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Originally posted by MrPenny
David O. Darling is not NASA. He is, what, an amateur astronomer?
Your insults are getting old.
Originally posted by syrinx high priest
lol, let me know when these "storms" involve water
Temperatures on the Lunar surface vary widely on location. Although beyond the first few centimeters of the regolith the temperature is a nearly constant -35 C (at a depth of 1 meter), the surface is influenced widely by the day-night cycle. The average temperature on the surface is about 40-45 C lower than it is just below the surface. In the day, the temperature of the Moon averages 107 C, although it rises as high as 123 C. The night cools the surface to an average of -153 C, or -233 C in the permanently shaded south polar basin. A typical non-polar minimum temperature is -181 C (at the Apollo 15 site). The Lunar temperature increases about 280 C from just before dawn to Lunar noon. Average temperature also changes about 6 C betwen aphelion and perihelion.
The water is in a frozen 100 square kilometer lake 50 feet deep (thick) at the south pole... everyone knows this... don't you guys ever get out and do ANY research yourself?
Originally posted by MrPenny
But never, have I attained this level of 'stretch'.....
Originally posted by MrPenny
Nothing in your post was particularly germane to the discussion.
Regardless, thank you for the contribution.
Source | MoonDaily | Watch Out For Flying Moondust
Here on Earth, no one pays much heed to dust or sand blasted out by a rocket launch because "atmospheric drag rapidly slows the lightweight particles so they fall harmlessly to the ground a few meters from the blast," he explains. But on the Moon? "There is no atmosphere to slow tiny particles." Small grit can travel enormous distances at high speeds, scouring everything in its path.
This isn't just theory. In November 1969, the Apollo 12 Lunar Module (LM, pronounced "lem") landed about 200 meters from Surveyor 3, a robotic probe that had landed on the Moon in April 1967. The Apollo 12 astronauts walked over to Surveyor 3 to photograph it and to retrieve some pieces for return to Earth. Right away, they noticed that most of Surveyor 3, which at launch was pristine white, had darkened to brown--a result of two-and-a-half years' exposure to extreme lunar conditions.
But the side of Surveyor 3 facing the LM had been sandblasted back to white. In fact, "every bolt, cable, or bracket blocking the spray of fine grit from Apollo 12 left permanent shadows etched onto Surveyor," Metzger says. From examining the returned artifacts, scientists later calculated the sandblasting resulted primarily from finest dust particles only 1 to 10 micrometers (0.00004 to 0.0004 inch) across.
The scoured surfaces were also pocked with hundreds of microscopic impact craters ranging from 30 to 60 micrometers (0.001 to 0.002 inch) across caused by particles of about the same size traveling at high speeds. Moreover, fine grit had been driven into tiny cracks and crevices, including inside Surveyor's camera.
This evidence concerns Metzger because in a future lunar outpost, high-speed fine grit could scour the reflective coating off thermal control blankets, roughen the surfaces of windows and other optics, compromise the surfaces of solar panels, and penetrate connectors or other mechanisms on digging machines or spacesuits, causing friction and even mechanical failure. Well, why not just land far enough away that speeding sand and dust ceases to be a problem?
Answer: You can run, but you can't hide. Dust particles accelerated by a rocket's exhaust could theoretically travel all the way around the Moon!
Metzger's team has analyzed how the impact craters formed on Surveyor 3 and finds that the particles must have been traveling at least 400 to 1,000 meters per second. "In fact, they may have been traveling as fast as the exhaust gases of the lunar lander-that is, at 1 or 2 kilometers per second."
Particles speeding horizontally at 1.7 kilometers per second will travel literally halfway around the Moon. Boost that speed to 2 kilometers per second, and the projectiles can completely circle the Moon. If no mountains got in the way, grit accelerated by a rocket landing could zip entirely around the Moon "and land back at the rocket's feet," says Metzger.
Space Settlements: A Design Study | APPENDIX J | IMPACT UPON LUNAR ATMOSPHERE
The present lunar atmosphere, arising from natural sources with a total rate less than 0.010 kg/s, has a mass of less than 10^4 kg and surface number densities less than 10^7 /cm^3.
Source | Johnson Space Center | Experiment Operations During Apollo EVAs | Experiment: Surveyor 3 retrieval
After a 30 month exposure of Surveyor 3 on the surface, the A-12 crew inspected the spacecraft and retrieved key parts from it for further analysis on Earth...sort of an LDEF of the Moon. The effects of the A-12 LM blast ejecta, micrometeroid effects on electronics (TV camera), cables, metal structure, mirrors, etc., analysis of the sampler scoop, effect of a low temperature oxygen plasma on the coatings, induced radioactivity, and microbe survival in the lunar environment, were a few of the studies conducted.
Source | Lunar and Planetary Institute | Apollo 12 Mission | Science Experiments - Surveyor III Analysis
A particularly important aspect of the Surveyor 3 analysis was the search for living material on the spacecraft. Surveyor was not sterilized prior to launch, and scientists wanted to know if terrestrial microorganisms had survived for two and a half years in space. One research group found a small amount of the bacteria Streptococcus mitis in a piece of foam from inside the TV camera. They believed that these bacteria had survived in this location since before launch.
Does this have something to do with the lunar atmosphere?
Heck, even the abrasive effect of the dust held aloft by an electrostatic effect should be of concern for any lunar operations.
Originally posted by NGC2736
Just a small question of no real importance except to me. Does anyone know where to find a cargo manifest for lunar missions?
The reason I ask, is with energetic dust, on whatever scale, it would seem like a spray bottle of Windex and a few cleaning rags might have been taken along. After all, there would need to be a way to keep the visors clean enough to see out of. ( It's not like they could use a sleeve the way the rest of us midwesterners do on a sumer day when our sunglasses get dirty. )
Originally posted by SpaceMax
Hydrogen has been detected, whether it's in the form if water ice is still unknown.
Q: What do you think this would look like if you could go right down and see it? Would you see a fairly large pond here, other ponds all over the place, some ice in crevices and rocks?
A: You would probably see... First of all you wouldn't see anything because you'd be in the dark. But if you had a flashlight and you illuminated the surface, you would see a surface that looked not unlike any place else on the moon, but if you were to dig down into that and pull it up, you would find that there would be ice crystals contained in the interstices between the dust grains. So it's not a sheet or a pond. It's not an ice rink on the moon. It's basically ice mixed into the dirt.
Q: What's the presumptive volume of it then, and how did you discern that?
A: As I mentioned, what we can tell from looking at the radar return is roughly the area that is covered by this. Assuming it reflects ice like ice on Mercury -- making that assumption. That's been well looked at. Then in order to see this back scatter effect, this roadside reflector effect; it's estimated that we have to see some number of wavelengths of our radar into the ice. In reviewing the paper, several of the reviewers posited we probably need to see somewhere between 50 and 100 wavelengths. So our wavelength is about six inches. So at the thickest case, it's roughly 50 feet.
Q: That translates to what in volume?
A: We were very conservative in the press release, but if you take basically 100 square kilometers by roughly 50 feet, you get a volume of something like a quarter of a cubic mile, I think it's on that order. It's a considerable amount, but it's not a huge glacier or anything like that.
Q: Can you compare that with something you know?
A: It's a lake. A small lake.