibcode=2009Sci...323.1041M |last3=Novak |first3=Robert E. |last4=Hewagama |first4=Tilak |last5=Bonev |first5=Boncho P. |last6=Disanti |first6=Michael A. |last7=Mandell |first7=Avi M. |last8=Smith |first8=Michael D.}}</ref><ref>{{Cite news |first=Eric |last=Hand |title=Plumes of methane identified on Mars |date=21 October 2008 |publisher=Nature News |url=http://esse.engin.umich.edu/psl/PRESS/Mars/NatureNews_2008.pdf |accessdate=2 August 2009 |language=}}</ref> This may indicate the presence of microbial life on Mars, or a geochemical process such as volcanism or hydrothermal activity.<ref>{{cite news |url=http://astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=2765&mode=thread&order=0&thold=0 |title=Making Sense of Mars' Methane |date=June 2008 |website=Astrobio.net}}</ref><ref>{{Cite news |first=Bill |last=Steigerwald |title=Martian Methane Reveals the Red Planet is not a Dead Planet |date=15 January 2009 |publisher=NASA |url=http://www.nasa.gov/mission_pages/mars/news/marsmethane.html |work=NASA's Goddard Space Flight Center |accessdate=24 January 2009}}</ref><ref name="Howe">{{Cite conference |last=Howe |first=K. L. |last2=Gavin |first2=P. |last3=Goodhart |first3=T. |last4=Kral |first4=T. A. |title=Methane Production by Methanogens in Perchlorate-Supplemented Media. |conference=40th Lunar and Planetary Science Conference |date=2009 |url=http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1287.pdf }}</ref><ref name="Levin2009">{{Cite journal |title=Methane and life on Mars |journal=Proc. SPIE |date=3 September 2009 |first=Gilbert V. |first2=Patricia Ann |last2=Straat |volume=7441 |issue=74410D |pages=74410D |doi=10.1117/12.829183 |last1=Levin |series=Proceedings of SPIE |bibcode=2009SPIE.7441E..0DL}}</ref>

The challenge to discern the source of methane in the atmosphere of Mars prompted the independent planning by ESA and NASA of one orbiter each that would carry instruments in order to determine if its formation is of biological or geological origin,<ref>{{Cite news |first=Paul |last=Rincon |title=Agencies outline Mars initiative |date=9 July 2009 |publisher= |url=http://news.bbc.co.uk/2/hi/science/nature/8130393.stm |website=BBC News |accessdate=26 July 2009}}</ref><ref>{{Cite news |title=NASA orbiter to hunt for source of Martian methane in 2016 |date=6 March 2009 |url=http://www.thaindian.com/newsportal/health/nasa-orbiter-to-hunt-for-source-of-martian-methane-in-2016_100163335.html |website=Thaindian News |accessdate=26 July 2009 |language=}}</ref> as well as its decomposition products such as [[Physics:Formaldehyde|formaldehyde]] and [[Chemistry:Methanol|methanol]].

=== Origins ===
ExoMars Trace Gas Orbiter was born out of the nexus of ESA's [[Astronomy:Aurora programme|Aurora programme]] [[Astronomy:ExoMars|ExoMars]] flagship and NASA's 2013 and 2016 Mars Science Orbiter (MSO) concepts.<ref name="smithtgm20090910">{{cite web |url=http://www.spacepolicyonline.com/pages/images/stories/PSDS%20Mars1%20Smith-TGM.pdf |title=Mars Trace Gas Mission: Science Rationale & Concept |series=Presentation to the NRC Decadal Survey Mars Panel |first=Michael |last=Smith |date=10 September 2009}}</ref><ref name="JointInstrument">{{cite web |url=http://mepag.jpl.nasa.gov/meeting/jul-09/JIDT_for_MEPAG.pdf |title=Report to MEPAG on the ESA-NASA Joint Instrument Definition Team (JIDT) for the Proposed 2016 Orbiter-Carrier |publisher=NASA |first1=R. |last1=Zurek |first2=A. |last2=Chicarro |date=29 July 2009 |archiveurl=https://web.archive.org/web/20090730203811/http://mepag.jpl.nasa.gov/meeting/jul-09/JIDT_for_MEPAG.pdf |archivedate=30 July 2009 |url-status=dead |df=dmy}}</ref> It became a flexible collaborative proposal within NASA and ESA to send a new orbiter-carrier to Mars in 2016 as part of the European-led ExoMars mission.<ref name="Mustard" /> On the ExoMars side, ESA authorised about half a billion Euros in 2005 for a rover and mini-station; eventually this evolved into being delivered by an orbiter rather than a cruise stage.<ref>{{cite web |url=http://spaceflight101.com/exomars/project-history/ |title=Brief ExoMars Project History |website=Spaceflight101.com |date=2016 |accessdate=12 November 2016}}</ref>

=== {{anchor|MSO}}Attempted collaboration with NASA ===
[[Organization:NASA|NASA]]'s '''Mars Science Orbiter''' (MSO) was originally envisioned in 2008 as an all-NASA endeavour aiming for a late 2013 launch.<ref name="smithtgm20090910" /><ref name="JointInstrument" /> NASA and ESA officials agreed to pool resources and technical expertise and collaborate to launch only one orbiter.<ref name="split">{{Cite news |first=Michael A. |last=Taverna |title=ESA Proposes Two ExoMars Missions |date=19 October 2009 |website=Aviation Week |url=http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/Exomars101909.xml&headline=ESA%20Proposes%20Two%20ExoMars%20Missions |accessdate=30 October 2009}}</ref> The agreement, called the [[Astronomy:Mars Exploration Joint Initiative|Mars Exploration Joint Initiative]], was signed on July 2009 and proposed to use an Atlas rocket launcher instead of a [[Engineering:Soyuz (rocket family)|Soyuz rocket]], which significantly altered the technical and financial setting of the European ExoMars mission. Since the rover was originally planned to be launched along with the TGO, a prospective agreement would require that the rover lose enough weight to fit aboard the Atlas launch vehicle with NASA's orbiter.<ref>{{cite news |publisher=Space News |url=http://www.spacenews.com/civil/nasa-could-take-role-european-exomars-mission.html |title=NASA Could Take Role in European ExoMars Mission |date=19 June 2009}}</ref> Instead of reducing the rover's mass, it was nearly doubled when the mission was combined with other projects to a multi-spacecraft programme divided over two [[Engineering:Atlas V|Atlas V]] launches:<ref name="split" /><ref name="oct12">{{Cite news |first=Jonathan |last=Amos |title=Europe's Mars plans move forward |date=12 October 2009 |url=http://news.bbc.co.uk/2/hi/science/nature/8302876.stm |work=BBC News |accessdate=12 October 2009}}</ref> the ExoMars Trace Gas Orbiter (TGO) was merged into the project, carrying a meteorological lander planned for launch in 2016. The European orbiter would carry several instruments originally meant for NASA's MSO, so NASA scaled down the objectives and focused on atmospheric trace gases detection instruments for their incorporation in ESA's ExoMars Trace Gas Orbiter.<ref name="trace-gas-orbiter" /><ref name="Mustard" /><ref name="JointInstrument" />

Under the FY2013 budget President [[Biography:Barack Obama|Barack Obama]] released on 13 February 2012, NASA terminated its participation in ExoMars due to budgetary cuts in order to pay for the cost overruns of the [[Astronomy:James Webb Space Telescope|James Webb Space Telescope]].<ref>{{cite news |first=Ken |last=Kremr |title=Experts React to Obama Slash to NASA's Mars and Planetary Science Exploration |date=1 February 2012 |url=http://www.universetoday.com/93512/experts-react-to-obama-slash-to-nasas-mars-and-planetary-science-exploration/ |website=Universe Today |accessdate=18 February 2012}}</ref> With NASA's funding for this project cancelled, most of ExoMars' plans had to be restructured.<ref name="cancellation">{{cite news |first=Megan |last=Whewell |title=Have Europe's Martian exploration plans been derailed by America? |date=15 February 2012 |website=MSN News |url=http://news.uk.msn.com/blog/the-space-blog-blogpost.aspx?post=1fac64fc-9e63-4c9c-9304-ce598c2ab71d |accessdate=15 February 2012 |archive-url=https://web.archive.org/web/20120511105820/http://news.uk.msn.com/blog/the-space-blog-blogpost.aspx?post=1fac64fc-9e63-4c9c-9304-ce598c2ab71d |archive-date=11 May 2012 |url-status=dead }}</ref>

=== Collaboration with Russia ===
On 15 March 2012, the ESA's ruling council announced it would press ahead with its ExoMars program in partnership with the Russian space agency [[Company:Roscosmos|Roscosmos]], which planned to contribute two heavy-lift [[Engineering:Proton (rocket family)|Proton launch vehicles]] and an additional entry, descent and landing system to the 2020 rover mission.<ref name="Svitak">{{cite news |first=Amy |last=Svitak |title=Europe Joins Russia on Robotic ExoMars |date=16 March 2012 |url=http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/awx/2012/03/15/awx_03_15_2012_p0-437120.xml&headline=Europe%20Joins%20Russia%20on%20Robotic%20ExoMars |website=Aviation Week |accessdate=16 March 2012}}</ref><ref name="Selding">{{cite news |first=Peter B. |last=De Selding |title=ESA Ruling Council OKs ExoMars Funding |date=15 March 2012 |url=http://spacenews.com/15032esa-ruling-council-oks-funding-for-mars-mission-with-russia/ |website=Space News |accessdate=16 March 2012}}</ref><ref>{{cite news |title=NASA drops ExoMars missions in 2013 budget |date=15 February 2012 |url=http://optics.org/news/3/2/23 |work=Optics |accessdate=15 February 2012}}</ref><ref>{{cite news |website=The Guardian |url=https://www.theguardian.com/science/2012/mar/16/spacewatch-nasa-mars-exomars |title=Spacewatch: Uncertainties for ExoMars |date=16 March 2012}}</ref><ref name="stillKeen">{{cite news |first=Jonathan |last=Amos |title=Europe still keen on Mars missions |date=15 March 2012 |url=https://www.bbc.co.uk/news/science-environment-17390576 |website=BBC News |accessdate=16 March 2012}}</ref>

Under the collaboration proposal with Roscosmos, the ExoMars mission was split into two parts: the orbiter/lander mission in March 2016 that includes the TGO and a {{convert|2.4|m|ftin|abbr=on}} diameter stationary lander built by ESA named [[Engineering:Schiaparelli EDM lander|''Schiaparelli'']],<ref name="ExoMars">{{cite web |url=http://www.russianspaceweb.com/exomars_2016.html |title=ExoMars |date= |accessdate=22 October 2013 |work=Russian Space Web}}</ref> and the [[Engineering:Rosalind Franklin (rover)|''Rosalind Franklin'' rover]] mission in 2020.<ref name="LaunchMoved2020"/> Both missions are using a [[Engineering:Proton-M|Proton-M]] rocket.

=== Launch ===
[[File:ExoMars 2016 Launch.jpg|thumb|left|Launch of the Proton carrier rocket]]
[[File:Animation of ExoMars Trace Gas Orbiter trajectory.gif |thumb|right| Animation of ExoMars Trace Gas Orbiter{{'s}} trajectory<br />{{legend2|Yellow| Sun}}{{·}}{{legend2|RoyalBlue| Earth}}{{·}}{{legend2|Lime| Mars}}{{·}}{{legend2|Magenta| ExoMars Trace Gas Orbiter }}]]
[[File:Animation of ExoMars Trace Gas Orbiter trajectory around Mars.gif |thumb|right| Animation of ExoMars Trace Gas Orbiter{{'s}} trajectory around Mars<br />{{legend2|Lime| Mars}}{{·}}{{legend2|Magenta| ExoMars Trace Gas Orbiter }}]]
The Trace Gas Orbiter and descent module ''Schiaparelli'' completed testing and were integrated to a Proton rocket at the Baikonur Cosmodrome in Kazakhstan in mid-January 2016.<ref>{{cite news |url=http://spaceref.com/mars/exomars-2016-schiaparelli-module-in-baikonur.html |title=ExoMars 2016 ''Schiaparelli'' Module in Baikonur |work=ESA |publisher=SpaceRef |date=6 January 2016 |accessdate=6 January 2016}}</ref> The launch occurred at 09:31&nbsp;[[UTC]] on 14 March 2016.<ref name="bbcnews20160314">{{cite news |url=https://www.bbc.co.uk/news/science-environment-35799792 |title=Mars methane mission lifts off |first=Jonathan |last=Amos |publisher=BBC |date=14 March 2016 |accessdate=14 March 2016}}</ref> Four rocket burns occurred in the following 10 hours before the descent module and orbiter were released.<ref name=Gibney_Nature_11_March_2016>{{cite journal |title=Mars launch to test collaboration between Europe and Russia |journal=Nature |date=11 March 2016 |first=Elizabeth |last=Gibney |doi=10.1038/nature.2016.19547 |volume=531 |issue=7594 |pages=288–299 |pmid=26983519 |bibcode=2016Natur.531..288G|doi-access=free }}</ref> A signal from the spacecraft was received at 21:29&nbsp;UTC that day, confirming that the launch was successful and the spacecraft were functioning properly.<ref>{{cite news |url=http://www.esa.int/Our_Activities/Space_Science/ExoMars/ExoMars_on_its_way_to_solve_the_Red_Planet_s_mysteries |title=ExoMars on its way to solve the Red Planet's mysteries |publisher=ESA |date=14 March 2016 |accessdate=15 March 2016 |archive-url=https://web.archive.org/web/20161026085720/http://www.esa.int/Our_Activities/Space_Science/ExoMars/ExoMars_on_its_way_to_solve_the_Red_Planet_s_mysteries |archive-date=26 October 2016 |url-status=dead }}</ref>

Shortly after separation from the probes, a Brazilian ground telescope recorded small objects in the vicinity of the [[Engineering:Briz (rocket stage)|Briz-M]] upper booster stage, suggesting that the Briz-M stage exploded a few kilometres away, without damaging the orbiter or lander.<ref name="exploded booster">{{cite news |last=King |first=Bob |url=http://www.universetoday.com/128073/exomars-mission-narrowly-avoids-exploding-booster/ |title=ExoMars Mission Narrowly Avoids Exploding Booster |work=Universe Today |date=24 March 2016 |accessdate=25 March 2016}}</ref> Briefing reporters in Moscow, the head of Roscosmos denied any anomaly and made all launch data available for inspection.<ref>{{cite news |last=de Selding |first=Peter B. |url=http://spacenews.com/roscosmos-gives-detailed-rebuttal-to-reports-of-proton-upper-stage-anomaly-after-exomars-separation/ |title=Roscosmos gives detailed rebuttal to reports of Proton ExoMars launch anomaly |work=Space News |date=5 April 2016 |accessdate=5 April 2016}}</ref>

=== Status ===
The ''Schiaparelli'' lander separated from the TGO orbiter on 16 October 2016,<ref name="separation">{{cite news |last=Malik |first=Tariq |url=http://www.space.com/34399-european-mars-lander-separates-exomars-mothership.html |title=European Mars Lander Separates From Mothership, Takes Aim at Red Planet |work=Space.com |date=16 October 2016 |accessdate=16 October 2016}}</ref> three days before it arrived on Mars, and entered the atmosphere at {{convert|21000|km/h|mph km/s|abbr=on}}.<ref name='NewSci March'>{{cite news |last=Aron |first=Jacob |url=https://www.newscientist.com/article/2079697-exomars-probe-set-to-sniff-out-signs-of-life-on-the-red-planet/ |title=ExoMars probe set to sniff out signs of life on the Red Planet |work=New Scientist |date=7 March 2016 |accessdate=7 March 2016}}</ref> ''Schiaparelli'' transmitted about 600 megabytes of telemetry during its landing attempt,<ref name="Selding2">{{cite news |url=http://spacenews.com/europes-exomars-successfully-inserted-into-mars-orbit-but-lander-may-be-lost/ |title=Europe's ExoMars enters Mars orbit, but lander feared lost |work=SpaceNews |first=Peter B. |last=de Selding |date=20 October 2016 |accessdate=21 October 2016}}</ref> before it impacted the surface at {{convert|540|km/h|mph|abbr=on}}.<ref name="guardian20161124">{{cite news |url=https://www.theguardian.com/science/2016/nov/24/mars-lander-smashed-into-ground-at-540kmh-after-misjudging-its-altitude |title=Mars lander smashed into ground at 540km/h after misjudging its altitude |work=The Guardian |agency=Agence France-Presse |date=24 November 2016 |accessdate=1 January 2017}}</ref>

The TGO was injected into Mars orbit on 19 October 2016 and underwent 11 months of [[Astronomy:Aerobraking|aerobraking]] (March 2017 to February 2018), reducing its orbital speed by {{convert|3600|km/h|mph|abbr=on}} and its orbit from an initial {{convert|98000|by|200|km|mi|abbr=on}} down to {{convert|1050|by|200|km|mi|abbr=on}}. Additional thruster firings through mid-April circularised the spacecraft's orbit to {{convert|400|km|mi|abbr=on}}, and full science activities began on 21 April 2018.<ref name="space20180223">{{cite news |url=https://www.space.com/39796-methane-sniffing-mars-orbiter-aerobraking-dives.html |title=Methane-Sniffing Orbiter Finishes 'Aerobraking' Dives Through Mars' Atmosphere |work=Space.com |first=Mike |last=Wall |date=23 February 2018 |accessdate=24 February 2018}}</ref><ref>{{cite conference |title=ExoMars Trace Gas Orbiter provides atmospheric data during Aerobraking into its final orbit |conference=49th Annual Division for Planetary Sciences Meeting. 15–20 October 2017. Provo, Utah. |first1=Hakan |last1=Svedhem |first2=Jorge L. |last2=Vago |first3=Sean |last3=Bruinsma |first4=Ingo |last4=Müller-Wodarg |display-authors=0 |date=2017 |bibcode=2017DPS....4941801S |id=418.01}}</ref>

== Specifications ==
[[File:ExoMars TGO size vs Mars Express.svg|thumb|right|Size of the Trace Gas Orbiter (left) with the ''Schiaparelli'' EDM attached, compared to ''Mars Express'' (right) and an average human]]
;Dimensions : The central [[Engineering:Satellite bus|bus]] is {{convert|3.2|×|2|×|2|m|ft|abbr=on}}<ref name="trace-gas-orbiter" />
;Propulsion : {{convert|424|N|lbf|lk=on|abbr=on}} [[Engineering:Liquid-propellant rocket|bi-propellant]] main engine, used for Mars orbit insertion and manoeuvres<ref name="trace-gas-orbiter" />
;Power : {{convert|20|m2|sqft|abbr=on}} solar arrays spanning {{convert|17.5|m|ft|0|abbr=on}} tip-to-tip, and capable of rotating in one axis;<ref name="tgosfk">{{Cite web |url=https://naif.jpl.nasa.gov/pub/naif/EXOMARS2016/kernels/fk/em16_tgo_v08.tf |title=Trace Gas Orbiter (TGO) Spacecraft Frames Kernel |date=2016-09-26 |access-date=2018-10-06}}</ref> generates about 2,000 [[Watt|W]] of power at Mars<ref name="trace-gas-orbiter" />
;Batteries : 2 modules of [[Engineering:Lithium-ion battery|lithium-ion batteries]] with approximately 5100 watt hours total capacity to provide power during eclipses over the prime mission<ref name="trace-gas-orbiter" />
;Communication : {{convert|2.2|m|ftin|abbr=on}} [[Physics:X band|X band]] high-gain antenna with a two-axis pointing mechanism and 65 [[Watt|W]] [[Engineering:Radio frequency|RF]] [[Engineering:Traveling-wave tube|travelling-wave tube amplifier]] to communicate with Earth<ref name="trace-gas-orbiter" />
: Two [[Engineering:Electra (radio)|Electra]] [[Physics:Ultra high frequency|UHF band]] [[Transceiver|transceiver]]s with a single [[Engineering:Helical antenna|helical antenna]] to communicate with spacecraft at Mars<ref name="trace-gas-orbiter" />
;Thermal control : Spacecraft [[Physics:Aircraft principal axes#Normal axis (yaw)|yaw axis]] control to ensure the three faces containing the science payload remain cold
;Mass : {{convert|3755|kg|lb|abbr=on}}, wet mass of the orbiter<ref name="trace-gas-orbiter" />
: {{convert|4332|kg|lb|abbr=on}}, wet mass of the orbiter plus ''Schiaparelli'' lander<ref name="trace-gas-orbiter" />
;Payload : {{convert|113.8|kg|lb|abbr=on}} of science instruments<ref name="trace-gas-orbiter" />

== Science ==
[[File:Maquette Exomars Orbiter Salon du Bourget 2015 DSC 0045.jpg|thumb|Scale model of the ''ExoMars Trace Gas Orbiter'' displayed during the Paris Air Show, 2015]]

The TGO separated from the ExoMars [[Engineering:Schiaparelli EDM lander|''Schiaparelli'']] demonstration lander and would have provided it with telecommunication relay for 8 [[Astronomy:Timekeeping on Mars#Sol|Martian solar days (sols)]] after landing. Then the TGO gradually underwent [[Astronomy:Aerobraking|aerobraking]] for seven months into a more circular orbit for science observations and will provide [[Astronomy:Communications satellite|communications relay]] for the [[Engineering:Rosalind Franklin (rover)|''Rosalind Franklin'' rover]] to be launched in 2020, and will continue serving as a relay satellite for future landed missions.<ref name="june2011" />

The FREND instrument is currently mapping hydrogen levels to a maximum depth of {{convert|1|m|ftin|abbr=on}} beneath the Martian surface.<ref name="Grayzeck">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2016-017A |title=ExoMars 2016 |work=[[Astronomy:National Space Science Data Center|National Space Science Data Center]] |publisher=NASA |accessdate=15 March 2016}}</ref><ref name="Gannon2016">{{cite news |last=Gannon |first=Megan |url=http://www.space.com/32250-exomars-mars-mission-science.html?adbid=10153371993821466&adbpl=fb&adbpr=17610706465 |title=The Science of ExoMars: New Mission to Hunt for Mars Life |work=Space.com |date=14 March 2016 |accessdate=16 March 2016}}</ref> Locations where hydrogen is found may indicate [[Astronomy:Water on Mars|water-ice deposits]], which could be useful for future crewed missions.

Particularly, the mission is in the process of characterising spatial, temporal variation, and localisation of sources for a broad list of [[Astronomy:Atmosphere of Mars|atmospheric trace gases]]. If [[Astronomy:Methane on Mars|methane]] ({{chem2|CH4}}) is found in the presence of [[Chemistry:Propane|propane]] ({{chem2|C3H8}}) or [[Chemistry:Ethane|ethane]] ({{chem2|C2H6}}), that would be a strong indication that biological processes are involved.<ref name="ExoMars ACS">{{cite web |url=http://www.planetary-department-iki.ru/projects/future/acs/ACS_meeting/presentations/montmessin_Presentation1.pdf |title=Atmospheric Chemistry Suite: Science Overview |last=Montmessin |first=F. |work=LATMOS CNRS, France |accessdate=14 March 2016 |quote=Determining the origin of methane on Mars can only be addressed by looking at methane isotopologues and at higher alkanes (ethane, propane). |page=44}}</ref> However, if methane is found in the presence of gases such as [[Chemistry:Sulfur dioxide|sulfur dioxide]] ({{chem2|SO2}}), that would be an indication that the methane is a byproduct of geological processes.<ref name="McKie 2016">{{cite news |last=McKie |first=Robin |url=https://www.theguardian.com/science/2016/feb/21/exomars-probe-life-mars-sniff-out-methane-rover |title='Giant nose in the sky' ready for lift-off in mission to sniff out traces of life on Mars |work=The Guardian |date=20 February 2016 |accessdate=21 February 2016}}</ref>

;Detection:
[[File:Martian Methane Map.jpg|thumb|Visualisation of a methane plume found in Mars' atmosphere during the northern summer season]]
The nature of the [[Astronomy:Methane on Mars|methane source]] requires measurements of a suite of trace gases in order to characterise potential biochemical and geochemical processes at work. The orbiter has very high sensitivity to (at least) the following molecules and their [[Physics:Isotopomers|isotopomers]]:
[[Chemistry:Water|water]] ({{chem2|H2O}}), [[Chemistry:Hydroperoxyl|hydroperoxyl]] ({{chem2|HO2}}), [[Chemistry:Nitrogen dioxide|nitrogen dioxide]] ({{chem2|NO2}}), [[Chemistry:Nitrous oxide|nitrous oxide]] ({{chem2|N2O}}), [[Chemistry:Methane|methane]] ({{chem2|CH4}}), [[Chemistry:Acetylene|acetylene]] ({{chem2|C2H2}}), [[Chemistry:Ethylene|ethylene]] ({{chem2|C2H4}}), [[Chemistry:Ethane|ethane]] ({{chem2|C2H6}}), [[Physics:Formaldehyde|formaldehyde]] ({{chem2|H2CO}}), [[Chemistry:Hydrogen cyanide|hydrogen cyanide]] ({{chem2|HCN}}), [[Chemistry:Hydrogen sulfide|hydrogen sulfide]] ({{chem2|H2S}}), [[Chemistry:Carbonyl sulfide|carbonyl sulfide]] ({{chem2|OCS}}), [[Chemistry:Sulfur dioxide|sulfur dioxide]] ({{chem2|SO2}}), [[Chemistry:Hydrogen chloride|hydrogen chloride]] ({{chem2|HCl}}), [[Chemistry:Carbon monoxide|carbon monoxide]] ({{chem2|CO}}) and [[Chemistry:Ozone|ozone]] ({{chem2|O3}}). Detection sensitivities are at levels of 100 parts per trillion, improved to 10 parts per trillion or better by averaging spectra which could be taken at several spectra per second.<ref name="nomad2011">{{cite web |last=Vandaele |first=A. C. |title=NOMAD, a spectrometer suite for nadir and solar occultation observations on the ExoMars Trace Gas Orbiter |publisher=Institut des NanoSciences de Paris |url=http://www-mars.lmd.jussieu.fr/paris2011/abstracts/vandaele_paris2011.pdf |accessdate=4 September 2015 |display-authors=0}}</ref>
;Characterisation:
*Spatial and temporal variability: latitude–longitude coverage multiple times in a Mars year to determine regional sources and seasonal variations (reported to be large, but still controversial with present understanding of Mars gas-phase photochemistry)
*Correlation of concentration observations with environmental parameters of temperature, dust and ice aerosols (potential sites for heterogeneous chemistry)<ref name="trace-gas-orbiter" />
;Localisation:
*Mapping of multiple tracers (e.g., [[Chemistry:Aerosol|aerosol]]s, water vapour, [[Chemistry:Carbon monoxide|CO]], [[Chemistry:Methane|{{chem2|CH4}}]]) with different photochemical lifetimes and correlations helps constrain model simulations and points to source/sink regions
*To achieve the spatial resolution required to localise sources might require tracing molecules at parts-per-billion concentrations

=== Payload ===
[[File:CaSSIS.jpg|thumb|Colour and Stereo Surface Imaging System]]
Like the ''[[Astronomy:Mars Reconnaissance Orbiter|Mars Reconnaissance Orbiter]]'', the Trace Gas Orbiter is a hybrid science and telecom orbiter.<ref name="Vago">{{cite news |url=http://esamultimedia.esa.int/multimedia/publications/ESA-Bulletin-155/offline/download.pdf |title=ExoMars, ESA's next step in Mars exploration |work=ESA Bulletin |first=J. |last=Vago |display-authors=0 |issue=155 |date=August 2013 |pages=12–23}}</ref> Its scientific payload mass is about {{convert|113.8|kg|lb|abbr=on}} and consists of:<ref name="trace-gas-orbiter" /><ref name="paylod2014">{{cite web |url=http://exploration.esa.int/mars/48523-trace-gas-orbiter-instruments/ |title=ExoMars Trace Gas Orbiter Instruments |accessdate=8 March 2014 |date=20 February 2014 |work=ESA |archive-url=https://web.archive.org/web/20160219211336/http://exploration.esa.int/mars/48523-trace-gas-orbiter-instruments/ |archive-date=19 February 2016 |url-status=dead }}</ref>

* The [[Engineering:Nadir and Occultation for Mars Discovery|Nadir and Occultation for Mars Discovery]] ('''NOMAD''') has two [[Physics:Infrared|infrared]] and one [[Physics:Ultraviolet|ultraviolet]] [[Physics:Spectrometer|spectrometer]] channels.<ref>{{cite journal |url=http://www-mars.lmd.jussieu.fr/granada2017/abstracts/thomas_granada2017.pdf |title=The NOMAD Spectrometer Suite on the ExoMars 2016 Orbiter: Current Status |journal=The Sixth International Workshop on the Mars Atmosphere: Modelling and Observation. 17–20 January 2017. Granada, Spain. |first1=I. R. |last1=Thomas |first2=A. C. |last2=Vandaele |first3=E. |last3=Neefs |first4=B. |last4=Ristic |first5=L. |last5=Hetey |first6=A. |last6=Mahieux |first7=S. |last7=Robert |first8=F. |last8=Daerden |first9=C. |last9=Depiesse |first10=J. P. |last10=Mason |first11=M. R. |last11=Patel |first12=J. J. |last12=Lopez Moreno |first13=G. |last13=Bellucci |display-authors=3 |date=2017 |pages=4401 |bibcode=2017mamo.conf.4401T}}</ref>  Developed by Belgium.
* The [[Engineering:Atmospheric Chemistry Suite|Atmospheric Chemistry Suite]] ('''ACS''') has three infrared spectrometer channels.<ref name="ACS">{{cite news |url=http://www.spacedaily.com/reports/Europe_to_invest_12_bln_euros_in_a_new_space_Odyssey_999.html |title=Europe to invest 12 bln euros in a new space Odyssey |first=Olga |last=Zakutnyaya |website=Space Daily |date=25 November 2012}}</ref><ref name="ria2014">{{cite news |url=http://en.ria.ru/russia/20140804/191710468/Russia-to-Construct-Landing-Pad-for-Russian-European.html |title=Russia to Construct Landing Pad for Russian-European "ExoMars-2018" Space Mission |work=RIA Novosti |location=Russia |date=4 August 2014 |accessdate=5 August 2014}}</ref> Developed by Russia.

:NOMAD and ACS are providing the most extensive spectral coverage of Martian atmospheric processes so far.<ref name="Vago" /><ref name="onTrack">{{cite news |first=Jonathan |last=Amos |title=Europe |date=18 June 2013 |url=https://www.bbc.co.uk/news/science-environment-22914025 |website=BBC News |accessdate=18 June 2013}}</ref> Twice per orbit, at local sunrise and sunset, they are able to observe the Sun as it shines through the atmosphere. Detection of atmospheric trace species at the parts-per-billion (ppb) level are possible.

*The Colour and Stereo Surface Imaging System ('''CaSSIS''') is a high-resolution, {{convert|4.5|m|ft|0|abbr=on|disp=x| per pixel (|/pixel)}}, colour stereo camera for building accurate digital elevation models of the Martian surface. It will also be an important tool for characterising candidate landing site locations for future missions. Developed by Switzerland.
*The [[Engineering:Fine-Resolution Epithermal Neutron Detector|Fine-Resolution Epithermal Neutron Detector]] ('''FREND''') is a neutron detector that can provide information on the presence of [[Chemistry:Hydrogen|hydrogen]], in the form of water or hydrated minerals, in the top {{convert|1|m|ftin|abbr=on}} of the Martian surface.<ref name="ria2014"/> Developed by Russia.

=== Relay telecommunications ===
[[File:Pia17952 electra transceiver dsc09326 0.jpg|thumb|An [[Engineering:Electra (radio)|Electra radio]], in this case the one for the ''MAVEN'' probe. Electra radios were also deployed on the ''Trace Gas Orbiter'' and on other Mars telecommunications assets.]]
Due to the challenges of entry, descent and landing, Mars landers are highly constrained in mass, volume and power. For landed missions, this places severe constraints on antenna size and transmission power, which in turn greatly reduce direct-to-Earth communication capability in comparison to orbital spacecraft. As an example, the capability downlinks on ''[[Engineering:Spirit (rover)|Spirit]]'' and ''[[Engineering:Opportunity (rover)|Opportunity]]'' rovers had only {{frac|1|600}} the capability of the ''[[Astronomy:Mars Reconnaissance Orbiter|Mars Reconnaissance Orbiter]]'' downlink. Relay communication addresses this problem by allowing Mars surface spacecraft to communicate using higher data rates over short-range links to nearby Mars orbiters, while the orbiter takes on the task of communicating over the long-distance link back to Earth. This relay strategy offers a variety of key benefits to Mars landers: increased data return volume, reduced energy requirements, reduced communications system mass, increased communications opportunities, robust critical event communications and ''in situ'' navigation aid.<ref>{{cite journal |url=https://mepag.jpl.nasa.gov/reports/decadal/CharlesDEdwards.pdf |title=Relay Orbiters for Enhancing and Enabling Mars ''In Situ'' Exploration |publisher=Mars Exploration Program Analysis Group |first1=Charles D. |last1=Edwards, Jr. |first2=William B. |last2=Banerdt |first3=David W. |last3=Beaty |first4=Leslie K. |last4=Tamppari |first5=Richard W. |last5=Zurek |date=15 September 2009}}</ref> NASA provided an [[Engineering:Electra (radio)|Electra telecommunications relay]] and navigation instrument to assure communications between probes and rovers on the surface of Mars and controllers on Earth.<ref>{{cite news |first=Peter B. |last=De Selding |title=U.S., Europe Won't Go It Alone in Mars Exploration |date=26 September 2012 |url=http://spacenews.com/us-europe-wont-go-it-alone-mars-exploration/ |website=Space News |accessdate=27 September 2012}}</ref> The TGO will provide the 2020 ''Rosalind Franklin'' rover with telecommunications relay; it will also serve as a relay satellite for future landed missions.<ref name="june2011" />

===Results===
[[File:Layered_deposits_at_the_south_pole_of_Mars_ESA394865.jpg|thumb|photo of South pole]]

The spacecraft took its first photos of the surface of Mars on 15 April 2018.<ref name="esa20180426">{{cite web |url=https://www.esa.int/Our_Activities/Space_Science/ExoMars/ExoMars_returns_first_images_from_new_orbit |title=ExoMars returns first images from new orbit |publisher=European Space Agency |first1=Nicolas |last1=Thomas |first2=Håkan |last2=Svedhem |first3=Markus |last3=Bauer |display-authors=1 |date=26 April 2018 |accessdate=18 June 2018}}</ref> In April 2019, the science team reported their first methane results: TGO had detected no methane whatsoever, even though their data were more sensitive than the methane concentrations found using ''[[Engineering:Curiosity (rover)|Curiosity]]'', ''[[Astronomy:Mars Express|Mars Express]]'', and ground-based observations.<ref>{{cite journal|doi=10.1038/s41586-019-1096-4|title=No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations|year=2019|last1=Korablev|first1=Oleg|last2=Vandaele|first2=Ann Carine|last3=Montmessin|first3=Franck|last4=Fedorova|first4=Anna A.|last5=Trokhimovskiy|first5=Alexander|last6=Forget|first6=François|last7=Lefèvre|first7=Franck|last8=Daerden|first8=Frank|last9=Thomas|first9=Ian .|last10=Trompet|first10=Loïc|last11=Erwin|first11=Justin T.|last12=Aoki|first12=Shohei|last13=Robert|first13=Séverine|last14=Neary|first14=Lori|last15=Viscardy|first15=Sébastien|last16=Grigoriev|first16=Alexey .|last17=Ignatiev|first17=Nikolay I.|last18=Shakun|first18=Alexey|last19=Patrakeev|first19=Andrey|last20=Belyaev|first20=Denis A.|last21=Bertaux|first21=Jean-Loup|last22=Olsen|first22=Kevin S.|last23=Baggio|first23=Lucio|last24=Alday|first24=Juan|last25=Ivanov|first25=Yuriy S.|last26=Ristic|first26=Bojan|last27=Mason|first27=Jon|last28=Willame|first28=Yannick|last29=Depiesse|first29=Cédric|last30=Hetey|first30=Laszlo|displayauthors=1|journal=Nature|pmid=30971829|volume=568|issue=7753|pages=517–520|url=http://oro.open.ac.uk/60547/2/2019%20Korablev%20TGO%20methane%20Nature_accepted.pdf|bibcode=2019Natur.568..517K}}</ref>

== See also ==
{{div col|colwidth=30em}}
* {{annotated link|Engineering:Curiosity (rover)}}
* {{annotated link|Astronomy:List of missions to Mars}}
* {{annotated link|Astronomy:Mars 2020}}
* {{annotated link|Astronomy:Mars Exploration Joint Initiative}}
* {{annotated link|Astronomy:Mars Express}}
* {{annotated link|Astronomy:Mars Global Surveyor}}
* {{annotated link|Astronomy:Mars Orbiter Mission}}
* {{annotated link|Astronomy:MAVEN}}
{{div col end}}

== References ==
{{reflist|colwidth=30em}}

== External links ==
* [http://exploration.esa.int/jump.cfm?oid=46475 ExoMars Trace Gas Orbiter] at ESA.int
* [https://www.flickr.com/photos/europeanspaceagency/albums/72157651339630276 ESA ExoMars] on Flickr

{{Exomars}}
{{European Space Agency}}
{{Russian space program}}
{{Astrobiology}}
{{Mars spacecraft}}
{{Solar System probes}}
{{2016 in space}}


[[Category:European Space Agency space probes]]
[[Category:Russian space probes]]
[[Category:Artificial satellites orbiting Mars]]
[[Category:Attached spacecraft]]

{{Sourceattribution|Trace Gas Orbiter|1}}