Moon Rocks and the Absence of Regolith

[Dalhousie]

And if we really want to confuse things up. And which no has brought up, Von Braun became very religious near the end of his life and joined an Evangelical Episcopalian Anglican congregation.

Most sources I have seen indicate this happened  in while at Fort Bliss, ie. 1945-1950.  Not "near the end of his life". Closer to half way through

[Dalhousie]

My, my, how far we are from photographs of lunar regolith and spacecraft stability.  You can't talk about the actual facts of the Apollo missions so you've shuttered yourself behind a vague, pontificatory fairy tale of what secret messages Wernher von Braun must have left on his tombstone.

The main people who think there is something sinister to appropriate use of a beautiful verse as an epitaph seem to be flat Earthers.  I wonder if this is his actual stance, hidden behind obfuscation about regolith, thrusters, hidden meanings behind epitaphs, and conspiracy theories about Gene Shoemaker and Neil Armstrong?

[mako88sb]

Hi Dalhousie,

 While it is debatable what he meant, many point to the fact he is talking about the firmament. Truth is God. And one of God's protective layers was the firmament in the bible that that is a protective layer over earth that can't be penetrated. While I personally don't believe there is a firmament, Neil was a very religious man. So if he is referring to the firmament he is suggesting that we cannot go the moon.

(And while all this may seem crazy, Wernher Von Braun, the man behind the Saturn program, also bizarrely on his own tomb stone puts only one thing on it, Psalms 19:1 ... "the firmament sheweth its handywork". Of the 4 or 5 billion people on earth at the time, Von Braun, given he sent a manned rocket to the moon, he should have been the very, very, very, very, very, very last one on earth to put something like this on his tombstone but he did. Completely bizarre)
 

I think you should take the time to read Jim Irwin's "To Rule the Night" and Charlie Dukes "Moonwalker". Both men were(Irwin)/are also very religious and they both said that their experiences on the moon strengthened their convictions about the existence of God. While you're at it, read Tom Kelly's Moon Lander book. You also might want to take the time to go through all the Apollo mission reports that are available online. So far that I know, every single supposed proof about hoaxed landings has been debunked, most of it quite easily. Of course the big problem with "your side" is the unwillingness to recognize how flawed the whole conspiracy is and how it would have been impossible to pull it off, never mind keep it from being discovered during the past 5 decades. 

[gillianren]

I'm going to emphasize "impossible," because that is just literally true.  We don't have the technology now to fake the Apollo missions the way they appear.

[ka9q]

Ignoring lateral velocity and assuming a vacuum, a particle traveling vertically upward from the lunar surface starting at velocity v will be slowed by acceleration -a.  The signs on the variables are different ....

You're right of course, but there is a much simpler way to explain it: conservation of energy. The moon has no atmosphere, so there is no atmospheric drag and no mechanism by which an object moving above the lunar surface can lose energy. So if it was launched from the surface without enough velocity to escape, then it must fall and hit with all the kinetic energy it had when leaving. The only possible difference would be if the impact site was at a different altitude than where it left the surface.

[ka9q]

Shoemaker died in a car crash. People do this a lot. Well, technically they only do it once, but car accidents are not infrequent and people with interesting careers are not immune to them.

I visited the Siding Spring Observatory in Australia not long after that happened. One of the locals opined a perfectly reasonable hypothesis. Shoemaker (and his wife, who survived with serious injuries) were looking for ancient impact craters, something they'd been doing for decades. They were on a remote single-lane road in the outback when they rounded a bend and saw a truck coming the other way. Shoemaker's American instincts kicked in and he swerved to the right. That wasn't the right thing to do in Australia.

[ka9q]

When designing a payload for space flight you always want to reduce weight where possible. Not at the cost of practicality, however.

If Einstein had been an aerospace engineer, he probably would have said something like "Everything should be as light as possible, but no lighter."

[ka9q]

These are not clouds in the sense of clouds of dust on Earth.  They are particles that have been ejected from the lunar surface by impact at velocities high enough to achieve orbit. This requires a velocity of at least 1.87 km/s but less than lunar escape velocity of 2.38 km.

I don't think it's possible for an object to be placed into orbit with a single impulse from the surface. It could escape with sufficient velocity, but otherwise it would have to hit the surface before completing its first orbit. That could still be very far from the launching point.

[Dalhousie]

These are not clouds in the sense of clouds of dust on Earth.  They are particles that have been ejected from the lunar surface by impact at velocities high enough to achieve orbit. This requires a velocity of at least 1.87 km/s but less than lunar escape velocity of 2.38 km.

I don't think it's possible for an object to be placed into orbit with a single impulse from the surface. It could escape with sufficient velocity, but otherwise it would have to hit the surface before completing its first orbit. That could still be very far from the launching point.

You are assuming that it material ejected from an impact can be equated to a single impulse launch.  Since material does end up in orbit from an impact even, clearly it's more complex than that.  Remember that the Moon is thought to have form from a giant impact, as possibly are Phobos and Deimos.  Dust clouds from impact have been observed round the satellites of Jupiter and Saturn as well. https://www.nature.com/articles/nature14479


It's how the Moon is thought to have been formed.

[JayUtah]

In a two-body sense, I think it would be difficult for a single impulse.  But when matter reaches an altitude that Earth and solar gravity has a significant effect, then you can begin to expect orbits.

[bknight]

In a two-body sense, I think it would be difficult for a single impulse.  But when matter reaches an altitude that Earth and solar gravity has a significant effect, then you can begin to expect orbits.

Difficult but not impossible, IIRC there have been some 15-20 Lunar meteorites discovered in the Antarctic.

[ApolloEnthusiast]

In a two-body sense, I think it would be difficult for a single impulse.  But when matter reaches an altitude that Earth and solar gravity has a significant effect, then you can begin to expect orbits.

Difficult but not impossible, IIRC there have been some 15-20 Lunar meteorites discovered in the Antarctic.

Those would fall under the escape velocity that ka9q mentioned, I believe. 

Unless I'm mistaken, I think what he was saying is that even with velocity sufficient for lunar orbit, the angle would either be to steep or too shallow, and in either case result in an "orbit" that impacts the surface.  From what Jay was saying, it sounds like Solar and Earth gravity can potentially provide the course corrections necessary to place the an object into a stable orbit.

I am speculating however, and welcome correction if I've misunderstood.

[JayUtah]

Difficult but not impossible, IIRC there have been some 15-20 Lunar meteorites discovered in the Antarctic.

That would be an example of something that escaped lunar gravity.  A closed orbit from any single impulse would likely impact the Moon.  In fact, I think this can be proven mathematically.  You need a second impulse.  For powered ascent, the velocity vector changes either constantly, or at least once subsequently.  So you go up for a while, then you go downrange for a while.  That's equivalent to multiple impulses.  It results in a velocity state that's consistent with a useful closed orbit.  This is why we have to invoke restricted n-body solutions to explain impact ejecta in lunar orbit -- N bodies because anything more than two is an iterative problem, and restricted because we ignore the gravitational effect of dust on the Moon.

An ejectum might rise high enough that Earth's gravity tugs at it just enough to circularize its orbit.  It would be a razor's edge between falling back down to the lunar surface and going into some sort of (open or closed) orbit around the Earth.  Or possibly even the Sun, in even rarer cases.  I would expect this to apply to only a tiny percentage of ejecta, and I think the tenuous clouds are consistent with that.  Particles can also accumulate in the stable Langrange points, depending on their velocity state.

ETA:  Ninja'ed by the newcomer.

[ApolloEnthusiast]

ETA:  Ninja'ed by the newcomer.

I got in faster but you certainly said it better lol

[bknight]

Difficult but not impossible, IIRC there have been some 15-20 Lunar meteorites discovered in the Antarctic.

That would be an example of something that escaped lunar gravity.  A closed orbit from any single impulse would likely impact the Moon.  In fact, I think this can be proven mathematically.  You need a second impulse.  For powered ascent, the velocity vector changes either constantly, or at least once subsequently.  So you go up for a while, then you go downrange for a while.  That's equivalent to multiple impulses.  It results in a velocity state that's consistent with a useful closed orbit.  This is why we have to invoke restricted n-body solutions to explain impact ejecta in lunar orbit -- N bodies because anything more than two is an iterative problem, and restricted because we ignore the gravitational effect of dust on the Moon.

An ejectum might rise high enough that Earth's gravity tugs at it just enough to circularize its orbit.  It would be a razor's edge between falling back down to the lunar surface and going into some sort of (open or closed) orbit around the Earth.  Or possibly even the Sun, in even rarer cases.  I would expect this to apply to only a tiny percentage of ejecta, and I think the tenuous clouds are consistent with that.  Particles can also accumulate in the stable Langrange points, depending on their velocity state.

ETA:  Ninja'ed by the newcomer.

Fair enough, since there have been so few found on earth so far.