Ancient aqueous environments at Endeavour crater, Mars.

Opportunity has investigated in detail rocks on the rim of the Noachian age Endeavour crater, where orbital spectral reflectance signatures indicate the presence of Fe(+3)-rich smectites. The signatures are associated with fine-grained, layered rocks containing spherules of diagenetic or impact origin. The layered rocks are overlain by breccias, and both units are cut by calcium sulfate veins precipitated from fluids that circulated after the Endeavour impact. Compositional data for fractures in the layered rocks suggest formation of Al-rich smectites by aqueous leaching. Evidence is thus preserved for water-rock interactions before and after the impact, with aqueous environments of slightly acidic to circum-neutral pH that would have been more favorable for prebiotic chemistry and microorganisms than those recorded by younger sulfate-rich rocks at Meridiani Planum.

Pancam multispectral imaging results from the Opportunity Rover at Meridiani Planum.

Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity during the mission. Astronomical observations captured solar transits by Phobos and Deimos and time-lapse observations of sunsets.

Localization and physical property experiments conducted by Opportunity at Meridiani Planum.

The location of the Opportunity landing site was determined to better than 10-m absolute accuracy from analyses of radio tracking data. We determined Rover locations during traverses with an error as small as several centimeters using engineering telemetry and overlapping images. Topographic profiles generated from rover data show that the plains are very smooth from meter- to centimeter-length scales, consistent with analyses of orbital observations. Solar cell output decreased because of the deposition of airborne dust on the panels. The lack of dust-covered surfaces on Meridiani Planum indicates that high velocity winds must remove this material on a continuing basis. The low mechanical strength of the evaporitic rocks as determined from grinding experiments, and the abundance of coarse-grained surface particles argue for differential erosion of Meridiani Planum.

Pancam multispectral imaging results from the Spirit Rover at Gusev Crater.

Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.

Localization and physical properties experiments conducted by Spirit at Gusev Crater.

The precise location and relative elevation of Spirit during its traverses from the Columbia Memorial station to Bonneville crater were determined with bundle-adjusted retrievals from rover wheel turns, suspension and tilt angles, and overlapping images. Physical properties experiments show a decrease of 0.2% per Mars solar day in solar cell output resulting from deposition of airborne dust, cohesive soil-like deposits in plains and hollows, bright and dark rock coatings, and relatively weak volcanic rocks of basaltic composition. Volcanic, impact, aeolian, and water-related processes produced the encountered landforms and materials.

Relationship between the neuroses and brief reactive psychosis: descriptive case studies in Africa.

Predominant psychopathology in a selected population group--adolescents and young adults at school--in a developing country, is described. The highly selective referral to services was supplemented by active case finding in the community over three years. There were 54 cases of somaticised anxiety (brain fag); 22 cases of depressive neurosis characterised by hypochondriasis, cognitive complaints, and culturally determined paranoid ideation; 23 cases of 'hysteria' in the form of dissociative states, pseudoseizures and fugues; and 39 cases of brief reactive psychosis which differed from the dissociative states more in duration and intensity than in form. There was a temporal relationship between transient psychosis and the school calendar. Anxiety or depression often predated the florid psychotic reaction which served as a form of help-seeking behaviour or defence in intolerable stress.

Brief reactive psychosis and the major functional psychoses: descriptive case studies in Africa.

In a three-year prospective study of service-based incidence of functional psychoses in Africa, 94 cases of brief reactive psychosis were compared with 56 cases of schizophreniform syndromes, 29 cases of DSM-III schizophrenia and 14 of manic-depressive psychosis. This was supplemented by retrospective study of the same syndromes not in their first episode. Brief reactive psychosis was found to be a composite syndrome. The 50% with preceding depression were a distinct group, in terms of course and demographic features. Of those with intense prodromal anxiety, most were a single episode precipitated by a major life event, a few showed a recurrent long-term pattern. Schizophrenia was heralded, or presented unequivocally months or years later, in 10-20%. The schizophreniform group comprised a range of atypical psychoses intermediate between the transient and major psychoses. The pattern of precipitants and the over-representation of education and paid employment in the acute syndromes, compared with the major psychoses, in a society which was largely first-generation educated, suggested a link with rapid social change.

Profile and prevalence of the brain fag syndrome: psychiatric morbidity in school populations in Africa.

The profile and prevalence of a syndrome of somaticised anxiety associated with education in Africa was explored by survey of 2040 senior secondary school students in different types of school: rural, urban, and elite. Response to two different screening methods, an open question to elicit symptoms spontaneously, and the SRQ-24, was compared. Symptom prevalence was higher in rural schools, 34%, than periurban, 22%, and elite, 6%, but the central urban school serving a shanty town was also high at 35%. Three categories of the culturally relevant symptoms were identified--somatic, cognitive and 'spiritual'--with affective symptoms sparsely represented in the cultural idiom. The SRQ-24 items screening for psychosis were associated with a range of spontaneous symptoms representing anxiety. This 'spiritual' expression of neurosis reflects the world views and beliefs of the culture. Intensification under stress could produce the picture of transient reactive psychosis.

Social origins of the brain fag syndrome.

The aetiology of psychiatric morbidity associated with education in Africa was explored using two different screening methods (as described in paper III, this supplement). The interactive effect of psychosocial variables was examined by Log linear analysis which demonstrated five independent factors: (a) the financial implications of education which represented the change from subsistence to cash economy; (b) fear of envy and bewitchment which represented the intense cultural response to education; (c) parenting in the pre-school years which was the independent family variable; (d) academic ability; (e) attributes of the school. Age of starting school and birth rank had a marginal effect. Current family adversity in terms of unstable parental union, paternal use of alcohol, polygamy and sibship size operated by interactive or additive effect. Gender and social status had no effect. The brain fag syndrome can be related to the complex social changes during rapid social transition where education is a major agent of change.

Three Mars years: viking lander 1 imaging observations.

The Mutch Memorial Station (Viking Lander 1) on Mars acquired imaging and meteorological data over a period of 2245 martian days (3:3 martian years). This article discusses the deposition and erosion of thin deposits (ten to hundreds of micrometers) of bright red dust associated with global dust storms, and the removal of centimeter amounts of material in selected areas during a dust storm late in the third winter. Atmospheric pressure data acquired during the period of intense erosion imply that baroclinic disturbances and strong diurnal solar tidal heating combined to produce strong winds. Erosion occurred principally in areas where soil cohesion was reduced by earlier surface sampler activities. Except for redistribution of thin layers of materials, the surface appears to be remarkably stable, perhaps because of cohesion of the undisturbed surface material.

One Mars year: viking lander imaging observations.

Throughout the complete Mars year during which they have been on the planet, the imaging systems aboard the two Viking landers have documented a variety of surface changes. Surface condensates, consisting of both solid H(2)O and CO(2), formed at the Viking 2 lander site during the winter. Additional observations suggest that surface erosion rates due to dust redistribution may be substantially less than those predicted on the basis of pre-Viking observations. The Viking 1 lander will continue to acquire and transmit a predetermined sequence of imaging and meteorology data as long as it is operative.

The surface of Mars: the view from the viking 2 lander.

Viking 2 lander began imaging the surface of Mars at Utopia Planitia on 3 September 1976. The surface is a boulder-strewn reddish desert cut by troughs that probably form a polygonal network. A plateau can be seen to the east of the spacecraft, which for the most probable lander location is approximately the direction of a tongue of ejecta from the crater Mie. Boulders at the lander 2 site are generally more vesicular than those near lander i. Fines at both lander sites appear to be very fine-grained and to be bound in a duricrust. The pinkish color of the sky, similar to that observed at the lander I site, indicates suspension of surface material. However, the atmospheric optical depth is less than that at the lander I site. After dissipation of a cloud of dust stirred during landing, no changes other than those stemming from sampling activities have been detected in the landscape. No signs of large organisms are apparent at either landing site.