Mars Orbiter Research Articles

Вычисления и визуализация искажений в морфографических проекциях

There are different ways of estimating the distortions that help us find the best cartographic projections and recommend them for a specific range of tasks from mapping the Earth to extraterrestrial mapping. Besides the planets and their satellites there are small bodies in the Solar System. For mapping these bodies it is advisable to use morphographic projections to show their non-spherical shape. These projections were developed by Philip Stooke. He also proposed replacement of a regular reference surface with a phoboid and methods for estimating distortions but practically implemented them on the example of a body with a regular shape approximated by test triaxial ellipsoid with a ratio of axes 4:3:2. In this regard we set the task of developing and implementing the method for determining distortions in morphographic projections for a body with an irregular shape. We used the algorithm of comparison cartographic cell on projection and on phoboid in order to estimate distortion. The object of mapping is Phobos, a satellite of Mars. Phobos is a non-spherical celestial body for which morphographic projections were first applied. Comparing our results by the values of distortions with the results obtained by Philip Stooke we can conclude that using morphographic projections makes less distortion at portraying a phoboid than a test triaxial ellipsoid.

The distribution, composition, and particle properties of Mars mesospheric aerosols: An analysis of CRISM visible/near-IR limb spectra with context from near-coincident MCS and MARCI observations

The Compact Reconnaissance Imaging Spectral Mapper (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) obtains pole-to-pole observations (i.e., full MRO orbits) of vertical profiles for visible/near-IR spectra (λ= 0.4–4.0 μm), which are ideally suited to identifying the composition and particle sizes of Mars ice and dust aerosols over 50–100 km altitudes in the Mars mesosphere. Within the coverage limitations of the CRISM limb data set, a distinct compositional dichotomy is found in Mars mesospheric ice aerosols. CO2 ice clouds appear during the aphelion period of Mars orbit (Solar Longitudes, Ls ∼ 0–160°) at low latitudes (∼20S–10N) over specific longitude regions (Meridiani, Valles Marineris) and at typical altitudes of 55–75 km. Apart from faint water ice hazes below 55 km, mesospheric H2O ice clouds are primarily restricted to the perihelion orbital range (Ls∼160 – 350°) at northern and southern mid-to-low latitudes with less apparent longitudinal dependences. Mars mesospheric CO2 clouds are presented in CRISM spectra with a surprisingly large range of particle sizes (cross section weighted radii, Reff = 0.3 to 2.2 μm). The smaller particle sizes (Reff ≤1 μm) appear concentrated near the spatial (latitude and altitude) boundaries of their global occurrences. CRISM spectra of mesospheric CO2 clouds also show evidence of iridescence, indicating very narrow particle size distributions (effective variance, Veff ∼ 0.03) and so very abrupt CO2 cloud nucleation. Furthermore, these clouds are sometimes accompanied by altitude coincident peaks in 1.27 μm O2 dayglow, which indicates very dry, cold regions of formation. Mesospheric water ice clouds generally exhibit small particle sizes (Reff = 0.1–0.3 μm), although larger particle sizes (Reff = 0.4–0.7 μm) appear infrequently. On average, water ice cloud particle sizes decrease with altitude over 50–80 km in the perihelion mesosphere. Water ice mass appears similar in clouds over a large range of observed cloud particle sizes, with particle number densities increasing to ∼10 cm−3 for Reff = 0.2 μm. Near coincident Mars Climate Sounder (MCS) temperature and aerosol profile measurements for a subset of CRISM mesospheric aerosol measurements indicate near saturation (H2O and CO2) conditions for ice clouds and distinct mesospheric temperature increases associated with mesospheric dust loading. Dayside (3 pm) mesospheric CO2 clouds with larger particle sizes (Reff ≥0.5 μm) scatter surface infrared emission in MCS limb infrared radiances, as well as solar irradiance in the MCS solar band channel. Scattering of surface infrared emission is most strikingly presented in nighttime (3 am) MCS observations at 55–60 km altitudes, indicating extensive mesospheric nighttime CO2 clouds with considerably larger particle sizes (Reff∼7 μm). Mesospheric CO2 ice clouds present cirrus-like waveforms over extensive latitude and longitude regions (10°×10°), as revealed in coincident Mars Color Imager (MARCI) nadir imaging. Solar tides, gravity waves, and the large orbital variation of the extended thermal structure of the Mars atmosphere influence all of these behaviors. Mesospheric dust aerosols appear infrequently over the non-global (planet encircling) dust storm era of the CRISM limb data set (2009–2016), and exhibit smaller particle sizes (Reff = 0.2–0.7 μm) relative to dust in the lower atmosphere. One isolated case of an aphelion (Ls = 96°) mesospheric dust layer with large dust particle sizes (Reff ∼2 μm) over Syria Planum may reflect high altitude, non-local transport of dust over elevated regions.

A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express

The first high-resolution Digital Terrain Model (DTM) of the entire South Pole of Mars has been produced. A modified version (Kim and Muller, 2009) of a NASA-VICAR-based pipeline developed by DLR (German Aerospace Centre) and JPL (Jet Propulsion Laboratory) has been employed with image matching based on the Gotcha (Gruen-Otto-Chau) algorithm (Shin and Muller, 2012) with a specialised setup for the polar region. DTM products have been produced with more than twice the resolution (50 m/pixel) of the gridded Mars Orbiter Laser Altimeter (MOLA) 512 pixels/degree (112 m/pixel) over the South Polar Residual Cap (SPRC) and the Mars South Polar region (82° - 90° S) in MOLA and areoid reference. The accuracy of the HRSC orbital DTMs are compared against a MOLA reference with good results. HRSC orthorectified strip images from 12.5 to 50 m have also been produced from the base DTMs and these have been processed into a 12.5 m mosaic. HRSC strip products are currently being assessed as base images for automatic co-registration of thousands of high-resolution images, making them geometrically consistent with the surface conditions imaged by HRSC. In some cases, Context Camera (CTX) DTMs have been automatically produced and co-registered to the HRSC image strips and these, in turn, are being employed for automated co-registration of higher-resolution images.

Challenges of identifying putative planetary-origin meteorites of non-igneous material

This paper summarizes the challenges of identifying planetary-origin meteorites of non-igneous composition - particularly those of sedimentary origin. Evidence for putative sedimentary-origin (sed-type) meteorites and their potential parent bodies is reviewed, suggesting that the list of candidate parent bodies for sed-type meteorites includes, but is not limited to, Mars, Enceladus, Ganymede, Europa, Ceres, Vesta, and other hypothetical planets that existed between the orbits of Mars and Jupiter in the past. The extraterrestrial origin and probable parent body for sed-type meteorites should be assessed based on multiple lines of evidence, and not solely limited to tests of oxygen and noble gas isotopes, whose signatures may undergo terrestrial contamination and which may exhibit significant heterogeneity within both the Solar System and parent cosmic bodies. The observed fall of a cosmic body, evidence of hypervelocity fall, signs of impact, presence of fusion crust, melting, and/or shock deformation features in impactor fragments should be considered as priority signs of meteoritic origin.

The potential science and engineering value of samples delivered to Earth by Mars sample return

The potential science and engineering value of samples delivered to Earth by Mars sample return

Grid Mapping the Northern Plains of Mars: Using Morphotype and Distribution of Ice‐Related Landforms to Understand Multiple Ice‐Rich Deposits in Utopia Planitia

AbstractThis work in Utopia Planitia is the first continuous regional mapping of ice‐related landforms integrated into an effort to study the three main basins (Arcadia, Acidalia, and Utopia Planitiae) in the northern plains. The distribution and morphotypes of these landforms, SHAllow RADar detections, and crater size‐frequency distribution measurements (>50 m in diameter) were used to understand the permafrost cryolithology and its past evolution in relation to climate in Utopia Planitia. Three assemblages of landforms were identified based on their spatial correlation and correlation with Mars Orbiter Laser Altimeter surface roughness along a strip from 30°N to 80°N. At 30°–38°N, the assemblage is formed by kilometer‐scale polygons, high‐albedo mounds, and thumbprint terrains. This assemblage is associated with a lobate deposit of 30 m in thickness with a crater retention age of 1 Ga. At 38°–47°N, the assemblage is comprised of large scallops, 100‐m‐diameter polygons, pits, and mantled deposits. This assemblage is correlated with a deposit of 80 m in thickness containing excess ice (~50–85% by volume) with a crater retention age of about 10 Ma. At 47°–78°N, the assemblage is composed of mantled deposits, textured terrains, and 30‐m‐diameter polygons. This assemblage is related to the ice‐rich, debris‐covered, latitude‐dependent mantle that has a crater retention age of about 1.5 Ma. Utopia Planitia appears to be a region of combined depositions of sediment and continuous cold climatic conditions that leaded to a complex distribution of ground ice.

Assessing martian bedrock mineralogy through “windows” in the dust using near-infrared and thermal infrared remote sensing

Much of Mars' surface is mantled by bright dust, which masks the spectral features used to interpret the mineralogy of the underlying bedrock. Despite the wealth of near-infrared (NIR) and thermal infrared (TIR) data returned from orbiting spacecraft in recent decades, the detailed bedrock composition of approximately half of the Martian surface remains relatively unknown due to dust cover. To address this issue, and to help gain a better understanding of the bedrock mineralogy in dusty regions, Dust Cover Index results from the Mars Global Surveyor Thermal Emission Spectrometer (TES) and analysis of images from the Mars Reconnaissance Orbiter Mars Color Imager (MARCI) were used to identify 63 small localized areas within the classical bright dusty regions of Arabia Terra, Elysium Planitia, and Tharsis Montes as potential “windows” through the dust; that is, areas where the dust cover is thin enough to permit infrared remote sensing of the underlying materials. The mineralogy of each candidate window was inferred using spectra from the Mars Express Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) NIR spectrometer and, where possible, TES. Twelve areas of interest returned spectra that are consistent with mineral species expected to be present at the regional scale, such as high- and low-calcium pyroxene, olivine, and iron-bearing glass. Distribution maps were created using previously defined index parameters for each species present within an area. High-quality TES spectra, if present within an area of interest, were deconvolved to estimate modal mineralogy and to support NIR interpretations. OMEGA data from Arabia Terra and Elysium Planitia are largely similar and indicate the presence of high-calcium pyroxene with significant contributions of glass and olivine, while TES data suggest an intermediate between the established compositions of the southern highlands and Syrtis Major. Limited data from Tharsis are consistent with low-calcium pyroxene mixed with lesser amounts of glass and high-calcium pyroxene. TES data from southern Tharsis correlate well with the previously inferred compositions of the Aonium and Mare Sirenum highlands immediately to the south. Of particular note is the detection of iron-bearing glass as a significant component of all three analyzed regions, especially in Tharsis. Overall, the underlying compositions of the classically dust-covered regions of Mars appear consistent with the compositions of adjacent and other low-albedo (not dust covered) regions of the planet identified in previous studies, with the noted contribution from iron-bearing glass.

MoMo: a new empirical model of the Mars ionospheric total electron content based on Mars Express MARSIS data

Aims: Several scientific landers and rovers have reached the Martian surface since the 1970s. Communication between the asset (i.e., lander or rover) and Mars orbiters or Earth antennas uses radio signals in UHF to X-band frequencies passing through the Mars’ ionosphere. It is consequently necessary to take into account electron density variation in the Mars’ ionosphere to correct the refraction of the signal transmitted. Methods: We developed a new empirical model of the Mars’ ionosphere called MoMo. It is based on the large database of Total Electron Content (TEC) derived from the subsurface mode of the Mars Express MARSIS radar. The model provides vertical TEC as a function of solar zenith angle, solar activity, solar longitude and location. For validation, the model is compared with Mars Express radio occultation data as well as with the numerical model IPIM (IRAP Plasmasphere-Ionosphere Model). Results: We discussed the output of the model in terms of climatology behaviour of the Mars’ ionosphere. The output of MoMo is then uses to quantify the impact of the Martian ionosphere for radio-science experiments. From our results, the effect is of the order of 10−3 mm s−1 in Doppler observables especially around sunrise and sunset. Consequently, this new model could be used to support the data analysis of any radio-science experiment and especially for present InSight RISE and futur ExoMars LARA instruments aiming at better understand the deep-interior of Mars.

Study of 3U Mars Airplane released from Mars orbiter

Study of 3U Mars Airplane released from Mars orbiter

Analysis of the Orbital Transfer between the Earth–Mars Orbit using Electric Propulsion based on the Direct Collocation Method

Analysis of the Orbital Transfer between the Earth–Mars Orbit using Electric Propulsion based on the Direct Collocation Method

Area and volume of mid-latitude glacier-like forms on Mars

Although a substantial ice cover has been identified within the mid-latitudes of Mars, there is uncertainty regarding the formation, current and former volume, and dynamic evolution of these ice masses. Here, we present the first comprehensive ice volume estimate of martian glacier-like forms (GLFs) from systematic population scale mapping and volumetric analysis. The outlines of 1243 GLFs were manually delineated from 6 m per pixel Context Camera (CTX) images and the volume of each determined using a volume–area scaling approach. Our results show that GLFs cover a surface area of 11344 ± 393 km2 and have a total volume of 1744 ± 441 km3. Using two end-member scenarios for ice concentration by volume of 30% (pore ice) and 90% (debris-covered glacier ice), we calculate the volume of ice contained within GLFs to be between 523 ± 132 km3 (480 ± 121 Gt) and 1570 ± 397 km3 (1439 ± 364 Gt), equivalent to a mean global water layer 3 to 10 mm thick. We investigate the local topographic setting of each GLF by reference to the Mars Orbiter Laser Altimeter (MOLA) digital elevation model. Our analysis reveals that globally GLFs are on average larger in latitudes >36° and on slopes between 2 and 8°. In the northern hemisphere GLFs between 500 and 2500 m in elevation and in the southern hemisphere GLFs with a northern aspect are also larger on average. The observed spatial patterns of GLF landform and volume distribution suggests that regional to local meteorological and topographical conditions play an important role in GLF ice accumulation and/or preservation. Assuming a net accumulation rate of 10 mma−1 typical of climatic excursions with high obliquity, we estimate a period of at least 13 ka is required to yield the average calculated GLF ice thickness of ∼130 m. Such a period is well within the timeframe of a high obliquity cycle (20–40 ka), suggesting that the current GLF volume could have formed during a single climate excursion.

The O(1S) 297.2‐nm Dayglow Emission: A Tracer of CO2 Density Variations in the Martian Lower Thermosphere

AbstractThe O(1S) metastable atoms can radiatively relax by emitting airglow at 557.7 and 297.2 nm. The latter one has been observed with the Imaging Ultraviolet Spectrograph onboard the Mars Atmosphere and Volatile Evolution Mars orbiter since 2014. Limb profiles of the 297.2‐nm dayglow have been collected near periapsis with a spatial resolution of 5 km or less. They show a double‐peak structure that was previously predicted but never observed during earlier Mars missions. The production of both 297.2‐nm layers is dominated by photodissociation of CO2. Their altitude and brightness is variable with season and latitude, reflecting changes in the total column of CO2 present in the lower thermosphere. Since the lower emission peak near 85 km is solely produced by photodissociation, its peak is an indicator of the unit optical depth pressure level and the overlying CO2 column density. Its intensity is directly controlled by the Lyman‐α solar flux reaching the Martian upper atmosphere. We take advantage of the Lyman‐α flux measurements of the solar Extreme Ultraviolet Monitor instrument onboard Mars Atmosphere and Volatile Evolution to model the observed OI 297.2‐nm limb profiles. For this, we combine photodissociation sources with chemical processes and photoelectron impact excitation. To determine the relative importance of the excitation processes, we apply the model to the atmospheric structure measured by the Viking 1 lander before applying it to a model atmosphere. We find very good agreement with the lower peak structure and intensity if the CO2 density provided by the Mars Climate Database is scaled down by a factor between 0.50 and 0.66. We also determine that the previously uncertain quantum yield for production of O(1S) atoms by photodissociation of CO2 at Lyman‐α wavelength is about 8%.

3D technology as an effective tool for reflection simulation: The Beagle 2 lander on Mars

Abstract Beagle 2, developed for the European Space Agency’s Mars Express Mission by the Beagle 2 Consortium, was due to land on Mars on 25 December 2003. After being successfully ejected from the ESA’s orbiter Mars Express, followed by an attempted landing, the spacecraft failed to communicate with Earth, and the mission was presumed lost. However, in January 2015, it was announced that satellite images from NASA’s Mars Reconnaissance Orbiter (MRO) indicated the possibility of a successful landing by Beagle 2. In the light of these findings and the considerable uncertainty still surrounding the outcome of the mission, a team of researchers from De Montfort University and the University of Leicester have joined in a collaborative project aimed at identifying whether the object captured by NASA’s HiRISE camera is Beagle 2, and detecting its possible landing configuration. The practical scientific experiment employed the innovative concept of ‘reflection analysis’, propounded by Dr Mark Sims – former Beagle 2 Mission Manager and professor of astrobiology and Space Instrumentation at the Space Research Centre, University of Leicester. The technique stemmed from the idea of simulating possible configurations of the Beagle 2 lander, testing how they reflect light and comparing the 3D renders to unprocessed images, available from the MRO’s HiRISE camera at a number of different sun angles. De Montfort University’s team used commercial 3D modelling technology to create a 3D model of the spacecraft and replicate virtually the sun angles at the times the satellite images were taken. This allowed a comparison of the simulated 3D renders to the satellite images to estimate the configuration of Beagle 2 on Mars. The results revealed that Beagle 2 probably deployed at least three, and possibly all four of its solar panels after landing on the planet’s surface.

Preliminary orbit design for a Mars sample return mission

Mars sample return missions are the focus of international deep space exploration planning in recent years. In this paper, the orbit design of the different flight phases of a Mars sample return mission is studied with consideration of practical engineering constraints, using 2028 launch opportunity as an example; based on comparative analysis of different schemes, feasible orbit designs are recommended for future Mars sample return missions. Preliminary analysis and design of the mission orbit are carried out and the analysis results of the main flight phases are provided in the paper, and the discussion focuses on launch opportunity, Earth to Mars transfer, Mars orbit insertion, rendezvous and docking in Mars orbit, and Mars to Earth transfer. It is shown in the paper that the launch opportunities for Mars sample return missions emerge every two years, and the launch windows in 2028 opportunity concentrate in the November; considering the high risk of the research and development of heavy lift rockets, the scheme that the descent and ascent module, the orbiter and reentry module are launched separately using two available rockets is recommended; the Mars to Earth return opportunities emerge about every two years, and the return windows open about two years after the Earth departure.

Autonomous Initial Orbit Determination with Optical Observations of Unknown Planetary Landmarks

Images are commonly used for spacecraft navigation. When close to the observed body it is often advantageous to perform such image-based navigation with observations of landmarks. This work demonstrates that it is possible to solve the initial orbit determination (IOD) problem using only observations of unknown landmarks if the spacecraft is assumed to be orbiting an ellipsoidal central body of known shape. Further, the solution developed here is noniterative and is based purely on geometric arguments. Example autonomous IOD results using only unknown landmarks are shown for a spacecraft in a circular Mars orbit and an elliptical Earth orbit.

A structured Solar System satellite relay constellation network topology design for Earth‐Mars deep space communications

SummaryThe deep space exploration missions require high quality of communication performance between the Earth stations and various deep space explorers, such as Mars orbiters and rovers. Due to the difficulties on improving the point‐to‐point physical wireless link capacity, it is necessary to study the relay network communications under the structured idea. In this paper, the structured Solar System satellite relay constellation network is proposed for Earth‐Mars deep space communications, including the mission background, mathematic model, topology design, and performance analysis. The satellite relay constellation could be modelled as a 2‐dimensional structure with multiple concentric circle loops and multiple relate satellites on each loop. With the different optimal objectives as shortest path, minimum hops and minimum nodes required under the constraint threshold distance for each hop, both the Monte Carlo method and modified Shortest Path First algorithms are studied to work out the optimal network topology designs. Simulation results show that, our network topology design could satisfy the requirements on continuous dual‐directional end‐to‐end communications between the Earth and Mars over the whole mission life period and guarantee the performance of end‐to‐end multihop links above the lowest boundary.

Variability of Martian Turbopause Altitudes

AbstractThe turbopause and homopause represent the transition from strong turbulence and mixing in the middle atmosphere to a molecular‐diffusion‐dominated region in the upper atmosphere. We use neutral densities measured by the Neutral Gas and Ion Mass Spectrometer on the Mars Atmospheric and Volatile EvolutioN spacecraft from February 2015 to October 2016 to investigate the temperature structure and fluctuations of the Martian upper atmosphere. We compare those with temperature measurements of the lower atmosphere from the Mars Reconnaissance Orbiter's Mars Climate Sounder. At the lowest Mars Atmospheric and Volatile EvolutioN altitudes we often observe a statically stable region where waves propagate freely. In contrast, regions from about 20 km up to at least 70 km are reduced in stability where waves are expected to dissipate readily due to breaking/saturation. We derive homopause altitudes from Neutral Gas and Ion Mass Spectrometer N2 and Ar densities and find that it varies between 60 and 140 km. From the standard deviations in monthly averaged temperature profiles, we determine the wave turbopause altitude where applicable and find that these altitudes agree with the homopause altitudes. We show that the homopause variability is driven by order of magnitude changes in CO2 densities, which drastically affect the altitude at which the eddy diffusion is equal to the molecular diffusion. These variations are observed as a function of local time, latitude, and season. That the turbopause/homopause does not track a fixed density level means that the eddy diffusion coefficient at the turbopause can vary significantly, suggesting differences in the dominant breaking waves and tidal modes.

Late-stage intrusive activity at Olympus Mons, Mars: Summit inflation and giant dike formation

By mapping the distribution of 351 lava flows at the summit area of Olympus Mons volcano on Mars, and correlating these flows with the current topography from the Mars Orbiter Laser Altimeter (MOLA), we have identified numerous flows which appear to have moved uphill. This disparity is most clearly seen to the south of the caldera rim, where the elevation increases by >200 m along the apparent path of the flow. Additional present day topographic anomalies have been identified, including the tilting down towards the north of the floors of Apollo and Hermes Paterae within the caldera, and an elevation difference of >400 m between the northern and southern portions of the floor of Zeus Patera. We conclude that inflation of the southern flank after the eruption of the youngest lava flows is the most plausible explanation, which implies that intrusive activity at Olympus Mons continued towards the present beyond the age of the youngest paterae ∼200–300 Myr (Neukum et al., 2004; Robbins et al., 2011). We propose that intrusion of lateral dikes to radial distances >2000 km is linked to the formation of the individual paterae at Olympus Mons. Two specific dikes to the SE of the volcano are inferred to have volumes of ∼4400 km3 and ∼6100 km3, greater than the volumes of individual calderas and implying triggering of both caldera collapse and lateral dike injection by the arrival of large inputs of magma from the mantle. A comparable disparity between lava flow direction and current topography, together with a tilted part of the caldera floor, has been identified at Ascraeus Mons.

Analysing some martian atmospheric characteristics associated with a dust storm over the Lunae Planum region during October 2014

This study analyses the vertical aerosol distribution and associated atmospheric characteristics during a dust storm event in early Martian southern summer. The analysis is based on the observations of the Mars Colour Camera (MCC) onboard the Indian Mars Orbiter Mission during October 11 and October 20, 2014. A local-scale dust storm is found within the north-eastern portion of the Lunae Planum region on October 11, 2014, which is observed to be relatively larger during October 20. The dust storm disappeared in the next image taken over the same region during October 28, 2014, leaving a thick haze over Lunae Planum and the Valles Marineris region. It is observed from the Mars Daily Global Maps of the Mars Color Imager (MARCI) on board the Mars Reconnaissance Orbiter (MRO) that the dust storm was generated in the Acidalia region, moved south and came over Lunae Planum and Tempe Terra. Later on, this northern hemispheric storm sequence crossed the equator and merged with a Hellas sequence over Noachis Terra. An increase in vertically integrated dust opacity derived from the observations of Mars Climate Sounder on board MRO was seen over a large latitudinal extent i.e., 60° S to 60° N. Analysis of dust and water ice opacity and temperature profile is carried out before, during and after the dust storm period as observed by MCC and MARCI images. Dust opacity is found to have increased drastically up to 20 km altitude. An increase of dustiness at the HATDM (High Altitude Tropical Dust Maximum) layer is seen, but with a temporal delay of 2° LS after the dust storm disappearance. The study implicates the variation of convective boundary layer growth in the tenuous Martian atmosphere during the dust storm scenario for this temporal delay in dust lifting. The dust lifting is found to be exclusively responsible for the increase in heating rate at this layer, not cloud radiative heating caused by water ice clouds.

Optical/radio/pulsars integrated navigation for Mars orbiter

In this paper, we address the issue of the integrated navigation algorithm with different combination of measurements for Mars orbiter. First, system dynamic model and navigation measurement models using optical measurement information, radio measurement information and X-ray pulsars measurement information are respectively established. Second, optical/radio/pulsars integrated navigation algorithm is proposed, and observability analysis of the integrated navigation system is also conducted. Third, adaptive extended Kalman filter is adopted to fuse measurement information and suppress measurement and process noise to optimally estimate the state of Mars orbiter. Monte Carlo simulation results show that optical/radio/pulsars integrated navigation can effectively improve the navigation accuracy and satisfy the navigation requirements of Mars orbiter.