Viking Research Articles

The Case for Extant Life on Mars and Its Possible Detection by the Viking Labeled Release Experiment.

The 1976 Viking Labeled Release (LR) experiment was positive for extant microbial life on the surface of Mars. Experiments on both Viking landers, 4000 miles apart, yielded similar, repeatable, positive responses. While the authors eventually concluded that the experiment detected martian life, this was and remains a highly controversial conclusion. Many believe that the martian environment is inimical to life and the LR responses were nonbiological, attributed to an as-yet-unidentified oxidant (or oxidants) in the martian soil. Unfortunately, no further metabolic experiments have been conducted on Mars. Instead, follow-on missions have sought to define the martian environment, mostly searching for signs of water. These missions have collected considerable data regarding Mars as a habitat, both past and present. The purpose of this article is to consider recent findings about martian water, methane, and organics that impact the case for extant life on Mars. Further, the biological explanation of the LR and recent nonbiological hypotheses are evaluated. It is concluded that extant life is a strong possibility, that abiotic interpretations of the LR data are not conclusive, and that, even setting our conclusion aside, biology should still be considered as an explanation for the LR experiment. Because of possible contamination of Mars by terrestrial microbes after Viking, we note that the LR data are the only data we will ever have on biologically pristine martian samples. Key Words: Extant life on Mars-Viking Labeled Release experiment-Astrobiology-Extraterrestrial life-Mars. Astrobiology 16, 798-810.

In situ measurement of atmospheric krypton and xenon on Mars with Mars Science Laboratory

Mars Science Laboratory's Sample Analysis at Mars (SAM) investigation has measured all of the stable isotopes of the heavy noble gases krypton and xenon in the martian atmosphere, in situ, from the Curiosity Rover at Gale Crater, Mars. Previous knowledge of martian atmospheric krypton and xenon isotope ratios has been based upon a combination of the Viking mission's krypton and xenon detections and measurements of noble gas isotope ratios in martian meteorites. However, the meteorite measurements reveal an impure mixture of atmospheric, mantle, and spallation contributions. The xenon and krypton isotopic measurements reported here include the complete set of stable isotopes, unmeasured by Viking. The new results generally agree with Mars meteorite measurements but also provide a unique opportunity to identify various non-atmospheric heavy noble gas components in the meteorites. Kr isotopic measurements define a solar-like atmospheric composition, but deviating from the solar wind pattern at 80Kr and 82Kr in a manner consistent with contributions originating from neutron capture in Br. The Xe measurements suggest an intriguing possibility that isotopes lighter than 132Xe have been enriched to varying degrees by spallation and neutron capture products degassed to the atmosphere from the regolith, and a model is constructed to explore this possibility. Such a spallation component, however, is not apparent in atmospheric Xe trapped in the glassy phases of martian meteorites.

BATCH CO-REGISTRATION OF MARS HIGH-RESOLUTION IMAGES TO HRSC MC11-E MOSAIC

Four NASA missions over the last forty years with onboard instruments for high-resolution orbital imaging have achieved both global coverage (with 6m CTX, 20m THEMIS-VIS and >8m Viking Orbiter cameras) as well as imaging with very high resolution in specific regions of interest (e.g. 25cm HiRISE and ≈1.5-12m MOC-NA cameras). Overall, this set of cameras have acquired more than 400,000 high-quality images of Mars with resolution between 25cm/pixel and 100m/pixel (Sidiropoulos and Muller, 2015). On the other hand, ESA has sent the only high-resolution stereo photogrammetric camera around Mars, HRSC onboard the Mars Express spacecraft, which has been mapping the Martian surface since 2004 with a resolution of 12.5 m/pixel (Jaumann et al., 2015). Initially the raw images are combined through an elaborate photogrammetric process to get (single-strip) 3D products (i.e. digital terrain models (DTMs) and derived orthorectified images (ORIs)). However, recently the processing chain has changed, and the single-strip product release was temporarily halted to be replaced by the production and release of mosaics of Mars quadrangles. The first product of this kind is the mosaic for the East part of quadrangle MC11 (i.e. the MC11-E mosaic), a product with 12.5 metres per pixel resolution in the panchromatic image and 50 metres per pixel resolution in the corresponding DTM (Gwinner et al., 2015). <br><br> Such a product provides an excellent basemap to co-register and orthorectify all NASA high-resolution (≤100m/pixel) orbital images. The need for this co-registration to HRSC comes from their poor areo-referencing, which often leads to large deviations (reaching up to several kilometres) between the area they are supposed to image and the area they are actually imaging. After co-registration, all products are projected onto an common 3D coordinate system, which allows an examination of dynamic features of Mars through the changes that happen on its surface. In this work, we present the results of the batch coregistration of all NASA high-resolution orbiter images of MC11-E, i.e. almost 8,000 images in total. This task was conducted with an in-house pipeline which was modified in order to handle the different parameters of the mosaic in comparison to single-strip HRSC products and to process the large input data volumes within a realistic time. An outline of the processing pipeline is given, along with examples of co-registered images and statistics of the co-registration performance. We demonstrate how such a time series representation of the surface will open up new areas for exploration and understanding of the Martian surface.

EU-FP7-iMARS: ANALYSIS OF MARS MULTI-RESOLUTION IMAGES USING AUTO-COREGISTRATION, DATA MINING AND CROWD SOURCE TECHNIQUES: PROCESSED RESULTS – A FIRST LOOK

Abstract. Understanding planetary atmosphere-surface exchange and extra-terrestrial-surface formation processes within our Solar System is one of the fundamental goals of planetary science research. There has been a revolution in planetary surface observations over the last 15 years, especially in 3D imaging of surface shape. This has led to the ability to overlay image data and derived information from different epochs, back in time to the mid 1970s, to examine changes through time, such as the recent discovery of mass movement, tracking inter-year seasonal changes and looking for occurrences of fresh craters. Within the EU FP-7 iMars project, we have developed a fully automated multi-resolution DTM processing chain, called the Coregistration ASP-Gotcha Optimised (CASP-GO), based on the open source NASA Ames Stereo Pipeline (ASP) [Tao et al., this conference], which is being applied to the production of planetwide DTMs and ORIs (OrthoRectified Images) from CTX and HiRISE. Alongside the production of individual strip CTX & HiRISE DTMs & ORIs, DLR [Gwinner et al., 2015] have processed HRSC mosaics of ORIs and DTMs for complete areas in a consistent manner using photogrammetric bundle block adjustment techniques. A novel automated co-registration and orthorectification chain has been developed by [Sidiropoulos & Muller, this conference]. Using the HRSC map products (both mosaics and orbital strips) as a map-base it is being applied to many of the 400,000 level-1 EDR images taken by the 4 NASA orbital cameras. In particular, the NASA Viking Orbiter camera (VO), Mars Orbiter Camera (MOC), Context Camera (CTX) as well as the High Resolution Imaging Science Experiment (HiRISE) back to 1976. A webGIS has been developed [van Gasselt et al., this conference] for displaying this time sequence of imagery and will be demonstrated showing an example from one of the HRSC quadrangle map-sheets. Automated quality control [Sidiropoulos & Muller, 2015] techniques are applied to screen for suitable images and these are extended to detect temporal changes in features on the surface such as mass movements, streaks, spiders, impact craters, CO2 geysers and Swiss Cheese terrain. For result verification these data mining techniques are then being employed within a citizen science project within the Zooniverse family. Examples of data mining and its verification will be presented.

BATCH CO-REGISTRATION OF MARS HIGH-RESOLUTION IMAGES TO HRSC MC11-E MOSAIC

Abstract. Four NASA missions over the last forty years with onboard instruments for high-resolution orbital imaging have achieved both global coverage (with 6m CTX, 20m THEMIS-VIS and >8m Viking Orbiter cameras) as well as imaging with very high resolution in specific regions of interest (e.g. 25cm HiRISE and ≈1.5-12m MOC-NA cameras). Overall, this set of cameras have acquired more than 400,000 high-quality images of Mars with resolution between 25cm/pixel and 100m/pixel (Sidiropoulos and Muller, 2015). On the other hand, ESA has sent the only high-resolution stereo photogrammetric camera around Mars, HRSC onboard the Mars Express spacecraft, which has been mapping the Martian surface since 2004 with a resolution of 12.5 m/pixel (Jaumann et al., 2015). Initially the raw images are combined through an elaborate photogrammetric process to get (single-strip) 3D products (i.e. digital terrain models (DTMs) and derived orthorectified images (ORIs)). However, recently the processing chain has changed, and the single-strip product release was temporarily halted to be replaced by the production and release of mosaics of Mars quadrangles. The first product of this kind is the mosaic for the East part of quadrangle MC11 (i.e. the MC11-E mosaic), a product with 12.5 metres per pixel resolution in the panchromatic image and 50 metres per pixel resolution in the corresponding DTM (Gwinner et al., 2015). Such a product provides an excellent basemap to co-register and orthorectify all NASA high-resolution (≤100m/pixel) orbital images. The need for this co-registration to HRSC comes from their poor areo-referencing, which often leads to large deviations (reaching up to several kilometres) between the area they are supposed to image and the area they are actually imaging. After co-registration, all products are projected onto an common 3D coordinate system, which allows an examination of dynamic features of Mars through the changes that happen on its surface. In this work, we present the results of the batch coregistration of all NASA high-resolution orbiter images of MC11-E, i.e. almost 8,000 images in total. This task was conducted with an in-house pipeline which was modified in order to handle the different parameters of the mosaic in comparison to single-strip HRSC products and to process the large input data volumes within a realistic time. An outline of the processing pipeline is given, along with examples of co-registered images and statistics of the co-registration performance. We demonstrate how such a time series representation of the surface will open up new areas for exploration and understanding of the Martian surface.

Nonlinear low frequency electrostatic structures in a magnetized two-component auroral plasma

Finite amplitude nonlinear ion-acoustic solitons, double layers, and supersolitons in a magnetized two-component plasma composed of adiabatic warm ions fluid and energetic nonthermal electrons are studied by employing the Sagdeev pseudopotential technique and assuming the charge neutrality condition at equilibrium. The model generates supersoliton structures at supersonic Mach numbers regime in addition to solitons and double layers, whereas in the unmagnetized two-component plasma case only, soliton and double layer solutions can be obtained. Further investigation revealed that wave obliqueness plays a critical role for the evolution of supersoliton structures in magnetized two-component plasmas. In addition, the effect of ion temperature and nonthermal energetic electron tends to decrease the speed of oscillation of the nonlinear electrostatic structures. The present theoretical results are compared with Viking satellite observations.

The Most Influential Scientists in the Development of Medical informatics (12): Joshua Lederberg.

JOSHUA LEDERBERG (1925–2008) Joshua Lederberg (May 23, 1925 - February 2, 2008) was an American molecular biologist known for his work in microbial genetics, artificial intelligence, and the United States space program. He was just 33 years old when he won the 1958 Nobel Prize in Physiology or Medicine for discovering about bacterial genetic information transfer. His father, Zvi Lederberg, was an orthodox rabbi; and his mother Esther a homemaker. Joshua felt drawn to science at an early age, stating in a homework assignment at age seven that his career aspiration was to become “like Einstein,” to “discover a few theories in science.” He graduated from Stuyvesant at the age of fifteen. At the Columbia University, his mentor Francis J. Ryan introduced him to the red bread mold, Neurospora, as an important new experimental system in the emerging field of biochemical genetics. In the United States Navy’s V-12 training program, he performed his military training duties and examined stool and blood specimen from malaria patients. After receiving his bachelor’s degree in zoology in 1944, he enrolled in Columbia University’s College of Physicians and Surgeons and continued to do his research. Lederberg carried out experiments with the intestinal bacterium Escherichia coli which demonstrated that certain strains of bacteria can undergo a sexual stage, that they mate and exchange genes. The most important of his discovery was the discovery of viral transduction, the ability of viruses that infect bacteria to transfer snippets of DNA from one infected bacterium to another and insert them into the latter’s genome. The use of viruses in manipulating bacterial genomes became the basis of genetic engineering in the 1970s. In the year 1958 he received a Nobel Prize in Physiology or Medicine, along with Tatum and George W. Beadle, “for his discoveries concerning genetic recombination and the organization of the genetic material of bacteria.” The launch of Sputnik in 1957 led Lederberg toward an interest in astronomy that lasted 20 years. His concern about the risk of spacecraft returning to Earth with contaminants from space resulted in a quarantine for space travel that remains in effect today. He went on to design experiments intended to detect the presence of life on Mars, resulting in the Mars Viking lander. Lederberg became increasingly aware of the value of computers. He formed collaborations with researchers at Stanford to create a program for analyzing mass-spectrometric data of molecular structures, called DENDRAL, which led to further programs for disease diagnosis and management. It was the first expert system for specialized use in science. Over the course of his life, Lederberg was elected to the National Academy of Sciences, the Institute of Medicine, received the National Medal of Science, was named an honorary life member of the New York Academy of Sciences, was awarded Foreign Membership of the Royal Society of London and holds the title of Commandeur, L’ordre des arts et des lettres in France. Lederberg published over 300 scientific and policy-related articles and was the editor of several books, including Papers in Microbial Genetics: Bacteria and Bacterial Viruses (1951), Emerging Infections: Microbial Threats to Health in the United States (1992), and Biological Weapons: Limiting the Threat (1999). His first marriage ended in divorce and he remarried Marguerite Stein Kirsch, a clinical psychologist, with whom he had two children. Following a battle with pneumonia, Lederberg passed away in New York in 2008 at the age of 82. Interesting facts: As a child, his idol was Einstein. He was a member of Royal Society of London for Improving Natural Knowledge. He studied how astronauts from Sputnik can contaminate Earth with space organisms - modern space quarantine. He invented first expert system for specialized use in science. He won a Nobel Prize at the age of 33.

The Boeing Milestones of Flight Hall, National Air and Space Museum, Smithsonian Institution

The Boeing Milestones of Flight Hall, National Air and Space Museum, Smithsonian Institution Matthew Hersch (bio) The bicentennial crowds that flocked to the grand opening of the Smithsonian Institution’s new National Air and Space Museum on the National Mall in Washington, D.C., needed no label cards to identify the holy relics before them. Like the medieval travelers who clogged the streets of Reims to prostrate themselves in the great cathedral, the Air and Space pilgrims of July 1976 knew exactly what they were going to see and needed little help in understanding it. Inside the striking stone and glass temple’s Milestones of Flight entrance atrium lay such treasures as the Wright Flyer, the Ryan NYP Spirit of St. Louis (the airplane that carried Charles Lindbergh across the Atlantic), and the diminutive Apollo 11 command module Columbia (its pilot, Michael Collins, loathed calling it a “capsule”) that, only seven years earlier, carried Commander Neil Armstrong, Collins, and lunar module pilot Buzz Aldrin to the moon and back. In a world abundant with dubious pieces of the One True Cross, these relics were undeniably real: irreplaceable flown artifacts lovingly restored, from Armstrong’s lunar vestments to the doubting finger of Edward White’s 1965 space suit glove. If that was not enough to satiate the appetite of the pious, Collins himself had stewarded the opening as the museum’s director. It was as if John the Baptist drove the bus on a Holy Land tour. I must confess: I was on that bus. Though too small to remember everything I saw, I was grandly amused by my first outing to what museum insiders call “NASM” shortly after it opened, as indeed, people of all ages continue to be when visiting a museum that was, until recently, the most trafficked in the world. Within a month of opening in 1976, the museum’s main building had received over a million visitors. A second large public [End Page 998] facility near Dulles Airport followed in 2003 as the National Air and Space Museum’s Steven F. Udvar Hazy-Center, presently home to space shuttle orbiter Discovery. In addition to displaying the technological heritage of the United States, though, NASM quickly emerged as the foremost center of scholarly research and public education in the history of aviation and spaceflight (as well as a prestigious site of research in earth and planetary sciences). Scarcely a single scholar in aerospace history has not benefited in some way from NASM’s generosity (myself included). Click for larger view View full resolution Fig. 1. Visitors enjoy the Boeing Milestones of Flight Hall on a hot July afternoon. At left, the flown Spirit of St. Louis is suspended over Project Apollo lunar module LM-2 (configured as Apollo 11’s Eagle). To its right, on the floor, are flown spacecraft Gemini IV and Mercury Friendship 7, followed by a Viking Mars lander. (Immediately above them hang Explorer 1 and Sputnik 1.) Hanging from the ceiling, from left to right, are Pioneer 10 and Mariner 2, the flown SpaceShipOne, and a flown X-15. Guests can touch an actual moon rock collected on the Apollo 17 mission at the kiosk on the bottom left. (Source: Photograph by author.) The decades have been kind to NASM’s main building on the mall but not, perhaps, to its famous physical edifice. Worn down by forty years and a total number of visitors roughly equal to the population of the United States, the main building is receiving an inside-out renovation that will replace (among other things) the structure’s famous marble façade and provide opportunities to re-curate galleries that, in some cases, date from the building’s opening in 1976. Chief among these is Milestones of Flight, [End Page 999] which houses some of the facility’s most famous artifacts spanning the history of flight, mounted and suspended from the ceiling like an airshow in a particularly amazing science fiction movie. In 2016, and with financial support from Boeing, Milestones reopened to visitors. This thoughtful and skillful refresh confronts directly the foremost challenge facing NASM in the twenty-first century: telling the history of explorations almost as remote...

The Corporation: The Pathological Pursuit of Profit and Power, Joel Bakan (Toronto: Viking Canada, 2004)

No Abstract

Obliquely propagating ion-acoustic solitons and supersolitons in four-component auroral plasmas

Arbitrary amplitude nonlinear low frequency electrostatic soliton and supersoliton structures are studied in magnetized four-component auroral plasmas composed of a cold singly charged oxygen-ion fluid, Boltzmann distribution of hot protons and two distinct group of electron species. Using the Sagdeev pseudo-potential technique, the characteristics of obliquely propagating nonlinear structures are investigated analytically and numerically. The model supports the evolution of soliton and supersoliton structures in the auroral acceleration region. Depending on the parametric region, the positive and negative potential solitons coexists at lower Mach numbers, but at higher Mach numbers only negative potential solitons and supersolitons can exist. The presence of hot protons restricted the Mach number of the nonlinear structures to exist only at the subsonic region. The present investigation concurs with the Swedish Viking satellite observations in the auroral region.

Simulation and Spacecraft Design: Engineering Mars Landings.

A key issue in history of technology that has received little attention is the use of simulation in engineering design. This article explores the use of both mechanical and numerical simulation in the design of the Mars atmospheric entry phases of the Viking and Mars Pathfinder missions to argue that engineers used both kinds of simulation to develop knowledge of their designs' likely behavior in the poorly known environment of Mars. Each kind of simulation could be used as a warrant of the other's fidelity, in an iterative process of knowledge construction.

Effect of excess superthermal hot electrons on finite amplitude ion-acoustic solitons and supersolitons in a magnetized auroral plasma

The effect of excess superthermal electrons is investigated on finite amplitude nonlinear ion-acoustic waves in a magnetized auroral plasma. The plasma model consists of a cold ion fluid, Boltzmann distribution of cool electrons, and kappa distributed hot electron species. The model predicts the evolution of negative potential solitons and supersolitons at subsonic Mach numbers region, whereas, in the case of Cairn's nonthermal distribution model for the hot electron species studied earlier, they can exist both in the subsonic and supersonic Mach number regimes. For the dayside auroral parameters, the model generates the super-acoustic electric field amplitude, speed, width, and pulse duration of about 18 mV/m, 25.4 km/s, 663 m, and 26 ms, respectively, which is in the range of the Viking spacecraft measurements.

Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System’s most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet’s upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform Boundary. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which was then completely submerged under a primordial northern plains ocean. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

Viking 1 launched

Viking 1 launched

Modeling the effects of martian surface frost on ice table depth

Ground ice has been observed in small fresh craters in the vicinity of the Viking 2 lander site (48°N, 134°E). To explain these observations, current models for ground ice invoke levels of atmospheric water of 20 precipitable micrometers – higher than observations. However, surface frost has been observed at the Viking 2 site and surface water frost and snow have been shown to have a stabilizing effect on Antarctic subsurface ice. A snow or frost cover provides a source of humidity that should reduce the water vapor gradient and hence retard the sublimation loss from subsurface ice. We have modeled this effect for the Viking 2 landing site with combined ground ice and surface frost models. Our model is driven by atmospheric output fields from the NASA Ames Mars General Circulation Model (MGCM). Our modeling results show that the inclusion of a thin seasonal frost layer, present for a duration similar to that observed by the Viking Lander 2, produces ice table depths that are significantly shallower than a model that omits surface frost. When a maximum frost albedo of 0.35 was permitted, seasonal frost is present in our model from Ls=182° to Ls=16°, resulting in an ice table depth of 64cm – which is 24cm shallower than the frost-free scenario. The computed ice table depth is only slightly sensitive to the assumed maximum frost albedo or thickness in the model.

Fiber cell development and fiber yield of flax (Linum usitatissimum L.) affected by the seasonal temperature pattern

Du, G.-H., Liu, F.-H. and Rowland, G. 2015. Fiber cell development and fiber yield of flax (Linum usitatissimum L.) affected by the seasonal temperature pattern. Can. J. Plant Sci. 95: 1215-1220. Three fiber flax cultivars ‘Ariane’, ‘Argos’ and ‘Viking’ were cultured in growth chambers under three seasonal temperature patterns (STPs) [parabolic (P), anti-parabolic (AP) and quasi-horizontal (QH) configurations]. The effect of STP was studied on fiber cell development and on fiber yield. The results indicated that, compared with the quasi-horizontal seasonal temperature pattern (QH-STP), the size of fiber cell cavity (SFCC) and fiber content (FC) decreased under parabolic seasonal temperature pattern (P-STP). However, the size of fiber cell (SFC) and SFCC decreased, but the number of fiber cells per bundle (NFCB) increased under anti-parabolic seasonal temperature pattern (AP-STP). Moreover, there was a significant positive correlation between fiber weight (FW) and width of fiber bundle (WFB), also between ...

Comment on Liquid Water and Life on Mars

The announcement this week of the detection of liquid water on Mars has come close on 4 decades after the arrival of the first Viking landers at the red planet in 1976 [1]. The temperatures at the two original landing sites of the Viking spacecraft in 1976 ranged between a high of -31°C and a low of -84°C, so no liquid water would have persisted at the surface. The Viking probes had also carried out in situ biological tests of Martian soil, the so-called Labeled Release Experiment, where an isotope-labeled nutrient was applied to the soil to test for the presence of microbial life [2]. An astoundingly positive result for the uptake of the nutrient and hence extant life was obtained; but it was quickly rejected on grounds of alleged uncertainties of interpretation, as well as the lack of organic molecules detectable at the landing site. A year later, in1977, a major dust storm enveloped the planet and H. Abadi and the present writer reported evidence of absorption properties of the Martian dust that was consistent with the presence of aromatic hydrocarbons [3]. In 2012 a careful reexamination of all the Viking results of 1976 led to the conclusion that a positive detection of microbial life on Mars may have been obtained at the time [4]. This is a position that Gil Levin has firmly held and defended against all his critics (Figure 1).

Chemistry and physics of extraterrestrial life

Planetary Science Is there life on other planets? To answer this question, scientists must first determine what makes a planet habitable. Mars provides a natural laboratory to explore this question. In a Perspective, Conrad explains that, starting with the Viking landers in 1976, numerous missions to Mars have attempted to determine whether the planet could support life—or was able to do so in the past. Mobile rovers have explored the surface, aided by orbiters and, most recently, have been equipped with the tools to dig below the surface. By interrogating the chemical and physical conditions both now and in the past, these missions may soon be able to provide a more definitive answer. Science , this issue p. [1288][1] [1]: /lookup/volpage/346/1288?iss=6215

The location of Airy‐0, the Mars prime meridian reference, from stereo photogrammetric processing of THEMIS IR imaging and digital elevation data

AbstractThe small crater Airy‐0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses in the year 2000 tied Viking Orbiter and Mars Orbiter Camera images of Airy‐0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to update the location of Airy‐0. Based upon this tie and radiometric tracking of landers/rovers from Earth, new expressions for the Mars spin axis direction, spin rate, and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Since the Mars Global Surveyor mission and Mars Orbiter Laser Altimeter global digital terrain model were completed some time ago, a more exhaustive study has been performed to determine the accuracy of the Airy‐0 location and orientation of Mars at the standard epoch. Thermal Emission Imaging System (THEMIS) IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image processing techniques. The Airy‐0 location was determined to be about 0.001° east of its predicted location using the currently defined International Astronomical Union (IAU) prime meridian location. Information on this new location and how it was derived will be provided to the NASA Mars Exploration Program Geodesy and Cartography Working Group for their assessment. This NASA group will make a recommendation to the IAU Working Group on Cartographic Coordinates and Rotational Elements to update the expression for the Mars spin axis direction, spin rate, and prime meridian location.

On Mars too expect macroweather

AbstractTerrestrial atmospheric and oceanic spectra show drastic transitions at τw ≈ 10 days and τow ≈ 1 year, respectively; this has been theorized as the lifetime of planetary‐scale structures. For wind and temperature, the forms of the low‐ and high‐frequency parts of the spectra (macroweather and weather) as well as the τw can be theoretically estimated, the latter depending notably on the solar‐induced turbulent energy flux. We extend the theory to other planets and test it using Viking lander and reanalysis data from Mars. When the Martian spectra are scaled by the theoretical amount, they agree very well with their terrestrial atmospheric counterparts. We discuss the implications for understanding planetary fluid dynamical systems.