To compare alien planets, Dr. Mendez at the Planetary Habitability Laboratory and his colleagues are creating an Earth Similarity Index that ranks worlds by their resemblance to our own planet, on a scale from zero to one, based on their mass, radius, density and surface temperature.

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Its delivery method is based on a well-characterized, FDA approved biodegradable chemical platform called PLGA. The company's nanoparticles incorporate a high density of attachment sites on their surface, enabling them to carry out multiple functions--like targeting tumors, enhancing diagnostic images, treating diseased tissue or concealing the whole package from the body's natural defenses.

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Due to its high density, a person would generally be expected to remain on the surface.

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