I need a list of Discovery missions from each of the competitions since the Discover Program commenced. Not including Lunar Prospector, for which I have plenty of information already. Can anybody help me out?

At a minimum I just need a list, I guess, but other information or sources would be very useful as well, as eventually I have to go there as well.

Phil

I can dig you up the complete set from the first solicitation -- but since then NASA has refused to provide a complete list of the Discovery proposals for any round, which means that all inquirers have had to do some digging. I'll see what has been come up with. (One of the more interesting was "Pele", Jeffrey Taylor's proposal, during the first round, of a lunar-adapted Soviet Marsokhod to land at Aristarchus and investigate its past volcanic activity. I have quite a bit of material on that.)

Thanks for this, Bruce.

I am compiling an atlas of lunar exploration. Past missions are basically finished now, and I am wrapping up the atlas with a look at other plans (such as Euromoon 2000 or Discovery) which did not happen.

I would like to include a brief mention - very brief - of all Moon-oriented Discovery proposals. Then, for any which proposed a specified landing site (even if only as an example of possible targets) or surface activities such as a rover route with sampling stops, I would like to illustrate that to the extent possible.

Any assistance would be sure to earn a big acknowledgement!

Phil

Following up on Bruce's comment, I can now confirm it - NASA has refused to release even a list of proposals for each competition to me.

Phil

Does anyone know *why* NASA is being secretive about the proposals? Is there some halfway rational explanation, or are they merely being precious?

Bob, I think a lot of what goes into a proposal - especially if there is a commercial partner - is proprietory.. from instrument or spacecraft design to observing strategies. But summaries of proposals, and science goals etc., really should not be, to my mind. Generally I find the people involved in the proposals are more forthcoming.

Phil

PS - it's OK, I was only kidding about not asking questions!

I haven't forgotten, Phil -- I've just been juggling several plates at once recently. I don't know why NASA withheld the proposals for the very first Discovery AO from you; they DID give that list in its entirety when they announced the four finalists. But other sources, such as one Space.com article, have provided the names and info on several lunar mission proposals during the next three rounds. I swear by the name of Arthur C. Clarke that I'll dig this information up for you. (For one thing, I haven't forgotten that fan letter you sent me a few years ago -- I don't get all that many, especially from Keith Cowing.)

First fruits of my labor already: I've got the list of 28 full-mission proposals for the first Discovery selection -- and they include 6 lunar missions. Besides Lunar Prospector and Pele, they were:

(1) Diana -- an odd mission, proposed by Chris Russell, which was a sort of early version of Dawn (and which made the cover of Aviation Week!). A SEP-powered orbiter equipped with instruments generally similar to Dawn's original payload would have spent 14 months mapping the Moon (and dropping off a small subsat for farside gravity mapping), then used its ion engines to leave the Moon, hit escape velocity, and rendezvous with the dried-out comet nucleus Wilson-Harrington.

(2) "Icy Moon Mission" (by Bruce Murray). A small lunar polar orbiter which, as its name suggests, would have used a radar scatterometer to look for polar ice deposits.

(3) "Interlune-1" (by Harrison Schmitt). Two lunar rovers -- one as tiny as Sojourner -- would have landed at the Apollo 15 site to reexamine its geology in more detail.

(4) "Lunar Discovery Orbiter" (by William Boynton). Basically a new version of the 1970s Lunar Polar Orbiter, but with fewer instruments.

I have more data on all these squirreled away somewhere -- I grilled almost all of the 28 Discovery proposers in this round, for an article I never got around to writing, and I still have all their mission descriptions squirreled away. I'll track those down, in addition to digging up that information I promised on later lunar Discovery proposals -- although that's a lot more scattered and fragmented, and it will take me a little while to chase down all of it that I remember seeing.

Just a thought, could the technology already developed for the MER rovers be adapted for lunar excursion or would they have to be re-designed from the ground up? In the budget strapped era that we are in it would make sense to try and use technology that is already developed. The MER rovers are a quantum leap over the Sojourner style rover. Sure the bottom line is more expensive, but there is no comparison to the amount of science returned for that dollar using the MER rovers.
The biggest hurdle that I see would be contending with the 14 day long nights.
How do you keep your electronics and instruments warm for that long without going nuclear. But that would apply to any rover developed.

Why would we want to go back to the Apollo 15 site other than nostalgia? Surely we could learn more by going an unexplored area......such as the poles.

Gary

There was a fascinating proposal about the time of the end of Apollo to go back to the Apollo 15 site... Harvest Moon, it was called, planned by "The Committee for the Future" based in Connecticut, I think (I'm doing this from memory, my notes are all in my office, so I may be off). It was written up briefly in Aviation Week in 1973.

The plan was to solicit donations from around the world to fund a mission using left-over Apollo hardware. It would have set up an observatory, a greenhouse experiment, deployed a long-range remote controlled rover and so on at the Hadley-Apennine site. I think some samples might have been sold to help pay for the mission. The site might have been chosen especially because it was so visually appealing rather than for science purposes.

Personally, I'd love to know more about this proposal. It went nowhere of course.

I have found a few references to Interlune-1 now, not very detailed, but they seem to have been directed at Mare Tranquillitatis, Apollo 11 rather than Apollo 15. Schmitt has long been interested in Helium-3, and Mare Tranquillitatis seems to be a good place for it. Interlune-1 was specifically designed to further the study of Helium-3, at least in part. Am I getting this right, Bruce?

Garybeau - Since the landing would be completely different there would be no need to have a foldable rover... so wheels need not be so small... power is different... could be driven by real-time commands... I'd say there is so little in common that MER doesn't help lunar rovers very much.

Phil

As you hinted at, the MERs already use radioisotope heaters in the warm electroinics box.

I'd imagine the components would need only minor adaptations to make the rovers suitable for lunar exploration. Maybe a larger high gain antenna, as decent throughput direct-to-Earth communications should be quite possible at such short range. Something might need to be done with the TES though, as that can take damage at night from extreme cold. Should something happen similar to Opportunity's stuck switch, requiring deep sleep at night, which a lunar rover would likely need during the 14 day-long nights, the TES would freeze if it weren't properly adapted.

Another thought - it wouldn't require as much energy to drive, as the gravity's lighter. More power available for heaters? Possibly additional batteries could be used?

Standardised components *must* at some point save time and money - everything from established management systems through to hardware and designs should be used more than once. It's crazy to still be building unique vehicles at ever-higher cost rather than having at least a degree of commonality between them. I *won't* rant on about the good ol' Soviet approach to production lines, but I *could* if you get me going...

...I wonder how many good missions we've lost to date due to the infamous 'Not Invented Here' Syndrome?

Slightly OT here, the thing I always found fascinating about Harvest Moon was that it proposed to use the leftover CSM and LM from the *original* Apollo 15 mission, the H mission (45 hour stay time, no rover, two EVAs) that was canceled during the final round of mission cutbacks in 1970.

One reason it went nowhere was that the people who were trying to sponsor it costed it out by referencing declassified NASA budget lines, but they never discussed the possibility with NASA itself. They quickly discovered that while they *might* have a shot at buying surplus Apollo hardware, they'd have to arrange for the NASA Apollo "Army" to support such a flight, from the launch preparations and support at KSC through the crew training, flight operations support, etc., at MSC (now JSC), not to mention the millions of dollars worth of support NASA got from the Navy and Air Force. Not only was NASA unwilling to fly surplus hardware for a private company interested in profits, the armed forces weren't interested in supporting such a thing, either. So Harvest Moon died a-borning.

It also didn't help that the Harvest Moon people wanted to return the Apollo 15 crew itself to the Hadley-Appenine site, announcing that Scott, Irwin and Worden would fly the mission, and just after their announcement, the stamp scandal hit. NASA was NOT going to allow Scott and his crew to fly in space for them again, much less support anyone who was going to use their skills to make profits from sending them back to the Moon.

-the other Doug

Bob is certainly right about standardised components etc. Even identical missions would be worthwhile in many cases. Flying MERs to two new sites would be great for science and a bargain... two more Voyagers for launch in the 1980s would have been great too, even if all they had done was to Jupiter... more views of Io, different satellite encounters... but of course you need to plan for it from the start.

But attempts to do something along those lines - Mariner Mark II for instance, or CRAF/Cassini - have gone nowhere. It may be a product of the budget process. If the instruction was 'you can have X dollars a year for exploration, do as much as you can with it' there would be more incentive to do as much as possible.

But for the standardised component thing to be useful, there still has to be enough in common between the missions, and I'm not convinced that moon rovers and MER have that similarity. MSL might be more adaptable to the Moon with the advantage that it *could* be planned that way from the start.

Phil

Jim Irwin's dream about following old tracks at Hadley-Appenine might *almost* have come true, then!

(sigh)

Hi, Bob!

Other Doug, do you have any information about things like landing targets at Hadley Or did it not get that far?

Phil

It didn't get so far as to have a design of EVAs or a specific targeted landing point, but the sampling objectives were (as I recall):

1 -- recovery of Apollo 15 equipment, for sale back on Earth to help defray the cost of the flight.

2 -- rocks from the supposedly volcanic craters of the North Complex (Pluton, Icarus and Chain).

Since Harvest Moon would have been limited to two walking traverses, I'd have to think they would target the landing site to the north of the Apollo 15 landing point, allowing one walking traverse to the south for purposes of scavenging the original mission's equipment, and a second walking traverse to the North Complex.

I know what a lot of you are thinking -- why not just recharge the Rover's batteries and use it? The problem, of course, was that those batteries were not rechargeable and the Rover's EPS was not designed for refurbishment in-place. Taking the batteries out and replacing them would have been difficult, if not impossible. (That's the Rover's main power batteries. The LCRU batteries, that powered the comm unit and TV camera, *were* replaceable in flight.) Besides, collecting pieces of the Rover was one of the higher-priority sampling objectives.

-the other Doug

I think the MER rovers will go down in history as two of the most successful robotic rovers. This is due mainly because of their freedom of mobility. If we are going to develop lunar rovers, we should at least keep this concept in mind.
If we go with a Sojourner style rover, is it going to be tied to the lander for communications?
What type of instrument suite is planned?

Phil is right -- I dug up all my material on all of the first-round Discovery lunar proposals, and while my printed stuff on Interlune-1 is unusually sparse (only 3 pages), there's no reference to it returning to the Apollo 15 site. But, if I remember correctly, there WAS a proposal for such a mission and Schmitt was involved in it -- I'll have to dig into my stuff on CD-ROM to look for more on this. (Interlune-1 did involve one larger and one smaller rover, and it was indeed largely -- though not entirely -- aimed at prospecting for He-3. Schmitt is something of a maverick in lunar science -- he continues to hold not only that the Moon's polar hydrogen is captured from the solar wind rather than being water ice, but also that the giant-impact theory is wrong and the Moon was gravitationally captured by the Earth. He also continues to be a wild fan of He-3 mining.)

I also have, on paper, 10 pages on Murray's "Icy Moon Mission", 8 on Pele, 7 on Boynton's "Lunar Discovery Orbiter", and two on Diana (plus that quite detailed Aviation Week article on Diana, which is on my CD-ROM collection). All my descriptions of them were correct. Let me know if you want me to send this stuff to you, Phil. I also have (monomania has its points) a huge backlog of stuff on other lunar missions, both manned and unmanned, going back to the Ranger program -- including NASA's prioritized list of experiments for the cancelled Lunar Observer, and a very detailed description of the two smaller Lunar Scout orbiters that NASA, back around 1991, was tentatively planning to replace the Lunar Observer. Send me a specific request list and I'll try to meet it. Meanwhile I'll also sift my CD-ROM documents for more on the later lunar Discovery proposals. (I do remember that there were at least two proposals for lunar polar landers to examine the ice -- at least one being a rover -- and that a second Lunar Prospector was once proposed with instruments complementary to the first one.)

Doug, could you post some links to info about the 'Stamp Scandal' (in a new thread?), I don't remember hearing about it.

Eric P / MizarKey

Bruce - many thanks for this. I seem to have lost my old email from you - can you please email me at pjstooke@uwo.ca so we can work this out?

And for others,

http://www.explore-biography.com/scientist...avid_Scott.html

briefly recounts the stamp story. Actually it's rather dumb, but every now and then somebody has to be made an example of... or whatever.

Phil

All three of the Apollo 15 astronauts were part of a deal wherein they carried some postage stamps on the mission as part of their personal payload allotment. Then they sold them to a collector for a hefty profit when they returned. When this got out, it was pretty scandalous, since it was basically a personal cash profit courtesy of a very expensive US government project. Somewhat askew in ethics, but very, very bad in PR. None of the three ever flew in space again. (Of course, with only 2 Apollo missions left, it might have turned out that way anyway.)

Sure, Phil. My new E-mail address is rmoomaw@sbcglobal.net.

Last night, I pretty much finished plowing through my CD-ROM documents, and have dug up four other lunar proposals sent to the later Discovery AOs (although this list can't be complete). First, in 1997, Michael Duke and William Whittaker of Carnegie Mellon teamed up for the "Lunar Ice" mission, in which a rover would have crawled around in the shadowed polar areas to look for ice.

Then Duke and Whittaker later went their separate ways. In 2000 Whittaker proposed Victoria -- an apparently souped-up version of that rover which would also have looked for Aitken Basin rocks -- while Duke proposed Moonraker, the initial version of his Aitken basin sample-return mission in which a single stationary lander would have raked up bits of Aitken material and returned them to Earth. (I have a fair amount of material on that -- he later simply doubled the landers to create his "Moonrise" NF proposal.)

Finally, we have "Polar Night", a mission proposed by P.G. Lucey of the Univ. of Hawaii for the next Discovery round after that, which would first have mapped polar ice deposits using radar, hydrogen abundance and temperature maps (sounds like LRO), and then launched 6 penetrators equipped with neutron and mass spectrometers into the discovered deposits to analyze the ice in detail. (There were -- I believe -- two lunar missions proposed for that AO, although it's possible that the other was a Mission of Opportunity. You'll recall that the ONLY Discovery proposal accepted for the abortive latest AO was another M.O.: Carlie Pieters' "MMM" near-IR mapping spectrometer, which will be added to India's lunar orbiter.)

This is the sum total of Discovery proposals I remember seeing -- except for that proposed follow-up to Lunar Prospector, equipped with complementary instruments such as an X-ray spectrometer, a mass spectrometer, and (I believe) a farside gravity-mapper subsat. I'm about to go through my files of stored letters to see if I can dig up the reference to that. (I also have a bit more on Inrerlune One -- including some pictures, a slightly more detailed experiment description, and the revelation that its project manager was none other than Michael Griffin.) A good deal of the stuff I've just mentioned is actually still on the Web, and I'll send you the URLs.

I'll reply in a new thread in the EVA forum for Manned Spaceflight.

-the other Doug

I finally found my super-sparse notes on that proposed Discovery reflight of Lunar Prospector (although I can't find which Discovery AO it was specifically proposed for). It was called "Lunar Star", masterminded by Alan Stern, and would actually have carried:

(1) X-ray spectrometer
(2) UV spectrometer
(3) Plasma spectrometer
(4) IR radiometer (to look for polar cold traps)
(5) Gravity subsatellite

You'll have to talk to him for any more data.

That was actually Charlie Duke's dream about following tracks at Descartes.

Bruce very kindly provided me with quite a bit of information on lunar Discovery proposals, as I had asked at the start of this discussion. Thanks! I have condensed it into a table for my current project. As I rummaged around my own stuff I came across some things I had photocopied at either Flagstaff or LPI - probably the former. One was an item from "Results and proceedings of the lunar rover/mobility systems workshop", held at LPI, Houston on April 29-30 1992. One invited presentation by Paul Spudis (then at LPI) discussed a scenario for two small rovers or one big one to do in situ characterization of lunar resources. Two sites were considered, Mare Tranquillitatis at 4N, 38E, and the Apollo 15 site. The name for this mission series (this was to be just the first of a series) was Artemis (not to be confused with the moon base people). One version illustrated in the proceedings was a walking robot, with a route from the Apollo 15 LM to north complex, then west to the rille and south to Spur crater at Hadley Delta.

Some of Bruce's comments may have referred to this, which as it stands was not a Discovery mision as such. There are, of course, zillions of paper missions like these. I am interested in any and all I can find.

As an aside, some folks will know I am working on an Atlas of Lunar Exploration for Cambridge. I have now completed the first draft... and the editing is beginning. Phew!

Phil

I've got quite a lot more coming for you, Phil -- it's already recorded, and all I have to do is find the time to send it to you. Tomorrow, if I can possibly manage it.

Thanks, Bruce! Anything relating to specific landing sites or surface activities is especially welcome.

Phil

Does anyone have addresses or contact information for members of the Apollo Site Selection Board (ASSB) or the Geology Lunar Exploration Panel (GLEP), which did most of the planning for the selected *and* unselected Apollo landing sites?

I know that Don Wilhelms refers, in his book "To a Rocky Moon," to a J-mission planned for the Davy crater chain. He speaks of it as if someone had done a first-take surface plan, including traverse plans and sampling objectives.

He also discusses sampling objectives identified for other proposed landing sites, such as Alphonsus, Copernicus, Censorinus, Marius Hills, Littrow (the H-mission site originally planned for Apollo 14, not the Apollo 17 Taurus-Littrow site), and even Tsiolkovsky. He even goes so far as to state that, as of February, 1970, the Apollo 14 crew was training for a landing at the Littrow landing site.

All of this implies that somewhere, there ought to be documentation of the sampling objectives and traverse plans worked up for the proposed Apollo landing sites that were not selected. And I would think that the members of the ASSB and/or the GLEP would be the best people to ask about it.

As for me, I would just like to see artist's representations of surface operations at these sites -- we know what the lunar surface looks like in general, and we have a fair idea of the topography of the unselected sites (since stereo imaging of the landing sites was a requirement for the later missions). In this age of CGI wizardry, it ought to be pretty easy to paint realistic pictures of what, for example, a LM landing about five kilometers away from the central peaks of Copernicus would have looked like...

-the other Doug

Doug - a few members may still be around but the best place to start is LPI in Houston where the full set of minutes of the Apollo Site Selection Board and its associated bodies (Group for Lunar Exploration Planning, Science Working Panel) are preserved. Thousands of pages! I went through them page by page, and also through a set of binders of ASSB materials assembled by Don Wilhelms and left in the Branch History Collection at USGS Flagstaff.

The material you are talking about occupies half of my atlas. It includes dozens of EVA alternatives at places like Rima Prinz, Copernicus, Marius Hills, not to mention multiple potential landing sites around Hadley. I have sampling objectives but not specific EVAs at Littrow (this is not the same site as Taurus-Littrow). I have landing points but not EVAs for Davy. One unfortunate note, the Flagstaff material lacked some of the last few sites (including details of Tsiolkovsky) because they had been borrowed by Harrison Schmitt when I was there (and are still out). I'll have to put it in a second edition.

The ASSB stuff and lots more was rescued from the dumpster, literally, by Fran Waranius, then librarian at LPI (Lunar Science Institute as it was then). At the end of Apollo the wretched engineers who run JSC just stacked it all up to be thrown out. She shuttled her car back and forth between JSC and LSI with her trunk full of these unique goodies.

Anyway, hang on a bit and you'll have what you need.

Phil

Doug:

Like a bunch of isolated hills, I expect, in a flat-to-rolling plain - and unless you got off the plain, no sign of the crater wall...

Bob Shaw

Bob, what you say would certainly apply to Ptolemaeus and many another very large shallow crater - what Patrick Moore would call a "walled plain". But not to Copernicus. It would be an incredible sight, with central peaks on the scale of the Apollo 17 massifs and walls easily, spectacularly, visible from the floor even near the peaks. The so-called picture of the century, the oblique Lunar Orbiter view across Copernicus, gives a very good idea what it would be like.

Phil

Fantastic! And maybe -- just maybe -- Jack Schmitt has more than just Tsiolkovsky materials. Maybe he also has the details on the Littrow traverse plans, and the Davy traverse plans, as well. I'm as sure as I can be (without ever actually having seen them) that these must have been worked up by someone, and I'm hoping against hope that they still exist somewhere...

Do you have decent copies of the Apollo 13 traverse plans, by the way? I've seen very poor PDF scans of them -- the target point for 13 was about 300 to 500 meters further west than the point designed for Apollo 14, and Lovell was supposed to make a call during final approach as to whether it was better to land short (to the eventual Apollo 14 landing point, between Triplet and Doublet) and attempt a traverse east to Cone Crater, or land west (beyond Doublet) and attempt a traverse to the smaller, slightly less "fresh" Star Crater. Traverse plans were developed for both contingencies, plus another plan designed for landing west of Star Crater (which would have been about 1.5 to 2 km downrange of the Apollo 14 point). And after the abort, as they rounded the Moon, Lovell radioed back to the ground that he was "still looking for Star Crater," which makes you wonder whether Apollo 13 would have ever even *tried* to visit Cone.

As for myself, I never could figure out why they didn't target for a landing point in the valley between Cone Ridge and the Triplet craters -- it was relatively flat and smooth, and would have obviated the need for a 1.5 km trek to get to the most important sampling site there. It's not like Cone Ridge was so high as to pose an impact threat to the LM as it descended, and beginning with the very next flight, the descent profile was adjusted to allow for passing over *much* taller mountains on the way to the landing point. It would have been easy to do.

-the other Doug

Phil:

OK, we're talking about a crater which is about 95km across, central peaks 1.2km (some sources) or 400m (other sources) high, greatest extent of the peaks about 15km. If the moon's diameter is about 3,500km, then surely only the tops of any ring wall mountains will be visible?

Where's VistaPro when you need it!

Bob Shaw

I take back what I said about a rolling plain - Copernicus is anything but! No large-scale lava flooding, loadsa baby rilles, hills and debris.

Doug, yes, I have Apollo 13 EVA plans, which differed in many details from Apollo 14 plan. Also a map of lots of potential landing points around the actual Cone Crater site - they wanted to sample the fra Mauro formation, but you can do that in lots of places.

It would have been easy to land east of Triplet, but they were being cautious, gradually expanding the envelope. It wasn't just the elevation of the ridge, I think they needed to be sure the landing radar could keep track of rapidly changing altitudes over rough terrain.

For all the Apollo enthusiasts out there... here's another puzzle - answer tomorrow! - Apollo 12 was supposed to demonstrate a pinpoint landing. The prime site was Surveyor 3. But what about the backup site? What was the pinpoint landing option at the backup?

Phil

Bob, yes, Copernicus is an amazing place. The fabulous images you posted do make it clear, I think, that the rim would not be below the horizon even at the foot of the central peaks. In fact the LM landing position was to be chosen specifically to allow the best view of the walls, as the peaks would hide a big chunk of the walls.

Phil

Phil:

Al Shepherd don't need no steenkeen' landin' radar!

As he almost demonstrated...

Bob Shaw

David Shayler's Apollo: The Lost and Forgotten Missions (Springer-Praxis, 2002) contains several images of unflown Apollo landing targets.

These include the *original* Apollo 17 Marius Hills site (p262) and the Apollo 18 Copernicus site (p263).

If I remember correctly, Apollo 12's backup target was Surveyor 1. (Don Wilhelms, in his book "To A Rocky Moon", bemoans at length the fact that S-1 wasn't Apollo 12's primary target, becuase the geology of its landing site was much more important.)

Bruce, the backup site for Apollo 12 and Apolo 13 was Apollo Site 5, north of Flamsteed. A site in Flamsteed was considered for the second landing, but it was not at Surveyor 1, it was next to one of the hills in the big ghost crater surrounding the Surveyor site. It was called Site 6R in the terminology of the time. After 13 there were no backup sites.
(but what was the pinpoint target? - answer tomorrow!)

Phil

Bob, the Shayler book is good, though hideously expensive. The interesting thing which it does NOT make clear, though, is that those examples of EVAs were only a few of many others that were considered, I found at least 3 different variations on each of the Tycho, Copernicus and Marius missions, and lots for Hadley.

Phil

Does anyone have maps of the traverses for a landing at Alphonsus? My tentative conclusion has always been that, if Apollo 13 had succeeded and #14 had been sent to the Littrow lava wrinkle ridge as planned, the Alphonsus site (near the western crater wall) would have been the most likely additional Apollo landing site (besides Hadley Rill and Descartes).

Yes, I have an Alphonsus traverse map, though without sample stations etc. Alphonsus was always popular as a second choice, but never made it to the top of the list. One problem was that the later Apollo sites had to have multiple objectives - at Taurus-Littrow you had the valley floor basalts, the Serenitatis basin massifs, the supposed volcanic vent at Shorty (incorrect interpretation) and a young landslide. Alphonsus had the dark halo craters, but the pre-Imbrian walls (suck old material was a major objective of the last 2 missions) were likely covered with a thick layer of Imbrium ejecta.

Phil

Phil and Bruce;

David Harland's excellent 'Exploring the Moon: The Apollo Expeditions' (Springer-Praxis, 1999) quotes the Flamsteed site as ALS-6, and confirms that it *wasn't* the Surveyor 1 site. He then goes on, however, to say that the Flight Dynamics guys *did* push for Surveyor 1, but that because both it and the ALS-6 site were so far west it had no back-up site and was abandoned (p34). The Apollo 12 Surveyor 3 target site (ALS-7) had the advantage of offering orbital imagery of both Fra Mauro and the Davy crater chain. The site numbering is obviously a tad awry somewhere, but the song remains the same.

And no, I'm not on a retainer from Springer-Praxis - they just do fine books!

Bob Shaw

OK, here's the Apollo 12 backup story. I think this has never been told fully before. Don Wilhelms, if I recall, mentions that nine points in the Site 5 ellipse were identified but does not give further details.

Apollo Site 5 at about 40 west, 2 north was the Apollo 12 backup. But the goal was not 'land anywhere' as Apollo 11's had been, it was 'achieve a pinpoint landing'. So a specific target point had to be selected. ASSB asked USGS to identify interesting points. Newell Trask of USGS chose nine points in the ellipse. All were small fresh craters with a characteristic morphology discovered in Lunar Orbiter photos - very rocky, with a concentric inner ridge. Craters like this, about 100 or 200 m across, are common in the maria and are thought to show where the crater penetrated through the regolith into underlying bedrock.

Now the detective work begins! First I found Trask's letter in the history collection at Flagstaff. (ASSB minutes don't say anthing about this.) The nine points are listed, but only as measurements on individual framelets of the lunar orbiter photo. So then I had LPI copy the appropriate frames for me and made those measurements. Sure enough the nine points can be found. But which was the landing point? Trask's letter identifies it. The landing point is just north of and between two of these small fresh craters near the south edge of the ellipse, with a distinctive pattern of four larger shallow craters ('four crater cross') just to the east to serve as a landmark during descent.

I attach two images (one attachment) to illustrate this. In the first, 'B', the nine dark circles are the locations of the nine fresh craters. Of course you don't land on the crater, so the target is beside one of them.

Phil

Click to view attachment

Phil:

Fascinating!

Bob Shaw

The function of how far you can see to the horizon, as a function of your height above a perfect sphere, varies approximately with the square root function (a very good approximation until you start to get a significant fraction of the radius above the perfect sphere). It varies linearly with radius of the body. For Luna, the coefficients make it:

D = 0.97 sqrt(h)

Where h is height in meters, and D is horizontal distance to the horizon in *kilometers*. Yes, that coefficient is close to 1.0, so you can save on paper.

For two elevated bodies (like a distance mountaintop and an astronaut), you can add the two distances. Of course, this is to determine merely if you can see the tippytop of the mountaintop.

Basically, to see the top half of a 10km, you'd need to be able to see a "peak" 5 km up, which on Luna, is possible from:

D = 0.97 sqrt(5000)
D = 68.6 km

68 km away. Near the center of Copernicus, then, you would not only be able to see the "near" wall, you would be able to see all portions of the *far* wall that weren't obscured by yet-closer peaks! And 5 km of visible wall, at a distance of 60 km or so, would subtend about 5 vertical degrees of arc, which would be a nice vista. But 40 km away, you could see 8.5 km of a 10 km wall, and it would subtend over 10 vertical degrees of arc. 20 km away, it would subtend about 25 vertical degrees of arc, which would be almost dizzying, I think. With the vaccum-based illusion that distant objects appear to be in the immediate foreground, the astronauts might lean to compensate!

I located the proposed Apollo 18 landing site on the larger scale image - it's the red dot, surrounded by circles at 1km. I think I may have located it in the Lunar Orbiter 'Picture of the Century' shot, too (probably just hidden behind the central row of mountains).

Here's the big picture (the landing point is just right of centre, at 2 o'clock).