RESUMEN
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.
RESUMEN
A patient with an infected atrial myxoma presented with clinical findings simulating bacterial endocarditis. The diagnosis was made with echocardiography, thus demonstrating the value of this rapid, noninvasive screening test. A ruptured mycotic aneurysm in the brain precluded early surgical excision of the tumor. The rapid evolution of this case to a fatal outcome underscores the need for prompt diagnosis.