- 3526 - MOON - rocket crash on the Moon, On March 4, 2022, a spent rocket booster will smack into the surface of the Moon at nearly 6,000 mph. Once the dust has settled, NASA’s Lunar Reconnaissance Orbiter will move into position to get an up-close view of the smoldering crater and hopefully shed some light on the mysterious physics of planetary impacts. At least on Moon impacts.
--------------------- 3526 - MOON - rocket crash on the Moon
- The Moon has been a steadfast witness to solar system history, its heavily cratered surface recording innumerable collisions over the last 4 billion years. Scientists rarely get a glimpse of the projectiles, asteroids, or comets that form these craters.
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- The upcoming rocket impact will provide a fortuitous experiment that could reveal a lot about how natural collisions pummel and scour planetary surfaces. A deeper understanding of impact physics will go a long way in helping researchers interpret the barren landscape of the Moon and also the effects impacts have on Earth and other planets.
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- The rocket is expected to crash into the large Hertzsprung crater just out of view of Earth on the far side of the Moon. Astronomers know that the object is an upper stage booster discarded from a high-altitude satellite launch. It is roughly 40 feet long and weighs nearly 10,000 pounds. Evidence suggests that it is likely either a SpaceX rocket launched in 2015 or a Chinese rocket launched in 2014, but both parties have denied ownership.
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- An instant after the rocket touches the lunar surface, a shock wave will travel up the length of the projectile at several miles per second. Within milliseconds, the back end of the rocket hull will be obliterated with bits of metal exploding in all directions.
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- A twin shock wave will travel downward into the powdery top layer of the Moon’s surface called the regolith. The compression of the impact will heat up the dust and rocks and generate a white-hot flash that would be visible from space if there happened to be a craft in the area at the time.
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- A cloud of vaporized rock and metal will expand from the impact point as dust, and sand-sized particles will be thrown skyward. Over the course of several minutes, the ejected material will rain back down to the surface around the now-smoldering crater. Virtually nothing will remain of the rocket.
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- NASA performed a similar experiment in 2009 when it intentionally crashed the Lunar Crater Observation and Sensing Satellite, or LCROSS, into a permanently shadowed crater near the lunar south pole.
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- By studying the composition of the dust plume lofted into the sunlight, scientists were able to find signs of a few hundred pounds of water ice that had been liberated from the Moon’s surface by the impact. This was a crucial piece of evidence to support the idea that for billions of years, comets have been delivering water and organic compounds to the Moon when they crash on its surface.
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- However, the LCROSS rocket’s crater is permanently obscured by shadows. This impact crater will not be visible from Earth, so scientists will rely on photos from the Lunar Reconnaissance Orbiter.
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- Since the impact is going to occur on the far side of the Moon, it will be out of view for Earth-based telescopes. But about two weeks after the impact, NASA’s Lunar Reconnaissance Orbiter will begin to get glimpses of the crater as its orbit takes it above the impact zone.
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- Once conditions are right, the lunar orbiter’s camera will start taking photos of the impact site with a resolution of about a 3 feet per pixel. The shape of the crater and ejected dust and rocks will hopefully reveal how the rocket was oriented at the moment of impact.
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- A vertical orientation will produce a more circular feature, whereas an asymmetric debris pattern might indicate more of a belly flop. Models suggest that the crater could be anywhere from around 30 to 100 feet in diameter and about 6 to 10 feet deep.
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- Unlike the moon surrounding Earth is a powerful magnetic field created by swirling liquid iron in the planet’s core. Earth’s magnetic field may be nearly as old as the Earth itself and stands in stark contrast to the Moon, which completely lacks a magnetic field today.
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- In the 1980s, geophysicists studying rocks brought back by Apollo astronauts concluded the Moon once had a magnetic field that was as strong as Earth’s. But a robust magnetic field requires a power source, and the Moon’s core is relatively small.
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- Scientists found that the Moon did not in fact have a long-lived magnetic field. Not only does this finding change the modern understanding of the Moon’s geologic history, it also has major implications for the presence of resources on the Moon that could be critical to future human exploration.
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- Certain rocks have the extraordinary ability to preserve records of past magnetic fields when they contain minerals with iron atoms that align with a magnetic field as the rock cools and solidifies. The best magnetic minerals at preserving evidence of a field are tiny, a thousand times smaller than the width of a human hair, because it takes a lot of energy to rearrange their atoms.
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- Geophysicists who study ancient magnetism recreate this process, reheating rock samples in the presence of known magnetic fields and comparing the new alignment of the iron atoms with the orientation of iron atoms before the rock was reheated. This allows researchers to learn about past magnetic fields.
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- Early researchers studying the first rocks brought back from the Moon by U.S. astronauts wanted to use this method to study the Moon’s magnetism. But they faced problems. Lunar rocks contain a certain type of iron, called native iron, that is easily altered by heat. Additionally, the native iron grains in lunar rocks are sometimes relatively large, making them less likely to reliably record past magnetic fields.
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- From the 1970s onward, geophysicists used alternative, nonheating methods to study the Moon’s magnetism. They found that some lunar samples had recorded strong magnetic fields, suggesting that the Moon had a magnetic field for over 2 billion years.
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- But this result only deepened the conundrum. The question of how the Moon’s core could produce a strong magnetic field remained unsolved. In the experiments, some Apollo samples showed evidence of strong magnetic fields but other samples did not. Some researchers attributed the missing magnetization to the presence of large native iron grains that were poor magnetic recorders. But many of the samples also contained small iron grains that should have recorded a field.
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- In 2011, scientists used an ultrasensitive superconducting magnetometer and a special carbon dioxide laser to rapidly heat samples in a way that avoids altering their iron minerals. We found that nearly all the rocks had profoundly weak magnetic signals.
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- So what explains the previous findings of a magnetic Moon? The answer was in one of the samples: a small, dark piece of glass containing tiny iron-nickel particles. This small piece of lunar glass was formed and magnetized by a meteorite impact and could explain the strong magnetic readings from the past.
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- The glass was made by a meteorite impact and showed clear evidence of a strong magnetic field. But it was formed only about 2 million years ago. Nearly all geophysicists agree the Moon did not have a magnetic field at that time, because after 4.5 billion years of cooling there was not enough heat left to power the churning of iron in the Moon’s core to generate a field.
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- The magnetic signature of the glass matched simulations of magnetic fields that can be generated by meteor impacts. This showed that meteorite impacts alone can create strong magnetic fields that magnetize rocks nearby. This could explain the high values previously reported from some Apollo rocks.
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- This new view of lunar magnetism has huge implications for the potential presence of valuable resources as well as information about the ancient Sun and Earth that may be buried in lunar soils.
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- Magnetic fields act as shields that prevent solar particles from reaching a planet or moon. Without a magnetic field, solar wind can hit the surface of the Moon directly and implant elements like helium-3 and hydrogen into the soil.
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- Helium-3 has many applications, but importantly, it could be a fuel source for nuclear fusion and future planetary exploration. The value of hydrogen comes from the fact that it can combine with oxygen to form water, another crucial resource in space.
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- Since the Moon did not have a long-lived magnetic field, these elements could have been accumulating in soils for billions of years longer than previously thought.
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- Elements embedded by solar wind could shed light on the evolution of the Sun. And as the Moon passes through Earth’s magnetic field, elements from Earth’s atmosphere can be deposited on the lunar surface, and these may hold clues about the earliest Earth.
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- The amount of heat generated from the impact will also be valuable information. If observations can be made quickly enough, there’s a possibility the lunar orbiter’s infrared instrument will be able to detect glowing-hot material inside the crater. This could be used to calculate the total amount of heat from the impact.
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- Impacts and crater formation are a pervasive phenomenon in the solar system. Craters shatter and fragment planetary crusts, gradually forming the loose, granular top layer common on most airless worlds. However, the overall physics of this process are poorly understood despite how common it is.
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- Observing the upcoming rocket impact and resulting crater could help planetary scientists better interpret the data from the 2009 LCROSS experiment and produce better impact simulations. With a veritable phalanx of missions planned to visit the Moon in the coming years, knowledge of lunar surface properties, especially the quantity and depth of buried ice, is in high demand.
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- Regardless of this wayward rocket’s identity, this rare impact event will provide new insights that may prove critical to the success of future missions to the Moon and beyond.
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March 27, 2022 MOON - rocket crash on the Moon 3520
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