But SOFIE provided a new kind of data that, when cross-checked with other analyses, could offer a more precise number. Scientists had so far disagreed how much cosmic material makes its way to into Earth’s atmosphere each day, with estimates ranging from two to more than 200 tons. Scientists used SOFIE’s data to create the first long-term, space-based survey of meteoric smoke, revealing that it contains mostly iron, oxygen, silicon, and magnesium. A few of the wavelengths are used to detect meteoric smoke. SOFIE can detect a variety of gases, including carbon dioxide and ozone, as well as aerosols - tiny solid or liquid particles suspended in the air. Plugging those intensity measurements into models, researchers can determine which atoms or molecules are present in the atmosphere. SOFIE measures the intensity of particular wavelengths of light at different altitudes in the atmosphere. The First Surveyįrom its orbit, SOFIE stares through Earth’s atmosphere at the Sun, inferring information about the atmosphere by measuring the sunlight that passes through it. NASA’s Solar Occultation for Ice Experiment (SOFIE), which launched onboard NASA’s Aeronomy of Ice in the Mesosphere (AIM) satellite in 2007, was the first instrument up to the task. They looked at tiny pieces of these space objects in polar ice cores and on urban rooftops, but they couldn’t reliably measure smoke in the atmosphere. Researchers also made guesses about the smoke’s composition by analyzing meteorites, fragments of meteors that arrived on Earth. The data they did collect were difficult to interpret. Previously, they tried to do so using suborbital rockets, but the instruments only had a few minutes to collect data before falling back to Earth. What the smoke is made of, how much of it there is, and what role it plays in the atmosphere are all questions scientists have been working to answer. Scientists had long predicted that meteoric smoke existed in Earth’s middle atmosphere, but at one-thousandth the width of a human hair, these high-altitude particles are difficult to study. The particles stick to each other and grow like tiny snowballs as they fall to Earth over several years. About 55 miles above Earth, the miniscule fireballs leave a puff of even tinier particles, called meteoric smoke. Produced when asteroids collide or comets are vaporized by the Sun, some of this material burns up when it enters the atmosphere, just like the Geminids but on a much smaller scale. What we can’t see with the naked eye is the steady rain of much smaller meteoroids, often called cosmic dust, that bombards our atmosphere every day of the year.
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