Viking 1 Lander on the surface of mars: Revised location

Late in 1977, the periapsis altitude of the Viking Orbiters was lowered from 1500 to 300 km. The higher resolution of pictures taken at the lower altitude (8 m/pixel) permitted a more accurate determination of the location of the Viking 1 Lander by correlating topographic features seen in the new pictures with the same features in lander pictures. The position of the lander on Viking Orbiter picture 452B11 (NGF Rectilinear) is line 293, sample 1099. This location of the Viking 1 Lander has been used in a revision of the control net of Mars (M.E. Davies, F.Y. Katayama, and J.A. Roth, R2309 NASA, The Rand Corp., Feb. 1978). The new areographic coordinates of the lander are lat 22.483° N and long 47.968° W. The new location is estimated to be accurate to within 50 m.     

Horizon Topography and the Location Of Viking Lander 2

The location of Viking Lander 2 on Mars is determined by matching features seen on the horizon with hills visible in Viking Orbiter images. Three possible positions are found, with one being preferred, confirming and refining the position determined previously by radio tracking. The often stated opinion that a lobe of ejecta from the large crater Mie is visible in lander images is shown to be false. The most prominent hill on the eastern horizonis Goldstone, a pedestal crater 8 km from the lander. Another hill16 km from the preferred position is just visible to the north. The image processing procedures used to enhance visibility of low relief features on the horizon should be useful for several future missions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mirages on Mars

The possibility of observing mirages on Mars from the Viking lander cameras is examined. A simple model for the production of both inferior and superior mirages is developed. Assuming the atmospheric index of refraction to be a linear function of density (i.e., temperature), ray curvatures are calculated through layers of large, expected thermal gradient.Assuming the Martian morning inversions of Gierasch and Goody (1968), calculations of ray curvature show the superior mirage to be an unlikely occurrence on Mars since the downward curvature of the ray through the inversion layer is less than the downward curvature of the planet. In order to examine the nature of inferior mirages we select a reasonable expression for temperature profile in the surface layer fitted to the midafternoon, midlatitude summer results of Gierasch and Goody. Integration of the expression for ray curvature yields a relation for the minimum distance between the lander cameras and an inferior mirage as a function of the surface superadiabatic lapse rate. Such calculations indicate that the Viking lander cameras will record inferior mirages at horizontal distances of a kilometer or so from the lander. Given the appearance of an inferior mirage at a measured minimum distance from the observer it should be a simple matter to calculate the corresponding mean temperature lapse rate at the surface.     

Are the Viking Lander sites representative of the surface of Mars?

Global remote-sensing observations of Mars are compared with remote-sensing observations of the two Viking Lander site regions and with orbiter and lander imaging of the sites. The lander sites do not fit most of the global trends of remote-sensing data. The presence of a duricrust in the top meter of the surface is inferred for most regions of high thermal inertia, although the duricrust is thinner at the lander sites than elsewhere. Regions of low thermal inertia are covered by greater than several centimeters of unconsolidated dust. A thin, microns-thick layer of bright dust appears at the surface at the lander sites, and these locations may be regions of incipient formation of low thermal inertia. The lander sites are intermediate in structure between classical bright and dark regions, and are distinctive from most of the rest of the planet.     

Study of Mars dynamics from lander tracking data analysis

After the touchdown of the two Viking landers on Mars, radio tracking measurements have been performed between them and Earth-based stations. With use of the first 9 months of data, we have improved the rotation rate and the mean orientation of the spin axis of Mars, referred to its mean orbit. For the first time, some nutations terms have also been estimated. Nevertheless the precise determination of the spin axis motion will require additional data collected during the extended mission. Our solution includes also the lander locations and the relativistic parameter .Paper presented at the European Workshop on Planetary Sciences, Organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.     

Beagle-2 position determination from the returned camera panoramas using MOLA data

After the Beagle-2 lander of the Mars Express mission comes to rest on the surface of Isidis Planitia in late December 2003 to carry out a range of geochemistry and exobiology experiments, there will be considerable interest in determining its exact location. This work considers the feasibility of identifying topographic features seen in the Mars Global Surveyor MOLA dataset in images of the horizon returned by the lander, and the probability of observing lesser features identifiable in orbital imagery. By taking bearings from such features, and attempting to match the configuration back to the available data, it may be possible to determine the spacecraft's position with high precision. Since the MOLA data is fairly coarse compared to the area of the landing ellipse, the range of visibility and likelihood of observation of each of the resolved craters in the area is considered. For the more numerous smaller craters and many small knobs a probabilistic view is taken.     

Crater streaks in the Chryse Planitia region of Mars: Early Viking results

High-resolution images of Chryse Planitia and eastern Lunae Planum from the early revolutions of Viking Orbiter I permit detailed analyses of crater-associated streaks and interpretation of related eolian processes. A total of 614 light and dark streaks were studied and treated statistically in relation to: (1) morphology, morphometry, and orientation, (2) “parent” crater size and morphology, (3) terrain type in which they occured, (4) topographic elevation, and (5) meteorological data currently being acquired by Viking Lander I. Three factors are apparent: (1) light streaks predominate, (2) most streaks form in association with fresh bowl-shaped craters, and (3) most light streaks are of the “parallel” type, whereas dark streaks are approximately evenly divided between convergent and parallel forms; moreover, very few light or dark streaks are divergent or fan-shaped. Light streaks have an average azimuth of 218° (corresponding to winds from the northeast), which approximates the orientation of 197 ± 14° for eolian “drifts” observed by the Viking Lander imaging team (Binder et al., 1977). This lends support to the hypothesis that light streaks are deposits of windblown sediments. Dark streaks are oriented at an azimuth of 42° (approximately opposite that of light streaks) and are nearly in line with the dominant wind direction currently recorded by the Viking meteorology instruments (Hess et al., 1977). Although the size of the sample area is not uniform among the various terrain types, the highest frequency of streaks per unit area occurs in the knobby terrain. This is partly explained by the probable production of fine-grained material (weathered from the knobs) to form streaks and other eolian features, and the higher wind turbulence generated around the knobs. The lowest frequency of streaks occurs on the elevated plateaus. The light streaks in Chryse Planitia appear to be relatively stable and to result from deposition of windblown material during times of relatively high velocity northeasterly winds. Dark streaks are more variable and probably result from erosion by southwesterly winds. Both types will be monitored during the extended Viking mission and the results compared with lander data.     

Advanced Russian Mission <Emphasis Type="Italic">Laplace-P</Emphasis> to Study the Planetary System of Jupiter: Scientific Goals,Objectives, Special Features and Mission Profile

The advanced Russian project Laplace-P is aimed at developing and launching two scientific spacecraft (SC)—Laplace-P1 (LP1 SC) and Laplace-P2 (LP2 SC)—designed for remote and in-situ studies of the system of Jupiter and its moon Ganymede. The LP1 and LP2 spacecraft carry an orbiter and a lander onboard, respectively. One of the orbiter’s objectives is to map the surface of Ganymede from the artificial satellite’s orbit and to acquire the data for the landing site selection. The main objective of the lander is to carry out in-situ investigations of Ganymede’s surface. The paper describes the scientific goals and objectives of the mission, its special features, and the LP1 and LP2 mission profiles during all of the phases—from the launch to the landing on the surface of Ganymede.     

Characterization of rock populations on planetary surfaces: Techniques and a preliminary analysis of Mars and Venus

Characteristics of rock populations on the surfaces of Mars and Venus can be derived from analyses of rock morphology and morphometry data. We present measurements of rock sizes and sphericities made from Viking lander images using an interactive digital image display system. The rocks considered are in the gravel size range (16–256 mm in diameter). Mean sphericities, form ratios, and roundness factors are found to be very similar for both Viking lander sites. Size distributions, however, demonstrate differences between the sites; there are significantly more cobble size fragments at VL-2 than at VL-1. A model calling for aphanitic basalts emplaced as ejecta or lava flows at the Viking sites is supported by the rock shape, size, and roundness data.Morphologic features pertaining to the modification history of a rock are considered for Mars and Venus. A multi-parameter clustering algorithm is utilized to objectively categorize martian and venusian rocks in terms of various criteria. Erosional markings such as flutes are demonstrated to be most important in separating VL-1 rock morphologic groups, while rock form (i.e., shape) represents the primary separator of subpopulations at VL-2 and the Venera landing sites. Fillets are common around VL-1 and Venera 10 fragments. Obstacle scours occur frequently only at VL-1. Cavities in rocks are ubiquitous at all lander sites except Venera 9. Eolian processes, possibly assisted by local solution weathering, are a strong candidate for the origin of cavities and flutes in martian rocks.     

Analysis of condensates formed at the viking 2 lander site: The first winter

A thin light-colored ground covering appeared on the surface of Mars near the Viking 2 lander from L_s = 230° to L_s = 16°, a total of 249 Mars days, during the lander's first winter on the surface. This paper presents a reduction of applicable lander imagery during the period. Imaging sequences, relative surface albedo, spectral reflectance estimates, and limited photometric data are presented and compared with previous laboratory measurements. Photometric data are best fit by an average Minnaert k = 1.1 (blue), k = 1.0 (green), and k = 0.95 (red). Appearance and disappearance rates, spectral reflectance, and photometric data all tend to confirm an earlier proposal that the covering was a combination of H₂O and CO₂, which fell already condensed onto dust particles brought northward by the season's first major dust storm. Under this assumption, the covering thickness is estimated to be between 0.5 and a few millimeters.     

Distribution and time-variation of spire streaks at Pavonis Mons on Mars

We documented the distribution and the time-variation of the specific dark wind streaks at Pavonis Mons. We focused on the streaks we named “Spire Streaks”, which are overlapping spindle shaped dark streaks at the upper boundary of the coalesced dark streaks on Tharsis volcanoes. We investigated both visible and infrared images obtained by Viking orbiter camera, Mars Orbiter Camera (MOC), THEMIS, CTX and HiRISE of the spire streaks at Pavonis Mons. We also used topographic data obtained by Mars Orbiter Laser Altimeter (MOLA) to see the relationship between the topography and the distribution of the spire streaks. The spire streaks at Pavonis Mons provide us high-resolution information about the direction of the nighttime slope wind, and could be indirect clues for the time-variation of the nighttime environment. We conclude that the spire streaks are erosional features. However, some features of the spire streaks reported in this paper are outside the scope of previous modeling for erosional process, and we need a new category of model for the formation.     

The Temperature Regime of the Surface Layer of the Phobos Regolith in the Region of the Potential Fobos–Grunt Space Station Landing Site

Because of the absence of the atmosphere, the short duration of the Phobos day (7.7 hours), and the presence of a highly porous and fine-grained soil on the Phobos surface, all components of the future Russian Fobos–Grunt lander will operate under frequent and sharp temperature changes: from positive to extremely low negative temperatures. As a consequence, information about the temperature regime directly on the surface of the Martian satellite and in the near-surface layer appears to be extremely important. The proposed publication contains both the information about the thermophysical properties of the surface regolith of Phobos, derived from observations made with the Mariner 9 orbiter, the Viking orbiter, the Fobos-2 spacecraft, and the Mars Global Surveyor orbiter, and the results of the numerical modeling of the thermal regime of the surface regolith layer (on diurnal and seasonal time scales) in the area of the potential Fobos–Grunt landing site. We performed this modeling by taking into account the seasons on Mars and the effects due to the eclipse of Phobos by Mars.     

Recession of Martian north polar cap: 1979–1980 Viking observations

The 1979–1980 regression curve for the north polar cap of Mars, determined from Viking orbiter images, is compared to Viking observations of the same season 1 (Martin) year earlier and to telescopic observations. Differences between the two years cannot unambigously be attributed to dynamical effects because of uncertainties introduced by limited longitudinal coverage.     

Biological experiments: The viking Mars lander

Biological interest in the exploration of Mars is briefly described as is the biological experiments package to be flown as part of the Viking 1975 lander payload.     

Mars and Earth: Comparison of cold-climate features

On Earth, glacial and periglacial features are common in areas of cold climate. On Mars, the temperature of the present-day surface is appropriate for permafrost, and the presence of water is suspected from data relating to the outgassing of the planet, from remote-sensing measurements over the polar caps and elsewhere on the Martian surface, and from recognition of fluvial morphological features such as channels. These observations and the possibility that ice could be in equilibrium with the atmosphere in the high latitudes north and south of ±40° latitude suggest that glacial and periglacial features should exist on the planet. Morphological studies based mainly on Viking pictures indicate many features that can be attributed to the action of ice. Among these features are extensive talus aprons; debris avalanches; flows that resemble glaciers or rock glaciers; ridges that look like moraines; various types of patterned ground, scalloped scarps, and chaotically collapsed terrain that could be attributed to thermokarst processes; and landforms that may reflect the interaction of volcanism and ice.     

Coordinates of features on the mariner 6 and 7 pictures of Mars

A control net of Mars has been computed from measurements of 115 control points identified on the Mariner 6 and 7 pictures. Most of these points are located with respect to topographic features on the surface of Mars, and their areographic coordinates were computed by photogrammetric techniques. These pictures offered the first opportunity to establish a control net of Mars based on topographic detail.     

The prospects for life on Mars: A pre-Viking assessment

Mariner 9 has provided a refutation or reinterpretation of several historical claims for Martian biology, and has permitted an important further characterization of the environmental constraints on possible Martian organisms. Four classes of conceivable Martian organisms are identified, depending on the environmental temperature, T, and water activity, a_w: Class I, high T, high a_w; Class II, low T, high a_w; Class III, high T, low a_w; and Class IV, low T, low a_w. The Viking lander biology experiments are essentially oriented toward Class I organisms, although arguments are given for the conceivable presence on Mars of organisms in any of the four classes. Organisms which extract their water requirements from hydrated minerals or from ice are considered possible on Mars, and the high ultraviolet flux and low oxygen partial pressure are considered to be negligible impediments to Martian biology. Large organisms, possibly detectable by the Viking lander cameras, are not only possible on Mars; they may be favored. The surface distribution of Martian organisms and future search strategies for life on Mars are discussed.     

A varying cosmological term as a link between cosmology and microphysics

The Weinberg relation (which connects the Hubble constantH to the mass of a typical elementary particle) is an empirical relation hitherto unexplained. I suggest an explanation based on the Zel'dovich energy tensor of vacuum in a Robertson-Walker universe with constant deceleration parameter,q = const. This model leads to

1. the Weinberg relation,
2. a varying cosmological term Λ scaling asH ²,
3. a varying gravitational constantG scaling asH,
4. a matter creation process throughout the universe at the rate 10^?47 g s^?1 cm³,
5. a deceleration parameter in the range -1 to 1/2, which allows a horizon-free universe and makes the lawG/H = constant, consistent with the Viking lander data on the orbit of planet Mars.

     

Harmakhis Vallis Source Region,Mars: Insights into the recent geothermal history based on geological mapping

The mapped area of Harmakhis Vallis, at the eastern Hellas Planitia region (35°30–42°50′S; 91°00–97°30′E), covers the surface area of about 212,000 km². The region displays an enhanced modification of the initial topography formed by the Hellas impact. The long and complex history of degradation and alteration involves mass-wasting processes, volcanism and fluvial activity, confronting effects of climate-induced slow mass-wasting processes to effects caused by temporary, catastrophic events (impact cratering, volcanism, etc.). Geological mapping at scale of 1:1,500,000 (full scale at 1:540,000) have been carried out on multiple co-registered data sets available from the past and ongoing orbiter missions to Mars. The mapped geomorphic features of small- and medium-scales reveal in detail events that shaped the topography of the region throughout history, providing specific constraints on the geologic and climatic history of the region. This study highlights events from the most recent Martian history, including fluvial activity recorded in relation to a debris apron flanking Centauri Montes, and evidence of recent positive geothermal anomalies of a high heat-flux with relatively small spatial extents, on the timescale of several million years ago.