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Three-dimensional surface templates are being used to identify and locate landmarks on Mars and Phobos. They can be aligned both with images and the MOLA map to help tie these two data types together. The Martian templates form a control network of well-defined and easily identified landmarks.
Initial mapping of Mars began with the early Mariner 4, 6 and 7 flybys in the 1960's. Mariner 9 obtained the first global coverage of Mars in 1971. Viking Orbiters 1 and 2 added new and higher resolution global coverage. The US Geological Survey produced the first digital global cartographic map products in black and white and in color, the mosaicked digital image models (MDIMs). In 1989, the Phobos 88 mission added imaging as well as multispectral mapping of Mars in the equatorial region. The Mars Global Surveyor (MGS) added to the black and white and color global coverage. The most important development for Mars cartography occurred on MGS with its global coverage of Mars using the Mars Observer Laser Altimeter (MOL A) producing precision ground control in latitude, longitude and radius. The next version of the MDIM was produced at 230 m spatial resolution using MOLA precision cartographic control. The Mars Odyssey mission THEMIS instrument has completed its global infrared mapping of Mars at 100 m spatial resolution. The Mars Express mission is completing its global coverage of Mars in stereo at 100 m spatial resolution or better. MGS, Odyssey and Mars Express continue to provide limited surface coverage at the 1 to 20 m resolution. Currently the new Mars Reconnaissance Orbiter is producing images at the 10's of cm level. All of these datasets provide a rich and historic perspective of Mars covering nearly five decades and allow global cartographic map products to be produced in visual and infrared at the 100 m level with specialized cartographic maps being produced for landing sites at the meter or sub-meter spatial resolution level. This work was produced at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration, NAS 7-7120.5d, within the NASA Mars Data Analysis Program and the MGS, Odyssey, Mars Express and MRO Participating Scientist Programs.
We study the condensation of CO2 in Mars atmosphere using temperature profilesretrieved from radio occultation measurements from Mars Global Surveyor (MGS) as wellas the climate sounding instrument onboard the Mars Reconnaissance Orbiter (MRO),and detection of reflective clouds by the MGS Mars Orbiter Laser Altimeter (MOLA). Wefind 11 events in 1999 where MGS temperature profiles indicate CO2 condensation andMOLA simultaneously detects reflective clouds. We thus provide causal evidence thatMOLA non-ground returns are associated with CO2 condensation, which strongly indicatestheir nature being CO2 clouds. The MGS and MRO temperature profiles together revealthe seasonal expansion and shrinking of the area and the vertical extent of atmosphericsaturation. The occurrence rate of atmospheric saturation is maximized at high latitudes inthe middle of winter. The atmospheric saturation in the northern polar region exhibits moreintense seasonal variation than in the southern polar region. In particular, a shrinking ofsaturation area and thickness from LS 270 to 300 in 2007 is found; this is probablyrelated to a planet-encircling dust storm. Furthermore, we integrate the condensation areaand the condensation occurrence rate to estimate cumulative masses of CO2 condensatesdeposited onto the northern and southern seasonal polar caps. The precipitation flux isapproximated by the particle settling flux which is estimated using the impulse responses ofMOLA filter channels. With our approach, the total atmospheric condensation mass canbe estimated from these observational data sets with average particle size as the onlyfree parameter. By comparison with the seasonal polar cap masses inferred from thetime-varying gravity of Mars, our estimates indicate that the average condensate particleradius is 822 mm in the northern hemisphere and 413 mm in the southern hemisphere.Our multi-instrument data analysis provides new constraints on modeling the global climateof Mars.
The primary objective of the Geologic Remote Sensing Field Experiment (GRSFE) is to acquire relevant data for geological sites that can be used to test models for extraction of surface property information from remote sensing data for earth, Mars and Venus in support of the Earth Observing System (EOS), Mars Observer, and Magellan, respectively. Over forty scientists from eight universities and three NASA centers are participating in GRSFE which is co-sponsored by the NASA Planetary Geology and Geophysics Program and the NASA Geology Program. Highlights of the airborne campaign included the first simultaneous acquisition of Airborne Visible and Infrared Imaging Spectrometer (AVRIS) and Thermal Infrared Multispectral Scanner (TIMS) data on September 29, 1989, and acquisition of Advanced Solid-State Array Spectroradiometer (ASAS), Polarimetric Synthetic Aperture Radar (AIRSAR), and Airborne Terrain Laser Altimeter System (ATLAS) data all within three months of each other. The sites covered were Lunar Crater Volcanic Field and Fish Lake Valley in Nevada; and Cima Volcanic Field, Death Valley, and Ubehebe Crater in California. Coincident field measurements included meteorological and atmospheric measurements, visible/near-infrared and thermal spectra, and characterization of geology and vegetation cover. The GRSFE airborne and field data will be reduced to a suite of standard products and submitted, along with appropriate documentation, to the Planetary Data System (PDS) and the Pilot Land Data System (PLDS). These data will be used for a variety of investigations including paleoclimatic studies in the arid southwestern United States, and analysis of Magellan data. GRSFE data will also be used to support Mars Observer Laser Altimeter (MOLA) and Mars Rover Sample Return (MRSR) simulation studies.
Design and performance data for two laser transmitters for spaceborne laser ranging are presented. The first laser uses a master oscillator/power amplifier configuration consisting of a diode pumped Nd:YAG slab ring and a multipass diode pumped slab amplifier which can operate at 40 Hz for more than ten to the ninth shots. The other laser is a diode pumped Nd:YAG slab standing wave oscillator which operates at 10 Hz for more than 0.6 x 10 exp 9 shots. The lasers were specifically developed for reliability, for use in space exploitation of the Earth and nearby planets. Applications include planetary altimetry of Mars (MOLA) and Earth (GLRS), as well as space geodesy, navigation, and tracking.
Laser altimeters measure the time of flight of the laser pulses to determine the range of the target. The simplest altimeter receiver consists of a photodetector followed by a leading edge detector. A time interval unit (TIU) measures the time from the transmitted laser pulse to the leading edge of the received pulse as it crosses a preset threshold. However, the ranging error of this simple detection scheme depends on the received, pulse amplitude, pulse shape, and the threshold. In practice, the pulse shape and the amplitude are determined by the target target characteristics which has to be assumed unknown prior to the measurement. The ranging error can be improved if one also measures the pulse width and use the average of the leading and trailing edges (half pulse width) as the pulse arrival time. The ranging error becomes independent of the received pulse amplitude and the pulse width as long as the pulse shape is symmetric. The pulse width also gives the slope of the target. The ultimate detection scheme is to digitize the received waveform and calculate the centroid as the pulse arrival time. The centroid detection always gives unbiased measurement even for asymmetric pulses. In this report, we analyze the laser altimeter ranging errors for these three detection schemes using the Mars Orbital Laser Altimeter (MOLA) as an example.
The objective of this study was to support the rebuild and implementation of the Mars Orbiter Laser Altimeter (MOLA) investigation and to perform scientific analysis of current Mars data relevant to the investigation. The instrument is part of the payload of the NASA Mars Global Surveyor (MGS) mission. The instrument is a rebuild of the Mars Observer Laser Altimeter that was originally flown on the ill-fated Mars Observer mission. The instrument is currently in orbit around Mars and has so far returned remarkable data.
The objective of this study was to support the rebuild and implementation of the Mars Orbiter Laser Aftimeter (MOLA) investigation and to perform scientific analysis of current Mars data relevant to the future investigation. The instrument is part of the payload of the NASA Mars Global Surveyor (MGS) mission. The instrument is a rebuild of the Mars Observer Laser Altimeter that was originally flown on the ill-fated Mars Observer mission.
Surface lidar techniques are now being demonstrated in low Earth orbit with a single beam of pulsed laser radiation at 1064 nm that profiles the vertical structure of Earth surface landforms along the nadir track of a spacecraft. In addition, a profiling laser altimeter, called MOLA, is operating in elliptical Martian orbit and returning surface topography data. These instruments form the basis for suggesting an improved lidar instrument that employs multiple beams for extension of sensor capabilities toward the goal of true, 3-dimensional mapping of the Moon or other similar planetary surfaces. In general the lidar waveform acquired with digitization of a laser echo can be used for laser distance measurement (i.e. range-to-the-surface) by time-of-flight measurement and for surface slope and shape measurements by examining the detailed lidar waveform. This is particularly effective when the intended target is the lunar surface or another planetary body free of any atmosphere. The width of the distorted return pulse is a first order measure of the surface incidence angle, a combination of surface slope and laser beam pointing. Assuming an independent and absolute (with respect to inertial space) measurement of laser beam pointing on the spacecraft, it is possible to derive a surface slope with-respect-to the mean planetary surface or its equipotential gravity surface. Higher-order laser pulse distortions can be interpreted in terms of the vertical relief of the surface or reflectivity variations within the area of the laser beam footprint on the surface.
The north polar residual ice deposits of mars are thought to be relatively young, based on the reported lack of any fresh impact craters in Viking Orbiter images. A handful of possible impact features were identified, but available data were inconclusive. Determining the number and current topographic characteristics of any craters on the polar residual ice surface is important in constraining the surface age, relative importance of polar cap resurfacing processes and ice flow dynamics, and the role of the cap deposits in the global volatile and climate cycles. Subsequent image processing advances and new Mars Orbiter Laser Altimeter (MOLA) data in the north polar region are now a considerable aid in impact feature identification. This study reconsiders the abundant Viking high-resolution polar images along with the new altimetry data. We examine possible impact features, compare their topography with known mars high-latitude impact features, and use their morphology as a constraint on crater modification processes.
Layered deposits and residual polar caps on Mars may record the deposition of ice and sediment modulated by periodic climate change. Topographic information relating to layer thicknesses, erosional processes, and formation of dark spirals within these deposits has been sparce or unreliable until the arrival of MOLA in orbit in September 1997. To assist in evaluating these terrains prior to launch and to assess formation and erosion processes in the polar deposits, we have assembled Viking stereo mosaics of the region and have produced the first reliable DEM models of the south polar deposits using automated stereogrammetry tools. Here we report our preliminary topographic results, pending final image pointing updates. The maximum total thickness of the layered deposits in the south polar region is 2.5 km. The thick layered deposits consist of a series of megaterraces. Each terrace is several tens of kilometers wide and is flat or slopes very gently toward the pole. These terraces step downward from a central plateau near the south pole. Terraces are bounded by relatively steep scarps 100-500 meters high that face toward the equator. These scarps correspond to the pattern of dark spirals observed within the residual cap in southern summer, and are interpreted as ice or frost-free surfaces warmed by solar insolation. Several tongue-shaped troughs, with rounded cirquelike heads, are observed near the margins of the deposit. These troughs are 300-600 meters in deep and may be similar to troughs observed in the northern polar deposit.
The Mars Orbiter Laser Altimeter (MOLA) is an instrument on the Mars Global Surveyor (MGS) spacecraft that is currently providing the first high vertical and spatial resolution topographic measurements of surface elevations on Mars. The shot size in the mapping orbit is about 100 m and the shot-to-shot spacing is 330 m. The instrument has a vertical precision of 37.5 cm and a vertical accuracy that depends on the radial accuracy of the MGS orbit that is currently in the range 5-30 km. The initial focus on observations in the nominal mapping mission will be on the southern hemisphere, which was not sampled during the MGS aerobraking hiatus and Science Phasing orbits. During the first several weeks of global mapping there will be emphasis on producing a digital terrain model (DTM) of the Mars '98 landing site.
The Shuttle Laser Altimeter (SLA) is a Hitchhiker experiment that has flown twice; first on STS-72 in January 1996 and then on STS-85 in August 1997. Both missions produced successful laser altimetry and surface lidar data products from approximately 80 hours per mission of SLA data operations. A total of four Shuttle missions are planned for the SLA series. This paper documents SLA mission results and explains SLA pathfinder accomplishments at the mid-point in this series of Hitchhiker missions. The overall objective of the SLA mission series is the transition of the Goddard Space Flight Center airborne laser altimeter and lidar technology to low Earth orbit as a pathfinder for NASA operational space-based laser remote sensing devices. Future laser altimeter sensors will utilize systems and approaches being tested with SLA, including the Multi-Beam Laser Altimeter (MBLA) and the Geoscience Laser Altimeter System (GLAS). MBLA is the land and vegetation laser sensor for the NASA Earth System Sciences Pathfinder Vegetation Canopy Lidar (VCL) Mission, and GLAS is the Earth Observing System facility instrument on the Ice, Cloud, and Land Elevation Satellite (ICESat). The Mars Orbiting Laser Altimeter, now well into a multi-year mapping mission at the red planet, is also directly benefiting from SLA data analysis methods, just as SLA benefited from MOLA spare parts and instrument technology experience [5] during SLA construction in the early 1990s.
Cosmos 49, Polar Orbit Geophysical Observatory (POGO) (Orbiting Geophysical Observatory (OGO-2, 4 and 6)) and Magsat have been the only low-earth orbiting satellites to measure the crustal magnetic field on a global scale. These missions revealed the presence of long- wavelength (> 500 km) crustal anomalies predominantly located over continents. Ground based methods were, for the most part, unable to record these very large-scale features; no doubt due to the problems of assembling continental scale maps from numerous smaller surveys acquired over many years. Questions arose as to the source and nature of these long-wave length anomalies. As a result there was a great stimulant given to the study of the magnetic properties of the lower crust and upper mantle. Some indication as to the nature of these deep sources has been provided by the recent results from the deep crustal drilling programs. In addition, the mechanism of magnetization, induced or remanent, was largely unknown. For computational ease these anomalies were considered to result solely from induced magnetization. However, recent results from Mars Orbiter Laser Altimeter (MOLA), a magnetometer-bearing mission to Mars, have revealed crustal anomalies with dimensions similar to the largest anomalies on Earth. These Martian features could only have been produced by remanent magnetization, since Mars lacks an inducing field. The origin of long-wavelength crustal anomalies, however, has not been completely determined. Several large crustal magnetic anomalies (e.g., Bangui, Kursk, Kiruna and Central Europe) will be discussed and the role of future satellite magnetometer missions (Orsted, SUNSAT and Champ) in their interpretation evaluated.
Tracking of the MGS spacecraft in orbit at Mars by the Deep Space Network since last September has provided doppler and range measurements that are being used to improve the model of the Mars gravity field. During most of October 1997, April 1998, and June thru August 1998 high quality tracking data were obtained while the periapse was in the northern hemisphere at altitudes in the 170 to 190 km range. The eccentric orbit had a period of about 11.5 hrs and an inclination of about 96.2 degrees so that low altitude tracking was obtained over most of the northern hemisphere, including the north polar icecap. Data from the earlier Mariner 9 and Viking missions have been added to the MGS data and a series of experimental gravity models developed from the combined datasets. These models have generally been of degree and order 70 and are a significant improvement over earlier models that did not include the MGS data. Gravity anomalies over the north polar cap region of Mars are generally less than 50 to 100 mgals and show no obvious correlation with the topography. Successive MGS orbits derived using these new models are showing agreement at the 100 meter level, and this has been confirmed with the laser altimeter (MOLA) on MGS These comparisons are expected to improve significantly as more tracking data get included in the solution and the MGS orbit becomes more circular giving a more balanced geographical distribution of data at low altitude. This will happen early in 1999 as the orbit approaches the mapping configuration of a circular orbit at about 400 Km.
Laser altimeter data and microwave tracking of the MGS (Mars Global Surveyor) spacecraft have been used to estimate rotation parameters for Mars. With the recent development of new high resolution gravity models for Mars and the determination of the orbit of the MGS spacecraft to the few meter level it has become possible to obtain rotational information about the planet. Perturbations of the spacecraft orbit by the planet's gravity field permit the gravity field to be estimated from the tracking data. But the perturbations arising from the non-zonal components of the gravity field have a periodicity related to the rotation of Mars on its axis and these perturbations enable the rotation rate and direction of the rotation pole in inertial space to be measured with respect to the orbit of the spacecraft. It is the anomalies in the gravity field that permit these parameters to be obtained. Similarly, altimetry data are sensitive to errors in the orbital altitude at orbital cross-over locations and the locations themselves are a function of the rotation of the planet. Thus, altimetric measurements by MOLA provide a geometric constraint on the rotation of the planet through the timing of the orbital cross-over pattern as well as information that improves the orbit determination. For a few months in 1999 MGS tracking and altimetry data have been used in a preliminary experiment to estimate the rotation rate of Mars and the right ascension and declination of the pole from an orbiting spacecraft. These preliminary results appear to have sufficient accuracy to permit detection of seasonal changes in rotation rate and also precession of the pole thus leading to a possible eventual measurement of the moment of inertia.
After a long period of aerobraking, Mars Global Surveyor entered a low altitude, near-circular and polar orbit about Mars on February 4, 1999. Since that time, the spacecraft has been tracked routinely by the antennae of the Deep Space Network (DSN). The X band tracking data for the first time provide us: with uniform low-altitude coverage over the entire planet. In terms of both quality and geographic distribution, these data supersede the S Band tracking obtained by the Viking Orbiters and Mariner 9. We have used all available tracking obtained by Mars Global Surveyor to determine improved models; of the Man geopotential to 70 x 70 in spherical harmonies. The new models provide an order of magnitude improvement in both accuracy and detail. For instance, the Valles Marimeris canyon system clearly appears in the gravity anomaly maps: with the new model. In this paper, we discuss the derivation of these new models, and we evaluate their performance in terms of observed features and orbit quality. We also discuss the use of altimeter data from the Mars Orbiter Laser Altimeter (MOLA) in the form of altimeter crossovers, and how these data can contribute to the determination of geopotential models for Mars.
Previous studies of channels associated with Argyre Planitia are compared with the recent MOLA topography. Argyre and the channels flowing into and out from it comprise the longest fluvial system in the solar system.