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- Harri, A.-M., et al.
(författare)
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Mars Science Laboratory relative humidity observations: Initial results
- 2014
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 119:9, s. 2132-2147
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Tidskriftsartikel (refereegranskat)abstract
- The Mars Science Laboratory (MSL) made a successful landing at Gale crater early August 2012. MSL has an environmental instrument package called the Rover Environmental Monitoring Station (REMS) as a part of its scientific payload. REMS comprises instrumentation for the observation of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. We concentrate on describing the REMS-H measurement performance and initial observations during the first 100 MSL sols as well as constraining the REMS-H results by comparing them with earlier observations and modeling results. The REMS-H device is based on polymeric capacitive humidity sensors developed by Vaisala Inc., and it makes use of transducer electronics section placed in the vicinity of the three humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The final relative humidity results appear to be convincing and are aligned with earlier indirect observations of the total atmospheric precipitable water content. The water mixing ratio in the atmospheric surface layer appears to vary between 30 and 75 ppm. When assuming uniform mixing, the precipitable water content of the atmosphere is ranging from a few to six precipitable micrometers.
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- Haberle, R. M., et al.
(författare)
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Secular Climate Change on Mars : An Update Using MSL Pressure Data
- 2013
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Konferensbidrag (refereegranskat)abstract
- The South Polar Residual Cap (SPRC) on Mars is an icy reservoir of CO2. If all the CO2 trapped in the SPRC were released to the atmosphere the mean annual global surface pressure would rise by ~20 Pa. Repeated MOC and HiRISE imaging of scarp retreat rates within the SPRC have led to the suggestion that the SPRC is losing mass. Estimates for the loss rate vary between 0. 5 Pa per Mars Decade to 13 Pa per Mars Decade. Assuming 80% of this loss goes directly into the atmosphere, and that the loss is monotonic, the global annual mean surface pressure should have increased between ~1-20 Pa since the Viking mission (19 Mars years ago). Surface pressure measurements by the Phoenix Lander only 2 Mars years ago were found to be consistent with these loss rates. Here we compare surface pressure data from the MSL mission with that from Viking Lander 2 (VL-2) to determine if the trend continues. We use VL-2 because it is at the same elevation as MSL (-4500 m). However, based on the first 100 sols of data there does not appear to be a significant difference between the dynamically adjusted pressures of the two landers. This result implies one of several possibilities: (1) the cap is not losing mass and the difference between the Viking and Phoenix results is due to uncertainties in the measurements; (2) the cap has lost mass between the Viking and Phoenix missions but it has since gone back to the cap or into the regolith; or (3) that our analysis is flawed. The first possibility is real since post-mission analysis of the Phoenix sensor has shown that there is a 3 (±2) Pa offset in the data and there may also be uncertainties in the Viking data. The loss/gain scenario for the cap seems unlikely since scarps continue retreating, and regolith uptake implies something unique about the past several Mars years. That our analysis is flawed is certainly possible owing to the very different environments of the Viking and MSL landers. MSL is at the bottom of a deep crater in the southern tropics (~5°S), whereas VL-2 is at a high latitude (~48°N) in the northern plains. And in spite of the fact that the two landers are at nearly identical elevations, they are in very different thermal environments (e.g., MSL is warm when VL-2 is cold), which can have a significant affect on pressures. For these reasons, our confidence in the comparison will increase as more MSL data become available. We will report the results up through sol 360 at the meeting.
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| 8. |
- Pla-García, J., et al.
(författare)
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Preliminary Interpretation of the Meteorological Environment Through Mars Science Laboratory Rover Environmental Monitoring Station Observations and Mesoscale Modeling
- 2014
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Konferensbidrag (refereegranskat)abstract
- In this study the Mars Regional AtmosphericModeling System (MRAMS) has been applied to theGale Crater region, the landing site of the Mars ScienceLaboratory (MSL) Rover Curiosity. The landingsite is at one of the lowest elevations in Gale,between the crater rim and the ~4 km high centralmound known as Mt. Sharp. As Curiosity headstoward its long term target of Mt. Sharp, the meteorologicalconditions are expected to change due to theincreasing influence of topographically-inducedthermal circulations that have been predicted by numerousprevious studies [1, 2, 3, 4]. The types ofperturbations of pressure, air and ground temperatureand wind measured by the Rover EnvironmentalMonitoring Station (REMS) [5] have never beenobserved at other locations and these data provide agreat opportunity to test the models at the most meteorologicalinteresting area measured to date. Weprovide a comparison of MRAMS predictions (pressure,air temperature, winds and ground temperature)to the REMS data available at the location of theRover for sols 21-25 (when first regular REMSmeasurements were obtained, Ls=163), sols 51-55(Ls=180), sol 215 (Ls=270) and sols 348-352 (Ls=0),in order to provide a baseline of model performance.
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- Rodriguez, Sébastien, et al.
(författare)
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Science goals and new mission concepts for future exploration of Titan's atmosphere, geology and habitability : titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON)
- 2022
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 54:2-3, s. 911-973
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Tidskriftsartikel (refereegranskat)abstract
- In response to ESA’s “Voyage 2050” announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn’s largest moon Titan. Titan, a “world with two oceans”, is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan’s remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a “heavy” drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan’s northern latitudes with an orbiter and in situ element(s) would be highly complementary in terms of timing (with possible mission timing overlap), locations, and science goals with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan’s equatorial regions, in the mid-2030s.
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