This article needs to be updated.March 2020)(
The ExoMars Trace Gas Orbiter (TGO or ExoMars Orbiter) is a collaborative project between the European Space Agency (ESA) and the Russian Roscosmos agency that sent an atmospheric research orbiter and the Schiaparelli demonstration lander to Mars in 2016 as part of the European-led ExoMars programme.
The Trace Gas Orbiter delivered the Schiaparelli lander on 16 October 2016, which crashed on the surface due to a premature release of the parachute.
The orbiter began aerobraking in March 2017 to lower its initial orbit of 200 by 98,000 km (120 by 60,890 mi). Aerobraking concluded on 20 February 2018 when a final thruster firing resulted in an orbit of 200 by 1,050 km (120 by 650 mi). Additional thruster firings every few days raised the orbiter to a circular "science" orbit of 400 km (250 mi), which was achieved on 9 April 2018.
A key goal is to gain a better understanding of methane (CH
4) and other trace gases present in the Martian atmosphere that could be evidence for possible biological activity. The programme will follow with the Kazachok lander and the Rosalind Franklin rover in 2020, which will search for biomolecules and biosignatures; the TGO will operate as the communication link for the ExoMars lander and rover and provide communication for other Mars surface probes with Earth.
Investigations with space and Earth-based observatories have demonstrated the presence of a small amount of methane on the atmosphere of Mars that seems to vary with location and time. This may indicate the presence of microbial life on Mars, or a geochemical process such as volcanism or hydrothermal activity.
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, as well as its decomposition products such as formaldehyde and methanol.
ExoMars Trace Gas Orbiter was born out of the nexus of ESA's Aurora programme ExoMars flagship and NASA's 2013 and 2016 Mars Science Orbiter (MSO) concepts. 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. 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.
Attempted collaboration with NASA
NASA's Mars Science Orbiter (MSO) was originally envisioned in 2008 as an all-NASA endeavour aiming for a late 2013 launch. NASA and ESA officials agreed to pool resources and technical expertise and collaborate to launch only one orbiter. The agreement, called the Mars Exploration Joint Initiative, was signed on July 2009 and proposed to use an Atlas rocket launcher instead of a 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. 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 Atlas V launches: 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.
Under the FY2013 budget President 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 James Webb Space Telescope. With NASA's funding for this project cancelled, most of ExoMars' plans had to be restructured.
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 Roscosmos, which planned to contribute two heavy-lift Proton launch vehicles and an additional entry, descent and landing system to the 2020 rover mission.
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 2.4 m (7 ft 10 in) diameter stationary lander built by ESA named Schiaparelli, and the Rosalind Franklin rover mission in 2020. Both missions are using a Proton-M rocket.
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. The launch occurred at 09:31 UTC on 14 March 2016. Four rocket burns occurred in the following 10 hours before the descent module and orbiter were released. A signal from the spacecraft was received at 21:29 UTC that day, confirming that the launch was successful and the spacecraft were functioning properly.
Shortly after separation from the probes, a Brazilian ground telescope recorded small objects in the vicinity of the Briz-M upper booster stage, suggesting that the Briz-M stage exploded a few kilometres away, without damaging the orbiter or lander. Briefing reporters in Moscow, the head of Roscosmos denied any anomaly and made all launch data available for inspection.
The Schiaparelli lander separated from the TGO orbiter on 16 October 2016, three days before it arrived on Mars, and entered the atmosphere at 21,000 km/h (13,000 mph; 5.8 km/s). Schiaparelli transmitted about 600 megabytes of telemetry during its landing attempt, before it impacted the surface at 540 km/h (340 mph).
The TGO was injected into Mars orbit on 19 October 2016 and underwent 11 months of aerobraking (March 2017 to February 2018), reducing its orbital speed by 3,600 km/h (2,200 mph) and its orbit from an initial 98,000 by 200 km (60,890 by 120 mi) down to 1,050 by 200 km (650 by 120 mi). Additional thruster firings through mid-April circularised the spacecraft's orbit to 400 km (250 mi), and full science activities began on 21 April 2018.
- The central bus is 3.2 m × 2 m × 2 m (10.5 ft × 6.6 ft × 6.6 ft)
- 424 N (95 lbf) bi-propellant main engine, used for Mars orbit insertion and manoeuvres
- 20 m2 (220 sq ft) solar arrays spanning 17.5 m (57 ft) tip-to-tip, and capable of rotating in one axis; generates about 2,000 W of power at Mars
- 2 modules of lithium-ion batteries with approximately 5100 watt hours total capacity to provide power during eclipses over the prime mission
- 2.2 m (7 ft 3 in) X band high-gain antenna with a two-axis pointing mechanism and 65 W RF travelling-wave tube amplifier to communicate with Earth
- Two Electra UHF band transceivers with a single helical antenna to communicate with spacecraft at Mars
- Thermal control
- Spacecraft yaw axis control to ensure the three faces containing the science payload remain cold
- 3,755 kg (8,278 lb), wet mass of the orbiter
- 4,332 kg (9,550 lb), wet mass of the orbiter plus Schiaparelli lander
- 113.8 kg (251 lb) of science instruments
The TGO separated from the ExoMars Schiaparelli demonstration lander and would have provided it with telecommunication relay for 8 Martian solar days (sols) after landing. Then the TGO gradually underwent aerobraking for seven months into a more circular orbit for science observations and will provide communications relay for the Rosalind Franklin rover to be launched in 2022, and will continue serving as a relay satellite for future landed missions.
The FREND instrument is currently mapping hydrogen levels to a maximum depth of 1 m (3 ft 3 in) beneath the Martian surface. Locations where hydrogen is found may indicate 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 atmospheric trace gases. If methane (CH
4) is found in the presence of propane (C
8) or ethane (C
6), that would be a strong indication that biological processes are involved. However, if methane is found in the presence of gases such as sulfur dioxide (SO
2), that would be an indication that the methane is a byproduct of geological processes.
The nature of the 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 isotopomers:
2O), hydroperoxyl (HO
2), nitrogen dioxide (NO
2), nitrous oxide (N
2O), methane (CH
4), acetylene (C
2), ethylene (C
4), ethane (C
6), formaldehyde (H
2CO), hydrogen cyanide (HCN), hydrogen sulfide (H
2S), carbonyl sulfide (OCS), sulfur dioxide (SO
2), hydrogen chloride (HCl), carbon monoxide (CO) and ozone (O
3). 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.
- 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)
- Mapping of multiple tracers (e.g., aerosols, water vapour, CO, CH
4) 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
- The Nadir and Occultation for Mars Discovery (NOMAD) has two infrared and one ultraviolet spectrometer channels. Developed by Belgium.
- The Atmospheric Chemistry Suite (ACS) has three infrared spectrometer channels. Developed by Russia.
- NOMAD and ACS are providing the most extensive spectral coverage of Martian atmospheric processes so far. 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, 4.5 m per pixel (15 ft/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 Fine-Resolution Epithermal Neutron Detector (FREND) is a neutron detector that can provide information on the presence of hydrogen, in the form of water or hydrated minerals, in the top 1 m (3 ft 3 in) of the Martian surface. Developed by Russia.
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 Spirit and Opportunity rovers had only 1⁄600 the capability of the 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. NASA provided an Electra telecommunications relay and navigation instrument to assure communications between probes and rovers on the surface of Mars and controllers on Earth. The TGO will provide the 2020 Rosalind Franklin rover with telecommunications relay; it will also serve as a relay satellite for future landed missions.
The spacecraft took its first photos of the surface of Mars on 15 April 2018. The first year of science operations yielded a wealth of new data and scientific discoveries, including: new observations of the atmospheric composition and structure, water-ice cloud enhancement during a global dust storm, new measurements of the atmospheric thermal structure and density, estimations of the timespan of the climate record of the south polar ice sheet, confirmation of dry-processes being responsible for Recurring Slope Lineae in Gale crater, and high-resolution maps of shallow subsurface Hydrogen, increasing the known amounts of probably near-surface buried water ice.
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 Curiosity, Mars Express, and ground-based observations.
- Curiosity (rover) – NASA robotic rover exploring the crater Gale on Mars
- List of missions to Mars – Wikipedia list article
- Mars 2020 – 2020 astrobiology Mars rover mission by NASA
- Mars Exploration Joint Initiative
- Mars Express – European Mars orbiter
- Mars Global Surveyor – A NASA Mars orbiter
- Mars Orbiter Mission – Indian Mars orbiter, launched in 2013
- MAVEN – Mars orbiter
- "ExoMars Trace Gas Orbiter and Schiaparelli Mission (2016)". European Space Agency. 16 October 2016. Retrieved 24 October 2016.
- Allen, Mark A.; Witasse, Olivier (2011). 2016 ESA/NASA ExoMARS/Trace Gas Orbiter. Mars Exploration Program Assessment Group. 15–16 June 2011. Lisbon, Portugal. hdl:2014/42148.
- "ExoMars Trace Gas Orbiter (TGO)". European Space Agency. 12 July 2012. Retrieved 8 March 2014.
- Amos, Jonathan (14 March 2016). "Mars methane mission lifts off". BBC. Retrieved 14 March 2016.
- Nowakowski, Tomasz (20 October 2016). "Lost on Mars: Schiaparelli lander falls silent shortly before touchdown". Spaceflight Insider. Retrieved 24 October 2016.
- Chang, Kenneth (19 October 2016). "ExoMars Mission to Join Crowd of Spacecraft at Mars". The New York Times. Retrieved 19 October 2016.
- Vago, J. L. (10 September 2009), "Mars Panel Meeting" (PDF), Planetary Science Decadal Survey, Arizona State University, Tempe (US): European Space Agency
- Mustard, Jack (9 July 2009). "MEPAG Report to the Planetary Science Subcommittee" (PDF). Mars Exploration Program Analysis Group. p. 3.
- Amos, Jonathan (19 October 2016). "Fears grow for European Schiaparelli Mars lander". BBC News. Retrieved 20 October 2016.
- "Surfing complete". European Space Agency. 21 February 2018. Archived from the original on 22 February 2018. Retrieved 1 May 2018.
- Mitschdoerfer, Pia; et al. (9 April 2018). "ExoMars poised to start science mission". European Space Agency. Retrieved 18 June 2018.
- "Second ExoMars mission moves to next launch opportunity in 2020" (Press release). European Space Agency. 2 May 2016. Retrieved 2 May 2016.
- "Mars Trace Gas Mission". MEPAG. 10 September 2009. Archived from the original on 21 July 2011.
- Mumma, Michael J.; Villanueva, Gerónimo L.; Novak, Robert E.; Hewagama, Tilak; Bonev, Boncho P.; Disanti, Michael A.; Mandell, Avi M.; Smith, Michael D. (20 February 2009). "Strong Release of Methane on Mars in Northern Summer 2003" (PDF). Science. 323 (5917): 1041–1045. Bibcode:2009Sci...323.1041M. doi:10.1126/science.1165243. PMID 19150811. S2CID 25083438.
- Hand, Eric (21 October 2008). "Plumes of methane identified on Mars" (PDF). Nature News. Retrieved 2 August 2009.
- "Making Sense of Mars' Methane". Astrobio.net. June 2008.
- Steigerwald, Bill (15 January 2009). "Martian Methane Reveals the Red Planet is not a Dead Planet". NASA's Goddard Space Flight Center. NASA. Retrieved 24 January 2009.
- Howe, K. L.; Gavin, P.; Goodhart, T.; Kral, T. A. (2009). Methane Production by Methanogens in Perchlorate-Supplemented Media (PDF). 40th Lunar and Planetary Science Conference.
- Levin, Gilbert V.; Straat, Patricia Ann (3 September 2009). "Methane and life on Mars". Proc. SPIE. Proceedings of SPIE. 7441 (74410D): 74410D. Bibcode:2009SPIE.7441E..0DL. doi:10.1117/12.829183. S2CID 73595154.
- Rincon, Paul (9 July 2009). "Agencies outline Mars initiative". BBC News. Retrieved 26 July 2009.
- "NASA orbiter to hunt for source of Martian methane in 2016". Thaindian News. 6 March 2009. Retrieved 26 July 2009.
- Smith, Michael (10 September 2009). "Mars Trace Gas Mission: Science Rationale & Concept" (PDF). Presentation to the NRC Decadal Survey Mars Panel.
- Zurek, R.; Chicarro, A. (29 July 2009). "Report to MEPAG on the ESA-NASA Joint Instrument Definition Team (JIDT) for the Proposed 2016 Orbiter-Carrier" (PDF). NASA. Archived from the original (PDF) on 30 July 2009.
- "Brief ExoMars Project History". Spaceflight101.com. 2016. Retrieved 12 November 2016.
- Taverna, Michael A. (19 October 2009). "ESA Proposes Two ExoMars Missions". Aviation Week. Retrieved 30 October 2009.
- "NASA Could Take Role in European ExoMars Mission". Space News. 19 June 2009.
- Amos, Jonathan (12 October 2009). "Europe's Mars plans move forward". BBC News. Retrieved 12 October 2009.
- Kremr, Ken (1 February 2012). "Experts React to Obama Slash to NASA's Mars and Planetary Science Exploration". Universe Today. Retrieved 18 February 2012.
- Whewell, Megan (15 February 2012). "Have Europe's Martian exploration plans been derailed by America?". MSN News. Archived from the original on 11 May 2012. Retrieved 15 February 2012.
- Svitak, Amy (16 March 2012). "Europe Joins Russia on Robotic ExoMars". Aviation Week. Retrieved 16 March 2012.
- De Selding, Peter B. (15 March 2012). "ESA Ruling Council OKs ExoMars Funding". Space News. Retrieved 16 March 2012.
- "NASA drops ExoMars missions in 2013 budget". Optics. 15 February 2012. Retrieved 15 February 2012.
- "Spacewatch: Uncertainties for ExoMars". The Guardian. 16 March 2012.
- Amos, Jonathan (15 March 2012). "Europe still keen on Mars missions". BBC News. Retrieved 16 March 2012.
- "ExoMars". Russian Space Web. Retrieved 22 October 2013.
- "ExoMars 2016 Schiaparelli Module in Baikonur". ESA. SpaceRef. 6 January 2016. Retrieved 6 January 2016.
- Gibney, Elizabeth (11 March 2016). "Mars launch to test collaboration between Europe and Russia". Nature. 531 (7594): 288–299. Bibcode:2016Natur.531..288G. doi:10.1038/nature.2016.19547. PMID 26983519.
- "ExoMars on its way to solve the Red Planet's mysteries". ESA. 14 March 2016. Archived from the original on 26 October 2016. Retrieved 15 March 2016.
- King, Bob (24 March 2016). "ExoMars Mission Narrowly Avoids Exploding Booster". Universe Today. Retrieved 25 March 2016.
- de Selding, Peter B. (5 April 2016). "Roscosmos gives detailed rebuttal to reports of Proton ExoMars launch anomaly". Space News. Retrieved 5 April 2016.
- Malik, Tariq (16 October 2016). "European Mars Lander Separates From Mothership, Takes Aim at Red Planet". Space.com. Retrieved 16 October 2016.
- Aron, Jacob (7 March 2016). "ExoMars probe set to sniff out signs of life on the Red Planet". New Scientist. Retrieved 7 March 2016.
- de Selding, Peter B. (20 October 2016). "Europe's ExoMars enters Mars orbit, but lander feared lost". SpaceNews. Retrieved 21 October 2016.
- "Mars lander smashed into ground at 540km/h after misjudging its altitude". The Guardian. Agence France-Presse. 24 November 2016. Retrieved 1 January 2017.
- Wall, Mike (23 February 2018). "Methane-Sniffing Orbiter Finishes 'Aerobraking' Dives Through Mars' Atmosphere". Space.com. Retrieved 24 February 2018.
- Svedhem, Hakan; Vago, Jorge L.; Bruinsma, Sean; Müller-Wodarg, Ingo; et al. (2017). ExoMars Trace Gas Orbiter provides atmospheric data during Aerobraking into its final orbit. 49th Annual Division for Planetary Sciences Meeting. 15–20 October 2017. Provo, Utah. Bibcode:2017DPS....4941801S. 418.01.
- "Trace Gas Orbiter (TGO) Spacecraft Frames Kernel". 26 September 2016. Retrieved 6 October 2018.
- "ExoMars 2016". National Space Science Data Center. NASA. Retrieved 15 March 2016.
- Gannon, Megan (14 March 2016). "The Science of ExoMars: New Mission to Hunt for Mars Life". Space.com. Retrieved 16 March 2016.
- Montmessin, F. "Atmospheric Chemistry Suite: Science Overview" (PDF). LATMOS CNRS, France. p. 44. Retrieved 14 March 2016.
Determining the origin of methane on Mars can only be addressed by looking at methane isotopologues and at higher alkanes (ethane, propane).
- McKie, Robin (20 February 2016). "'Giant nose in the sky' ready for lift-off in mission to sniff out traces of life on Mars". The Guardian. Retrieved 21 February 2016.
- Vandaele, A. C.; et al. "NOMAD, a spectrometer suite for nadir and solar occultation observations on the ExoMars Trace Gas Orbiter" (PDF). Institut des NanoSciences de Paris. Retrieved 4 September 2015.
- Vago, J.; et al. (August 2013). "ExoMars, ESA's next step in Mars exploration" (PDF). ESA Bulletin (155). pp. 12–23.
- "ExoMars Trace Gas Orbiter Instruments". ESA. 20 February 2014. Archived from the original on 19 February 2016. Retrieved 8 March 2014.
- Thomas, I. R.; Vandaele, A. C.; Neefs, E.; et al. (2017). "The NOMAD Spectrometer Suite on the ExoMars 2016 Orbiter: Current Status" (PDF). The Sixth International Workshop on the Mars Atmosphere: Modelling and Observation. 17–20 January 2017. Granada, Spain.: 4401. Bibcode:2017mamo.conf.4401T.
- Zakutnyaya, Olga (25 November 2012). "Europe to invest 12 bln euros in a new space Odyssey". Space Daily.
- "Russia to Construct Landing Pad for Russian-European "ExoMars-2018" Space Mission". RIA Novosti. Russia. 4 August 2014. Retrieved 5 August 2014.
- Amos, Jonathan (18 June 2013). "Europe". BBC News. Retrieved 18 June 2013.
- Edwards, Jr., Charles D.; Banerdt, William B.; Beaty, David W.; Tamppari, Leslie K.; Zurek, Richard W. (15 September 2009). "Relay Orbiters for Enhancing and Enabling Mars In Situ Exploration" (PDF). Mars Exploration Program Analysis Group. Cite journal requires
- De Selding, Peter B. (26 September 2012). "U.S., Europe Won't Go It Alone in Mars Exploration". Space News. Retrieved 27 September 2012.
- Thomas, Nicolas; et al. (26 April 2018). "ExoMars returns first images from new orbit". European Space Agency. Retrieved 18 June 2018.
- Svedhem, H.; Vago, J. L.; Rodionov, D. (1 December 2019). "The ExoMars Trace Gas Orbiter - New Results and Future Plans". AGU Fall Meeting Abstracts. 23.
- Trokhimovskiy, A.; Perevalov, V.; Korablev, O.; Fedorova, A. A.; Olsen, K. S.; Bertaux, J.-L.; Patrakeev, A.; Shakun, A.; Montmessin, F.; Lefèvre, F.; Lukashevskaya, A. (1 July 2020). "First observation of the magnetic dipole CO2 absorption band at 3.3 μm in the atmosphere of Mars by the ExoMars Trace Gas Orbiter ACS instrument". Astronomy & Astrophysics. 639: A142. doi:10.1051/0004-6361/202038134. ISSN 0004-6361.
- Olsen, K. S.; Lefèvre, F.; Montmessin, F.; Fedorova, A. A.; Trokhimovskiy, A.; Baggio, L.; Korablev, O.; Alday, J.; Wilson, C. F.; Forget, F.; Belyaev, D. A. (18 January 2021). "The vertical structure of CO in the Martian atmosphere from the ExoMars Trace Gas Orbiter". Nature Geoscience: 1–5. doi:10.1038/s41561-020-00678-w. ISSN 1752-0908.
- Stcherbinine, A.; Vincendon, M.; Montmessin, F.; Wolff, M. J.; Korablev, O.; Fedorova, A.; Trokhimovskiy, A.; Patrakeev, A.; Lacombe, G.; Baggio, L.; Shakun, A. (2020). "Martian Water Ice Clouds During the 2018 Global Dust Storm as Observed by the ACS-MIR Channel Onboard the Trace Gas Orbiter". Journal of Geophysical Research: Planets. 125 (3): e2019JE006300. arXiv:1912.08018. doi:10.1029/2019JE006300. ISSN 2169-9100.
- Siddle, A. G.; Mueller-Wodarg, I. C. F.; Bruinsma, S.; Marty, J. -C. (23 October 2020). "Density structures in the martian lower thermosphere as inferred by Trace Gas Orbiter accelerometer measurements". Icarus: 114109. doi:10.1016/j.icarus.2020.114109. ISSN 0019-1035.
- Becerra, Patricio; Sori, Michael M.; Thomas, Nicolas; Pommerol, Antoine; Simioni, Emanuele; Sutton, Sarah S.; Tulyakov, Stepan; Cremonese, Gabriele (2019). "Timescales of the Climate Record in the South Polar Ice Cap of Mars". Geophysical Research Letters. 46 (13): 7268–7277. doi:10.1029/2019GL083588. hdl:10150/634664. ISSN 1944-8007.
- Munaretto, G.; Pajola, M.; Cremonese, G.; Re, C.; Lucchetti, A.; Simioni, E.; McEwen, A. S.; Pommerol, A.; Becerra, P.; Conway, S. J.; Thomas, N. (1 August 2020). "Implications for the origin and evolution of Martian Recurring Slope Lineae at Hale crater from CaSSIS observations". Planetary and Space Science. 187: 104947. doi:10.1016/j.pss.2020.104947. ISSN 0032-0633.
- Malakhov, Alexey; Mitrofanov, Igor; Golovin, Dmitry; Sanin, Anton; Litvak, Maxim; Mokrousov, Maxim; Kozyrev, Alexander; Tretyakov, Vladislav; Djachkova, Maya; Nikiforov, Sergey; Lisov, Denis (1 April 2019). "Mars subsurface hydrogen as seen by FREND onboard TGO". 21: 16504. Cite journal requires
- Korablev, Oleg; et al. (2019). "No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations" (PDF). Nature. 568 (7753): 517–520. Bibcode:2019Natur.568..517K. doi:10.1038/s41586-019-1096-4. PMID 30971829. S2CID 106411228.