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Mars Polar, Ice, and Climate Science: a Summary of Recent Work and Our Current State of Knowledge

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Mars Polar, Ice, and Climate Science: a Summary of Recent Work and Our Current State of Knowledge Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089) 6306.pdf MARS POLAR, ICE, AND CLIMATE SCIENCE: A SUMMARY OF RECENT WORK AND OUR CURRENT STATE OF KNOWLEDGE. I. B. Smith,1,2 1York University, Toronto, Ontario, Canada; 2Plane- tary Science Institute Lakewood, Colorado. Contact: [email protected]. Polar and Climate Community activity since the and climate science, already recognized as important 8th Mars conference: Investigations of Mars’ ice and topics for future exploration, but they included active climate have rapidly increased in number and breadth surface processes that have only recently been recog- since the 8th edition of the International Conference on nized for their important role in shaping the surface of Mars was held in 2014. In particular, exciting discover- Mars. Because of this, an entirely new sub-objective ies of mid-latitude ice deposits [1,2] have opened the related to present activity was created under the geolo- door for much more detailed, and creative analysis of gy sub-objective of the goals document. Also, at the permafrost and periglacial terrains [3-7]. At the north spring 2018 36th MEPAG face-to-face meeting, a fo- and south polar layered deposits (NPLD and SPLD), rum of posters highlighted important science and fu- new techniques for stratigraphic studies using high ture investigations, of which polar and climate science resolution stereo [8, 9] and radar [10-12], along with comprised more than half of all submissions [25]. revised surface crater statistics [13] have put more pre- Concurrent to this activity, there have been several cise age constraints on the NPLD. Numerous other studies designed to summarize the state of polar and papers have studied surface changes based on interac- climate science and then use the highest priority sci- tions with volatiles, predominantly CO2 [e.g. 14,15]. ence questions to generate a list of measurements Importantly, models of climatic processes, from needed for future investigations. The Keck Institute for large [16,17] to meso-scale [18-20] continue to im- Space Studies (KISS) hosted and supported two work- prove their underlying physics to better match ob- shops for climate studies. The first was called “Un- served surface and atmospheric changes. locking the Climate Record Stored within Mars' Polar Besides the investigations, two meetings, the 6th Layered Deposits” [26], and the second was called International Conference on Mars Polar Science and “MarsX: Mars Subsurface Exploration” [27]. Addi- Exploration and the first Mars Workshop on Amazon- tionally, private industry, namely SpaceX, has con- ian and Recent Climate have identified numerous sci- ducted several workshops with the goal choosing land- ence questions and goals for future investigations [21, ing sites for future humans based on availability of ice. 22]. Those two meetings used community input, in the Directly relevant to Mars science priorities, form of multiple discussions in conference sessions MEPAG chartered two Science Analysis Groups and a public vote, to identify the top tier science ques- (SAGs) for identifying top priority science goals and tions for Mars polar and climate science. Additionally, missions that feasible to launch in the next decade. The The Late Mars workshop focused on modern and re- first, called the Next Orbiter Science Analysis Group cent processes associated with volatiles [23]. Finally, (NEX-SAG), looked at all science to be done from special sessions dedicated to Mars polar and climate orbit and had a significant portion of the payload dedi- processes have taken place at bigger conferences, such cated to atmospheric and ice measurements [28]. The as LPSC and AGU, indicating the community-wide second focused exclusively on ice and climate: the Ice attention that polar and climate science has gained. and Climate Evolution Science Analysis Group (ICE- All of this activity has generated a buzz of discus- SAG) [29]. That SAG supported the NEX-SAG results sion related to polar and climate science, which has and described additional landed missions of priority. been recognized in the 2018 revisions of the Mars Ex- All of the reports coming from those studies will be ploration Program Analysis Group (MEPAG)’s goals important inputs for the upcoming Decadal Survey. document [24]. The revisions focused primarily on ice This abundance of recent work, in the form of Figure 1: HRSC image depicting polar winds blowing clouds away from the pole. Winds provide the mechanism to transport H2O across the planet, a major component of the climate system. Ninth International Conference on Mars 2019 (LPI Contrib. No. 2089) 6306.pdf many tens of peer-reviewed papers, special issues, dedicated conferences, special ses- sions, MEPAG goals updates, science analysis groups, and mission concept work- shops, illuminates the enormous amount of activity and productivity the polar and cli- mate communities have generated. This current of activity promises to be even more important and exciting going forward, as indicated by the level of interest of early career researchers. Students, have been ~25% of recent polar and climate work- shops [21, 22], and scientists who have completed their Figure 2: Schematic of Mars Climate System, Ph.D. in the last five years increases this number to depicting many of the processes and fluxes that occur closer to 50%. This field is young and growing quickly. in present day in the polar regions and at the mid- Top priority Questions as outlined by the recent latitudes. Boxes 1-3 point out the relationship between workshops and studies: The polar and climate com- the major four questions. Question four asks what is munities have identified several themes that have risen the current state and past states of this system? to highest priority. All are in the topic of understanding the current and recent climate. These themes are con- References: nected by the topical workshops [17-19] and the mis- [1] Bramson et al. (2015) Geophys. Res. Lett. 42, sion architecture studies [22-26], showing how rele- 2015GL064844. [2] Stuurman et al. (2016) Geophysi- vant they are to many cross-cutting investigations. cal Research Letters 43, 9484–9491. [3] Ramsdale et There are four main priority areas that come up in al. (2017) Planetary and Space Science 140, 49–61. [4] every report: Ramsdale et al. (2019) JGR-Planets 124, 504–527. [5] 1. What are the present large scale fluxes of CO2, Séjourné et al. (2019) JGR-Planets 124, 483–503. [6] H2O, dust, and other refractory materials around Orgel et al. (2019) JGR-Planets 124, 454–482. [7] the planet, especially into and out of the polar re- Morgan et al. (2019) LPSC abst#2918. [8] Becerra et gions? (Figures 1 and 2) al. (2017) GRL 2016GL071197. [9] Guallini et al. 2. What are the rates and processes of surface- (2018). Icarus, Mars Polar Science VI 308, 76–107. atmosphere interactions, including layer formation [10] Smith et al. (2016) Science 352, 1075–1078. [11] and surface modification, that create a climate Bierson et al. (2016) GRL 43, 4172–4179.8. [12] record to be read? (Figure 2) Putzig et al. (2018) Icarus, Mars Polar Science VI 308, 3. What are the vertical (layered) and horizontal 138–147. [13] Landis et al. (2016) GRL 43, (regional) distributions and preservation states of 2016GL068434. [14] Portyankina et al. (in press) polar and off-polar ice reservoirs, including com- Icarus. [15] Hansen et al. (2015). Icarus, Dynamic position an ice grain structure? Mars 251, 264–274. [16] Kahre et al. (2017) The At- 4. What is the record of climate stored in the vari- mosphere and Climate of Mars 18, 295. [17] Haberle ous layered deposits, and what are their ages? et al. (2017). Cambridge University Press. [18] Smith The Future of Mars Polar and Climate Sciences: and Spiga (2018) Icarus, Mars Polar Science VI 308, Considering the goal of reading the climate record, this 188–196. [19] Spiga and Smith (2018). Icarus, Mars presentation will summarize the important advances Polar Science VI 308, 197–208. [20] Spiga et al. made since the 8th Mars Conference and then address (2017) Nature Geoscience 10, 652–657. [21] Smith et the main questions that need to be answered as the al. (2018) Icarus, Mars Polar Science VI 308, 2–14. community proceeds forward. I will discuss the moti- [22] Diniega and Smith, (in review) Planetary and vation behind addressing those questions, including the Space Science. [23] https://www.hou.usra.edu/meet- application to numerous other investigations of Mars, ings/latemars2018/ [24] https://mepag.jpl.nasa.gov/ such as ancient climate, atmospheric science, vul- reports/MEPAG%20Goals_Document_2018.pdf [25] canology, geomorphology and aeolian sciences, biolo- https://mepag.jpl.nasa.gov/meetings.cfm [26] Smith et gy, and human exploration. Mars polar science is ex- al. (in review) Planetary and Space Science. [27] Sta- ceptionally broad, so these question and ongoing work menković et al. (2019). Nature Astronomy 3, 116. [28] are relevant to nearly every study of the planet, mean- MEPAG NEX-SAG Report (2015) at http://mepag.- ing that everyone benefits when new discoveries are nasa.gov/reports.cfm [29] MEPAG ICE-SAG Report made related to present-day climate. http://mepag.nasa.gov/reports.cfm.
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