4.5.7 - Day 7: Final Approach

The next photograph is one that only emerged recently after an enquiry on collectspace.com, where contributor LM-12 asked for the location of several ‘missing’ Hasselblad magazines recorded in inventories but not found on any of the usual Apollo related websites.

LM-12 mentioned magazine 63 from Apollo 13, and a quick search revealed that half a dozen images could be found at the Gateway to Astronaut Photography, and copies have also now found their way on to the AIA

. Close examination of the photographs revealed that they were all of the same view taken with different exposure settings. One of these photographs is shown below in figure Alongside the image is a mock up of a lunar module interior, in which can be seen the panel and equipment details shown reflected in the window through which Earth has been photographed. The simulator view has been rotated to match the view seen in the Apollo image.

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Figure Left - AS13-63-9045 (Source), Right - Apollo 14 astronauts in a Lunar Module simulator as seen through one of the windows, rotated to match the Apollo 13 view (Source).

Before dealing with the view of Earth, it’s worth pointing out that there are clear shots of the interior of the lunar module in the Apollo 13 photograph. I’m sure someone idiot will point out that the other photograph I’ve used is a simulator blah blah that’s how they did it drone drone, but what they have to then get around is the fact that there is a large planet Earth in the picture. Speaking of which, let’s have a look at what we can see on it, and when it might have been taken.

The shape of the crescent suggests very strongly that it belongs in the closing stages of the mission, so the search began on ESSA images from that part. The weather systems we are looking for turned up on the satellite view taken on the 16th, and this is shown below with a rotated and cleaned up version of the Apollo 13 photograph in figure

Figure Zoomed and cropped version of AS13-93-9045 compared with ESSA satellite image dated 16/04/70 and SkySafari view of Earth set at 05:30 on 17/04/70

The first point of identification was the ‘y’ shaped system identified in the red arrow, only faintly visible on the Apollo view, but once that was spotted the rest fell in to place. The key to the time is the system shown by the magenta arrow on the east coast of Australia, placing the time at around 06:30 on the 17th.

There isn’t much confirmation of this in the mission transcript - the crew were supposedly on a rest period after some fairly intense technical exchanges aimed at getting them home in one piece. They complained that it was too cold to sleep, and one of them must have used a quiet moment to snap a photograph of home. It’s worth pointing out the green arrow, which identifies Tropical Cyclone Isa.

We do get a small clue that confirms that Australia should be in shot at the time I suggest it was taken. About an hour after Stellarium’s time capcom tell them that they will shortly be handing over to Honeysuckle Creek on Australia’s east coast - confirming that the Pacific would dominate their view of Earth at the time the photograph was taken. As for the satellite image, the visible area is best described by track number 7, or orbit 5181, which began at 03:02 on the 17th.

It’s are remarkable testament to the consistency of the Apollo record that a photograph that very few people even know exist, and equally few people have seen, can reveal details that match what should be visible. Yet another one in the eye for Apollo deniers.

The final image in this sequence is from a so far unused magazine, AS13-59-8492.

It occurs as part of a short sequence of images immediately before photographs of the jettisoning of the damaged service module part of the CSM, which occurred at 13:14 on the 17th. Prior to this are a number of photographs taken from within the CSM. The Apollo image is shown in figure, and the satellite analysis in figure

Figure AS13-59-8492 (Source)

Figure AS13-59-8492 compared with ESSA satellite images and SkySafari estimate of time at terminator.

As with the previous analysis, the main land mass visible is that of the Indian sub-continent, and there are a number of similarities between the two photographs. There are, however, subtle differences. The terminator line here crosses the coast of Vietnam, meaning it was taken before the previous one in terms of a single rotation (Stellarium estimates a time of 11:00). The concavity of the terminator line has increased which means that there has been a change in the apparent phase of the Earth, at least in terms of the view from the Apollo 13 craft, the crescent appearing narrower than the preceding day's photograph.

There are also clues in the shape of the cloud systems. While there is the same band of cloud covering the Himalayas, the green and blue arrows point to bands of cloud that do not show on the previous day's photographs of the area. The land either side of the broad swathe of Himalayan cloud is considerably clearer than in the photograph taken on the 16th.

ESSA's image, labelled the 16th, still covers this rotation of the Earth, and the most relevant orbital path is number 5184 (track 10), which was commenced at 09:08 on the 17th.

The crew were now only 48000 miles and 7 hours from a safe landing, At 136 hours into the mission (11:15), they ask about settings for black and white film for the upcoming separation from their CM, so the camera was around at this time too. 10 hours earlier, there was a considerable discussion about what cameras were available for photographing the separation manoeuvres, and some concern at the degree of misting on the windows that might interfere with it. This misting is visible on some of the photographs in other magazines.

Speaking of separation manoeuvres, we have one more set of images to look at.

At 16:43 on April 17th the LM Aquarius was cast adrift from the CM on the last lap of their journey home. A series of images was captured of that separation, which occurred just over 11000 miles about the Earth. Sharp-eyed contributor to collectSpace LM-12 spotted that reflected in the LM window was Earth. Figure shows the best of the images (AS13-59-8555), with a close up of the window in question.

Figure AS13-59-8555 and a close up of the LM window

So, can we work out where we are looking? Well, we have a precise time and we have a precise altitude. We also know, thanks to the mission report, the precise position above Earth of the LM at separation (1.23 S 77.55 E), which means we can narrow it down quite a lot - especially with the aid of SkySafari. Figure shows its interpretation of the likely view.

Figure SkySafari depiction of the view at separation

The terminator is running down the centre of Africa, and realistically not much should be visible in daylight other than eastern Africa and perhaps a little of Europe. The trajectory line indicates that the view is more likely to be of equatorial Africa rather than Europe given the approach Apollo 13 took to its eventual landing site. However it’s also possible that the trajectory could have pointed the camera towards the north or south! It is likely, however, that it is looking along the equatorial region.

So, we should have a view of equatorial African reflected in the LM window. Let’s see how that turns out. First of all, we need to invert the view of Earth to stop it being a mirror image, and we can also help ourselves in identifying any weather patterns by stretching the view a little (figure

Figure Earth seen in the LM window. The view has been level adjusted and sharpened, and the view on the right perspective corrected.

Can we realistically identify weather patterns here? Well, to be honest not with any great degree of certainty, particularly as we don’t really know how wide an area we are looking at. The width of the sunlit area here pretty much rules out anything other than central and sub-equatorial Africa, and the amount of curvature on show suggests a relatively small field of view, so let’s have a look at that the data from ESSA’s shots on the 17th (figure

Figure ESSA image from April 17 of Africa, and a zoom and crop of south-west Africa.

As I said, nothing I would bet my house on, and I base my judgement on logical deduction rather than precise identification, but for now I am pinning my hopes on the the area I’ve zoomed into above. It’s in the right place and contains the right sort of broken cloud. It’s just a shame that the satellite images aren’t as clear cut as in other examples.

Even if I am wrong in my estimate , what is interesting is that even in images reflected in a lunar module window there are clear details of the Earth and its weather systems, and the clouds even have shadows underneath them - such is the level of detail.

Apollo 13. Around the moon and home again, with the photographs to prove it.

Click the final link below to look at synoptic charts for the mission.