[HN Gopher] Antarctic Study Shows How Much Space Dust Hits Earth...
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Antarctic Study Shows How Much Space Dust Hits Earth Every Year
Author : manikandarajs
Score : 27 points
Date : 2021-04-29 14:03 UTC (8 hours ago)
(HTM) web link (www.scientificamerican.com)
(TXT) w3m dump (www.scientificamerican.com)
| mywacaday wrote:
| I wonder how many large meteors are buried in the ice sheets and
| if there is any reliable way to detect and recover them?
| jandrese wrote:
| That sounds like a serious needle in a haystack situation.
|
| Recovering them is easy, just do nothing about climate change
| and they'll melt out on their own.
| tryptophan wrote:
| It's about 90e-18% of the earth's mass per year, FYI.
| drknownuffin wrote:
| Maybe more to the point:
|
| > With clean sampling techniques and accurate ages for dust
| deposits, the researchers calculated around 5,200 metric tons
| of micrometeorites fall to Earth every year.
| nosianu wrote:
| To complete the TL;DR:
|
| Further down for "dust" and not just meteorites:
|
| > _between 4,000 and 6,700 metric tons of space dust falls to
| Earth each year_
|
| > _The total dust mass input before atmospheric entry is
| estimated at 15,000 tons /yr_ (from the study itself)
|
| Where it came from:
|
| > _The team found that more than 60 percent of the dust
| probably originated from Jupiter family comets, which are
| herded into orbital periods of less than 20 years by the
| giant planet's gravitational influence. About 20 percent of
| the dust likely came from the main asteroid belt._ (yes that
| leaves 20% unexplained)
|
| How reliable is it:
|
| > _...a geologist at the U.S. Naval Research Laboratory, who
| was not involved in the research, is impressed by the study
| but cautions that its estimate cannot be the final word._
|
| Tiny sample size, methodology but also randomness had a big
| influence. A study that improves upon previous ones and is
| just one of many more to come. As always, a headline of
| something taken randomly by a press office from a long line
| of study points that actually need to be looked at in context
| and together. It _does_ seem to give a good estimate about
| the order of magnitude to a casual reader like me though.
|
| .
|
| I admit even after reading through some details I can't say
| if the first number is part of the second, or if I need to
| add them? They _do_ talk about "meteorites and dust", so
| they counted two separate things? On the other hand, the
| first number for "meteorites" has the dust in the same
| sentence (" _With clean sampling techniques and accurate ages
| for dust deposits, the researchers calculated around 5,200
| metric tons of micrometeorites fall to Earth every year_ ").
| I'm confused. Maybe I should not have started with the
| article but with the actual study.
|
| Reading that study (linked in the article), the 5,200 is a
| complicated product of a lot of measurements and statistics
| (you see it in the abstract already) - and they say "dust" in
| the context of that number.
|
| .
|
| Given that both numbers are close and the uncertainty is
| large I won't spend any more time trying to figure it out,
| the magnitude is the same and it's all I think one can take
| away from this as a casual reader. The really interesting
| stuff probably only interests few and is all the many many
| details of how they did it exactly, for example " _The errors
| are derived assuming that the number of influx particles
| follows Poisson statistics_ " => from the study, one of
| hundreds of important details that the linked article
| compresses into something easier to read, but with quite a
| bit of information loss.
| adgjlsfhk1 wrote:
| The typical way of writing this would be 9e-19 of the earth's
| mass.
| bumbledraven wrote:
| Yeah. And since they're being approximate, they might as well
| just write 10-18 of the earth's mass. That and 9 x 10-19 are
| within +- 12% of each other.
| throwaway189262 wrote:
| Do you indent with spaces?
| adgjlsfhk1 wrote:
| (unless you meant 90e(-18%)=90*10^-.18=59% of the earth's
| mass)
| ericbarrett wrote:
| 5,200,000 kg of quartz (silicon dioxide, a.k.a. rock) is about
| 4/5 the volume of an Olympic swimming pool, according to
| Wolfram Alpha; the same mass of iron is about 1/3 of that. So
| whatever the actual composition of micrometeorites it is not a
| lot of material even on a human scale.
| ortusdux wrote:
| https://www.wolframalpha.com/input/?i=6700+metric+tons+%2F+t...
| bcraven wrote:
| You don't need to go far if you want to find your own micro-
| meteorites!
|
| https://web.archive.org/web/20210131191401/https://www.nytim...
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(page generated 2021-04-29 23:02 UTC)