I had the 2000mm Ritchey-Chretien astrograph telescope out in front of my place last week and even though I got an early start it took an amazingly long time to get going that particular night. I have a new small camera that I used to take my Mars pics at Opposition on October 13th but thought it might make for a more sensitive guide camera because the pixels on the camera detector are smaller and the chip is larger than my usual guide cam.
The 2000mm Ritchey-Chretien Astrrograph Scope
Why is it never easy?
And the R-C scope with its long focal length is always demanding that everything be running really well so I thought this would be a way to up my game. As it turns out this new guide camera was constantly losing stars in the guiding software and after taking almost an hour trying to find a setup and setting that would work for it I went back to the old camera which has proven to be solid.
When I’m shooting from the house I can’t see the north star so I have to use the drift-alignment method which is very accurate and takes a long time to get right sometimes. Well, this particular night my rig was real finicky and it took even longer than usual. I started getting things out and ready about sundown which was 5:30 PM and it was now 11:00 and I was barely ready to shoot. I slewed the scope over to my target for the evening, the galaxy M77 in Cetus.
There was near a full moon in the sky that night (97% illuminated or one day past full) and to my dismay even with a 60-second exposure I couldn’t even tell if my target was in the frame, even though the software assured me it was. Crap!
Well by now I was getting tired and if I was going to get anything serious shot that would take at least until 5 AM so I decided to just get as good a shot of the moon as I could and call it a night; just something to make the evening not a total bust. Also, I haven’t tried the new monochrome camera on this scope yet; all the shooting I’ve been doing in October/November has been with the 4-inch refractor for big widefield targets like the North American Nebula (two posts earlier than this one) in this blog. So I was interested in seeing how much sky I could see with this high magnification setup.
Pixels & Moonbeams
So I found the moon and tried to figure out the exposure which because the camera is so sensitive and the moon so bright I ended up taking 30 exposures at, get this: .005 seconds! Needless to say I was done pretty quickly and put the scope away. I didn’t even shoot in color, just straight black and white frames.
I got around to going through the images yesterday and found that 20 of the 30 just didn’t really measure up for one reason or another. I was really surprised that some of the photos were motion blurred; I was figuring at .005 seconds that would be short enough to ‘freeze’ anything!
So had ten pretty good ones and did some stacks of 3, 5, and all 10 to see if there was any difference, none that I could tell. So I did the usual processing maneuvers which in this case was to make the dark areas of the moon a little darker to create better contrast when zooming in and I also ran some sharpening filters to eke out every possible detail.
Well the monochrome camera is just freaking fantastic in it’s detail and the photo I got shows details on the moon I’ve only glimpsed through my telescope visually, even with the 18-inch. So here is a moon pic that is one day past full, 97% illuminated.
Click on this image to open in a lightbox style window to see all the juicy details in this image.
Ok so this is a pretty good image of the Moon. What now? Well you know, sometimes you spend so much time making the image it’s easy to forget to really look at what you’ve got and I can’t think of a better place to do that than the Moon. It is only 245,000 miles away, has no atmosphere so everything is crystal clear on the surface and there’s all kinds of interesting things going on so I decided to really zoom in and take a good look around.
I prepared some closeups of my favorite places since it’s hard to zoom in on images in a web browser although you can right-click on an image tell it to “open image in a new window” and then use Command/Ctrl + or – to zoom in and out.
The bright and obvious crater Tycho, with ‘ejecta’ debris that spreads for over a thousand miles!
Crater Tycho is my favorite crater! This is a testament to what a geek I am; how many people have a favorite lunar crater? Located in the most heavily cratered part of the southern hemisphere it stands as a testament to a really big fast-moving something that walloped the moon back in the early days of the solar system during what is aptly called the “period of heavy bombardment”. Indeed! There are so many impacts in this area of the moon that the craters are overlapping in places.
Here’s a real closeup and you can see that this crater was made by an object that came streaking in from about 4 o’clock and hit the moon obliquely. We can tell this because the central peak is off center and the crater walls on the following edge (10 o’clock) are less well defined.
Hitting Eject
One of the things I like best about Tycho but is not unique to it are the prominent rays of ‘ejecta’ that emanate outwards in all directions. This is lunar soil and rock that got so hot during the impact it turned white as it was being sprayed all over the moon. You can trace these rays out over a thousand miles in some places.
Ejecta from craters on the moon is commonplace for the larger impacts as we will see. In fact they are scientifically useful since if you park your spacecraft on one of the ejecta rays, you can sample the crater itself without having to actually go down in there, which is probably more dangerous than you would want to attempt.
Copernicus
After Tycho, the crater Copernicus is one of the most readily identified because it’s huge and sort of off by itself at mid latitudes in the west-central portion of the moon.
Copernicus Crater and the Apennine mountains curving in from the upper right corner.
There are lots of ejecta coming from this crater but they look a little more random and don’t go out as far suggesting that the object hitting the moon here was larger and slower than the one that made Tycho crater.
The Apennine Mountains in the upper right are a very interesting area of the moon to observe with a telescope when the moon is half lit because the day/night dividing line goes right through here and all kinds of interesting things happen with the long shadows from the low sun angle. I remember one time where half of the mountains were in darkness except the tips of the peaks which were still being lit looking like these super bright points in the “dark side” of the moon.
The brilliant white crater at top left is crater “Aristarchus” and through a scope draws your eye as probably the whitest thing on the moon.
Moonar History
In order to understand what you see in the next photo you need to know how the moon formed in the first place. Early in the solar system’s history the Earth was really just a round blob of molten lava, rock and was starting to cool down into something more cohesive. At that time it’s theorized that something about the size of Mars slammed into us and gouged out a bunch of material that made it out past the Roche Limit where it was too far away to fall back. In a relatively short period of time all this stuff condensed into the moon which conveniently is just about the same size as the Pacific Ocean, which could be the biggest ‘impact crater’ on Earth.
So if the Earth was molten at the time then so would have been the Moon but as it cooled it wasn’t exempt from the general bombardment taking place throughout the solar system and was repeatedly struck in its semi-molten state.
The Southwest portion of the Moon.
I love this part of the lunar terrain because it tells a story. In the center of the image you see a lot of craters where all you really see is the rim but the crater bowl is filled in. Well, these must have been made pretty early when the moon was still fairly sloppy because the crater bowls got filled in with the lava that was still pretty much sloshing around. There’s probably dozens of these in this area. Also notice that the really well-formed, deep craters are much smaller indicating that they are younger due to not being filled in and since all the really big stuff had hit what it was going to hit by now.
You can see some of the ejecta rays from Tycho coming up on the right side of the photo and that’s the brilliant white Byrgius crater (had to look that one up) in the upper left.
Sea In Crisis
The large dark areas of the moon are referred to as “Seas” or in Latin, “Mares” because they looked smooth to the eye, as if watery. We know now that the moon is a very dusty place with the dust made up of what could essentially be thought of as powdered glass; very abrasive and will present a challenge to people and machinery if we ever go live there.
The ‘Seas’ are large expanses of lava that cooled relatively late in the early history of the moon. How do we know? Not so many craters on average as the lighter areas of the moon meaning that the period of heavy bombardment was winding down at that point. You see a crater with a bunch of craters inside it? Old crater.
The Sea of Crises in the NE quadrant of the Moon
This is an interesting one because it’s obviously an old crater, but it’s huge enough to get the designation of “sea” which must give it a terrible identity crisis. Perhaps that’s why it’s the ‘Sea of Crises’…' Or not…
I love the little changes in elevation on the smooth parts leaving a hint of shadow where parts of it have subsided. You can see this kinda thing easily with any decent telescope at around 100x magnification.
Calm Seas
If you back off and look to the left from the Sea of Crises you encounter two more famous moon seas, the Sea of Serenity and the Sea of Tranquility.
The two dark areas in the center of this photo are the Sea of Serenity (top) and the Sea of Tranquility (bottom)
Obviously a newer surface due to the relatively few craters and would have a much higher chance of having a smooth place to land if you should decide to go there, which we did in 1960 and managed to make it happen on July 20th, 1969.
So I have this rockin’ moon image now which is great, but what are you gonna get out of it besides posting it? I thought, “you know, it might be fun to try and track down and mark the locations of all the Apollo missions and read about why those spots were chosen and why in that order”; my inner geek showing through there.
Map On
I have a great Moon app on my phone called MoonGlobe HD (highly recommended) and using it I was able to track down all 6 moon landing sites. I was amazed at how clear my photo turned out and I started wondering how accurately my plot of the landing sites was going to be so I made a rough calculation and it seems that 1 pixel of my moon photo is equal to 1.34 miles on the moon! Pretty cool.
The red box encompasses the area where all the Apollo missions landed. Notice how they completely avoided the rough southern hemisphere although as their methods and successes advanced they did start landing in some fairly adventurous places because the missions were more and more about geology science and less about “hey, look what we can do.”
So here’s my photo with all of the Apollo landing sites marked.
All six Apollo landing sites. That’s crater Copernicus on the middle left. Click for a larger image.
Apollo 11
We all remember the phrase “Tranquility Base here, the Eagle has landed” and the reason it was called Tranquility Base because the Sea of Tranquility was selected as the first landing site out of an original list of 30.
Although NASA would never characterize it this way Apollo 11 was pretty much all about, “Can we pull this off without killing them!” which is understandable since nobody had ever set foot on another world before and quite a bit of the lunar part of the mission was going to be done for the first time ever with no actual rehearsal, just the benefit of careful planning and a calculated reasonable margin of error. There was also, “Oh leave some reflectors and seismographs behind and get a couple suitcases of a variety of rocks…”
The criteria for the landing site were, smooth landing site, no more than 2° slope in the approach path, no mountains and boulders nearby in case targeting was off and mountains might fool the landing radar, minimum fuel consumption, and be reachable with an overall mission on what’s known as a “free return trajectory”.
A free return trajectory is a safety measure that NASA employed in case something went wrong with the spacecraft on the way to the moon after leaving Earth’s orbit. Basically they worked it out so that they would arrive at the Moon slightly ahead of it (to the left) at exactly the right altitude and speed that, if needed, the spacecraft would just sling around the Moon once and head straight back to where Earth was going to be in 3 or 4 days so even if the spacecraft was in poor shape they could at least be at Earth to make a reentry. One of the reasons Apollo 13 was such a dicey mission was that it was not on a free return trajectory.
Apollo 12
The landing criteria for Apollo 12 were pretty much the same as Apollo 11 but NASA wanted to see if they could up their game on navigation and conduct a truly precise pinpoint landing at a specific, preplanned spot as opposed to Apollo 11 which was pretty much, “Anywhere that looks good Neil!”.
So they decided to try and land within walking distance to Surveyor 3 which was part of a fleet of reconnaissance missions to try and get super close pics of potential landing sites.
The mission was almost over in the first minute when the launch vehicle (which was mostly 6 million pounds of liquid hydrogen and liquid oxygen) was struck by lightning twice in the first minute of flight! The engines continued firing however and after reaching orbit a thorough checkout of all systems showed no damage so the mission proceeded.
Apollo 12 had an upgraded flight navigation computer (the landing computer on Apollo 11 was in an almost constant state of overload close to landing) and was used to update 12’s position and get them on track for the precision touchdown which happened ‘by the numbers’ landing less than 200 yards from Surveyor.
In addition to deploying more sophisticated lunar surface instruments, an S-band comm antenna, and a core sample along with the usual rocks, they went over to Surveyor and found some pieces they could take off and bring back with them since engineers on Earth were curious to see how various metals did when exposed to the harsh space environment for and extended period of time. They also brought back some wiring conduit which they knew left the Earth with some organic compounds inside and they wanted to see if any of those had survived three years in space.
Apollo 13
See the movie! Fantastic story and pretty much everything you see in that movie is the way it happened.
Apollo 14
This was essentially the ‘do-over’ from Apollo 13 taking place after a precision landing less than 31 yards from target at the Fra Mauro Formation that was located in the debris field from the huge, relatively recent impact that formed the Imbrium Basin (the big dark area north of Copernicus).
The mission went very will and they got a good variety of geological material (rocks) to bring back for study.
Alan Shepard takes a mulligan on the Moon
At the end of the mission, Alan Shepard became the only person to play golf on another world by hitting two golf balls in lunar gravity using a six-iron head he had had modified to mate to the lunar sample pickup stick tool (you could change out tools on the end). The spacesuit was so bulky that he could only swing with one hand and he duffed the first shot but hit the second one clean and said that even though it was probably a 35 yard shot on Earth, it went about 200 yards on the Moon. So there are two golf balls on the moon. Alan never told anyone the brand of those golf balls either.
Apollo 15
The landing site chosen for Apollo 15 was on the eastern margin of the Imbrium Basin in the region known as Palus Putredinis. There were two main objectives for this landing site. First, the rim of the Imbrium Basin could be sampled along the Appenine Mountains. It was expected that this would provide material from deeper in the lunar crust than was sampled in the Fra Mauro Formation by Apollo 14. Second, this site provided an opportunity to explore Hadley Rille, a photogenic channel in the mare surface that was probably formed by volcanic processes.
Apollo 15 was the first of the so-called J missions, which considerably expanded the capabilities for doing science on and near the Moon. For the first time, three 7-hour-long EVAs would be performed, and a lunar rover would significantly extend the distance a crew could travel over the lunar surface. In addition, the restriction on landing near the equator was lifted. Finally, a sophisticated suite of science experiments was also carried in the service module and used to map the Moon from orbit.
Apollo 16
The Apollo 16 landing site was selected to obtain samples of two highland geologic units, the Descartes Formation and the Cayley Formation, which are widespread on the lunar nearside. Prior to the mission, it was thought that both were of volcanic origin, but the returned samples demonstrated that this is incorrect. Three of the first four Apollo Moon landings were in mare regions and the fourth was in ejecta from the Imbrium impact. When selecting the Apollo 16 landing site, the highest priority was given to landing at a site in the lunar highlands, which occupy more than five times the surface area occupied by ‘Mare’ units.
The Descartes site was certified as safe for landing on the basis of Apollo 14 orbital photography. The specific landing site was selected between two fresh, young impact craters, North Ray Crater (1000 meters in diameter) and South Ray Crater (680 meters in diameter). These craters provided natural drill holes through the regolith at the site, exposing samples of the underlying bedrock in ejecta fragments for sampling by the Apollo 16 crew.
Apollo 17-Final Mission
Because Apollo 17 was the last lunar landing of the program, all of the high-priority candidate landing sites were given consideration again. However, many were eliminated from consideration for either scientific or operational reasons. A landing near the central peaks of Copernicus crater had long been considered, but was now regarded as of lower priority, both because some Apollo 12 samples may have provided an age for this impact event and because three landings had already occurred in the vicinity of Mare Imbrium. A landing in the southern highlands near Tycho crater was rejected because of concerns about rough terrain and mission safety.
A landing on the lunar farside in Tsiolkovsky crater was considered, but rejected because of operational difficulties and the added expense of providing the communications satellites that would be necessary to maintain radio contact between the landing site and ground controllers. A highland site southwest of Mare Crisium was considered, but was rejected because this region of the Moon was easily accessible to spacecraft launched by the Soviet Union. In fact, the Luna 20 spacecraft landed in this region in February 1972, just a week after the Apollo 17 site selection was made, and returned 30 grams of samples to Earth for analysis.
Old Highland Material
The first priority was obtaining samples of old highlands material (older than the Imbrium impact) from as large a distance as possible from the Imbrium basin. All three of the final candidate sites were between 800 and 1000 kilometers from the Imbrium basin.
Young Volcanic Material
The second objective was investigating the possible existence of young (less than 3 billion year old) volcanic activity. This was considered important both for understanding the thermal evolution of the Moon and also because interpretations of orbital photography suggested that young volcanism might have been explosive in nature and hence associated with a high abundance of volatile materials such as water.
Orbital Science
There were two competing objectives for obtaining orbital science coverage on the Apollo 17 mission. First, there was a desire to have orbital ground tracks that had minimal overlap with those of Apollo 15 and 16, so that the maximum amount of new information could be obtained. On the other hand, because Apollo 17 carried several new instruments, overlapping ground tracks with earlier missions would allow data from the new and old instruments to be compared over common areas.
So There You Have It
Well I managed to get hours of entertainment out of a single moon image. Hope you enjoyed it and did a little exploring on your own!
Bill the Sky Guy
December 6th, 2020