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Apollo Sites from LRO
James Fincannon
post May 8 2012, 01:47 PM
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Apollo Lunar Surface Journal on Apollo Flags as seen by LRO.

This link is to this page:
Apollo Lunar Surface Journal Apollo Flags Link
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machi
post May 8 2012, 11:10 PM
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Interesting animated gifs!

Evidently I didn't see all LRO's images of Apollo sites, because I recognized only few frames.


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stevesliva
post May 10 2012, 04:52 PM
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For what it's worth, you have to take the idea that "UV light will surely destroy the nylon" with a grain of salt-- I've never seen anyone say for certain whether UV light can destroy nylon in a vacuum.
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Mr Valiant
post May 11 2012, 02:46 PM
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Good call. Many of the corrosive forces that take place on the surface of the Earth, rely on oxidation. Degradation by UV is a form of sloww cooking.
Lets say the flags have survived? That can be a big plus for future Moon exploration. We could use 'plastic' habitats and machines and be confident
that they can survive the harsh Lunar enviroment. Gotta take a closer look!
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wildespace
post Jul 25 2015, 08:11 AM
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A very cool and informative way to view Apollo sites at different times of the lunar day is to use the "flip book", like this one for Apollo 17: http://www.lroc.asu.edu/featured_sites/view_site/6

You can see the shadows from various hardware (including the flags) grow of shrink depending on sun angle. As the shadow from the flags is clearly hovering above ground level, this shows that the flags are still up on their flagpoles.


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Phil Stooke
post May 21 2016, 12:03 AM
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One of the puzzles about LRO imaging of Apollo sites has been the lack of evidence for the LM Ascent Stage impacts. Like many people, I have searched for them without success. But I have just observed something curious very close to the expected location of the Apollo 12 LMAS. I have attached two images. One 'zooms in' to the expected impact area and shows an ellipse where the impact was thought to have occurred. That ellipse contains a fantastic crater which would be marvellous candidate except that it clearly exists in a Lunar Orbiter image taken before Apollo. But I have just noted that on the west end of the ellipse is a curious area of small dark streaks, looking like some of the distal ejecta splotches the LRO team has reported around very recent impacts. Except -they don't form a radial pattern and only occur in a linear band oriented pretty much as the LM was travelling. My second image shows the area of this observation - just screen grabs from Quickmap at this stage.

It would be really nice if this could be traced back to some kind of surface disturbance - even if not a very obvious crater. But I don't see anything of the sort.

Impossible to be sure of anything, but I thought I would point it out. It would be interesting to see if similar features occur at other LMAS locations.

Phil

Attached Image


Attached Image


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nprev
post May 21 2016, 08:37 AM
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Newbie questions: With respect to the image orientation, from which direction was the ascent stage expected to come in from? I'm assuming from the right side.

Also, were they intentionally deorbited in any way, or were they completely uncontrolled? Reason I ask is that if they were just allowed to decay then a grazing impact seems possible. Maybe the hardware got widely distributed along the track instead of forming a nice neat crater given the overall fragility of the vehicle. Probably the only thing that could be expected to survive is the engine.


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Phil Stooke
post May 21 2016, 04:24 PM
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You're a newbie?

The spacecraft approached from the east - all Apollo missions orbited east to west (the Lunar Orbiters orbited west to east). Apollo 12 was commanded to impact, but still a grazing impact. Apollo 11 and 16 were not commanded and fell at unknown locations. Apollos 12, 14, 15 and 17 were commanded to impact. None of the crashed LM ascent stages have been associated with any impact crater yet.

Phil



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dvandorn
post May 21 2016, 10:55 PM
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All of the LM ascent stages were grazing impacts, but all of them caused rather strong seismic signals, picked up quite clearly and distinctly even by seismometers emplaced hundreds of kilometers away. The fact that the A16 LM ascent stage impact wasn't noted on any of the seismometers I always put down to the likelihood that it impacted on the far side, with most of the Moon's bulk between it and the seismometers.

You would have to think that anything that generated such seismic signals would have created a crater, wouldn't you?

It also seems to me that the dark streaks seem radial. If you ran lines back along the streaks, wouldn't that point you back to the origin point of all of them? There couldn't have been a lot of interactions that would have sent off debris on non-radial trajectories, so most of the streaks ought to point directly back to the impact point, right?


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Phil Stooke
post May 22 2016, 09:53 PM
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"If you ran lines back along the streaks, wouldn't that point you back to the origin point of all of them? There couldn't have been a lot of interactions that would have sent off debris on non-radial trajectories, so most of the streaks ought to point directly back to the impact point, right?"

If only I had thought of that! Actually - I did:

"It would be really nice if this could be traced back to some kind of surface disturbance - even if not a very obvious crater. But I don't see anything of the sort."


Phil


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stevesliva
post May 23 2016, 07:00 AM
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QUOTE (dvandorn @ May 21 2016, 05:55 PM) *
all of them caused rather strong seismic signals


Just one blip? Or a medium blip and a lot of littler blips?
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James Fincannon
post May 23 2016, 04:44 PM
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QUOTE (Phil Stooke @ May 21 2016, 01:03 AM) *
One of the puzzles about LRO imaging of Apollo sites has been the lack of evidence for the LM Ascent Stage impacts. Like many people, I have searched for them without success. ...
Phil


I had forgotten about those impacts.


Its interesting how the chart on this link (http://history.nasa.gov/SP-4029/Apollo_18-29_LM_Lunar_Impact.htm) makes it seem that the location is _so_ precise. Also, an estimated crater diameter (29.9 ft... that's to the tenth of a foot!). One Apollo 12 report says the lunar radius at impact was 5,697,847 ft. Pretty accurate! They say -3.944 deg by -21.196 deg. Again with the accuracy! (from pg 5-34 of Apollo Mission 12, Trajectory Reconstruction and Post-flight Analysis Volume 1). Elsewhere I saw the mass at impact was supposed to be 5254 lbs.

Perhaps the use of topographic maps could help see what may be going on. If the height was different than they thought maybe it would hit earlier or later.
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Phil Stooke
post May 23 2016, 06:34 PM
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I think you are right about topographic maps. We have this problem everywhere on the Moon. Consider the locations of the Ranger 4 and Lunar Orbiter impacts on the lunar far side. When they occurred we knew nothing about farside topography, so the calculations combined the best estimate of trajectory with a spherical moon to predict the impact location. Today we could re-do the analysis with LOLA topography to get a much better idea of the location. But as far as I know the re-analysis has never been done.

For Apollo 12 and other Earthside impacts, obviously they did have better topography to work with, but it was still quite uncertain compared with today's topography - they had not yet had even the late Apollo altimeters. So a re-analysis with LOLA topography would be really useful. The precision in those quotes is unwarranted.

Incidentally, if you put those coordinates for Apollo 12 into Quickmap, the position is about 500 m south of the dark streaks I noted.

Phil


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James Fincannon
post May 23 2016, 07:19 PM
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"APOLLO MISSION 12, TRAJECTORY RECONSTRUCTION AND POSTFLIGHT ANALYSIS VOLUME 1"
An excerpt:
"The rev 34 (deorbit) trajectory for the LM was reconstructed from MSFN doppler data from RID (Madrid, 2-way), MIL, ACN (100 observations pre-burn and 159 observations post-burn), 5 SXT shaft angles, 2 SXT trunnion angles, 7 VHF ranging points, and the thrust profile of the deorbit burn obtained from IMU accelerometer data.

The converged residual statistics for all of the observations used in the fit are as follows:
No. OBS. Station Type Mean Sigma
86 RID MSFN .348 cps 1.404 cps
87 MIL MSFN .235 cps 1.416 cps
86 ACN MSFN .342 cps 1.356 cps
5 CSM SXT Shaft .001 deg .019 deg
2 CSM SXT Trunnion .033 deg .128 deg
7 CSM VHF Range -470 ft 506 ft

The accumulated thrust velocities in IMU platform coordinates due to the deorbit burn are:
Delta Vx = -188.57 ft/sec
Delta Vy = 54.15 ft/sec
Delta Vz = -6.21 ft/sec

The time of impact is estimated to be 149:55:16.46 GET. The selenographic coordinates of the impact point are:
LATITUDE = -3.944 deg
LONGITUDE -21.196 deg
RADIUS = 5697847 ft
Selenographic Orbit Inclination = -14.531 deg
Relative Velocity Magnitude = 5517.2 ft/sec
Relative Flight Path Angle = 3.717 deg"

Two images from the report offer a little more data. The one shows the above mentioned 7 VHF range data points from the CSM to the LM.
Attached Image

Attached Image
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dvandorn
post May 24 2016, 02:44 AM
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QUOTE (Phil Stooke @ May 22 2016, 04:53 PM) *
"If you ran lines back along the streaks, wouldn't that point you back to the origin point of all of them? There couldn't have been a lot of interactions that would have sent off debris on non-radial trajectories, so most of the streaks ought to point directly back to the impact point, right?"

If only I had thought of that! Actually - I did:

"It would be really nice if this could be traced back to some kind of surface disturbance - even if not a very obvious crater. But I don't see anything of the sort."


Phil


Of course you did. Sometimes I can sound like an idiot without even trying very hard. sad.gif

Sorry, it was just the logical thing that popped into my head. I plead pain meds (had an emergency surgery a month ago, to fix something that wasn't connected back up right after those major surgeries I had two years ago... sigh...), it seems like all those little inner voices you can normally filter out keep popping out, in my posts and my conversations. Certainly no offense meant.

I'm still fascinated by an impact that could generate relatively strong seismic signals and yet not seem to leave any obvious crater. Gonna have to think about that one.

-the other Doug


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