airless vaccum on the moon? answer me this then.....

reply to post by flexy123


I would not say space is even close to a perfect vacuum

What we refer to as space is full of gases, particles, and debris, not to mention planets, suns, asteroids and comets...

The space junk alone revolving around the earth is HUGE

Outer space is the void that exists beyond any celestial body, including the Earth.[1] It is not completely empty, but consists of a hard vacuum containing a low density of particles: predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, and neutrinos. Theoretically, it also contains dark matter and dark energy.

Wiki

Granted it is pretty darn empty as 'space" is so huge, but there is a lot if really interesting stuff floating around up there..

Semper

There is a lunar atmosphere, but it is closer to a vacuum when compared to the density of Earth's atmosphere.

Consulting Wikpedia:

The average daytime abundances of the elements known to be present in the lunar atmosphere, in atoms per cubic centimeter, are as follows:

Argon: 40,000
Helium: 2,000-40,000
Sodium: 70
Potassium: 17
Hydrogen: fewer than 17

reply to post by semperfortis


I think you're confusing 'Vacuum' with 'void'.

Totally different things mate.

reply to post by spikey


Nope

Not confused at all

But thanks

Semper

reply to post by charlyv


Don't forget good old H2O, however transitory it might be.

Water ice has been confirmed....sun vaporises it, it floats across the surface as a thin ethereal mist / cloud of fine vapour and either immediately refreezes in permanently dark (shielded from direct sunlight) craters, or is lost to space.

This has been observed and recorded scientifically.

Not an atmosphere as we would be used to..but 'atmospheric'.

reply to post by semperfortis


It was your mention of huge amounts of space junk and debris that made me think you'd confused the two.

Physical objects, (junk) might donate a tiny amount of gas and atoms to space, but is like thinking a grain of sand makes a desert. Same thing with planets and so on, they constantly leak atmosphere to space, but the sum amount is so tiny, it has no effect on the 'emptiness' of space...a handful of atoms per square foot is what the rough calculations show for space.

A lab vacuum flask or vessel can contain physical objects, which would be analogous to our space junk and still be a vacuum.

The same flask or vessel containing no objects would be a void.

Preaching to the choir i suspect, but that's the reason i thought you were confused.

reply to post by spikey

The little lander doesn't come back to Earth on it's own.

The little lander doesn't come back to earth at all..
They get in the CM and jettison the lander...

Jeez.

Don't people get taught basic science these days? This is High school stuff.

Newtons Third Law. Every Action has an equal and opposite reaction. Thats the principal at work here. The fuel and oxidiser mix, creating a hot gas that expands and shoots out through the nozzle in one direction, and the reaction pushes the rocket in the other direction.

Its that simple. And its basic science. Deny ignorance.

Just like religon with God,can scientist prove air and oxygen actually exist's? Photo or it didn't happen
Jez that's really deep of me!

Yeah!!....And they flew in Chinese Lanterns, not space capsules....everyone knows that.

Since you actually have several questions in your post, I'll try to hit them one at a time.

if it's airless vaccum on the moon, how did the rocket thrusters work?

Rockets are actually more efficient in a vacuum.
Newton's famous Third Law of Motion - For every action, there is an equal and opposite reaction.
Now..imagine a cylinder full of gas under pressure. The gas presses against all sides of the cylinder, the top, and the bottom. Pressure on any point on the side is matched by pressure on the opposite side. Pressure on the top is matched by pressure on the bottom. Now, replace the bottom of the cylinder with an open nozzle. Pressure on the sides of the cylinders cancel each other out, but there's nothing countering the pressure against the top, because the bottom is open. That unbalanced force pushes the cylinder upward. That's a vastly oversimplified 'how do rockets work'...the gas under pressure can come from a tank, or it can be generated by a chemical reaction, but in no case does it require anything external to 'push against'.

i'll bet you a dollar to a dime that a combustion engine does not work in a vaccum

Absent a source of oxygen (or an oxidizing agent...ironically, there are better ones than oxygen itself, but that's another story), you'd win the bet. Rocket engines, however, do carry oxidizer,

.....they wouldn't have had enough oxygen in a tank to make it back to the earth if they used a tank....there's no way......i know that a flame does not burn in a vaccum so please someone explain this to me......

The Lunar Excursion Module didn't have sufficient oxidizer to make the return trip from the Moon. It did, however, have enough oxidizer and fuel in the ascent stage to (barely) make the relatively easy lift from the lunar surface to lunar orbit. Once there, it linked up with the Command and Service Module. The Service Module's engine had sufficient delta-V to insert the vehicle into an Earth-return trajectory. Once on course, thanks to the lack of friction out there, they simply drifted back to Earth, where another burn was made to put the spacecraft into a stable Earth orbit.

Essentially, they used several tanks, and got rid of as much mass as possible, as quickly as possible (the whole idea behind 'staging' in a rocket stack) to minimize the amount of fuel and oxidizer needed.

Originally posted by neformore
Jeez.

Don't people get taught basic science these days? This is High school stuff.

Newtons Third Law. Every Action has an equal and opposite reaction. Thats the principal at work here. The fuel and oxidiser mix, creating a hot gas that expands and shoots out through the nozzle in one direction, and the reaction pushes the rocket in the other direction.

Its that simple. And its basic science. Deny ignorance.

ha ha, no duh!!! we're discussing, or atleast trying to discuss amount of fuel and oxydizer to get back to earth from the moon............

Originally posted by 13th Zodiac
Just like religon with God,can scientist prove air and oxygen actually exist's? Photo or it didn't happen

Jez that's really deep of me!

ha ha, it was so deep, i was having a hard time wrapping my head around it

Originally posted by patternfinder

Originally posted by neformore
Jeez.

Don't people get taught basic science these days? This is High school stuff.

Newtons Third Law. Every Action has an equal and opposite reaction. Thats the principal at work here. The fuel and oxidiser mix, creating a hot gas that expands and shoots out through the nozzle in one direction, and the reaction pushes the rocket in the other direction.

Its that simple. And its basic science. Deny ignorance.

ha ha, no duh!!! we're discussing, or atleast trying to discuss amount of fuel and oxydizer to get back to earth from the moon............

Yup; force=mass x acceleration.

Sir Isaac Newton (born 25 December 1642 – died 20 March 1727): A body at rest tends to remain at rest;A body in motion tends to remain in motion;unless acted upon by an outside force...

Once you get a sufficient velocity for the mass you simply coast in the frictionless-zero gravity vacuum/"void" that is"space".
A lot of mass takes a bigger thrust(push);or a smaller push for a longer time.to achieve the same velocity than a smaller mass.

How much fuel did they take( in the"service module engine ") to return the crew and samples to earth in the command module?


enough...

a few seconds:"burn" here and there to adjust velocity/trajectory/.

Seriously:
Don't third grade science period teachers holdup inflated balloons? let them go, and watch them zoom around "ploo-oooottt... "jetting all over the classroom anymore?
(We were building estes model rockets in fourth grade science...)

No?

But third graders damn sure know why heather has two mommies...frickin sad.

Originally posted by charlyv
There is a lunar atmosphere, but it is closer to a vacuum when compared to the density of Earth's atmosphere.

Consulting Wikpedia:

The average daytime abundances of the elements known to be present in the lunar atmosphere, in atoms per cubic centimeter, are as follows:

Argon: 40,000
Helium: 2,000-40,000
Sodium: 70
Potassium: 17
Hydrogen: fewer than 17

Hi charlyv

I read/heard that the lunar atmosphere is predominantly made up of the exhaust gases from the rockets used on the various Moon missions . Is this correct ?

Edit to add +++++++

The total mass of the Moon's atmosphere is estimated to be just 10,000 kilograms, which is comparable to the amount of gas released (primarily as rocket exhaust) by each Apollo landing.

The Cold Cathode Gauge easily detected outgassing from the astronauts' space suits whenever they were near the instrument.

The effects of landing site contamination decay with time, so measurements were made for several years in order to estimate the abundance of the normal (uncontaminated) lunar atmosphere.

link

So it would seem that most if not all traces of rocket exhaust are no longer present.

Originally posted by Shamatt

Originally posted by chr0naut


Sad thing is it's likely that we'll never do anything that grand and risky again. If the bean counters and PC crew continue to rule (as they are now) we'll never leave the Earth and we'll never become a space-faring species.

Except Rusia, who are still (Or will be if they figure out why the last one went pop) sending up rockets and crew to the internation space station.
And China, who today launched the first part of their new space sation.
And the British company Virgin who will be taking passengers into space in the next year or two.
Or all the small independent US organisations who are planning to follow Virgin's example.
It's just NASA which is lagging behind.

ETA: And I forgot to mention the Eurpean Space Agencies most excellent rocket programme.

edit on 30-9-2011 by Shamatt because: (no reason given)

None of them are going anywhere near as far as the moon. We should be way past that by now.

Originally posted by spoor

Originally posted by chr0naut
\When they first landed on the moon, they only had less than a minute's fuel left to allocate to landing the module. If they'd have made a mistake in the calculations, they'd never have had enough fuel to return to Earth.

Wrong actually, the fuel and engine used to land the module was a different engine and fuel used to take off from the moon

en.wikipedia.org...

Yeah, I actually know that. What I was getting at was that there was like 58 seconds worth of fuel left when the module landed.