(Visited 71 times, 1 visits today)FacebookTwitterPinterestSave分享0 New study of craters shows that moon’s surface gets churned every 81,000 years, not every million years.“I like it when theories are proven wrong, or exciting new things come up,” remarked Kathleen Mandt of Southwest Research Institute, quoted by New Scientist. That’s how to put a cheerful spin on an orders-of-magnitude correction. “The Lunar Reconnaissance Orbiter is starting to show there’s a lot we don’t know about the moon.” Data from LRO are showing a much higher influx of meteorites to the moon’s surface, implying that future astronauts stand a bigger-than-trivial chance of being in danger from flying rocks and dust. The data raise questions about the age of the lunar surface.The revised number of craters suggests the moon is pummeled by space rocks much more frequently than predicted, says Kathleen Mandt of the Southwest Research Institute in San Antonio, Texas. It also suggests that the soil on the lunar surface is turning over so often that materials like water molecules could escape into space sooner than previously thought. That could have important implications for researchers trying to date rocks on the moon, or future initiatives hoping to mine resources out of the moon.Space.com says of the “Impact!” of the finding, “New Moon Craters Are Appearing Faster Than Thought.” Part of the new estimate comes from crater counts by LRO, including a whopping 222 new craters appearing just in the last 7 years, says Alexandra Witze in Nature. The other part comes from estimates of secondary craters formed from each new impact.The scientists also found broad zones around these new craters that they interpreted as the remains of jets of debris following impacts. They estimated this secondary cratering process is churning the top 0.8 inches (2 centimeters) of lunar dirt, or regolith, across the entire lunar surface more than 100 times faster than thought.Realization of widespread secondary cratering upset the crater-count dating method a decade ago (9/25/07), rendering the method essentially unreliable (5/22/12). Even if a future moon colonist avoids a direct hit, he or she could be at risk of debris from a distant impact if rocks and dust fly in all directions with no atmosphere to slow them down. Picture yourself working at a futuristic moon base stepping outside to watch the Earthrise:“For example, we found an 18-meter (59-foot) impact crater that formed on March 17, 2013, and it produced over 250 secondary impacts, some of which were at least 30 kilometers (18.6 miles) away,” Speyerer said. “Future lunar bases and surface assets will have to be designed to withstand up to 500 meter per second (1,120 mph) impacts of small particles.“PhysOrg says the meteoritic rain is so heavy, it gives the moon a facelift every 81,000 years, overturning the top two centimeters of lunar dust. Some impactors were big. The astronomers found 33% more craters than expected with diameters at least ten meters.None of the articles asks the obvious question: what does this mean over the assumed lifetime of the moon? If the moon really formed 4.5 billion years ago, as secular planetary scientists believe, that would be 5,555 facelifts. (It should be noted that the 81,000-year estimate uses models that assume the billions-of-years age of the moon. All they can really observe is the current impact rate. The new observations, however, imply a faster production rate than the favored model assumes.)Another consequence of the study affects all the planets and moons of the solar system. Does the impact rate need to be revised upward everywhere else? Are primary and secondary craters occurring much more frequently than expected at Mars and the moons of Saturn, or at Pluto? Meteor flux could vary at different radii from the sun. It’s also a factor of gravitational pull. But without a reconnaissance orbiter at each planet or moon, it’s hard to be sure. New craters have been observed at Mars – again, at a higher rate than expected (2/13/14).Earth, with its higher gravity, attracts meteors at an even higher rate, but our atmosphere causes most of them to burn up high in the sky. Meteors are commonly observed by skywatchers. The occasional meteor shower increases the rate when Earth passes through the dust stream of a comet. The rare meteorites (meteors that reach Earth’s surface) are prized by collectors. Some of them come from Mars and other planets, when glancing blows send rocks our way (3/25/08).The research paper in Nature by Speyerer et al. contains before-and-after photos of impact sites.The trend in crater-count dating has been up and down: up in the number of impact events and secondaries, down in the method’s credibility. It’s clear that these results were surprising. Despite all those thousands of craters, the moon doesn’t have to be billions of years old.This paper should stimulate creationists to revisit the moon dust problem. In the Apollo era, all the secular astronomers were astonished at the thinness of the lunar regolith. The Surveyor landers proved that the dust was not meters thick with fine dust as some had predicted. Apollo astronauts found the dust to be so shallow, they could scratch the bedrock with their boots. It seemed that fine dust had not been accumulating for billions of years. When subsequent estimates of dust influx were substantially reduced, many creationists abandoned the moon-dust argument for a young moon.Perhaps that was premature. This paper shows that impacts send up jets of dust that settle back under ballistic trajectories. If the top two centimeters can be completely “gardened” in just 81,000 years, it seems highly implausible to believe this has happened over 5,000 times. Some creation physicist ought to read the new paper and revisit the implications for age.
Justice MalalaSouth Africa has not had the best of years. We’ve had power cuts and we’ve had xenophobic attacks. We’ve had all sorts of upheavals and sometimes, in conversation and in our media, one would think that we have nothing still to inspire us.Yet we do. Again and again I am amazed at how much we have given to the world, and how proud we should be for these gifts. For example, as I write this, the world is both mourning Miriam Makeba and celebrating her life, a remarkable life of commitment, activism – and the most beautiful and haunting art.The world over, many are mourning with us the gifts that a remarkable South African has given to the world. I cannot tell you how many foreigners I have met who knew only two things about South Africa – The Click Song and the committed woman behind it, and Nelson Mandela.Many of these people found themselves at marches to protest against apartheid after being moved by the words uttered by these two icons.November has been a remarkable month for the world. Barack Obama, a young man who has wowed the world and restored people’s faith in politics, was voted in overwhelmingly as president of the most powerful country in the world.But what is inspiring is that were it not for the inspiration that Obama received from our own country, he may have gone on to become a rich lawyer (he is a Harvard Law School graduate after all) and never entered politics.Obama told the South African Institute for International Affairs on his visit to South Africa in 2006 that he was inspired by a group of exiled African National Congress (ANC) members to go into politics.Writer Peter Fabricius records that Obama said at the South African Institute of Race Relations meeting that “people often ask me how I got involved in politics”.“I tell them I was not born into a political family; I was not active in student government in high school. But when I was in college there was one issue that moved me for the first time in my life to become politically active. The issue was apartheid. And, as a young college student, I became deeply involved with the divestment movement in the US.“I remember meeting a group of ANC leaders, hearing of their struggles for freedom and their leader Nelson Mandela.”Fabricius writes that Obama then described how Mahatma Gandhi began his quest for India’s independence in South Africa, which inspired Martin Luther King, whose civil rights movement, in turn, helped move South Africans such the ANC’s leaders to act against apartheid.“It is likely that I would not be here today speaking to you as a United States senator had I not met with those ANC members,” he said.Today, everywhere one goes, the election of Obama is being spoken of in terms that are likened to Mandela’s release from prison in 1990 after 27 years of incarceration. Many see in Obama the qualities, the transcendence over race and bitterness, that Mandela embodied. His election unleashed that same emotion in people across the world: the world is capable of surpassing its everyday, mediocre, standards.“This is America’s Mandela moment!” shouted US consul general for South Africa Alberta Mayberry to a reporter – while watching the Obama victory on television – when it became reality.Mayberry told reporters that there was an extraordinary poignancy in experiencing the election of America’s first black president while in Nelson Mandela’s country.And it is true.Way back in 2004, an unknown Barack Obama stood up at the Democratic National Convention and gave a speech that, within four years, would catapult him to the presidency of the US.“My presence on this stage is pretty unlikely,” he said. “I stand here knowing that my story is part of the larger American story… and that, in no other country on earth, is my story even possible.”None of us in South Africa even had an inkling that a young man was making history across the Atlantic. But we identified with this sentiment, because we had heard before from the lips of Mandela.“I have cherished the ideal of a democratic and free society in which all persons live together in harmony and with equal opportunities. It is an ideal which I hope to live for and to achieve. But if needs be, it is an ideal for which I am prepared to die,” Mandela had said from the dock during the Rivonia Trial in 1964.That country that Mandela yearned for is the same dispensation that Obama was talking about when he spoke of his own American dream.A lot of people and countries now claim Obama as their own. He cannot belong to everyone. He is an American president. But it is a deeply comforting thought that we, too, had a small part in giving the world such an outstanding leader.Justice Malala is an award-winning former newspaper editor, and is now general manager of Avusa’s stable of 56 magazines. He writes weekly columns for The Times newspaper and Financial Mail magazine, as well as a monthly media and politics column for Empire magazine. He is the resident political analyst for independent television channel e.tv and has consulted extensively for financial institutions on South African political risk. Malala was also an executive producer on Hard Copy I and II, a ground-breaking television series on SABC 3. Hard Copy I won the Golden Horn Award for best television series. Malala’s work has been published internationally in the Wall Street Journal, The Guardian, Financial Times, The Independent, Forbes, Institutional Investor, The Age and The Observer. read more
Lawyers across the State burnt effigies of Chief Minister Naveen Patnaik at noon on Wednesday in front of the offices of their respective Bar Associations. Alleging that the State government had not taken any initiative to resolve the lawyers-police bickering, the High Court Bar Association, which has been agitating for over two months now, on Tuesday had given the call to burn the effigies.Responding to the call, over 160 Bar Associations on the day burnt Mr. Patnaik’s effigies after taking out ‘mourning processions’ with biers. The lawyers also raised slogans against Mr. Patnaik, his government, the Biju Janata Dal Legal Front and the police. ‘Politically motivated’ Reacting to the protests, BJD Legal Front adviser and senior advocate Asim Amitav Dash alleged that the ongoing strike by the High Court Bar Association is politically motivated and those leading it have ulterior motives. “The State government had, in fact, taken several measures to resolve the face-off between lawyers and police,” Mr. Dash said, adding that the BJD Legal Front has distanced itself from the ongoing strike. read more
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