My "kicked dust" discovery

[AstroBrant]

Maybe someone else discovered this before I did. This would be a good place to find out. I put this in the hoax section because I thought it might be useful in discussions with hoax nuts about dust movement on the moon.

While watching ytmoog's video of the A15 rover deployment, I noticed a puff of dust above the descent stage, and it could be seen hitting the ground up to maybe 50 feet away. (Right after the wheels pop out.)

Anibal Vilela started a thread asking about the "flash". After a little discussion, I suggested that it was dust that had been kicked up by one of the astronauts, but I couldn't figure out how. I turned the audio back on again, and sure enough, it became very clear that Jim had fallen down. I also noticed that as Dave was saying, "Okay, here, let me help you," his reflection could be seen on the bottom of the rover, moving from right to left.

So Jim is closer to the camera, and that's why we can't see the dust at first -- it's going across the LM's shadow. A little can be seen coming in from the right. That dust hits the LM and splashes upward where it is easily seen.

If I'm right, this should be one of the best "kicked dust" examples yet. I mean, it's damned impressive! What a shame we can't see Jim falling down and how he kicked the regolith, or maybe propelled it with a swipe of his hand as he was going down.

Still, this can't compare to Data Cable's discovery of Venus in Al's pictures, but it's about the best I've ever done. (I think.)

[raven]

Not to mention, it shows what so many ignorant (now there's an unnecessary adjective) conspiracy theorists have asked, how did they get the rover out of the LM. Whenever one asks, and it happens fairly frequently, I can just point to that video and say 'That's how!' Thank you, Internet!

[onebigmonkey]

That's a fine spot!

I'm not sure I can see the dust hitting the LM, but you can see reflection of Dave's suit on the underside of the LRV as he moves over to help!

It occurred to me that a fall close to the LM ought to be visible as scuff marks on the ground, but I can't see anything obvious on the photographs.

[ka9q]

I knew about this incident a while ago, but hadn't thought about it's utility.

I don't think the dust actually hits the LM; I think it simply flies up behind it, where it momentarily scatters some sunlight forward. The left side of the LM was in shadow, but the left front RCS thruster cluster is silhouetted by the sunlit dust, and this probably could not have happened if the dust was rebounding off the LM's left side. Besides, you very clearly see the dust hit the ground behind the LM.

I think Irwin actually kicked the dust that high, which shouldn't be that hard in 1/6g and no drag.

[Dr.Acula]

Maybe someone else discovered this before I did. This would be a good place to find out. I put this in the hoax section because I thought it might be useful in discussions with hoax nuts about dust movement on the moon.

While watching ytmoog's video of the A15 rover deployment, I noticed a puff of dust above the descent stage, and it could be seen hitting the ground up to maybe 50 feet away. (Right after the wheels pop out.)

Anibal Vilela started a thread asking about the "flash". After a little discussion, I suggested that it was dust that had been kicked up by one of the astronauts, but I couldn't figure out how. I turned the audio back on again, and sure enough, it became very clear that Jim had fallen down. I also noticed that as Dave was saying, "Okay, here, let me help you," his reflection could be seen on the bottom of the rover, moving from right to left.

So Jim is closer to the camera, and that's why we can't see the dust at first -- it's going across the LM's shadow. A little can be seen coming in from the right. That dust hits the LM and splashes upward where it is easily seen.

If I'm right, this should be one of the best "kicked dust" examples yet. I mean, it's damned impressive! What a shame we can't see Jim falling down and how he kicked the regolith, or maybe propelled it with a swipe of his hand as he was going down.

Still, this can't compare to Data Cable's discovery of Venus in Al's pictures, but it's about the best I've ever done. (I think.)

Thank you very much for this link. I'm actually looking for a clip about rover deployment. You've saved some time for me 

[tikkitakki]

It is mentioned on the ALSJ:
http://www.hq.nasa.gov/alsj/a15/a15.lrvdep.html#1201605

...
[Irwin, from the 1971 Technical Debrief - "I was pulling on the lanyard with one hand and trying to take pictures with the other. And of course I fell down there because I tripped backing up in that soft soil."]
...
[As a final note to this little incident, Journal Contributors John Pfannerstill and Karsten Rinkema have noted a brightening of the TV image at the right side of the frame, immediately after Dave finishes saying "Easy, Jim! Easy! Oop.". This is undoubtedly dust that Jim kicked aloft as he fell. He had been backing away from the LM with the TV on his left and his fall must have lofted some dust into the field-of-view. At 120:08:50, Joe suggested that Dave put the TV in the LM shadow. Dave did so, as can be seen in the TV record at that time. Consequently, the flying dust we see after Jim falls must have been lofted high enough and far enough to the right to be in sunlight.]

[Echnaton]

To me the dust looks to be moved by the lanyard hitting the surface, rather than anything kicked up.  Look at how the lanyard is in the sun when in use and snaps back and falls to the right of the leg at the same time the dust appears. 

[ka9q]

To me the dust looks to be moved by the lanyard hitting the surface

I see what you mean, but I don't think that's the cause. The lanyards are pretty thin and light, and I don't see how they could launch that much dust that high by falling slack. Also, we can assume that Irwin kicked up the dust at the same time he lets go of the lanyard. Dust starts hitting the surface behind the LM when the lanyard falls next to the LM's side, giving the dust no time (or a clear path) to get there if it was picked up by the lanyard. Also, the backlit dust higher up (behind the RCS quad) appears only slightly later, again giving it no time to get there unless Irwin kicked it there.

I think he must have lost his balance and fallen backward, kicking a big spray of the stuff toward the rear of the LM. This doesn't seem hard to do when you're wearing a heavy backpack high on your back and you're only been on the lunar surface for half an hour or so. The spray was much like one of the rooster tails during the Grand Prix on Apollo 16, only higher.

If we can estimate Irwin's distance from the LM, we could check the height and timing of the dust sprays (again assuming he kicks it as he lets go of the lanyard) and see if it's consistent with 1/6 g.

[smartcooky]

The video does illustrate just what a hugely difficult environment the Moon must have been to work in. Here are two intelligent, well trained astronauts who must have either rehearsed this procedure, or at least thoroughly trained on it and understood it well, who after fully disconnecting the rover from the descent stage, were still unable to see what was keeping it in place.   

[AstroBrant]

It is mentioned on the ALSJ:
http://www.hq.nasa.gov/alsj/a15/a15.lrvdep.html#1201605

...
[Irwin, from the 1971 Technical Debrief - "I was pulling on the lanyard with one hand and trying to take pictures with the other. And of course I fell down there because I tripped backing up in that soft soil."]
...
[As a final note to this little incident, Journal Contributors John Pfannerstill and Karsten Rinkema have noted a brightening of the TV image at the right side of the frame, immediately after Dave finishes saying "Easy, Jim! Easy! Oop.". This is undoubtedly dust that Jim kicked aloft as he fell. He had been backing away from the LM with the TV on his left and his fall must have lofted some dust into the field-of-view. At 120:08:50, Joe suggested that Dave put the TV in the LM shadow. Dave did so, as can be seen in the TV record at that time. Consequently, the flying dust we see after Jim falls must have been lofted high enough and far enough to the right to be in sunlight.]

Thanks for that reference and for the dialog. While I'm a little disappointed that I wasn't the first, I do have the consolation of solid confirmation.

[AstroBrant]

I don't think the dust actually hits the LM; I think it simply flies up behind it, where it momentarily scatters some sunlight forward. The left side of the LM was in shadow, but the left front RCS thruster cluster is silhouetted by the sunlit dust, and this probably could not have happened if the dust was rebounding off the LM's left side. Besides, you very clearly see the dust hit the ground behind the LM.

I think Irwin actually kicked the dust that high, which shouldn't be that hard in 1/6g and no drag.

Also to OneBigMonkey:

I definitely have the impression of a "splash" off of the dark angled surface below the RCS thrusters. Of course, this doesn't mean that a lot of dust didn't also just fly over the whole thing.

Besides, you very clearly see the dust hit the ground behind the LM.

Yes. As I mentioned, it goes quite an impressive distance. It's too bad we didn't see this from farther away so we could see how Jim fell. I am imagining him instinctively rotating as he felt himself falling backward, and then his grounded foot kicking back with great force as he tried to break his fall with the other foot. If he hadn't fallen, I'm picturing him lunging out of control for 20 feet or so.

[Echnaton]

I see it now that I am on a better monitor.  There is a slightly visible cloud that goes just past the LRV wheel then hits the side of the LM.