View source for Engineering:Atmospheric Chemistry Suite

{{Infobox spacecraft instrument
| Name = Atmospheric Chemistry Suite
| Image =
| Caption =

| Operator = [[Organization:European Space Agency|European Space Agency]]
| Manufacturer = Russia & France
| Type = [[Physics:Infrared spectroscopy|Fourier infrared spectrometer]]
| Function = Atmospheric chemical analysis
| Mission_Duration = 7 years (planned)
| Began = 19 October 2016 
| Ceased = <!--date operations ceased (single instruments only)-->
| Webpage =

| Mass = 
| Dimensions =
| Number = <!--number launched-->
| Power_consumption = 
| Resolution = 
| Spectral_Band = [[Physics:Infrared|Infrared]]
| Data_Rate =

| Spacecraft = [[Astronomy:ExoMars Trace Gas Orbiter|ExoMars Trace Gas Orbiter]] <!--spacecraft it is hosted aboard-->
| SC_Operator = [[Company:Roscosmos|Roscosmos]]
| Launch = {{start-date|14 March 2016, 09:31}}&nbsp;[[UTC]]
| Rocket = [[Engineering:Proton-M|Proton-M]]/Briz-M
| Launch_Site = Baikonur 200/39
| COSPAR = 2016-017A
| Orbit = [[Astronomy:Mars|Mars]]
}}

The '''Atmospheric Chemistry Suite''' ('''ACS''') is a science payload consisting of three [[Physics:Infrared spectroscopy|infrared spectrometer]] channels aboard the [[Astronomy:ExoMars Trace Gas Orbiter|ExoMars Trace Gas Orbiter]] (TGO) orbiting Mars since October 2016.<ref name='Korablev 2014'>''Three infrared spectrometers, an atmospheric chemistry suite for the ExoMars 2016 Trace Gas Orbiter''. Korablev, O., et al., 2014. J. Appl. Remote Sensing. 8, 4983.</ref>  The three channels are: the near-infrared channel ([[Physics:Near-infrared spectroscopy|NIR]]), the mid-infrared channel (MIR), and the far infrared channel (FIR, also called TIRVIM).

The ACS was proposed in 2011 by Russian Academy Section and eventually accepted by the [[Organization:European Space Agency|European Space Agency]] (ESA) and [[Company:Roscosmos|Roscosmos]] as one of two Russian instruments onboard TGO.<ref name='Korablev 2016'>[http://www-mars.lmd.jussieu.fr/granada2017/abstracts/korablev_granada2017.pdf Science Investigations for the Atmospheric Chemistry Suite on ExoMars TGO]. (PDF) O. Korablev, N. I. Ignatiev, A. A. Fedorova, A. Yu. Trokhimovskiy, A. V. Grigoriev, A. V. Shakun, Space, F. Montmessin, F. Lefevre, F. Forget. ''Sixth International Workshop on the Mars Atmosphere: Modelling and Observations''. Granada, Spain 17–20 January 2017.</ref>  The instrument was funded by Roscosmos and Centre national d'études spatiales (CNES) of France, and has components of both Russia and France. Its development and fabrication was under Russian leadership. The functionality of all the three channels was confirmed during cruise to Mars.

==Objectives==

The main objective of the ACS suite is to make an inventory and map minor atmospheric species or trace gases in the [[Astronomy:Atmosphere of Mars|atmosphere of Mars]]. This will allow scientists to profile the upper limits on the [[Astronomy:Atmosphere of Mars#Methane|methane contents]], and to possibly to detect sulfur dioxide ([[Chemistry:Sulfur dioxide|{{chem|SO|2}}]]), a gas of volcanic origin.<ref name='Korablev 2016'/>

== Channels ==

The [[Physics:Near-infrared spectroscopy|near-infrared]] channel (NIR), is a compact spectrometer operating in the range of 0.7–1.7 μm
with a resolving power of λ/Δλ ~ 20,000 and with a spectral range of 10–20&nbsp;nm. It is designed to operate in [[Nadir|nadir]] and in  [[Astronomy:Occultation|solar occultation]] modes.<ref name='Korablev 2016'/>

The mid-infrared channel (MIR) is an [[Physics:Echelle grating|echelle]] spectrometer with crossed dispersion, designed exclusively
for solar occultation measurements in the 2.2–4.4 μm spectral range with a resolving power of approximately 50,000.<ref name='Korablev 2016'/>

The far-infrared channel covers the [[Physics:Thermal infrared spectroscopy|thermal infrared spectroscopy]]; it is a [[Physics:Planetary Fourier Spectrometer|Fourier spectrometer]] called the TIRVIM. It has an aperture of ~5&nbsp;cm and it measures the spectrum of 1.7–17 μm. Its main task will be for temperature sounding of the [[Astronomy:Atmosphere of Mars|Martian atmosphere]] in the 15-μm {{chem|CO|2}} band. TIRVIM has 10 times higher
performances than the PFS spectrometer of [[Astronomy:Mars Express|Mars Express]] orbiter.<ref name='Korablev 2016'/>
{| class="wikitable"
|-
!  style="width:100pt; text-align:left;"| Channel designation
!  style="width:100pt; text-align:center;"| Abbreviation
!  style="width:150pt; text-align:center;"| [[Wavelength]]
!  style="width:150pt; text-align:center;"| Trace gas detected<ref name='Korablev 2016'/>
|-
|align="left"| Near-Infrared
| style="text-align:center;"| NIR
| style="text-align:center;"| 0.7–1.7&nbsp;µm
| [[Astronomy:Water on Mars|{{chem|H|2|O}}]],  [[Chemistry:Oxygen|{{chem|O|2}}]],  [[Chemistry:Carbon dioxide|{{chem|CO|2}}]],  [[Chemistry:Superoxide|{{chem|O|2|-}}]] ,  [[Chemistry:Hydroxide|{{chem|OH|-}}]],  and [[Chemistry:Nitric oxide|{{chem|NO|-}}]]
|-
|align="left"| Mid-Infrared
| style="text-align:center;"| MIR
| style="text-align:center;"| 2.2–4.4&nbsp;µm
| [[Astronomy:Atmosphere of Mars#Methane|{{chem|CH|4}}]], {{chem|H|2|O}},  [[Chemistry:Hydroperoxyl|{{chem|H|O|2}}]], [[Chemistry:Semiheavy water|HDO]], [[Chemistry:Hydrofluoric acid|HF]], [[Chemistry:Hydrogen chloride|{{chem|H|Cl}}]], [[Chemistry:Carbon monoxide|CO]], [[Chemistry:Sulfur dioxide|{{chem|SO|2}}]], [[Chemistry:Carbon dioxide|{{chem|CO|2}}]] and their [[Physics:Isotope|isotope]]s, etc.      
|-
|align="left"| Far-Infrared<br>(Thermal-Infrared)
| style="text-align:center;"| FIR or TIRVIM 
| style="text-align:center;"| 1.7–17&nbsp;µm
| Temperature profiles, {{chem|CO|2}}, [[Chemistry:Hydrogen peroxide|{{chem|H|2|O|2}}]], dust, [[Astronomy:Water on Mars|water ice]].
|}

==Methane==

Of particular interest to this astrobiology mission, is the detection and characterization of the [[Astronomy:Atmosphere of Mars#Methane|atmospheric methane]] ({{chem|CH|4}}), as it may be of geological or biological nature. Large differences in the abundances were measured between observations taken in 2003, 2006, and in 2014 NASA reported that the ''Curiosity'' rover detected a tenfold increase ('spike') in methane in the atmosphere in late 2013 and early 2014.  This suggests that the methane was locally concentrated and is probably seasonal. Because methane on Mars would quickly break down due to ultraviolet radiation from the Sun and chemical reactions with other gases, its persistent presence in the atmosphere also implies the existence of an unknown source to continually replenish the gas.<ref name='Webster 2015'>{{cite journal |title=Mars methane detection and variability at Gale crater |journal=Science |date=23 January 2015 |last=Webster |first=Christopher R. |volume=347 |issue=6220 |pages=415–417 |doi=10.1126/science.1261713 |bibcode = 2015Sci...347..415W |pmid=25515120|s2cid=20304810 |url=https://authors.library.caltech.edu/52526/7/Webster.SM.pdf }}</ref>

Measuring the ratio of [[Chemistry:Hydrogen|hydrogen]] and [[Chemistry:Methane|methane]] levels on Mars may help determine the likelihood of [[Astronomy:Life on Mars|life on Mars]].<ref name="PNAS-20120607">{{cite journal |last1=Oze |first1=Christopher |last2=Jones |first2=Camille |last3=Goldsmith |first3=Jonas I. |last4=Rosenbauer |first4=Robert J. |title=Differentiating biotic from abiotic methane genesis in hydrothermally active planetary surfaces |date=7 June 2012 |journal=PNAS |volume=109| issue =  25 |pages=9750–9754 |doi=10.1073/pnas.1205223109 |bibcode = 2012PNAS..109.9750O |pmid=22679287 |pmc=3382529|doi-access=free }}</ref><ref name="Space-20120625">{{cite web|author=Staff |title=Mars Life Could Leave Traces in Red Planet's Air: Study |url=http://www.space.com/16284-mars-life-atmosphere-hydrogen-methane.html |date=25 June 2012 |publisher=Space.com |access-date=27 June 2012 }}</ref> According to the scientists, "...low H<sub>2</sub>/CH<sub>4</sub> ratios (less than approximately 40) indicate that life is likely present and active."<ref name="PNAS-20120607" />

==References==
{{reflist}}

{{Mars}}
{{ExoMars}}
{{Astrobiology}}
{{Satellite and spacecraft instruments}}

[[Category:Astrobiology]]
[[Category:Spacecraft instruments]]
[[Category:Geophysical imaging]]
[[Category:Spectrometers]]

{{Sourceattribution|Atmospheric Chemistry Suite}}