4.9.3 - Apollo 17 Day 3 - Final Approach

Before we get to the next photograph, Schmitt continues his weather forecasting duties by describing what he can see at around 02:00:

044:26:14 Schmitt: Okay. Got a little information on what we were talking about yesterday with respect to southern Pacific weather, if you've got nothing else going on.

044:26:26 Roosa: Go; speak to me.

044:26:32 Schmitt: Okay, looks like a little - cyclonic circulation we had over New Zealand is still there. It's - looks like the front it was associated with is broken up a little bit; however, that pattern is - seems to be hugging the New Zealand area, and - but not - has not intensified. If - if not - it may have even weakened a little bit since yesterday. It's hard to be sure exactly. The front does not look as strong, and it still seems to be hanging - just stabilized, and with all of Australia clear now and the western edge of that front being just offshore north of Brisbane. The - there is - east of New Guinea - in the vicinity of the Solomon islands, it looks like a fairly moderate-sized cyclone developing at the western edge of the - of a front that was somewhat farther north and west than the one over New Zealand. North of that - Wake/Kwajalein region that was of interest yesterday to the ARIA people - still seems to be in general overcast condition, but the clouds do not look very heavy or impacted at all. New Guinea is just on the limb, so…

Let’s have a look at what should be visible at this point in figure

CATM Home OBM Home
CATM Home OBM Home

Figure SkySafari depiction of the Earth at the time of crew comments compared with 3D satellite reconstruction.

The satellite image here is around 3 hours behind the Apollo 17 description, but there is a clear match with what Schmitt is recounting to the ground. Of particular relevance is the comment about the location of Papua New Guinea, which is indeed on the limb. A few minutes later Gene Cernan gets in on the act:

044:35:55 Cernan: Okay, I think that big storm that Jack was referring to - that has moved off to the - well to the east of Australia. Very definite counterclockwise rotation and then it stretches to the south or what might even be the southeast. And then just rolls right - we [garble] a big frontal pattern and then it rolls right into another - another clockwise - clockwise rotating low down there near Antarctica. It gives me the impression of a - of a parrot's comb when he's got his feathers ruffled. And it, in turn, has another low trailing it, arcing and then flowing into another - another low that is very near the continent down there of Antarctica. They form a chain, as I just described froming - coming from - well, possibly southeast of Antarctica - it's hard to really tell what east is down there - on up to due west of Australia by several hundred miles.

044:37:13 Overmyer: Roger. [Pause.]

044:37:21 Cernan: South of Australia, you get a hint of a very large cloud mass, from there all the way down to Antarctica, that has the tendency to...

There’s a disruption in comms here, which is resumed in a few minutes:

044:40:17 Overmyer: Just wanted to get comm there again. We had some switchover there. You might be interested; we've got an ATS map in here from this morning. Just - you're just about on - We can see the flow patterns in the Antarctic just about at - 120 degrees west, which is a little closer to South America than what you're calling, I guess. But we do - we do see that activity down there.

044:40:46 Cernan: Okay, Bob. And there is a very large cloudy air mass between Australia and Antarctica. It has a tendency to want to start a rotation, and you can see a hint of that; it's not too strong right now. We're seeing about three-quarters of the Earth, I guess. Judging from our clocks and what we can see, it looks like the Sun is setting out over the west coast; and it leaves us with about three-quarters of the Earth available to us.

Again, they’re correct about the sunset, and about what’s going on beneath them. It’s interesting that Houston has access to an ATS image, which would be nice to have here!

A couple of hours later, Schmitt updates his analysis, and figure shows the view that he’s describing.:

046:35:56 Schmitt: I'm ready to update your weather in the Western Pacific, if you're interested.

046:36:02 Overmyer: Roger. Go ahead.

046:36:07 Schmitt: Still can't quite figure out what that circulation around New Zealand means. It looks like it's merging with some more weather to the southeast. I suspect it's stormy there, but I still - It's not a terribly well-developed storm, although it seems to be broadening in its extent. Australia is completely free of any significant weather and almost completely free - free of clouds. The - There appears to be a front - although right now it does not look too intense - approaching from the southwest. And it looks like it's about 5 degrees of longitude south of the southwestern tip of Australia. The typhoon Cirrus - or Therese, I guess it is - appears to be just about the same position it was yesterday. And that is north of Borneo and between Vietnam and the Philippines.

20 minutes later he posts an update:

046:50:47 Schmitt: I need to make a correction. Roger. I need to make a correction. It looks as if that storm area that was in New Zealand yesterday has moved up across the two islands and is now sitting northwest. It's getting a little hard to identify the smaller islands in the pacific, but - pretty sure I've got it in the right place now looking at the map. And it is northwest of New Zealand. And it looks like New Zealand is probably having reasonably good weather today, although I suspect it rained last night.

046:51:27 Overmyer: Roger, Jack. That's interesting because on my prog it doesn't show a thing down that area. This just may not be up to date here yet.

046:51:36 Schmitt: Well, there may be nothing down there except some cloud patterns and - but that's all I can see, of course. The front that's south of Australia now - I presume front - just looking at a fairly well-developed, although narrow, cloud line, is about 5 - about 10 degrees south of Perth right now, southwest of Perth and runs on a northwest-southeast line - over to a point about 10 or 15 degrees southwest of Tasmania. And then it intersects a curved front that runs from there up to - to Tasmania, and then back around down south of New Zealand about 10 degrees.

Jack continues his synoptic deliberations during the next hour or so, culminating in the next photograph in his long sequence. We’ll catch up on his narrative after seeing the scene he’s describing (figures and 4.

Figure AS17-148-22747 compared with NOAA satellite mosaic and SkySafari depiction of time. Far left is 3D reconstruction of digitally restored NOAA data.

Figure AS17-147-22747

Such has been Jack Schmitt's influence on this part of the narrative of Apollo 17 that mention of the actual satellite photographs that are the point of this research has been almost put to one side. To redress the balance slightly, the satellite image used here, dated the 8th but showing cloud formations on the 9th of December, is a clear match with what Jack sees and describes from Apollo 17. The northern hemisphere mosaic has issues with data quality, and some of the features are difficult to identify clearly – particularly in the eastern part of the picture. There is a clear line on the mosaic inland of China's east coast where the clouds are much better defined.

It is still, however, possible to pick out the patterns. Therese (about we will hear from Jack later) is just visible, highlighted in blue and heading for landfall in Vietnam. Southern hemisphere systems are much better defined, and the clouds off Australia and over New Zealand are very easy to identify. The time markings suggest a rough time at the terminator on the NOAA mosaic of around 22:00.

 Systems easy to identify in an image taken from a few hundred miles up are still easy to identify from over 150000 miles away, with the benefit of good monocular viewing equipment (anyone with a telescope will have a similar level of detail available to them of the much smaller Moon from much further away!). After the hiatus of testing the LM systems, Jack is able to return to his meteorological observations.

The emerging cyclone he described in the preamble to this photograph is the one identified with the purple arrow, and the front south of Brisbane in yellow.

Cernan’s comments from earlier are trying to describe the front that rolls up from Antarctica towards New Zealand, heads westward towards Tasmania before merging with a thin front off Perth. Closer examination of the Apollo image does show other systems with similar patterns below that large front, and the cloud mass is indeed fairly solid below that towards the ice sheets.

Schmitt's appraisal of Australia's conditions are spot on. He identifies the thin front to the south-west (magenta arrow), and correctly notes that New Zealand is also out from under the clouds. His greater detail on the thin front shows we have correctly picked out what he was describing earlier, and the Tasmanian front we have identified using a yellow arrow is also very obvious. All of these antipodean systems are evident on the NOAA mosaic.

Later on he moves back to SE Asia, and the north-east trending cloud from the Philippines is identified here by a cyan arrow. Schmitt continues his description of

046:59:36 Schmitt: Okay. That generally - South China looks clear. I haven't had a real good look at it yet, it's out on the limb. It's clearly, however, overcast over Korea and Manchuria. It does not appear to be frontal weather there, though. The dominant front in the northwestern Pacific stretches on a northwest line from just off Luzon on up as far as I can see to the terminator. And it seems to be an extremely strong front with what I would guess is heavy air-mass weather all along it. And up to the east-northeast of Japan, there's an excellent example of a shadow line from some fairly thick high clouds on solid overcast of lower clouds. Don't see any major cyclone development along it, or wave development. It just locks like a very strong air-mass front.

047:00:51 Overmyer: Roger, Jack. We've got it on our prog here. We don't show the one on the northeast part of Japan, but we do show a front prog for tomorrow morning going off of Taiwan and - right from Taiwan eastward - past the Ryukyu islands and just on into the northern Pacific there. Looks like pretty heavy cloud mass over there.

047:01:14 Schmitt: Roger. That's the one I'm - Roger. That's the one I'm looking at. Extremely heavy. And right now it - in fact starts about at Luzon. It looks like Taiwan is almost on the back side of it.

The main front he is describing there is the one picked out by the cyan arrow, and rather than “north-west” being the compass bearing, he means “north to west”, as this line of cloud does go from the Philippines area to the terminator. The 'shadow line' he refers to is close to the terminator, pretty much on the point of the cyan arrow, where the smooth lower level cloud to the left of the arrow point contrasts with the higher altitude 'lumpier' cloud mass to the right of it.

Capcom again tell Schmitt that they don't have all of the area he describes on their charts, but that what they do have matches what he's telling them. Schmitt then goes back to Australia and predicts heavy weather for South Australia in a few day's time.

047:50:30 Schmitt: Well, I still am, as a matter of fact. The old Earth's coming by. And, say, I mentioned a couple of fronts that joined together about 20 degrees south of - of - the south coast of Australia. And it looks like that's a fairly healthy storm center developing down in there - conceivably may migrate up across Tasmania and maybe up - up the Sydney-Brisbane coastal area in the next few days.

That frontal system is picked out by the yellow arrow.

 He then tells Capcom at 47:43 (c. 05:15 GMT) that:

047:59:15 Schmitt: Bob, we're still on November November frame 140, and I'm going to take two more pictures before I go to sleep.

Followed later by

048:14:53 Schmitt: Roger. One final word. I got those pictures; and, I tell you, that typhoon off - north of Borneo - looks like it's right off the coast of - the east coast of Vietnam now, and it's about as tightly organized and solid as anything I can remember seeing in photographs. It looks as if, from yesterday, it's moved quite a bit to the west.

048:15:26 Overmyer: Roger. We concur. The prog for 12:00 - Let's see, that's about 6 hours from now - shows it to be right over the Vietnam area, the Viet - Vietnam peninsula there. So it looks like it's moving the way they're progging it, huh?

048:15:42 Schmitt: Yes; well, it's right there. Yes, it certainly is. It's - it's moved from just a little bit west of Luzon over to the coast there. So it's a pretty healthy storm.

048:15:59 Overmyer: Roger. It looks - on the prog chart here - it looks real tight. It's a very - very centralized thing and real tight circular.

048:16:12 Schmitt: Oh, yes, you better believe it. It in really - it is tight. It - it's really - really no bigger than the - in terms of cloud pattern - no bigger than the - say, South Vietnam itself.

048:16:31 Overmyer: Roger. How're you getting that, Jack? Are you looking with the monocular now?

048:16:39 Schmitt: That's affirm. Monocular still gives real good resolution on the cloud patterns. [Music] Naked eye, you just see the masses; but with the 10-power monocular, it's perfectly adequate for seeing the kind of patterns we're talking about.

So we have a pretty accurate time for the image under discussion of 05:30 GMT, and an examination of the Stellarium inset included in the previous figure shows that the distance between the terminator and Australia matches exactly what it should be, as does (allowing for the relative viewpoints of Stellarium and Apollo 17) the distribution of Asian land masses on the western limb.

A reminder here that capcom isn’t looking at satellite photographs, the prog charts are ‘prognostic’ charts - forecasts of where weather systems are heading.

The photographs to which he is referring are general pictures of hurricanes and tropical storms, not this specific one, although we do know that photographs of a nicely formed spiral Therese with a defined eye were around before launch. Therese has indeed moved west, and is due to make landfall in Vietnam in the very near future. Capcom's weather charts also show a tightly formed storm, and predict that landfall will be in another 6 hours time. Jack is even able to describe Therese as being roughly the size of South Vietnam, which is a reasonable estimate of its diameter.

We have a couple of Landsat passes to examine on this date that cover areas of this image, namely central Australia and Antarctica. Earth is getting increasingly distance and the amount of resolvable detail in close up is reducing all the time, but we should at least have a go. Figure gives the details.

Figure SkySafari depiction of the Earth at the time of crew comments compared with 3D satellite reconstruction.

Figure Landsat paths shown on AS17-148-22747 (top left) and Google Earth (bottom left), with the Antarctic shown centre and central Australia shown above. Australia’s image has been rotated to save space.

The most obvious feature of the two sets of satellite views is that central Australia is clear of cloud in both Apollo and Landsat, but to be fair it often is. Antarctica is covered in ice in both images, but despite the lack of detail you can make out the changes in contrast. The Landsat view shows clear sea in a couple of coastal patches, and there is a similar area to be seen in the Apollo view, but this is not unusual and it also assumes that I have the right area under scrutiny - something much more difficult to prove in these much more distant images. Again, they are consistent with each other, but not in any way conclusive. Australia’s start time isn’t recorded for Landsat, but Antarctica’s is given at 11:40 and it is on the same orbit, so there is a good 6 hours separating Apollo and Landsat.

Next up in magazine 148 is AS17-148-22749. This must have been taken some time after the previous image, as it now shows west Africa and south America, so the Earth has rotated some distance during the 'overnight' rest period. The image itself is shown in figure, and the satellite analysis after that in figure

Figure AS17-148-22749 compared with NOAA satellite mosaic and SkySafari time depiction. Left is a 3D reconstruction using digitally restored NOAA data.

Figure AS17-148-22749 

The terminator on the image runs almost through the prime meridian, at least in the northern Hemisphere, and has been set by Jack’s confirmation of the time given below.

The mosaic again suffers from very poor image quality, with lighter clouds difficult to make out, and a large data 'hole' in the north Atlantic off the coast of north America.  Sub-tropical clouds southern hemisphere weather systems have fewer issues of this type.

As far as the weather systems themselves are concerned, we again have Jack's observations, found at 58:39 MET in the transcript:

058:39:45 Schmitt: Okay, Gordy. That little storm - fairly big storm - that was off the coast of northwest Africa yesterday, has moved inland and presumably is giving those people up there some weather. Might even be getting some snow up in the Atlas Mountains. It's still fairly well organized and inland a few hundred miles - or the edge of it is inland a few hundred miles. The people at the Cape of Good Hope ought to be seeing some clouds that are forerunners of a large circulation system that's south-southwest of them - that, although large, seems to have most of its heavy clouds to the southeast of the center. And they may not get any major weather out of this one. But they'll probably have cloudiness for a few days. The storm that was over Buenos Aires yesterday has apparently moved out to sea and is now west - or east-southeast of that area. Otherwise the - except for those three storm areas, the South Atlantic looks relatively calm. The zero phase point is now off the - east coast of South America, and it looks fairly dull and gray. And I suspect no extensive choppiness in that area.

Schmitt's description of the large and spectacular frontal system that used to be in the north Atlantic is again accurate, and it is interesting to note that while his description (and the observable reality of the photograph) find the leading edge of that storm (indicated by the green arrow) inland on north Africa, it is still on the shore 5 hours or so earlier in the NOAA mosaic. The tight central spiral of cloud is also not visible on the NOAA image, but it is possible that NOAA's sensors and/or the mosaic compilation process have not used the required level of detail to see what are obviously thin clouds.

The large system he identifies off the Cape of Good Hope is picked out by the magenta arrow. The other system picked out by Jack is the one that was over Buenos Aires, which is picked out here by the yellow arrow. In the Apollo image this storm has moved almost completely out to sea, as Jack describes, but in the NOAA mosaic it is still half over the Argentinian capital.

A few moments later, at 59:20 MET, or 16:50 GMT, Schmitt tells us that:

059:20:41 Schmitt: While I got you, I took three pictures of the Earth I thought I might have moved one of them. And we're on frame 145.

The image used in this particular analysis is indeed one of three, rather than the pairs of images Schmitt has been taking to date.

The next images in magazine 148 show the CSM as viewed from the LM, as Cernan and Schmitt carry out some telemetry checking from the LM. Following this sequence of pictures, the next one of Earth is AS17-148-22758. This is shown in in figure, and analysed in figure Also included is one of the Nikon images that were obviously taken at the same time.

Figure AS17-148-22758 and AS17-162-24071

Before seeing what Cernan and Schmitt have to say about their view of Earth when these were taken, NOAA should be given a quick examination. The image used is from the 9th of December, and for once the quality of the cloud representations is roughly equal between the hemispheres, although there is a substantial gap off the east coast of North America. For this photograph this gap is of no consequence as it is that part of the Earth is no longer visible. The two most obvious features are the large loop of cloud from the Antarctic up towards Australia, and the '<' shaped twin bands of clouds stemming from the western Pacific towards California and south America. The terminator line just on from the US east coast would have been scanned by NOAA at roughly 15:00 GMT.

As for what Apollo's image shows us, it is Cernan who takes up the narrative in the build-up to the photographs at 62:52 MET (roughly 20:25 GMT):

062:52:11 Cernan: Okay, now that we got another look at you, Gordy, it looks like Houston might be right on the fringes of either being clear or clearer. The entire Gulf is pretty nice. Florida looks pretty clear, and Mexico looks pretty clear. There's a big air mass of clouds that looks like it picks up somewhere around the coast at Houston, heads on up north, and then covers most of the Midwest and the East, from about the middle of Mississippi, Alabama, and Georgia on north. It's clear enough now to even see the coral reefs down off of Florida. And it looks like west Texas is probably also pretty clear, at least in a run from east to west. We can see Baja, and on up the coast of California up north.

His description is, as expected, an accurate one. The cloud mass covering Houston and northwards is picked out by the green arrow, and his assessment of the clear areas matches what we can see. Schmitt then takes over the narrative, effectively repeating Gene's description:

063:11:52 Schmitt: Gordy, this is Jack. I think Gene was right. You got some - probably scattered cloud weather, but not very far away from you there's a pretty heavy mass of clouds. It may be the forerunner of that dry cold front you were talking about yesterday, which I can see stretching over into Sonora. But where it hits the stateside, it's got quite a mass of clouds associated with it. It looks like they're moving in your direction.

063:12:24 Fullerton: Okay, Jack, thanks for the warning.

063:12:30 Schmitt: Clear behind it, in Arizona and New Mexico and maybe southern Colorado, it looks like there may be another front stretching, or maybe it hits northern Arizona and Utah and up through northern Colorado, and on in to Canada, trending northeast.

063:12:57 Fullerton: You're calling it right on, Jack. I'm looking at the surface chart, and that's about what we see. [Long pause.]

063:13:20 Schmitt: Looks like a low might be developing on that one - a wave up in northern Colorado and - although the clouds are a little hard to read.

before commenting on the southern Hemisphere:

063:14:29 Schmitt: One of the more unusual features is developed - as I see - developed in the southeast Pacific just north of the Ross Sea and that is a very striking mushroom pattern on a very large scale. It has north/south clouds streaming - streamers from the Ross Sea. And when it gets up about the latitude of Tierra del Fuego, but quite a bit west of that land, it branches out to the east and west in a large mushroom pattern. And it looks like the top of that mushroom may be a curved cold front that's pushing its way up into the southeast Pacific. It currently - the eastern edge of that front is probably 10 degrees longitude from Tierra del Fuego, and it looks like that land in southern Chile is picking up high clouds, probably associated with that front's movement.

063:15:49 Fullerton: Roger. [Pause.]

063:15:56 Schmitt: I'll get some shots of that next time around. That's a spectacular pattern. You almost get the feeling that the cold airmass moving out of Antarctica streams for a while north/south. And then it picks - The cloud patterns change and as it starts to migrate, the winds start to change from east to west, Maybe that's where it encounters the jetstream.

The mushroom pattern is the system identified by the magenta arrow, and again the description is very accurate, right down to the 'streamers' that head northwards from roughly where the magenta arrow head is., and the high clouds mentioned next to Tierra del Fuego are marked by the red arrow.

After a brief discussion on whether he can see any changes in the Ross Sea,

064:19:57 Schmitt: Yeah, about this icepack in the Ross Sea. The - as I remember a couple days ago, there were two clear areas, triangular in shape and quite elongate, that were projecting out into the sea from the innermost part of the bay, or of the - from the continent. Today those are not apparent, at least the first look I made. And it looks like there is an elongate, more irregular clear area that is roughly parallel to the Antarctic coastline within the sea itself. We'll check that a little more closely and see if that's right.

Capcom given another mention of their use of satellite images, saying at 64:21 MET:

064:21:13 Fullerton: I'm looking at a satellite picture here, which I guess is around 12 hours old though. But over to the east of Australia, maybe about a continent width east of Australia, there's a really striking long frontal system - striking because it's so long and so straight, sort of west-northwest, trending west-northwest and east-southeast trending. Can you see that?

Capcom's description matches what Jack & Gene have already described, but his ATS image must lack the detail of their monocular view of a colour Earth.

At this point Gene takes over again, and discusses the various sub-Antarctic systems he can see:

064:23:41 Cernan: Okay. Now Jack and I may be talking about two different frontal systems or patterns, but the one I think you might be referring to is the one I referred to yesterday as a ruffled parrot's beak. Actually two of them tied together, one starting up probably southeast of Australia and - and then heading down with a long arcing frontal system to another clockwise rotational parrot's - parrot's cone, I should say, down around - near the tip of South America, between it and Antarctica. There is one strong tributary front heading up to the north-northwest from the western side of this big, arcing, frontal mass. And I think that's probably what you're referring to. I'm not sure. I can't quite see Australia coming up over the - over the horizon yet.

Gene is right in thinking that this is the same weather system he described earlier, and all three of them are describing the same system, but Jack's “mushroom” analogy is the better description of it. Capcom tells Gene that his ATS image doesn't go as far south or west as far as he is describing, after which Gene continues to describe the same system:

064:25:15 Cernan: There is some tremendous - western side of that curve front is a tremendous clockwise rotational airmass. It must cover hundreds of square miles. The one down near - near the continent of Antarctica, down there, near the tip of South America, seemed to be squashed slightly as if there is possibly some - some squashing or effect coming off - off the South Pole area near Antarctica. I think, if I turn around and look at it the way Jack was looking at it, it's a cap of a mushroom. Only instead of simply curving in underneath the cap, it has clockwise rotations on both sides as it curves under.

In this passage Cernan first describes the system marked by the purple arrow – where there are several circles of cloud at one end of the 'mushroom'. The other system he mentions is at the eastern end, just below the  clouds marked by the red arrow.

Confirmation of the timing of the Apollo photograph comes from Schmitt at 64:28 MET, when he says that:

064:28:22 Schmitt: Gordy, I just took two pictures of the Earth at the present time, and those are, right now the camera is on frame 153.

and after another brief exchange about what Capcom's ATS image covers goes on to give his description:

"...that mushroom pattern we've been talking about, on either edge - either end of the cap - and the mushroom points north - is a major cyclone circulation system. And also taking - moving, in one case - or trending, in one case, to the north-west and the other to the north-east, there are some linear cloud patterns. Gives it a very symmetrical and a striking appearance.”

A few moments later, Jack confirms that he has taken some more photos of Earth with the Nikon:

064:48:12 Schmitt: Gordy, I just took a series of pictures of the Earth with the 35-millimeter using the polarizing filter in the two positions. And the frame count is now 39. I took six pictures. And with the filter, on the first of each pair, in the Down position. The second's in the Up position. And I changed the f-stop from - the first set at f/4, the second set at f/2, and the third set at f/8.

This suggests a 20 minute gap between the Hasselblad and Nikon photos, so it is worth looking to see if we can notice any discernible rotation between the two (figure

So we have both Gene Cernan and Jack Schmitt describing weather patterns, many of which are not available on Capcom's ATS images, showing an Earth that matches exactly what should be visible according to SkySafari. The weather systems they see and describe are matched by NOAA's satellite mosaic, and there is even a consistent and measurable degree of rotation between the two images.

In addition to the civilian satellites recording the view we also have Corona images taken on this date and there are two small areas covered of western USA. The images concerned are shown in figure

Figure AS17-148-22758 and AS17-162-24071 compared. The Hasselblad image has been rotated to match. Above is SkySafari time depiction for the Nikon image

Figure AS17-148-22758 compared with NOAA satellite data, 3D satellite reconstruction and SkySafari time depiction. AS17-162-24071 shown with the same arrows.

Figure AS17-148-22758 showing area covered by Corona pass (top left) and the same area with the Corona image on Google Earth (bottom left), close up of Apollo image covered by Corona (centre) and the Corona images themselves (right). The Apollo image has been brightness adjusted to clarify detail.

What we have visible in the Corona image is a band of cloud stretching from offshore onto land and we have the same pattern visible in the Apollo image. The Apollo image was taken at around 14:00 local time, and the Corona image was likely to have been taken an hour or so before that. The patch of cloud shown in the northernmost images taken by Corona is also matched well by the Apollo photograph. As with other Corona images it has not totally conclusive, but it is vedry consistent.

We have another satellite to choose from as well for this image, namely a long Landsat pass over central Canada and the USA. There is also a pass over a small section of British Columbia, but it is at such an angle on the Apollo image it would not provide any useful information. Figure shows the relevant locations and details of these images.

Figure Landsat pass over North America shown in AS17-148-22758 (top left) and Google Earth (bottom left), and in close up (right)

As usual there is a broad correspondence with the Apollo image - we have clear skies with some cloud and land surface visible in the south and an increasingly white covering as you move north. At the top end the white starts to fade as the land surface becomes visible again.

The timings given for the remaining images in the mission are open to some confusion, as there was an update to the mission clocks during TLC. Updates to the clock were done where, for example, a launch delay introduced a lag between the planned time of events for the mission (eg ultra-violet photography, EVAs) and the actual time thanks to the delay. The aim of changing the clock was so that the time shown on the mission clocks (usually referred to as GET, or Ground Elapsed Time in the transcripts, but what this research has called MET) was synchronised with the events programmed into the flight plan. It is analogous to the change in the clocks for daylight saving time.

Technical problems during the countdown sequence for Apollo 17 introduced a substantial delay to the flight plan, and as a result at 65 hours GET 2 hours and 40 minutes were added to the mission clocks. This event is referred to in both the timeline and the mission transcripts referred to here, but there is no apparent alteration to the actual times recorded. It is assumed that times referred to by Capcom and the crew are the adjusted times, while the times recorded in the documents themselves are the unaltered original elapsed times. Certainly when photographs are recorded as being taken, the recorded times match those derived from Stellarium, rather than the time 160 minutes later. The analogy here is that, for example, the astronauts are using daylight saving time, but all the documents continue to record GMT.

Having accounted for any likely discrepancies in what the various mission personnel may say and when they are recorded as saying it, we can move on to discussing the next image in the sequence.

That next photograph of Earth is one that wasn’t originally considered for this project, and it was only when looking at the descriptions in the transxcripts that I took another look. The transcripts says this:

068:04:33 Schmitt: Okay, Bob, we're getting ready for the ALFMED. I just took a red-filter and a blue-filter pictures, - On frame 41 now, with the 35-millimeter - pictures of the Earth. And I took them one stop smaller - that is, more open - than the lightmeter said, hoping to compensate for the small Earth. The Earth just barely fills the most inner - the innermost circle of the spotmeter. Also, there's a very strong band of clouds, shaped sort of like a narrow fir tree, with a base about 20 degrees of longitude west of Baja California, that extends up, I believe, into the vicinity of Hawaii. And the top terminates in a very strong northern cyclone pattern.

So this is a good couple of hours later than the previous Nikon photograph and opur first test for working what the actual time is.The AFJ gives the adjusted time, so in terms of this analysis 68:04 is the equivalent of 65:24 under the old clock, which is 22:57 GMT. Figure shows the Nikon photograph.

Figure AS17-162-24072 in close-up, with SkySafari time depiction and comparison with AS17-148-22758

It’s difficult to compare with the the previous Nikon image, as it is so over-exposed and we can’t see any oif the South American land mass to act as a guide, but by comparing it with the earlier Hasselblad the rotation over time is clear, and is entirely consistent with the time gap between them of just under an hour.

The timing of the next image, as you’ll see when you follow the link to go look at it, is open to debate - it was around midnight, but to keep the page lengths sensible we’ll go with the 10th. Click the link below.

Intro Day 2 - 08/12/72 Day 3 - 09/12/72 Day 4 - 10/12/72 Day 5 - 11/12/72 Day 6 - 12/12/72 Day 7 - 13/12/72 Day 8 - 14/12/72 Day 09 - 15/12/72 Day 10 - 16/12/72 Day 11 - 17/12/72 Day 13 - 13/12/72 Synoptic
Intro Day 2 - 08/12/72 Day 3 - 09/12/72 Day 4 - 10/12/72 Day 5 - 11/12/72 Day 6 - 12/12/72 Day 7 - 13/12/72 Day 8 - 14/12/72 Day 09 - 15/12/72 Day 10 - 16/12/72 Day 11 - 17/12/72 Day 13 - 13/12/72 Synoptic