![]() ![]() The isotope microscope we discuss here, an instrument for imaging isotope distributions in solid surfaces, implements just such a technique-and is an invaluable tool for unearthing buried treasures. The development of analogous techniques for visualizing isotope ratios would enable the detection of exotic substances masquerading as pebbles of conventional matter in blended samples-substances that may be indistinguishable from conventional substances by shape or color, and may be of arbitrary size and elemental compositions, their exotic natures revealed only by the isotope ratio. The method of X-ray elemental mapping is widely used to visualize the elemental composition of electronmicroscope samples. The upshot is that, by combining quantities of oxygen and silicon at specific temperatures and pressures, we can create substances whose elemental compositions precisely match those of substances originating in outer space-and which, moreover, retain characteristic “scars” encoding the trajectory along which their isotopic composition evolved over time, making them difficult to counterfeit. When the steam cools and reverts to the liquid phase, the history of the evaporation process remains encoded in the distribution of light isotopes. Oxygen ( 16O, 17O, 18O) give rise to slight variations in the velocity and chemical bonding activity of water molecules, with the consequence that the lightest molecules (H 2 16O) preferentially evaporate to form steam, while the water remaining in the kettle grows heavier-with an isotope ratio ( 17O/ 16O : 18O/ 16O) of roughly (1:2), corresponding to the ratio of mass differences between the numerator and denominator. For example, when we boil water in a standard household kettle, the mass differences between the three isotopes of On the other hand, distinct isotopes of a given element have largely identical chemical properties, whereupon variations in isotope ratios offer straightforward indications of mass differences. The distinct chemical properties of the oxygen, silicon, and other elements present in the pebbles give rise to a wide variety of elemental compositions and proportions depending on temperature, pressure, and other environmental conditions. Eventually, the explosion of the star sent dust clouds of atoms streaming through space, where- influenced by phenomena such as gravitational contraction and collision-mergers between celestial bodies-they underwent evaporation, melting, solidification, and other physiochemical processes, eventually coming to rest by the side of that road on our Earth. But this appearance is deceiving, for a typical pebble has the remarkable property that almost every one of its atoms was created before the formation of our solar system in the interior of a distant star via the process known as nucleosynthesis. In this article, we discuss the use of isotope microscopy as a tool for analyzing solar-system formation via isotope analysis of extraplanetary matter.Īn ordinary pebble-found, perhaps, by the side of a road-may appear at first glance to hold no particular mysteries. To this end, we have used an instrument known as an isotope microscope (Figure 1) to analyze several samples of extraplanetary origin-including meteorites, sand from the surface of the Moon retrieved by Apollo astronauts, and samples from the Itokawa asteroid retrieved by Japan’s Hayabusa space probe-with the goal of understanding the evolution of matter and the formation of our solar system 1-4). Apollo program, has evolved into an arena of vigorous economic competition among a crowded field of players, including both nations-large and small-and corporations meanwhile, the unabashed pursuit of rocket technology by the world’s wealthiest individuals has accelerated the pace of development so dramatically that the once-unimaginable prospect of human life in space may well become a reality within the present generation.Īs we set our sights on new heavenly horizons, precisely what sorts of new destinations will we encounter? When we discover new planets, what will they be made of? Will there be water-and air? What useful resources will be available? In planning and deploying resource-reconnaissance missions and protocols to investigate these questions in new extraplanetary arenas, it will be of great benefit not only to understand the chemical compositions and physical properties of target destinations, but also to develop insight into the large-scale mechanisms governing their formation. The exploration of theĬosmos, once the exclusive province of large-scale national initiatives such as the U.S. Today we find ourselves at the dawn of a grand new era of adventure and discovery in space.
0 Comments
Leave a Reply. |