The controversy about color Mars lander image calibration, begun in 1976 during the Viking mission, continues with the 2004 Spirit and Opportunity missions. Officially released color images at web site "Photojournal.JPL.NASA.Gov" continue to show wide variation. Two sets of filters are used by NASA to produce color images from Spirit. One conventional set of red, green and blue filters has been used for images of the calibration chart alone and small pieces of the soil. Another set of infra-red, green and blue filters is used for larger panoramic images. While most objects in the Martian scene are not affected by this change, the appearance of the color calibration chart changes drastically. An extreme example of this can be found in the comparison of the blue color panel using the two different sets of filters. When the blue panel is seen in the panorama images, it appears to be bright red. Small blue wire ties on the rover also appear to be bright red in the panoramas. NASA claims that the blue color panel is unusually reflective in the near infra-red. This makes inspection of the color balance more difficult and many problems exist in published "true color" images. This paper will round up this and other issues involving Spirit color image calibration.
Correct color calibration of images sent from Mars is essential to their usefulness in providing mineralogical, geochemical, chemical and, possibly, biological information. This paper demonstrates the impact of correct calibration on the Viking Mission images. The color charts imaged by the Viking Landers are compared to the color chart on the duplicate Viking Lander at the Smithsonian. When the R, G and B levels obtained from the gray panels are aligned, good agreement is found with the Martian red color panel. The B and G color panels in the Viking image "raw data" as published, however, appear greatly dissimilar to the actual panels viewed on Earth. An excess of red is found on all of the Martian blue and green panels. Limits on the multiplicative intensity properties are derived showing that only extreme red illumination could change the Martian B and G color charts so dramatically. Such extreme illuminations are shown to be incompatible with the gray panels. It appears that the true raw image data have been modified prior to publication to convert the blue and green pixels to gray, rendering a grossly changed image.
Key to the possibility of Martian biology is the availability of liquid water. The issue hinges on the physics of water under an atmosphere whose total pressure is only slightly higher than the triple point of water. The general consensus, that liquid water cannot exist on the Martian surface, was first challenged in 1998. This paper offers a more detailed analysis.
While orbital images from Mariner 9 onward have shown evidence of ancient water flows, recent Global Surveyor and Odyssey orbiters have produced images of apparently active erosion. The 1997 Pathfinder Lander measured surface atmospheric temperatures well above freezing, while temperatures one meter higher were as low as -40° C. The low vapor capacity of the atmosphere just above the surface acts as a lid, or barrier, to evaporation. This could allow ice to melt into liquid water instead of subliming to vapor. In 2000, in a demonstration made in a simulated Martian environment, water ice melted and remained liquid. However, many questions have been raised about the physics of this experiment. In this paper, numerical simulation provides values for the thermodynamic quantities controlling the phase of water. The binary diffusion coefficient of water vapor in CO2, and the law of binary gas diffusion are applied. Fluxes of water vapor under Martian conditions, including wind speeds, are calculated for various distances from surface ice sources. Evaporative heat loss is compared to the heat available from the sun. The paper provides the theoretical, if counterintuitive, basis for the existence of liquid water on the present Martian surface.
The field of moving target Automated Target Recognition (ATR) relies on the exploitation of one-dimensional high range resolution (HRR) profiles. Individual profiles can contain a large amount of target information; however, the evidence from one profile is generally not sufficient to reliably classify a Ground Moving Target Indicator (GMTI) target. When multiple looks are correctly combined, classification accuracy can improve dramatically. At X-band, HRR profiles of typical ground vehicles decorrelate for aspect angle changes greater than 0.1 degree, thus, all looks in a practical system are independent. From the ATR perspective, the challenge is one of correctly associating HRR profiles from one look to the next. If the problem is examined from the opposite point of view, the ATR evidence can greatly improve the association accuracy of a tracker above and beyond that of kinematics. This ATR information assists tracking in regimes of high traffic density or low revisit rates through better association of the high-value targets from one epoch to the next. In this paper, we present a new HRR-aided tracker. The performance of this tracker will be characterized in a simulation and compared to the performance of a purely kinematic tracker. These results show that HRR-aided tracking can tolerate at least an order of magnitude higher traffic density than trackers functioning on kinematics alone. This improvement in performance is reduced, but not eliminated, if the additional radar resources for HRR are considered.
Many objections have been raised to challenge a biological interpretation of the 1976 Viking Mission Labeled Release (LR) life detection experiment on Mars. Over the years, they have dwindled in the face of the failure of experiments and theories to demonstrate a nonbiological alternative. Recently, NASA's chief scientist, responding to the rapidly accumulating knowledge about life in extreme environments, reduce the remaining obstacles to a single one: the lack of liquid water. A model is consistent with the thermodynamics of the triple point of water. Viking and Pathfinder meteorological data are congruent with the model, as are Viking Lander images of deposits of water ice-frost and snow on the ground. The amounts of soil moisture predicted by the model are within the moisture content range of terrestrial soils in which the LR detected living microorganisms. The last objection to a biological interpretation of the LR Mars data is thus met. Consequential recommendations for the near-term planetary program are made.
A new image processing system, MRIPS/MEDx, is being deployed at NIH to facilitate the visualization and analysis of multidimensional images and spectra obtained from different radiological imaging modalities.