OSIRIS-REx Contamination Control Strategy and Implementation.

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm2 of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.

Chronic dieting and the belief that smoking controls body weight in a biracial, population-based adolescent sample.

OBJECTIVE: To evaluate the prevalence of weight concerns and smoking for body weight reasons as a function of race and gender. DESIGN: A questionnaire measuring a number of factors thought to be predictive of smoking was administered. SETTING: The Memphis (Tennessee) school system. PARTICIPANTS: Participants were 6961 seventh-grade students (mean age 13 years). This population consisted of 80.8% black children, 16.5% white children, and 2.7% of other ethnic origins. MAIN OUTCOME MEASURES: Weight concerns were assessed using items from a restraint scale. Students were questioned regarding their smoking status, beliefs that smoking controls body weight, and their own weight-control smoking behaviour. RESULTS: Dietary restraint interacted with race in that, whereas white girls scored the highest on dietary restraint, black boys scored higher on dietary restraint than white boys. Almost 40% of subjects at this school level believed that smoking controls their body weight. Of the regular smokers, 12% indicated they have smoked to control their weight, with white girls endorsing this belief significantly more than other respondents. CONCLUSIONS: The propensity to smoke for weight control reasons, previously described by other researchers among white females of college and high-school age, was also found among this sample of students of junior high school age.