Scientists Solve a Mystery By Firing a Laser at the Moon (yahoo.com) 37
"The moon is drifting away," reports the New York Times.
Every year, it gets about an inch and a half farther from us. Hundreds of millions of years from now, our companion in the sky will be distant enough that there will be no more total solar eclipses.
For decades, scientists have measured the moon's retreat by firing a laser at light-reflecting panels, known as retroreflectors, that were left on the lunar surface, and then timing the light's round trip. But the moon's five retroreflectors are old, and they're now much less efficient at flinging back light. To determine whether a layer of moon dust might be the culprit, researchers devised an audacious plan: They bounced laser light off a much smaller but newer retroreflector mounted aboard a NASA spacecraft that was skimming over the moon's surface at thousands of miles per hour. And it worked...
Dust can be kicked up by meteorites striking the moon's surface. It coated the astronauts' moon suits during their visits, and it is expected to be a significant problem if humans ever colonize the moon. While it has been nearly 50 years since a retroreflector was placed on the moon's surface, a NASA spacecraft launched in 2009 carries a retroreflector roughly the size of a paperback book. That spacecraft, the Lunar Reconnaissance Orbiter, circles the moon once every two hours, and it has beamed home millions of high-resolution images of the lunar surface...
In 2017, Dr. Erwan Mazarico, a planetary scientist at NASA Goddard Space Flight Center and his collaborators began firing an infrared laser from a station near Grasse, France — about a half-hour drive from Cannes — toward the orbiter's retroreflector. At roughly 3 a.m. on Sept. 4, 2018, they recorded their first success: a detection of 25 photons that made the round trip... After accounting for the smaller size of the orbiter's retroreflector, Dr. Mazarico and his colleagues found that it often returned photons more efficiently than the Apollo retroreflectors... "For me, the dusty reflector idea is more supported than refuted by these results" he said.
Laser-reflection measurements over long periods of time and across several reflectors "have revealed that the Moon has a fluid core," NASA notes. "Scientists can tell by monitoring the slightest wobbles as the Moon rotates."
For decades, scientists have measured the moon's retreat by firing a laser at light-reflecting panels, known as retroreflectors, that were left on the lunar surface, and then timing the light's round trip. But the moon's five retroreflectors are old, and they're now much less efficient at flinging back light. To determine whether a layer of moon dust might be the culprit, researchers devised an audacious plan: They bounced laser light off a much smaller but newer retroreflector mounted aboard a NASA spacecraft that was skimming over the moon's surface at thousands of miles per hour. And it worked...
Dust can be kicked up by meteorites striking the moon's surface. It coated the astronauts' moon suits during their visits, and it is expected to be a significant problem if humans ever colonize the moon. While it has been nearly 50 years since a retroreflector was placed on the moon's surface, a NASA spacecraft launched in 2009 carries a retroreflector roughly the size of a paperback book. That spacecraft, the Lunar Reconnaissance Orbiter, circles the moon once every two hours, and it has beamed home millions of high-resolution images of the lunar surface...
In 2017, Dr. Erwan Mazarico, a planetary scientist at NASA Goddard Space Flight Center and his collaborators began firing an infrared laser from a station near Grasse, France — about a half-hour drive from Cannes — toward the orbiter's retroreflector. At roughly 3 a.m. on Sept. 4, 2018, they recorded their first success: a detection of 25 photons that made the round trip... After accounting for the smaller size of the orbiter's retroreflector, Dr. Mazarico and his colleagues found that it often returned photons more efficiently than the Apollo retroreflectors... "For me, the dusty reflector idea is more supported than refuted by these results" he said.
Laser-reflection measurements over long periods of time and across several reflectors "have revealed that the Moon has a fluid core," NASA notes. "Scientists can tell by monitoring the slightest wobbles as the Moon rotates."
Small wonder (Score:5, Funny)
"Every year, it gets about an inch and a half farther from us."
Firing with lasers on it all year round _caused_ this.
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I'd move too if someone kept shooting at me.
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Firing with lasers on it all year round _caused_ this.
Came here to say this! :D
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Someone needs to tell the sharks to knock it off.
Laser (Score:2)
Why didn't the moon blow up when they did that? Or at least the cheese should have melted. Seems like they failed.
Re:Laser (Score:5, Funny)
We've set the lasers to stun.
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This is why we can't hang with the rest of the galazy, we're too soft. I mean how is the moon supposed to respect us if we don't smack it with some force? After all the orange hairdo has been telling us for the last four years that fear and respect are the same thing.
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I think it's a little bit more runny than you like it, sir.
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I don't care how excrementally runny it is!
This is why I watch Austin Powers (Score:1)
This is what I keep telling my colleagues at the lab. There is no scientific query that can not be solved by lasers.
And if it doesn't work? ADD MORE LASERS!
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There is no scientific query that can not be solved by lasers.
And if it doesn't work? ADD MORE LASERS!
Don't forget the sharks...
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And if it doesn't work? ADD MORE LASERS!
Ah, I see you work in the field of inertial containment fusion.
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Hey that's better than the bigger magnets guys.
What is the story here ? (Score:3, Insightful)
Somewhere, buried in the quoted text between the irrelevant first sentence , ""The moon is drifting away," reports the New York Times." and the irrelevant last two sentences, is the "mystery" in the OP's title.
Editors ! EDIT !
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I remember reading about the Moon slowly moving away from Earth back in the 70's after the Apollo landings. LRRR (Lunar Range Retro Reflector) on Apollo 11, 12 and 15. Hell, even the Russians put some up there with Luna 17 and 21.
This is click bait from the NYTimes - we have know about this and the rate that it is happening for well over 51 years. Fucking NYT Millennial reporters, they do not know jack shit.
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Came here to say this.
As I recall, the Apollo astronauts found that a layer of moon dust hovers above the surface, due to static electricity generated from sunlight. (May have specific cause wrong).
So we've known that dust would be a problem. I can't imagine what an alternate theory would be for lowered efficiency.
About all that's news is that they found a usable, clean baseline in orbit to compare to.
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While dust was always the assumption, now they have evidence. Verifying assumptions is good science, but yeah, not a big mystery, agreed. I wasn't aware that dust hovers on the moon, so thanks for that.
NYT article is dumb (Score:2)
Another story is that the retros left there in the 60s and 70s are losing efficiency, possibly due to dust. Interesting.
Those two have nothing to do with each other and even the source quoted in the article says that getting a return from the LRO retroreflector does not prove or disprove the hypothesis that the surface retroreflectors are covered in dust.
So what mystery is solved exactly?
Re: NYT article is dumb (Score:1)
Lasers! (Score:2)
Really, is there any problem that can't be solved by firing lasers at something? I don't think so.
Oh dear, the comments (Score:2)
This place has lost about 100 IQ points since it was sold. I'm heading elsewhere. God help america, that country is getting dumber by the minute.
Re: Oh dear, the comments (Score:1)
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I keep thinking the same thing, leave for a while, and then when I fail to find anywhere with better commenters end up drifting back. With your UID I suspect you've done the same at least once.
CHA (Score:3)
[chairface redacted]
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Glad someone posted that before I did.
Lesson learned (Score:1)
The scientists discovered that, 9 out of 10 times, nothing on the moon fires back.
At least the moon isn't gettin closer to earth (Score:1)
Just wait... (Score:3)
I blame Trump (Score:3)
Everyone on the Eurasian tectonic plate is also moving 1" further away from North America every year. The Moon is quite consistent with the rest of the world.
Better than the alternative (Score:2)
Better to be drifting away than TOWARD us.