Lunar Discovery Proposals, Proposed missions to the Moon Options

[Phil Stooke]

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

[Guest_BruceMoomaw_*]

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.)

[Phil Stooke]

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

[Phil Stooke]

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

[Bob Shaw]

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

[Phil Stooke]

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!

[Guest_BruceMoomaw_*]

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.)

[Guest_BruceMoomaw_*]

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.

[garybeau]

(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.

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

[Phil Stooke]

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

[Jeff7]

How do you keep your electronics and instruments warm for that long without going nuclear. But that would apply to any rover developed.

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?

[Bob Shaw]

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?

[dvandorn]

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.

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

[Phil Stooke]

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

[Bob Shaw]

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

(sigh)

[Phil Stooke]

Hi, Bob!

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

Phil

[dvandorn]

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

[garybeau]

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?

[Guest_BruceMoomaw_*]

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.)

[MizarKey]

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

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

[Phil Stooke]

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

[JRehling]

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

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.)

[Guest_BruceMoomaw_*]

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.

[dvandorn]

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

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

-the other Doug

[Guest_BruceMoomaw_*]

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.

[MiniTES]

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

(sigh)

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

[Phil Stooke]

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

[Guest_BruceMoomaw_*]

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.

[Phil Stooke]

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

Phil

[dvandorn]

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

[Phil Stooke]

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

[Bob Shaw]

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:

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

[Phil Stooke]

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

[dvandorn]

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

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

[Bob Shaw]

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

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[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.

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[Phil Stooke]

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

[Phil Stooke]

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

[Bob Shaw]

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.

Phil

Phil:

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

As he almost demonstrated...

Bob Shaw

[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).

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[Guest_BruceMoomaw_*]

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.)

[Phil Stooke]

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

[Phil Stooke]

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

[Guest_BruceMoomaw_*]

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).

[Phil Stooke]

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

[Bob Shaw]

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

[Phil Stooke]

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

[Bob Shaw]

Phil:

Fascinating!

Bob Shaw

[JRehling]

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

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!

[Bob Shaw]

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).

Attached thumbnail(s)

 

[Bob Shaw]

More Apollo 18 - 50% and 25% reductions of the last post.

Attached thumbnail(s)

 

[Bob Shaw]

Apollo 18, a rather closer view (actually a crop from the big file) - still with the circles etc.

Attached thumbnail(s)

 

[Bob Shaw]

And the location - I think - on the Lunar Orbiter oblique image.

Which means, if I'm right, that we actually *do* have a surprisingly good idea of what the guys on the ground would have been lookng at!

Attached thumbnail(s)

 

[Bob Shaw]

The function of how far you can see to the horizon...

Thanks! That's a keeper!

[Guest_BruceMoomaw_*]

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 (such old material was a major objective of the last 2 missions) were likely covered with a thick layer of Imbrium ejecta.

Phil

Yeah, I know about that problem. My main reasons for suspecting that it would still likely have been chosen are that:

(1) Apollo 14 would have revealed Littrow to be a failure as a source of young volcanics (restoring interest in Alphonsus for that purpose); and

(2) There don't seem to have really been any other possible sites that were more promising as a source of highlands material uncontaminated by Imbrium ejecta (although that WAS the single most important science goal for Apollo 17). Taurus-Littrow, would, I imagine, have been ruled out as too close to the Apollo 14 site (as well as having no young volcanics), and other sites in the highlands between Mares Serenitatis and Crisium (according to the Apollo 17 postflight report) were ruled out on the grounds that there was a good chance the Soviets would sample them (which, in fact, they later did). By contrast, there was considered to be at least a fair chance that Alphonsus would have some non-Imbrium highlands material (which Gassendi, Copernicus, Davy Rill and the Marius Hills would definitely not have had), as well as those young volcanics.

Still, there's obviously a huge amount of guesswork in this conclusion of mine. After Apollo 14 had revealed Littrow not to have young volcanics as expected, it's hard to really predict where the last three missions would have been sent (except that Descartes strikes me as a certainty for one of them).

[dvandorn]

Still, there's obviously a huge amount of guesswork in this conclusion of mine.  After Apollo 14 had revealed Littrow not to have young volcanics as expected, it's hard to really predict where the last three missions would have been sent (except that Descartes strikes me as a certainty for one of them).

If 13 had landed at Fra Mauro and 14 at Littrow, I don't think that would have affected the selection of either Hadley or Descartes. Assuming the same eventual cancelation of the Apollo 15 H-mission and of Apollo 19, you would be looking at selecting sites for the J missions using the same requirements as were actually used -- multiple sampling opportunities, Imbrium and pre-Imbrium impact materials, lava features -- all of which drove the selection of Hadley-Appenine. And Descartes was going to get a J mission somewhere.

I will point out that Descartes was originally a prime site consideration for the *first* J mission, but was bumped to the second because of lack of good photography. When 13 aborted and was unable to get good Descartes pictures, it was left for Apollo 14 to get good coverage of Descartes so that it could be validated as a safe landing site. But since the good site photography wasn't available until after Apollo 14 (and after the site for 15 had to be selected), Descartes fell out of the running for 15. If 13 had gotten that good Descartes coverage, I think Apollo 15 *would* have flown to Descartes.

*Then* you can ask whether Hadley would have been the 16 or the 17 site. Without something like Taurus-Littrow beckoning (and I agree, if 14 had landed at the original Littrow site, Taurus-Littrow would never have been selected for a J mission), then I think it likely that 16 would have landed at Marius Hills and that 17 would have landed at Hadley.

-the other Doug

[Guest_BruceMoomaw_*]

Once again, however, they very badly wanted to get samples of highlands material uncontaminated by Imbrium ejecta -- in fact, that was officially listed as an even more important goal for Apollo 17 than the young volcanics were. And they would have had at least a chance of getting that at Alphonsus, but not at the Marius Hills.

While we're on the subject, Apollo 15 came close to being sent to the Marius Hills instead -- the final choice was made because they wanted a better spread pattern for the first three ALSEP seismometers and because David Scott said he thought a Marius landing would be somewhat harder. Apollo 16's choice was between Descartes and Alphonsus; they picked the former largely on the assumption that #17 would be sent to the latter. But by the time that they actually picked #17's site, both Taurus-Littrow and the center of Gassendi Crater had moved ahead of Alphonsus in the rankings, with the latter finally being rejected because of its lack of non-Imbrium highlands material and because the Gassendi floor looked rugged enough that the rover might have trouble reaching the central peak. (I have no doubt, though, that there are a lot of things that I don't yet know about in the Apollo landing site selections.)

[Phil Stooke]

One other factor was not in Alphonus's favor: the orbital remote sensing was not very different from that of Apollo 16. By the time the last site was actually being selected (so I don't mean earlier when lots of alternatives were being examined for the last few flights) they knew Apollo 16 was going to Descartes. The real contenders in those days were Gassendi, Alphonsus and a site in the general area they referred to as "SW of Crisium". They looked at several sites in that area, including Azout Domes (very close to the later Luna 24) and Proclus, but as Bruce said, rejected them because they were accessible to the Lunas. Gassendi was not ideal topographically or geologically (as Bruce said) but it offered fabulous remote sensing across northern Orientale. SW of Crisium gave the best chance of really old stuff not mantled by Imbrium ejecta, and reasonable remote sensing, though a bit too similar to Apollo 15. But Alphonsus lost out on both counts. Yet Alphonsus had those volcanic vents. But then somebody (I think Farouk el-Baz) found the 'cinder cones' in the Taurus-Littrow valley and that blew Alphonsus out of the water. I still think some of the cinder cones were probably real, further west, but they chose one that wasn't! - Shorty Crater. Oh well, can't win 'em all.

Phil

[Phil Stooke]

I just want to follow up on Bob's comment on Apollo site numbering.

After a long selection process there were five candidate sites for the first landing, ALS (Apollo Landing Site) 1 to 5, very close to the equator, numbers increasing to the west and all shown on the Nat. Geog. map of the time. As Bob said, ALS-6 was in Flamsteed, but it was NW of Surveyor 1 in the plains. ALS-7 was near Surveyor 3. Each was a roughly 5 by 8 km ellipse. But after the first landing they would need pinpoint targets (defined as within 1 km of an interesting feature), and so a set of those targets were also identified within or at least near the ellipses. The idea was, the autopilot system would bring the LM down into the ellipse and the Commander would then 'bias' (tweak) the trajectory towards the point of interest. So they were called 'biased sites' or 'redesignated sites', and numbered ALS-1R, ALS-2R and so on. ALS-6R was up against one of the hills surrounding Surveyor 1. ALS-7R was Surveyor 3. (for completeness, 1R was a hill, 2R was a secondary crater, 3R was a mare ridge near Surveyor 6, 4R was first a ridge, then a Tycho secondary, 5R... - can't remember!)

Phil

[Bob Shaw]

Phil and Bruce:

You've both said that the US mission planners were aware of the areas where the later Luna sample return missions could target. My reading of the Lunas is that yes, they were quite limited in latitude/longitude due to trajectory constraints (though, unlike Apollo, demonstrably not at all limited in terms of time of lunar day (other than presumably avoiding the depths of night-time cold or the noon heat)). That understanding, however, is based on both information from the memoirs of ex-Soviet space programme participants and the detective work of various western researchers, largely working backwards from the trajectories which were flown by the later Luna samplers and Lunokhod busses.

So: how did the Apollo-era planners know what the capabilities of the Luna system were before they flew? The unclassified CIA material which I've seen is actually quite vague in terms of payload weights, upper stages etc for Proton, and just a few percentages out would make a helluva difference in terms of actual capacity to change trajectory out at the Moon.

Bob Shaw

[Phil Stooke]

Luna 16 flew before Apollo 14. Its flight profile would have been understood at once even without CIA help. The Luna sample return capability only entered the ASSB deliberations (at least in the minutes) at the last meeting, 11 February 1972 which was also after Luna 18 and only 2 weeks before Luna 20. The exact area accessible might have depended on details as you suggest, but the general area (S or SW of Crisium) was known well enough.

Phil

[Phil Stooke]

I should have added, there is a map in the last ASSB meeting minutes showing the remote sensing coverage... and it looks like there never was a site ALS-5R until the backup for Apollo 12 was chosen.

Phil

[Guest_BruceMoomaw_*]

"So: how did the Apollo-era planners know what the capabilities of the Luna system were before they flew? The unclassified CIA material which I've seen is actually quite vague in terms of payload weights, upper stages etc for Proton, and just a few percentages out would make a helluva difference in terms of actual capacity to change trajectory out at the Moon."

I believe it had to do mostly with the limited number of Soviet ground stations capable of communicating with the craft -- something which was always an enormous hindrance to the Soviet spce program. In any case, this belief that the Soviets were going to concentrate on the near-Crisium region is explicitly mentioned in the final Apollo 17 science summary report's discussion of the landing site selection process. (I have no inside documents on this subject.)

[Phil Stooke]

The near-Crisium region is defined by orbital dynamics and the chosen flight prifile.

Imagine you lift off from the Moon at slightly over escape velocity. At a certain distance above the Moon you are leaving it with a bit of excess speed. If you are going in the direction of the Moon in its orbit around Earth, your spacecraft is now in Earth orbit, but going faster than the Moon, so it's heading into a higher Earth orbit... obviously not what you want if you're heading home.

But if you leave the Moon with that bit of excess velocity, but going 'backwards' along the Moon's orbit - backwards relative to the Moon - now you are in Earth orbit, but going slower than the Moon. So you 'fall' into a lower orbit. To get home all you have to do is plan the excess velocity so it's enough to bring you back.

This could be made to work two ways... lift off, go into orbit, then when your orbit vector faces the right way burn out of lunar orbit and fall towards Earth. Or, just lift directly off the lunar surface, not needing a second burn. But that only works if you are in the correct location on the Moon. In the longitude 60 East region, going upwards points you in the right direction and all you have to control is the velocity.

This is the simplest way to get home. Landing anywhere else, you have to do the partial orbit plus second burn method to get home. This was clear as soon as the design of the return capsule was known - it had no trajectory correction or second burn capability - well, certainly not second burn.

Phil

[Bob Shaw]

Phil:

There must be more than that to it, as the Luna sample-retrieval capsules had to be targetted to Soviet territory. OK, you could leave the Moon with a trajectory which was Earth-impacting, but to leave with one which would only hit a certain longitude and latitude within the northern hemisphere... ...more complicated. I can think of a certain amount of targetting as a function of time of launch vs speed (the Earth rotates under the orbit), but unless the Luna system's verniers could produce mid-course corrections, how would that allow a return to the USSR itself?

Bob Shaw

[Phil Stooke]

Well, Bob, yes, there's more to it, but that's the basics. But really, all you need to control is the plane of the orbit and the exact timing. And the Soviet Union was quite a big target. I confess I'm not sure if there was absolutely no correction ability, or a little bit, but it wasn't much if any. The point is, details aside, the procedure in question works for a limited area on the moon and that was well known.

Phil

[Bob Shaw]

Well, Bob, yes, there's more to it, but that's the basics.  But really, all you need to control is the plane of the orbit and the exact timing.  And the Soviet Union was quite a big target.  I confess I'm not sure if there was absolutely no correction ability, or a little bit, but it wasn't much if any.  The point is, details aside, the procedure in question works for a limited area on the moon and that was well known.

Phil

Phil:

So it was all done as a single-impulse trajectory, presumably with the ascent stage hard-engineered in such a way as to 'seek' a particular trajectory, wth the actual aiming done by time of launch and (perhaps) a rotation during ascent (as they couldn't be 100% sure of the alignment of the lander)? That fits with the philosophy behind their original satellite launchers, which used rotating bases (Soyuz uses the system to this day) and biased launch vehicles just like the V2 did.

I always wondered why there were only two vernier motors in the illustrations of the ascent stage - if they only had to deal with a strictly limited range of inputs to the trajectory then that's explained!

Really, very clever!

Bob Shaw

[dvandorn]

Yes, Bob, that's exactly how the Soviets did it. They set up landing sites where their probes had to only lift straight up, angle slightly to the right declination, and cut off the motor at a precisely pre-planned time, and if the lift-off time was calculated *precisely*, the sample return capsule would land on Soviet soil. There are only a few places on the Moon that are located in the right spot to do that, and Mare Fecundatitis and the surrounding highland plateau are a couple of the places where that is possible.

The Luna sample returns happened at landings on Mare Fecunditatis and the surrounding highland plateau.

Coincidence? I think not.

-the other Doug

[tedstryk]

"The Luna sample returns happened at landings on Mare Fecunditatis and the surrounding highland plateau."

Also Mare Crisium (Luna 24), which is immediately adjacent.

[Phil Stooke]

Applied Space Resources (RIP) planned a mission called Lunar Retriever, a commercial sample return mission. It would fly a similar flight profile to the Lunas, but with different details, so its landing area could be further west. They were intending to go to Mare Nectaris.

I think they were done in by expense. If I recall, the mission would cost about $160 million and they couldn't raise it. I expect a microsat approach today might bring the cost down a lot below that. though I know nothing about such matters. Come on Jay! You can do it!

Phil

[Phil Stooke]

Since we have been talking about the Luna sample return flight profile and landing sites... (even if it is off topic)

There is another side to this: for operational reasons it was often desirable to descend to the Moon's surface vertically rather than obliquely. For instance, Rangers 3,4,5 needed to take nested images (with small slow cameras, not the Ranger 7 type cameras) to locate the landing site. Any horizontal movement would stop the nesting and the process would not work. Ditto Surveyor 1 with its descent imager.

The easiest way to descend vertically is to get into an elliptical orbit with its high point near the Moon, at just the time the Moon is nearby, and then when the orbit vector is parallel to the lunar surface, burn a retrorocket to kill forward velocity along the orbit. The s/c then just falls down a radius to the surface. A gross oversimplification, but that's the basic idea. This was the procedure planned for the early Rangers, for Surveyor 1, for the early Luna landers. And it works best in a limited area as well, near the equator on the western half of the earthside, a mirror-image of the sample return situation. Differences in detail of the trajectories made the Lunas go to a different place than the Rangers or Surveyor 1, but all in the basic area. Early (very early) Apollo planning was briefly directed at this area too.

Phil Stooke

[Guest_BruceMoomaw_*]

Huh? The retrorocket on the Block 2 Rangers would only have slowed the lander capsule -- not the main craft, which carried the TV camera. A near-vertical approach trajectory was desired -- not only for the reason you state (which makes sense, though I've never heard it before), but also to minimize the total velocity that the capsule retrorocket had to null out.

Similarly, Surveyor 1 was coming down at an angle of only 6 degrees from the vertical BEFORE its retrorockets ignited. I believe the main reason for given for that -- at least on the first mission -- was to maximize the ease with which the multi-beam RADVS radar could lock onto the lunar surface, since that was supposed to lock on before the main solid retromotor had finished firing and so the craft was still coming down somewhat off vertical when the RADVS turned on. As early as the unsuccessful Surveyor 2, however, they were ready to increase the off-vertical pre-retrofire approach angle to 23 degrees.

[Phil Stooke]

Bruce is quite right and what I said was unintentionally quite misleading. I initially described a hypothetical, generic method for getting to the Moon, and I would have been better off leaving it out. If you plan that initial very elliptical path out from Earth correctly, as the s/c arrives in the Moon's gravitational influence it is pulled in on a near-vertical descent path IN THAT SPECIFIC AREA of the Moon. That's the easiest way to get there - the trajectory brings you in just as you want to come in, vertically.

So we'll forget what I said about braking at a distance, that was not done on those missions. It would have been on some versions of Apollo flights without lunar orbit rendezvous. The point is, though, there is a specific vertical descent area just as there is a simple 'return to Earth' area.

The vertical descent was needed by early Ranger to enable image nesting. It was also needed by the first Surveyor for that reason, though in the end they didn't use the descent imager, and it was dropped from flights after Surveyor 2. As Bruce said, on that first test flight the vertical descent also made it easier to get the radar to work, but that was not essential for its operation and would not apply later.

Surveyor 1's landing site was actually chosen to meet three criteria: it had to be in the (near-) vertical descent region, in the Apollo zone, and at the smoothest place they could find in the intersection of those two areas. USGS and JPL had drawn up lists of suitable sites in 1965 and 1966, and that particular site at Flamsteed was pretty much the only one that worked for it. After that they allowed the 'unbraked impact angle' (angle between incoming trajectory and surface if no braking is done) to increase to 25 degrees for Surveyor 2, and to the outer limit of 45 degrees for Surveyor 5.

Who says the Internet has no quality control? Thanks for picking up my gaffe, Bruce.

Phil

[Guest_BruceMoomaw_*]

Actually, I'm relieved that I was correct -- the only one of my statements I was absolutely certain about was the lack of a retrorocket on the Ranger Block 2 main spacecraft. In quoting the approach angles for Surveyors 1 and 2, I was working off a 39-year-old memory. (I knew that Surveyor 5 had the most extreme approach angle of all, but couldn't remember what it was.)

Given my ignorance of fundamental orbital mechanics, was I correct in saying that a near-vertical approach also minimized the total approach velocity for the Block 2 Rangers and thus allowed lightening of the retrorocket? (By the way, that retrorocket was one of the few things salvaged from the Block 2 fiasco -- it worked very well as the high-powered kick motor to put the early Vela nuclear-test-monitor satellites into their circular orbits 60,000 miles from Earth starting in late 1963.)

[dvandorn]

I have the (in)famous Ranger issue of National Geographic, but it's somewhere in storage right now and I don't have it at hand.

What I don't recall is how the hard-lander "ball" was to be controlled in attitude during the retro-rocket firing. Was it spin stabilized? I sure don't remember it having anything like a sophisticated RCS. Perhaps a control-moment gyro system? A CMG wouldn't have to be all that heavy, since the ball was fairly light.

But I do recall that the lander only really had the one-axis seismometer, a transmitter and a battery. No camera, no other particles and fields sensors that I recall off the top of my head.

-the other Doug

[Bob Shaw]

I have the (in)famous Ranger issue of National Geographic, but it's somewhere in storage right now and I don't have it at hand.

What I don't recall is how the hard-lander "ball" was to be controlled in attitude during the retro-rocket firing.  Was it spin stabilized?  I sure don't remember it having anything like a sophisticated RCS.  Perhaps a control-moment gyro system?  A CMG wouldn't have to be all that heavy, since the ball was fairly light.

But I do recall that the lander only really had the one-axis seismometer, a transmitter and a battery.  No camera, no other particles and fields sensors that I recall off the top of my head.

-the other Doug

Yup, spin-stabilised. I think via a 'thread' in the motor, like one V-2 vane...

[Guest_BruceMoomaw_*]

It had a smaller solid motor inside the big conical nozzle of the main retrorocket, with (I think) two little nozzles pointed along the inside tangents of the nozzle's wall. It ignited 1 second before the main engine ignited, at which point the little spin-stabilizing motor was blown out of the nozzle and became the very first part of the craft to hit the Moon. (Similarly, the Altitude Marking Radar package that ignited the solid retromotor on the Surveyors was inside that motor's nozzle and was blasted out of the nozzle straight into the Moon.)

By the way, the hard-lander capsule was designed to be tough enough to have a good chance of surviving even if the retromotor failed to separate from it after burnout -- although, as I've said before, there were serious doubts (at least as of the launch of Ranger 3) on whether the drop tests had been rigorous enough to provide confidence that the capsule actually would survive even normal impact.

And, yep, the one-axis seismometer was the only instrument; its fluctuating signal output was directly hooked to the analog-channel radio transmitter. However, it would also double as a penetrometer to provide a profile of landing shock and thus of surface hardness.

[edstrick]

...."on whether the drop tests had been rigorous enough to provide confidence that the capsule actually would survive even normal impact."

Considering that candidate landing tartet materials probably included bare lava flows or pumice-like rock, the almost universal meter-plus thick regolith layer on the moon would have greatly improved a "marginal" design's chances of surviving impact.

[dvandorn]

The lunar regolith compacts very, very quickly into a material with some cohesiveness and pretty good bearing strength. The surface is only "soft" for the first inch or two (a little more on crater rims).

Yes, that first inch or so gives you a tiny advantage -- but not that much.

-the other Doug

[Bob Shaw]

The lunar regolith compacts very, very quickly into a material with some cohesiveness and pretty good bearing strength.  The surface is only "soft" for the first inch or two (a little more on crater rims).

Yes, that first inch or so gives you a tiny advantage -- but not that much.

-the other Doug

I wonder what the difference between a 90 degree angle of impact and a much more oblique one is, in terms of effect on a hard-lander (or, say, a redundant LM ascent stage). Or is the instantaneous shock still so utterly enormous as to provide explosive vapourisation of the projectile, as with typical rocky impacts?

And what sort of debris field will have resulted from the LM impacts (and the S-IVB stages)? If the Apollo 12 S-IVB stage was identified spectroscopically (thanks to the titanium oxide paint, not a normal constituent of Earth-crossing asteroids!) then will spacecraft debris fields also be identifiable?

Answers on a postcard, please!

[edstrick]

The LM impacts were extremely oblique... 80 degrees off vertical or more.

The SIV-B impacts were more or less vertical. Later Apollo missions were able to get images of some of the earlier impact points. I don't recall about Clementine.

The Ranger impacts were pretty easily identified, except for 8's, which was looking off impact target to get more pictures of terrain, accepting motion blur and non-contiguous last images. The surprise which hindered identification for a while was that the Ranger impact ejecta was DARK, like scuffed up lunar dirt disturbed by the astronauts.

The reason is a mix of the Rangers not pulverizing bedrock, just re-distrubuting regolith, and the non-hyper-velocity speed of the impacts, compared with natural impacts.

[Bob Shaw]

The LM impacts were extremely oblique... 80 degrees off vertical or more.

*Really* oblique natural impacts produce craters with oddly shaped ejecta, often as a 'fan' shape. Presumably the LM impacts would have been somewhat similar, then...

[Phil Stooke]

The best reference for artificial impact craters on the Moon is Ewen Whitaker's short article in the Apollo 16 Preliminary Science Report - should be easy to track down in any good university or big city library. He saw the craters made by Ranger 7 and 9 in Apollo 16 pan camera frames, and Ranger 8's was seen by a Lunar Orbiter. Then he found the SIVB impact craters from Apollo 13 and Apollo 14, and the Apollo 14 LM ascent stage impact ejecta (not crater). A few of these can be seen in Clementine LWIR images - I have Ranger 7 and Apollo 14 SIVB at least. No other impacts were found at that time. The later Apollo impacts were in areas not phtographed at high resolution at that time.

I have a tentative ID of Ranger 6's impact ejecta. It was on LOPD (LPOD is still on hiatus alas...):

http://www.lpod.org/LPOD-2004-08-05.htm

It's an odd triangular patch, dark in Clementine LWIR images, so bright in albedo. Unfortunately the Consolidated Atlas frame of the area was taken after Ranger 6, so I have not been able to see if the bright spot is new. But the resolution would be marginal. The triangle opens to the east as Ranger 6's trajectory would suggest it should.

LRO will allow a search for all impact craters - including, presumably, Ranger 4, Lunas 2, 5, 7 and 8, Hiten... quite a few.

Speaking of impacts... It was commonly said that Luna 2's upper stage rocket hit the Moon 30 minutes after Luna 2 itself. But where? If it followed the same trajectory but a bit slower (assuming separation slowed it and speeded up Luna 2), it would be displaced by the Moon's orbital motion, which would put it near the east limb. I never came across any mention of this.


Phil

[AndyG]

*Really* oblique natural impacts produce craters with oddly shaped ejecta, often as a 'fan' shape. Presumably the LM impacts would have been somewhat similar, then...

...but still probably quite small.

A LM ascent stage, massing about 2000kg once empty, hitting the surface at around 1680m/s (i.e. Lunar low orbital speed) would make for an impact energy of 2.8GJ - say about 2/3rds of a tonne of TNT.

The resultant crater size for a vertical impactor with that energy would be in the "few tens of metres' diameter" range, perhaps disturbing up to 200 tonnes of regolith. A shallower impact would, as you suggest, spray debris further downrange - probably up to several kilometres if my back of an envelope is to be believed - but the bulk of the material would be landing within a couple of hundreds of metres.

It should be easily visible from orbit: is there any photography (from Clementine?) which depicts the results of LM and SRB impacts? A quick google only raises endless Moon-Hoax rubbish.

Andy G

[ljk4-1]

The best reference for artificial impact craters on the Moon is Ewen Whitaker's short article in the Apollo 16 Preliminary Science Report - should be easy to track down in any good university or big city library. 

The Apollo 16 Preliminary Science Report may be found online here:

http://history.nasa.gov/alsj/a16/as16psr.pdf


Also, if you go to this Web page:

http://www.geocities.com/bobandrepont/apollopdf.htm

Scroll down to the Apollo 16 section, where you will find links to other relevant documents regarding the geology of the landing site and even a brief report on the impact of an upper Saturn stage just 10 km from the landing area.

[ljk4-1]

The Apollo 16 Preliminary Science Report may be found online here:

http://history.nasa.gov/alsj/a16/as16psr.pdf
Also, if you go to this Web page:

http://www.geocities.com/bobandrepont/apollopdf.htm

Scroll down to the Apollo 16 section, where you will find links to other relevant documents regarding the geology of the landing site and even a brief report on the impact of an upper Saturn stage just 10 km from the landing area.

And the 1968 NASA book, Exploring Space with a Camera, has an image of the Ranger 8 impact crater from Lunar Orbiter 2 and the famous image of Surveyor 1 on the lunar surface from Lunar Orbiter 3.

Starting here:

http://history.nasa.gov/SP-168/section2b.htm#94

[edstrick]

Phil said: LRO will allow a search for all impact craters - including, presumably, Ranger 4, Lunas 2, 5, 7 and 8, Hiten... quite a few... Also the Lunar Orbiters, at mostly utterly unknown locations. Orbiter 1 was intentionally impacted to "open" radio channel space for Orbiter 2.

I hope we get good coverage of the Luna 9 and 13 landing sites. Precise locations not known, to maybe a degree or somewhat better in lat and long. Luna 9 is supposedly on the edge of mare at the west edge of Procellarum, but the panoramic images show a hummocky rolling terrain very much like subdued parts of Fra Mauro, and I'm convinced it's in the adjacent very subdued highland patch by the nominal landing site. Luna 13 is totally unambiguously on mare.

Note the Luna landers ejected two instrument compartments before retrofire, then jettisoned the hard lander sphere at retro burnout while the main spacecraft went *CRUNCH-TINKLE* (well.. no tinkle in vaccuum...) nearby. I was a bit surprised I never could recognize the wreckage in post-landing panoramas, but it may have simply been out of view for both missions.

[ljk4-1]

Phil said: LRO will allow a search for all impact craters - including, presumably, Ranger 4, Lunas 2, 5, 7 and 8, Hiten... quite a few... Also the Lunar Orbiters, at mostly utterly unknown locations.  Orbiter 1 was intentionally impacted to "open" radio channel space for Orbiter 2.

I hope we get good coverage of the Luna 9 and 13 landing sites.  Precise locations not known, to maybe a degree or somewhat better in lat and long.  Luna 9 is supposedly on the edge of mare at the west edge of Procellarum, but the panoramic images show a hummocky rolling terrain very much like subdued parts of Fra Mauro, and I'm convinced it's in the adjacent very subdued highland patch by the nominal landing site.  Luna 13 is totally unambiguously on mare.

Note the Luna landers ejected two instrument compartments before retrofire, then jettisoned the hard lander sphere at retro burnout while the main spacecraft went *CRUNCH-TINKLE*  (well.. no tinkle in vaccuum...) nearby.  I was a bit surprised I never could recognize the wreckage in post-landing panoramas, but it may have simply been out of view for both missions.

Do not forget the later Lunas like 23 and 24, which should be even more visible as they are larger. How well do we know their landing sites?

And the famous Luna 15, which tried to beat Apollo 11 back with regoltih samples.

And Ranger 4 - I'd like to know if the balsa wood sphere survived.

And of course Surveyor 4 - did it land okay or did it crash? Lunar Orbiter 3 could essentially tell the difference with Surveyor 1.

One more - Luna 2 supposedly spread shiny USSR Coat of Arms all over the place of its impact site. Could those be seen from orbit, especially if the sunlight hits them just right?

[edstrick]

"And of course Surveyor 4 - did it land okay or did it crash? "

Surveyor 4 went from "nominal" to zero signal essentially instantaneously, right about the time of maximum thrust from the solid retro-rocket, a second or so before burnout. The failure review found no smoking gun in preflight documentation and absolutely nothing in the telemetry. They concluded that the retro may have exploded, or that there was a sudden and total power failure to two separate transmitter systems at the same time <as I recall>, which could include the entire spacecraft's power, of course.

Either it scattered shredded metal bits over a square kilometer plus of moonscape, hit the surface at the some 500 miles/hr remaining at retro burnout and lined a crater with shiny metal bits, or it more or less successfully landed or did a low speed impact after continuing a descent in the blind.

Sinus Meridiani contains the shiny-metal-bit lined crater of Surveyor 2, the remains of 4, and successfully landed Surveyor 6. As a very old mare with very deep.. estimated 10 meter thick.. regolith, the site has very few large loose rocks and is a generally good place to look for geologically fresh disturbances, though as old mare, the medium size crater population is large.

[Phil Stooke]

Meridiani? Yikes, it was off course!

Phil

[ljk4-1]

"And of course Surveyor 4 - did it land okay or did it crash? "

Surveyor 4 went from "nominal" to zero signal essentially instantaneously, right about the time of maximum thrust from the solid retro-rocket, a second or so before burnout.  The failure review found no smoking gun in preflight documentation and absolutely nothing in the telemetry.  They concluded that the retro may have exploded, or that there was a sudden and total power failure to two separate transmitter systems at the same time <as I recall>, which could include the entire spacecraft's power, of course.

Either it scattered shredded metal bits over a square kilometer plus of moonscape, hit the surface at the some 500 miles/hr remaining at retro burnout and lined a crater with shiny metal bits, or it more or less successfully landed or did a low speed impact after continuing a descent in the blind. 

Sinus Meridiani contains the shiny-metal-bit lined crater of Surveyor 2, the remains of 4, and successfully landed Surveyor 6.  As a very old mare with very deep.. estimated 10 meter thick.. regolith, the site has very few large loose rocks and is a generally good place to look for geologically fresh disturbances, though as old mare, the medium size crater population is large.

Assuming Surveyor 4 did not explode, could it have survived from the height it was at when the retrorockets stopped firing? By survive I mean land in more or less one piece?

Would Surveyor 4 have started an automatic program of basic exploration? Or did it need to wait for commands from Earth? How sad to think it might have been trying to send data home that no one could detect.

[edstrick]

"Meridiani? Yikes, it was off course!"

Phil: I believe <would have to check> Surveyor 2 and 4 were targeted for Sinus Meridiani, 6 finally validated that site for Apollo. Actually, I have absolutely no idea where Surveyor 2 impacted. When one vernier engine didn't fire during the midcourse maneuver, it went into a fast tumble, and every attempt to pulse the engines just increased the tumble rate.. it was up to 1 or 2 revs/second at the end.

Having lost all hope of landing Surveyor 2, they powered it up and fired the retro to exercise systems as engineering tests. The battery was nearly depleted at that time, and they lost signal sometime during the retro burn, shortly before impact. They didn't seem to really know if the LOS was due to the battery running down during high curent loads, or the vehicle disintegrating under the combined tumble and many G's of retrofire acceleration.

[edstrick]

Assuming Surveyor 4 did not explode, could it have survived from the height it was at when the retrorockets stopped firing? By survive I mean land in more or less one piece?
Would Surveyor 4 have started an automatic program of basic exploration? Or did it need to wait for commands from Earth? How sad to think it might have been trying to send data home that no one could detect.

LJK: Surveyors were STUPID. No real computer on board. They could store timing and angular info in hardware registers, so they could load parameters for a mindcourse maneuver into registers and issue an execute command and have the spacecraft turn to the loaded attitude. Another command would enable and execute the motor burn, etc.

For landing, they loaded retrofire delay time <after the altitude marking radar said "Now" for a given distance from the surface. It counted down a few seconds from then to retro, turned on the verniers, got the spacecraft stable, and lit the solid. On solid burnout, the onboard sequencer powered the verniers up to full thrust and dropped the retro-case out from under the spacecraft. The rest of the ride to the surface was automated with closed loop control systems through the range and doppler velocity radar system. All the way down, including when under power <I think> they were giving commands to switch telemetry mode, change systems power status, etc. Not much during landing, but everything else was direct from Earth command driven.

If they lost power at the time of LOS of signal, they were still miles high and doing some hundreds of miles an hour... CRUNCH.

[Phil Stooke]

Medii, edstrick! Sinus Medii... Meridiani is quite some way from there.

You are quite right, of course, about Sinus Medii being the target for both Surveyors 2 and 4 before Surveyor 6 finally accomplished the landing. Apollo planners and the Surveyor/Orbiter Utilization Committee required one Surveyor landing in each of the eastern and western maria and in Sinus Medii (plus the first landing in the vertical descent area) before they would free up a Surveyor for a 'science site'.

Phil

[Guest_BruceMoomaw_*]

Apparently Surveyor 4 lost contact at precisely the time (as indicated by ground studies) that the solid fuel in its retromotor had burned down to the point that individual loose seams between the segments of fuel attached to its chamber walls were exposed, making it highly probable that at that moment one such segment peeled loose and got blown into the nozzle, resulting in a pressure buildup and an instant explosion. There are other possibilities mentioned in the final failure report: the explosion of one of the pressurized gas tanks (or even of a shock absorber!), the breakage of a power cable, or even the breakage of a cable to the transmitters. But while the latter raises the long-shot possibility that the craft did land intact but incommunicado, the odds are overwhelming that it is now in little bitty pieces.

As for Surveyor 2: if I remember correctly it landed about 50 miles off target, thanks to the failure of its midcourse maneuver (which is where the trouble started). We don't know precisely where, since we lost contact en route -- but there was a story at the time in "Technology Week" that Lunar Orbiter 2 had photographed a fresh crater in about the right place. I don't know what that story eventually came to.

One final little historical note: Don Wilhelms says in his authoritative book on Apollo-era lunar geology, "To A Rocky Moon", that despite the failures of Surveyors 2 and 4, serious consideration was given to saying the hell with Sinus Medii and rediverting #6 to a purely scientific site -- with the plain just outside the Hyginus Rill being the front-runner. (Tycho, #7's final destination, was not on the list.) NASA HQ, however, vetoed this on the grounds that a successful Apollo mission came beyond all consideration of science.

[Bob Shaw]

Will any of the mineralogical instruments under consideration as Lunar payloads be any good at picking out the materials of which spacecraft, upper stages etc are made (especially when, er, 'well distributed' on the surface!)? It'd be nice to be able to say look, there's the Mylar, that's the paint, etc, with no room left for uncertainty or debate...

[Phil Stooke]

Bruce, that Technology Week story would be interesting... can you say any more about it?

But I wouldn't expect it to amount to anything. The Surveyor 2 location would be very uncertain as you said, and the Orbiters saw small fresh craters all over the place. It was probably nothing more than 'hey, there's a fresh-looking crater... I wonder if...!?!?!'

It certainly doesn't get any mention in the Surveyor Program final report (1969).

Phil

[Bob Shaw]

Bruce, that Technology Week story would be interesting... can you say any more about it? 

But I wouldn't expect it to amount to anything.  The Surveyor 2 location would be very uncertain as you said, and the Orbiters saw small fresh craters all over the place. It was probably nothing more than 'hey, there's a fresh-looking crater... I wonder if...!?!?!' 

It certainly doesn't get any mention in the Surveyor Program final report (1969).

Phil

Phil:

I think that's exactly why it'd be nice to spectroscopically identify debris fields from orbit!

Bob Shaw

[edstrick]

Medii, edstrick! Sinus Medii... Meridiani is quite some way from there.

Phil... I have a very very technical comment to make: "Duh."

[Guest_BruceMoomaw_*]

Bruce, that Technology Week story would be interesting... can you say any more about it? 

But I wouldn't expect it to amount to anything.  The Surveyor 2 location would be very uncertain as you said, and the Orbiters saw small fresh craters all over the place. It was probably nothing more than 'hey, there's a fresh-looking crater... I wonder if...!?!?!' 

It certainly doesn't get any mention in the Surveyor Program final report (1969).

Phil

Completely plausible -- the only refence to it I've ever seen was a one-sentence note in Technology Week that they had seen a fresh-looking crater that was suspected of POSSIBLY being Surveyor 2. Since I've never heard anything since, I've tended to assume that it came to naught. In any case, since I saw this when I was 12, my memories are a bit fuzzy.