UVNS: An UVvis-NIR Spectrometer for Mars airglow.
Airglow from a planetary atmosphere can yield important information on composition and dynamics. In this poster we examine the scientific return for the Mars Science Orbiter goals using a set of compact light instruments with a proven heritage (OSIRIS, SOIR, and SHOW) which span the UV-vis-NIR-SWIR part of the spectrum measuring scattered light and airglow from the limb and also stellar and solar occultation. A nadir viewing option is also a possibility for the UV spectrometer. The prime instruments consist of (a) a NIR- tomographic Ox imager (NTOI) (provenance OSIRIS) and (b) a high resolution IR spectrometer provenance SOIR) operating in solar and stellar occultation modes. By imaging the O2(1Δ) with the NTOI in the vertical it should be possible to derive a 2D structure for ozone during the daytime and O at night, providing chemical structure in the 50-80 km height range. The observed structure, analysed using 3D chemistry climate models, will also provide much needed information on dynamics and possibly the role of gravity waves and thermal tides. The HRIRS/SOIR occultation instrument, with a sensitivity of 2 ppbv at 3.3 microns will provide a unique opportunity to detect methane and measure any spatial variability. But other species such as CO should be detectable. A third instrument (c) uses the spatial heterodyne method of the SHOW instrument and it should be possible to measure water vapour and SO2 and perhaps tune the instrument for other species. (d) The UV-Vis spectrometer (UVS) would be based on the OSIRIS spectrometer but tuned for 200-600 nm to measure NO airglow and aurorae ∼ 200 nm, Herzberg II bands, ozone column in the Herzberg continuum at ∼ 250 nm with nadir viewing. Rayleigh scattering would provide temperature and pressure. Thus measurements of ozone column and water vapour will continue the climatology of these species initiated by MAWD on the Viking orbiters, TES on MGS and PFS on Mars Express. The unambiguous detection of methane and its distribution would be a major achievement and contribute to the question of its source. The UVNS will also measure aerosol (dust, water ice, and CO2 ice) optical depth and with the inclusion of infrared channels [SOIR] will provide improved information on the size distribution (Bourassa et al., 2008). A secondary objective would be to use the airglow data that would be observed to extend the MAVEN science mission and characterise the interaction of the solar wind with the Martian upper atmosphere by means of detailed airglow measurements.
Simulation Study of Observations of the Martian Atmospheric Wind Field by a Michelson Wind Imager, DynAMO
Although Martian wind measurements have been identified as important for understanding the Martian atmosphere and for operational needs (for Entry/Descent/Landing, aerocapture, aerobraking, and orbit lifetimes), to date there has not been a wind instrument capable of measuring winds globally on Mars included in any mission . The Dynamic Atmosphere Mars Observer (DynAMO) is an instrument concept initially formulated in 2000 (Ward et al., 2002) and proposed as an instrument for the CNES Mars 2007 Orbiter in 2002. The instrument is a field widened Michelson interferometer, designed to measure vertical profiles of wind in the Martian atmosphere. The two emission targets are the O2 IR atmospheric band at 1.27 microns and an oxygen recombination emission, the green line from O(1S) at 557.7 nm. These emissions allow winds in the Martian atmosphere to be observed from 10 to 45 km and 80 to 160 km during the day and 55 to 75 km and 80 to 100 km at night. In this presentation, dynamical signatures from a Martian general circulation model (M3M), being developed at York University, are reported, and the implementation of a forward model developed at the University of New Brunswick for DynAMO is summarized. An overview of the DynAMO concept is followed by an outline of the observing conditions associated with a nominal orbit and the modelled atmospheric conditions derived from a run of the M3M. The coupling of these two models provides the means to investigate the scientific capabilities of this instrument. These capabilities have the potential to significantly advance our understanding of Martian winds.
The Mars Phoenix MET Pressure Sensor - Technical Implementation, Quality of Data and Data Processing
Meteorological conditions on the landing site of the Mars Phoenix lander were monitored with the MET experiment, provided by Canadian Space Agency (CSA). The MET experiment includes a LIDAR, three temperature sensors and a pressure sensor. The Phoenix MET pressure sensor is provided by Finnish Meteorological Institute (FMI) and is based on technology developed by Vaisala corporate. Three Barocap sensor heads are used to measure pressure and two Thermocap sensor heads to measure housekeeping temperature. The engineering data measured by the Phoenix MET pressure sensor is introduced. This data includes sensor level tests, spacecraft level tests, measurements during the interplanetary cruise and health check measurements during the mission on Mars. The following characteristics of the sensor are determined using this data: resolution, repeatability, temperature dependence, stability, total accuracy and time constant. Data processing methods used to calculate corrected pressure readings from the raw data are introduced.
Microphysical Modeling for Interpretation of Phoenix Lidar Observations
A microphysical model for Mars dust and ice clouds (Daerden et al, 2009) has been applied to aid in interpretation of the Phoenix LIDAR observations of clouds in the planetary boundary layer (PBL). The cloud model is driven by temperature data provided by the PBL model of Davy et al. (2009). The formation of water ice clouds near the PBL top altitude shortly after midnight is reproduced by the model. During the subsequent cold nighttime hours ice particles in these clouds grow to sizes of tens to hundreds of microns, leading to an increasingly fast sedimentation. This model scenario is consistent with the lidar observations of precipitation of ice crystals in the early morning hours. The model is being applied to investigate the extent to which the precipitation of ice crystals acts to confine water to the PBL and whether this local process plays a role in the seasonal variation of atmospheric humidity.
Lidar Observations of Martian Dust Optical Properties During the Phoenix Mars Mission
On 25 May 2008 the Phoenix spacecraft landed on the Northern Plains of Mars (68.22oN, 234.25oW), and operated for five months through mid-summer (solar longitude LS=76o to 149o). The lidar instrument on the Phoenix spacecraft measured the backscatter of pulsed light emitted upward into the atmosphere, and provided height resolved measurements of dust that were continuous in time. The essential capability of the lidar was that it could resolve the vertical distribution of the dust that drifted past the landing site. The optical extinction coefficient was derived from the lidar measurements and this provided a measure of the dust loading. Diurnal variations of the extinction coefficient profiles indicate an increase in the dust loading in the afternoon as well as a growth of the planetary boundary layer (PBL) height from under 3 km in the morning to above 4 km in the afternoon. In early summer, 35 sols after landing (LS=97o), a dust storm was observed that lifted dust up to 10 km and caused a sharp increase in the dust extinction coefficient and optical depth. The observed dust loading generally decreased after LS=97o. In the latter half of the mission (after LS=117o) there was a regular occurrence of ground fog and clouds within the PBL at night.
Hot Hydrogen Ion Precipitation in the Martian Ionosphere in the Vicinity of Strong Crustal Magnetic Field Anomalies
High energy H/H+ ion precipitation into Mars' upper atmosphere in the vicinity of strong crustal magnetic field anomalies is modeled and discussed. Such particle transport has previously been modeled for Earth for more uniform magnetic field conditions and we have extended this work for the Martian ionosphere using different cross sections for relevant Martian "background" species. Solar wind protons as well as pick-up ions from the planetary exosphere routinely enter and alter the upper atmosphere. A study of the ionization, excitation, and energy deposition is conducted. The result is a detailed examination of the influence of energetic ion transport on the Mars upper atmosphere.
The Faint Young Sun Paradox: a Resolution
The "faint young sun" paradox, the apparent existence of mild climate conditions (especially liquid water) during a time when the standard model of stellar evolution predicts solar luminosity 20-30% less than at present, has proven difficult to resolve. It is widely recognized that higher concentrations of greenhouse gases offer a reasonable mechanism to eliminate the paradox. Suggestions that higher CO2 concentrations could accomplish the necessary warming require concentrations so high that even the sparse early geologic record should exhibit clear effects. The actual concentrations of CO2 in the early atmosphere remain the subject of considerable debate, but there is skepticism that CO2 levels sufficient to resolve the paradox were maintained throughout the Hadean and Archean. Suggestions that either methane or ammonia, considerably more potent greenhouse gases than CO2, have been met with the objection that their rapid rate of destruction by ultraviolet light, and thus removal from the atmosphere, preclude levels high enough to maintain warm conditions for any considerable length of time. Further suggestions that biologic production of methane may have been a factor in maintaining high methane levels may be reasonable for the later Archean, but would be problematical for the earlier Archean unless the necessary organisms had developed very early in Earth's history, a point still under discussion. However, if the early Earth had a large surface reservoir of reduced carbon compounds, whether in solution, suspension, floating or deposited on the ocean floor, a strictly non-biologic mechanism - hydrothermal processing, could produce both methane and ammonia at rates high enough to counteract photochemical destruction in the atmosphere and thus maintain levels sufficient for global warming during the Hadean and Early Archean.