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Darth Fluffy

NP comic Tuesday December 14, 2021

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Since the Moon has no global magnetic field, a magnetic compass (as opposed to an inertial compass) would be useless for direction-finding. With a proper chronometer, one would do better by using the sun or stars as a reference, so a sextant might be in order instead.

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4 hours ago, ijuin said:

Since the Moon has no global magnetic field, a magnetic compass (as opposed to an inertial compass) would be useless for direction-finding. With a proper chronometer, one would do better by using the sun or stars as a reference, so a sextant might be in order instead.

On Earth, the north magnetic pole has been moving rapidly in recent years, is now in Siberia. So, not so great, even here.

I was wondering what you would get on the moon, with several strong magnetic fields far away, and little local interference. Or would some iron cores from impacts dominate and confuse the scene? Seemed prudent to avoid the issue and bring the golf gear.  

 

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I actually know the survival puzzle that Dan is referencing. The original was actually about ranking the 15 items in order of importance.

For anyone that wants to play:

You are a member of a space crew originally scheduled to rendezvous with a mother ship on the lighted surface of the moon. However, due to mechanical difficulties, your ship was forced to land at a spot some 200 miles from the rendezvous point. During reentry and landing, much of the equipment aboard was damaged and, since survival depends on reaching the mother ship, the most critical items available must be chosen for the 200-mile trip. Below are listed the 15 items left intact and undamaged after landing. Your task is to rank order them in terms of their importance for your crew in allowing them to reach the rendezvous point. Place the number 1 by the most important item, the number 2 by the second most important, and so on through number 15 for the least important.

A box of matches
Food concentrate
50ft of nylon rope
Parachute silk
Portable heating unit
Two .45 caliber pistols
One case of dehydrated milk
Two 100lb tanks of oxygen
A stellar map
A self-inflating life raft
A magnetic compass
20L of water
Signal flares
A first aid kit, including an injection needle
A solar-powered FM receiver-transmitter.

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On the surface of the Moon, the vacuum environment would render the matches and heater useless (plus it’s daylight for at least the next week, so staying cool is more important than staying warm).

The lack of any bodies of water makes the life raft useless as well—you can’t even use it as a sledge to carry your other gear because the moon dust is so abrasive that it will quickly tear holes in it.

Since there is no known native wild fauna on the Moon due to the aforementioned vacuum, the .45 caliber pistols would be unnecessary dead weight unless there is a chance of encountering hostile people.

The compass would be useless due to the aforementioned lack of a lunar magnetic field.

The food, milk, water, and first aid kits would be useful if there is a way of getting them inside your space suits in order to consume them without exposing yourselves to the surrounding vacuum.

The oxygen would be vital to staying alive beyond however many hours’ worth that your space suits normally carry. Battery power of your suits may be the limiting factor if you have no spares and no solar panels sufficient to recharge them during your trek.

The radio would be useful for maintaining contact with your destination—they may even be able to determine your bearing relative to them using it, and thus guide you in their direction. I would say that this is the most valuable item after the “keep you alive” stuff.

The signal flares and map would likewise be useful in finding your way to the mothership.

Finally, the rope and parachute cloth would be useful for rigging carrying harnesses for the 100-pound oxygen tanks. The tanks would weigh less than 20 pounds on the Moon, but 100 on-Earth pounds of oxygen is about 50 liters (about seven US gallons), so they would be rather bulky.

Edit: 100 pounds of oxygen is closer to 40 liters, which is about eleven US gallons. My bad.

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3 hours ago, mlooney said:

Yeah, but with the golf gear you can only swing with one arm.  Might limit the range of the drive.

His shots were not great, it is true.

 

9 hours ago, ijuin said:

... so a sextant might be in order instead.

Outstanding suggestion, even if the spelling threw me at first. Yes, a pressurized sex tent would give you access to access to several interesting firsts.

 

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5 minutes ago, Darth Fluffy said:

Outstanding suggestion, even if the spelling threw me at first. Yes, a pressurized sex tent would give you access to access to several interesting firsts.

 

Not a sex tent, a Sextant, the angle-measuring device used for navigation.

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Just now, ijuin said:

Not a sex tent, a Sextant, the angle-measuring device used for navigation.

Damn, dude, you just won pedantic points, but lost the equivalent elsewhere.

Last I heard, from an actual USAF navigator, training still included star sightings with a sextant. That was decades ago, I don't know if it is still true. But many of the large air frames designed back in the day that are still flying have a sextant port built in, a small hole in which to insert a specialized sextant device. Having a plan C for wartime operations can come in handy. 

 

 

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I remember my 7th grade Astronomy class (Before the Voyagers reached Saturn)

The teacher spent a good part of the class explaining that Earth's Moon had no magnetic field, and some kid (not me this time) was still insisting that the Moon's magnetic field was what let the Apollo space craft stay in orbit

Magnetism isn't necessary for orbit.  For that you need Tang (Which should be at the TOP of any space survival list)

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37 minutes ago, ijuin said:

On the surface of the Moon, the vacuum environment would render the matches and heater useless (plus it’s daylight for at least the next week, so staying cool is more important than staying warm).

The lack of any bodies of water makes the life raft useless as well—you can’t even use it as a sledge to carry your other gear because the moon dust is so abrasive that it will quickly tear holes in it.

Since there is no known native wild fauna on the Moon due to the aforementioned vacuum, the .45 caliber pistols would be unnecessary dead weight unless there is a chance of encountering hostile people.

The compass would be useless due to the aforementioned lack of a lunar magnetic field.

The food, milk, water, and first aid kits would be useful if there is a way of getting them inside your space suits in order to consume them without exposing yourselves to the surrounding vacuum.

The oxygen would be vital to staying alive beyond however many hours’ worth that your space suits normally carry. Battery power of your suits may be the limiting factor if you have no spares and no solar panels sufficient to recharge them during your trek.

The radio would be useful for maintaining contact with your destination—they may even be able to determine your bearing relative to them using it, and thus guide you in their direction. I would say that this is the most valuable item after the “keep you alive” stuff.

The signal flares and map would likewise be useful in finding your way to the mothership.

Finally, the rope and parachute cloth would be useful for rigging carrying harnesses for the 100-pound oxygen tanks. The tanks would weigh less than 20 pounds on the Moon, but 100 on-Earth pounds of oxygen is about 50 liters (about seven US gallons), so they would be rather bulky.

I think you nailed the overall scheme. My .02 credits:

Oxygen is the single utmost top priority. You will go through a lot. So the tanks are #1, and the harness to take them along would make the rope and cloth #2 and #3.

The radio would confirm you are alive and attempting rendezvous; #4.

The .45s, if you know there are hostiles, #5, otherwise, leave them. (Potentially useful if there is not enough oxygen for everyone, and the commander needs to choose who makes it. I'm guessing there is 'enough'.)

The flares may be vital for way finding, #6; maybe should replace the guns even if there are hostiles.

The stellar map seems useless, you are only 200 miles apart. OTOH, the moon is small, it might still help you, and it is presumably easy to carry. #8

Water, milk, and food depend on how they interface with the suit you are stuck in, or if they will be needed for the return trip to Earth once you rendezvous. The suit should have some facility for using the water, and may be needed. #7, perhaps should be as high as #5. You can live longer without food, so milk and food concentrate may be unnecessary, and are less likely to interface with the suit. 'A crate of' would be burdensome. But, there is nothing else you really need, so taking some food and/or milk would not be unreasonable. #9 and #10, because there is nothing else you need, but not the whole amount.

Unknowns: Might the life raft be needed by the entire mission after you return to Earth? Otherwise, seems odd that you have one. It might be worth taking the compass for similar reasons.

 

 

 

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11 minutes ago, Pharaoh RutinTutin said:

I remember my 7th grade Astronomy class (Before the Voyagers reached Saturn)

The teacher spent a good part of the class explaining that Earth's Moon had no magnetic field, and some kid (not me this time) was still insisting that the Moon's magnetic field was what let the Apollo space craft stay in orbit

Magnetism isn't necessary for orbit.  For that you need Tang (Which should be at the TOP of any space survival list)

Magnetism is important for shielding from the solar wind. Our Earth is uniquely suited for doing that well.

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2 hours ago, Darth Fluffy said:

 

Water, milk, and food depend on how they interface with the suit you are stuck in, or if they will be needed for the return trip to Earth once you rendezvous. The suit should have some facility for using the water, and may be needed. #7, perhaps should be as high as #5. You can live longer without food, so milk and food concentrate may be unnecessary, and are less likely to interface with the suit. 'A crate of' would be burdensome. But, there is nothing else you really need, so taking some food and/or milk would not be unreasonable. #9 and #10, because there is nothing else you need, but not the whole amount.

Unknowns: Might the life raft be needed by the entire mission after you return to Earth? Otherwise, seems odd that you have one. It might be worth taking the compass for similar reasons.

The raft, compass, etc. seem like emergency supplies meant for a landing on Earth. The Mercury, Gemini, Apollo, and Soyuz spacecraft all carried such gear and the astronauts had survival training in case they landed far away from rescue and had to spend days on their own. The parachute cloth was also meant to double as an improvised tent.

As for the food and milk, they are nice-to-have if you have a way to eat them, but healthy adults can function without food for longer than 20 liters of drinking water is likely to last for a group of two or more people. There is also the issue that you have nowhere to poop besides a diaper that you cannot change, so perhaps it is preferable to keep eating to a minimum. The water is going to be the limiting factor if electrical power is not, unless the suits have some kind of water recycling system. I an assuming also that there is some kind of urine collection and dumping system that can function for several days.

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I'll let you guys keep discussing it, but I want to point out that the rankings are a part of the puzzle - the exercise also comes with a list of how NASA ranks each item. You score points based on how far your ranks differ, and this is one where you want a 'LOW score - it means you got close to the correct ratings for everything.

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1 hour ago, AFNB said:

the exercise also comes with a list of how NASA ranks each item. You score points based on how far your ranks differ...

Because the first committee designing a hypothetical situation would know better than any other person looking at said problem at a later time.

And as a test of competence, this is designed not to prove how innovative you are, but how much you think like previous generations of NASA administrators.  Clearly a far more useful skill set in a bureaucratic setting

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49 minutes ago, Pharaoh RutinTutin said:

Because the first committee designing a hypothetical situation would know better than any other person looking at said problem at a later time.

It would matter when the “official” answers were first thought up. If it was done before the Apollo landings actually happened, then they would not have known about how jagged and abrasive the lunar dust is, and might have assumed that using the life raft as a sledge was viable, for example.

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28 minutes ago, ijuin said:

It would matter when the “official” answers were first thought up. If it was done before the Apollo landings actually happened, then they would not have known about how jagged and abrasive the lunar dust is, and might have assumed that using the life raft as a sledge was viable, for example.

There are too many unknowns to answer this this much better than we did. What is our destination? An established moon base with resources, or is the mother ship constrained to return to Earth shortly? Does our craft have some of the entire expeditions' necessary survival gear? Life raft and compass at the terminus, perhaps even the matches?

For that matter, could we radio the mother ship and have them land closer? Presumably, they have enough fuel to land once; but if we are proactive, they could be closer. Or perhaps 200 miles is the proactive answer.

Why do we even have guns? This implies a scenario in space that we have not yet had to deal with.

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56 minutes ago, ijuin said:

It would matter when the “official” answers were first thought up. If it was done before the Apollo landings actually happened, then they would not have known about how jagged and abrasive the lunar dust is, and might have assumed that using the life raft as a sledge was viable, for example.

It's apparently from 1999.

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1 hour ago, Pharaoh RutinTutin said:

Because the first committee designing a hypothetical situation would know better than any other person looking at said problem at a later time.

And as a test of competence, this is designed not to prove how innovative you are, but how much you think like previous generations of NASA administrators.  Clearly a far more useful skill set in a bureaucratic setting

The NASA rankings also give the reasoning behind them, and while not necessarily innovative, some of them do have some good ingenuity behind them. Others rely more on actual knowledge of how such things work.

I also mainly gave the clarification of the points system because Darth Fluffy was the only one to assign any numbers, and even then only went to 10.

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It is a bit difficult to assign relative rankings to items that are both equally useless. Perhaps the one that is more encumbering is lower ranked if they are both useless?

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3 hours ago, AFNB said:

Okay, since people seem to be about done with the exercise, here's the link to the actual thing:

https://www.csuchico.edu/anthmuseum/_assets/documents/nasa-exercise-survival-on-the-moon.pdf

Thanks for posting.

Given HOW they ranked the items, using them on Earth is not a factor, which begs Grace's question about those items.

There was missing information, "... will fit a special aperture in NASA space suit"

The line of sight limitation of the radio is based on frequency, also unknown, but probably guessable. There is no ionosphere on the moon to duct a signal, and the curvature is sharper, so the horizon is closer, OTOH, 200 miles isn't all that far. (Yes, I agree, I wouldn't want to walk it on the moon.)

The references to the utility of propulsion make no sense to me. Seems like an invitation to have an accident and tear your suit. Stability counts for a lot.

"A stellar map is your primary means of navigation" is surprising. Seems too coarse.

The flares near the bottom is also surprising.

Again, thanks.

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12 minutes ago, Darth Fluffy said:

The flares near the bottom is also surprising.

I know that explosives (other than Thermobaric and other "fuel/air" types) will work with out air, due to them having their own oxidizer, but will flares?

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Signal flares have their own oxidizer, and in this context probably also have a launcher (flare pistol) included that will hurl them a good hundred meters upward in Earth gravity and atmosphere (probably at least a kilometer up with 1/6 gravity and no air resistance).

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