They determined it's predominantly H2O that exists on the lunar surface, rather than hydroxyl. In the first study, scientists examined the moon's face in infrared, zeroing in on the source of the chemical signature in exquisite clarity. On Monday, two studies, published in the journal Nature Astronomy, rewrite the moon water story once again. The discoveries in 2009 led scientists to suspect much of the moon's "water" was hydroxyl, because it's more thermally stable than molecular water. Scientists couldn't pull apart the chemical signature to definitively say how much was "molecular" water, the stuff we know as H2O, and how much was hydroxyl, a molecule that's one hydrogen atom short of becoming water (OH). Our moon wasn't soaking, but it was damp. The spacecraft picked up the telltale chemical signature of water. Data collected by the robotic travelers indicated Earth's only natural satellite was not a dry, dusty desert as we'd long believed. on 9 October 1992, had a very shallow flight-path angle that closely mimicked that of a human-made object.Eleven years ago, a trio of spacecraft changed our view of the moon forever. There are also examples of meteors lasting tens of seconds in duration. For example, the Peekskill meteorite, which reentered over the Eastern U.S. An example of this was seen during the reentry of the WT1190F spacecraft on 13 November 2015. human-made object rule-of-thumb doesn’t work. This occurs when the speed or flight-path angle of the object in question mimics values that are more typical for objects in the opposite category.įor instance, a human-made space object might reenter the atmosphere at a steep enough angle causing its reentry to last a much shorter duration than most reentries. More meteor entry videos, as seen from the ground: This video taken by ESA from an observation aircraft shows a close up view of the ATV-1 spacecraft reentering over the Pacific Ocean after completing its ISS resupply mission. If there seems to be a single object, or it appears to explode, then it might be a bolide meteor.If the object is moving extremely fast, and the event is gone in a flash or a few seconds, then it is very probably a meteor.If there appear to be a tight cluster of bright points all moving in the same direction at similar speeds, and all leaving streaks behind them, then it is very probably a reentry breakup.If an object moves slowly and steadily across the sky at a speed similar to how a fast aircraft would move, and it is trailing a long glowing streak behind it, it is probably a reentry.So, how can you tell the difference? The general rule-of-thumb is that natural meteor reentries happen quickly and typically last less than a few seconds while human-made reentries happen slowly, and typically can last 20 – 90 seconds or more. However, meteors usually come from natural debris left over from the formation of the solar system and are typically in orbit about the sun. As the Earth swings around the sun, it encounters meteors as it sweeps through space at 30 km/sec, or 67,000 miles per hour. These meteors can hit the Earth at all angles and from all directions, and only occasionally appear to be moving parallel to the ground. Meteors are often seen near dusk, when the sky overhead is facing the leading edge of our motion around the sun. Meteor showers can appear to radiate from a particular point in the sky (e.g. The images were taken from a plane sent to watch and record data externally, while the REBR collected data internally. This was the reentry of ATV-6, which had an Aerospace REBR on-board. Still images from a high definition TV camera on one of the aircraft taking part in the Jules Verne ATV re-entry observation campaign.
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