Could underweight Apollo command modules (CMs), weighing 36% less than claimed, indicate that these modules did not actually make the specified journeys?
What was the actual weight of the Apollo CM? Doubts have arisen regarding the reliability of the weight values as stated by NASA for the CMs that returned from the Apollo missions to the Moon in the late 1960s and early 70s.
The weight of an object can be determined if such an object lands on water and floats. For this investigation, NASA’s key document , was examined that contains the CM illustrations and data required for these calculations:
The details that can guide analysis of the available film/video and photographic documents are highlighted in Fig. 1. In particular, the side engine nozzles were of interest, underlined in red, the REACTION CONTROL YAW ENGINES (YE), and the front engine nozzles, REACTION CONTROL PITCH ENGINES (PE), underlined in green.
The following diagram clearly shows that the bottom of the module was spherical:
The radius of the sphere can be determined in a computer application such as CorelDRAW®. A circle was superimposed on the CM image. Then, by adjusting the radius of the circle, it was possible to match the curvature of the bottom of the CM with the circle. The resulting radius was calculated by comparing with the known CM diameter (3.91 metres).
In this paper the area where the spherical segment of the bottom (the aft heat shield) merges into the conical body is described as a ‘curved bottom’. Its upper edge is usually highlighted by a light-coloured strip :
To answer the question ‘how deep should the CM have submerged into the water?’ it was necessary to calculate the volume of displaced water, and then by applying Archimedes' principle in this case where the weight of the displaced water is equal to the weight of the CM. To calculate the volume the following approximation was used:
In Fig. 4 the spherical segment with the specified parameters is highlighted in blue: R – the radius of the sphere, h – the height of the segment. The disk with radius Rd and height hd is highlighted in pink. The truncated cone with height hc, which was adjusted to the final volume of 0.9m³ is highlighted in green.
Totalling these volumes gives 5.3m³, with a margin of error of 3% (due to the density of sea water of about 1025-1028 kg/m³), according to NASA (see Fig.1) means that the weight of the CM was 5.3 tonnes.
Thus, according to the drawing in Fig. 4, the underwater level of the CM floating in an upright position must coincide with the upper edge of the green sector, and the engine nozzles (YE, PE) would be partially below the water level. The depth that the CM would sit in the water was then ascertained based on film/video recordings and photographic evidence.
The only problem was that the CM’s centre of mass had shifted to the back (away from the hatch), so that in a still state it floated with a considerable vertical deviation :
Due to the CM’s complex shape it was not clear as to what level the CM with its off-centre mass would be in the water. To answer this question, a 1:60 scale CM model was made. Its weight was chosen so that the model submerged to the required level marked with horizontal lines:
Fig. 6. Is the CM scale model. Fig. 7. Is the CM scale model floating vertically submerged in water up to the level of RCS nozzles – marked with horizontal lines. And Fig. 8. is the CM scale model floating with off-centre mass.
It was observed that when shifting the centre of mass to the rear, the side engines nozzles YE (identified by the horizontal line segments) were also submerged. It was assumed that the CM’s axis of back-and-forth rocking coincided with the straight line connecting these engines. The Apollo boilerplate capsule in the image depicting training in the Gulf of Mexico was submerged in much the same way :
The photo description reads:
Prime crew for the first manned Apollo mission relax in a life raft during water egress training in the Gulf of Mexico with a full scale boilerplate model of their spacecraft.
It should be understood that this training was conducted with a boilerplate model that was to NASA’s declared weight and dimensions. Such training sessions were also carried out in a pool :
Both cases (Figs. 9 & 10) show that the top of the ‘curved bottom’ in the zone of the side engines (YE) was under water, and although there were no engines on the model, the depiction of the extent of the submergence roughly corresponds to Fig. 8.
Unfortunately images of any freely-floating modules are sparse. Thus the next picture shows the Apollo 4 CM having just returned from an unmanned test mission ( – excerpt):
The amount of the Apollo 4 CM that was sitting beneath the waterline was rather small – the top edge of the curved bottom was above the waterline, not to mention the engines nozzles YE. Apparently the CM's weight was eased considerably, which affected its floatability. The observed level of the Apollo 4 CM submersion is marked with a red waterline:
Correlating Fig. 12 to the drawing in Fig. 4, the weight of the Apollo 4 capsule was estimated. It corresponded approximately to the sum of volumes of the blue sector and one third of the pink sector, which is 3.2 tonnes.
Then, a photograph of the CM of Apollo 7 splashdown was examined :
Again, there are no other suitable Apollo 7 resources. But even here it is clear that the YE nozzles were above the waterline, which suggest an underweight capsule. This may, however, raise the question of an inflatable raft hanging on the CM: would it increase the buoyancy or not? Elementary arguments suggest that the answer is no. Moreover, limited information did not provide sufficient grounds for full confidence in the capability to correctly estimate the CM's weight.
It was noted that crew of the Apollo 7 craft, (as seen in the photographs) all of whom had allegedly been in Zero-G for 11 days, looked surprisingly cheerful, showing no discomfort whatsoever from having endured such a long stay in space, a factor that must be attributed to a very mysterious and never-properly-explained phenomenon!
We moved on to study the video recording  of a close-up of the Apollo 13 CM after splash down. Below are the images in which the floating capsule was close to the vertical position:
Fig. 14 YE is high above the water level; the top edge of the curved bottom is visible, which is entirely above the surface; the black strip of the curvature itself is visible; the foam on the right is surging up from under the bottom.
Fig. 15 YE is high above the water, the top edge of the curved bottom is visible which is entirely above the surface; the foam on the right is surging up from under the bottom.
Fig. 16 foam surging up from under the bottom of the craft created a white rim; YE is high above the waterline; the top edge of the curved bottom is visible, which is entirely above the surface; the black strip of the curvature itself is visible.
Fig. 17, the view from the other side, YE is high above the water; the right edge is hanging over the surface of the water; at the back the foam is surging up from under the bottom.
Fig. 18 is similar to the previous image (Fig. 17); the strip of the curved bottom is clearly visible.
In all these photographs it can be clearly seen that the CM was sitting in an upright position, it was not submerged up to the YE engine nozzles; they were always visible above the waterline. Moreover, in most images the curved bottom was completely or partially exposed, which provided a reason for us to draw the waterline for the Apollo 13 CM no higher than the middle of the curved bottom:
According to Fig. 4, it was necessary to combine the blue sector and half of the pink sector, which matched roughly 3.5 tonnes of the CM’s weight.
In the NASA archive there is also a photograph of the floating Apollo 15 CM which, as in the previously discussed cases, looks ‘under loaded’ ( – fragment):
The capsule was turned with the hatch facing the photographer; the YE engines are not visible, but submersion could be estimated by the noticeable PE engine nozzles (two black spots under the hatch). And the capsule was tilted to a large extent due to the tension of the parachute suspension lines that were submerged in the water, so the rocking axis had shifted. It is possible to specify the nature of the Apollo 15 CM plunge, based on a frame from the video recording  that depicted the capsule splashing down:
Due to the low quality of the video, the YE side engine nozzles are barely noticeable, but they are easily identified by the bright rectangular reflection on the CM’s body (see examples in Fig. 14, 17, 18). On the left the foam surging up from under the bottom; the black strip of the curved bottom is easily noticeable over the entire CM profile – from right to left, which leads to the unequivocal conclusion:
The YE nozzles were above the water level. Comparing Fig. 21 with Fig. 20, it can be concluded that the rocking axis in Fig. 20 proximately passed through the engine PE, which as we have seen, was also above the water surface.
As is clearly visible in Figs. 20 & 21, the curved bottom allowed us to draw the waterline below its upper edge:
In this case, the depiction of the submersion corresponds to Fig. 19; for which the weight estimate gave 3.5 tonnes.
The craft that took part in the joint Apollo-Soyuz Test Project (ASTP) space flight is of interest here. According to NASA it was the last remaining craft that was unused on the Apollo missions. The video recording  showing the capsule splashdown was selected as initial material for the analysis of Apollo ASTP CM buoyancy:
Fig. 23a — left side view, b — right side view.
Unfortunately there are no photographs in the archives of the freely-floating capsule. Fig. 23a shows a moment when the heavily rocking CM was ‘caught’ in a position close to vertical. We can clearly see that the YE nozzles were above the surface, which intersects the top line of the curved bottom to the right of the YE engine.
We then moved the focus of our observations to the CM drawing in Fig. 24a. The waterline is shown in red; pink is the level of submersion of the vertically-floating module. From a comparison with the drawing in Fig. 4 it was concluded that it is necessary to add 2/3rds of the pink sector to the blue one. When converted to the CM weight it totalled 3.8 tonnes.
Fig. 24a – the waterline for Fig. 23a, b – the waterline for Fig. 23b.
In the second image of the floating Apollo ASTP CM (Fig. 23b) the moment was captured when swimmers had somehow managed to ‘pacify’ the rocking capsule which allowed them to proceed with attaching an inflatable raft. Since it was not inflated, its effect on the CM buoyancy was insignificant, and could even make the CM heavier.
A characteristic detail is thereby emphasized – the right YE engine nozzles rose above the water level which, generally speaking, was recorded in almost all of the CM pictures with an inflatable raft (e.g., Fig. 13). A curved bottom under the nozzles was exposed as well. The diagram in Fig. 24b, similar to Fig. 24a shows the observed waterline – red in colour and pink for the upright position.
As these results of the measurements have demonstrated, to determine the volume of displaced water, the blue sector (see Fig. 4) and 0.4 of the pink one have to be added to each other which results in the CM weighing 3.3 tonnes.
The average for the two Apollo ASTP CM weight values obtained above, results in a figure of 3.6 tonnes.
In the end, the four CM weight measurements obtained were: (3.2 + 3.5 + 3.5 + 3.6)/4 = 3.5 tonnes. Thus, the assessment of the capsule’s weight carried out based on the available NASA’s photographic and film/video recordings provided the following result: 3.5 ± 0.3 tones, which is 1.8 tonnes (36%) lower than the NASA stated value.
Conclusion and Summary
This paper has evaluated the weight of the Apollo command module, which confirms the assumption made above. The capsule weight was found to be 3.5 ± 0.3 tonnes instead of 5.3 tonnes, as stated in NASA’s document .
The method of calculation was based on visual assessment of the nature of the CM submersion after splashdown in the ocean. NASA’s photos and film/video recordings that are available to the public were used as the source of data.
Characteristically, the obtained result matches exactly the observed buoyancy of the CM acquired from the photographs with inflatable life rafts:
Fig. 25. CM Apollo 16 
The significance of such pictures is that there are many in NASA’s archives and they can more accurately capture the depth of CM submersion. In particular, this image shows clearly that the upper edge of the curved bottom below the YE nozzles was above the water, and the submersion depth corresponds to the CM weighing about 3.5 tonnes, against a claimed weight of 5.4 tones. However, once again, to avoid possible objections we have made a reservation – the main calculations were made without the use of any photographic and film/video recordings with inflatable rafts.
The reason for the CM’s weight discrepancy is obviously related to the fact that a lightweight version of the descent capsule was used. And in the case of the Apollo 4 CM (see Fig. 11) an even greater difference in weight was found – it ‘lacks’ about 300 kgs compared to the capsules returning with crew.
The weight of three adult men to a large extent compensated for this ‘shortage’, but the issue with the ‘shortage’ of almost 2 tonnes of weight requires a different explanation. And now it would be appropriate to discuss the above-noted oddity in the behaviour of the crew of Apollo 7, allegedly returning after a long mission (11 days, which was considered an extremely long period at the time) without any signs of distress or adversity.
Moreover, no Apollo crew reportedly complained about the vestibular system disorder and other ailments caused by a prolonged stay in weightlessness. This condition of these astronauts was in very sharp contrast to that observed in the Soviet cosmonauts, who had to be literally carried out of their re-entry capsules.
Today, an 11-day space mission inflicts serious consequences upon astronauts return to Earth:
“Coming back was [a] very difficult physical test. In space you get used to different conditions", said Guy Laliberté at his press conference in Moscow.
According to Guy Laliberté returning to Earth kicks a lot of adrenaline, but "when you come out of the capsule, it seems that no strength for the next step is left".
A space tourist said that the landing was "very difficult" for him.  (Author's note: Immediately after his landing Laliberté had to be moved on a stretcher, he did not even attempt to walk.)
But to all the US astronauts, their landings came with remarkable ease! They were never taken out of their CMs helpless an/or powerless; they jumped out of the capsules entirely unaided. What can explain such a surprising tolerance by the Apollo crews to the adverse effects of space travel?
The only possibilities are: either there was no prolonged exposure out in space, or the Apollo crews did not return from space at all.
A lightweight Apollo descent capsule, as identified in this study, fits this context. If these returns from space were actually simulated, then the CM was a substitute for a fully-fledged space module, so there was no need to load it with unnecessary equipment and supplies for a prolonged space journey.
This conclusion also explains the incredible accuracy of the Apollo splashdown locations – an accuracy still unattainable in present-day space exploration:
Fig. 26. Apollo Distance to splashdown target  (Apollo ASTP )
A deviation of a few tens of kilometres from the landing target for Soyuz spacecraft was considered to be the norm. But even an ideal Soyuz spacecraft was often thrown by ballistic re-entry, and then the miscalculation was over 400 kms [18-20].
However, for craft returning from lunar orbit, the re-entry trajectory was much more complicated due to their higher velocity (escape velocity is 11 km/s), and it was necessary to perform either a skip re-entry or a lifting re-entry followed by the descent to the Earth’s surface.
The number of factors (that cannot be predicted in advance) to be taken into account to accurately determine the re-entry trajectory were certainly higher than for a craft performing low-Earth orbit re-entry. An error in just one parameter – at a speed of 10 m/s results in a miss at the landing point of about 350 kms . Consequently, the chances of hitting a location with radius of several kilometres were practically zero.
But in the special case of Apollo, in spite of everything, NASA demonstrated phenomenal accuracy – the returning craft managed to splash down at the reference points in 12 cases out of 12. Moreover, how the crippled Apollo 13 actually managed to hit the target (the miss was less than 2 km!) is known only to the late Arthur C. Clarke .
The aforementioned circumstances clearly indicate the fact that NASA simulated the Apollo re-entry, dropping the CMs from a cargo aircraft , the pilot of which was only required to accurately ‘target’ to avoid hitting the waiting recovery carrier below.
It is interesting to note that the above arguments are valid for the Apollo ASTP as well! Its CM weight was almost the same as for the Apollo mission models. Judging by the video recording , the crew of Apollo ASTP held fast on their feet after allegedly spending nine days in space, looking healthy and happy, cheerfully speaking at the meeting immediately after splashdown.
However, during re-entry the crew was allegedly poisoned and nearly killed by toxic propellant vapours. But their faces show neither traces of any poisoning nor the signs of enduring many days in a Zero-G environment.
An explanation of the predicament faced by the United States
In 1961 NASA was given the task to land US astronauts on the Moon by the end of the decade. In this race to the Moon not only was the reputation of the great powers at stake, but also the ability of world's political systems to overcome the most difficult problems. And at a time when the Soviet Union was perfecting various technical options to achieve victory in this Moon race, the US took its own route, leaving them no alternatives, the main components of which were the Saturn V booster and the Apollo spacecraft itself.
However, the Saturn V had not reached an acceptable performance – the last test launch (second in a row) in April 1968 was unsuccessful , but Apollo had previously suffered an even more tragic fate – during training the crew of Apollo 1 was burnt alive in its oxygen atmosphere . NASA learned the hard way that a spacecraft with an oxygen atmosphere was a dead end. But there was no time to develop a new craft with a robust case and near earth atmosphere less than two years before the scheduled lunar orbital mission.
Furthermore, the lunar module (LM) was also designed for an oxygen atmosphere, and therefore it would also have been subject to complete redesign. Robust spacecraft cases would significantly increase the requirements for the Saturn V payload, which already was not mission worthy. As a result, by 1968 NASA was left without any foundation for its lunar missions.
But Americans would not be Americans if they didn't consider all possible scenarios, including the most negative – which, in the end, they had to adopt. Using breakthrough Hollywood photographic technology NASA was able to pull off an unprecedented-in-scale set of missions, enabling all of mankind to believe in the American miracle.
With the assistance of the Soviet Union [25, 26] NASA successfully bluffed its way through the Moon race. But the nature of any bluff, as is well known, is the art of concealment. In confirmation of this fact NASA defiantly dumped all the previous developments which allegedly brought them the international fame and leadership, scrapping the marvellous Saturn V booster, the Apollo spacecraft and Skylab Space Station.
The next chapter in its history had to be written from scratch – a ‘start again job’ – the development of the Space Shuttle spacecraft  which had nothing whatsoever to do with its famous predecessors.
Aulis Online, September 2012
English translation from the Russian by BigPhil
For purposes of clarification, the tonnes referred to in this article are metric tonnes. NASA’s CM weight of 5.3 tonnes refers to the splashdown weight of 11,700lbs. Documentation from North American-Rockwell states that the CM at launch weighed 12,800lbs including crew, plus 270lbs of fuel, a total of 13,070lbs. Other NASA documents as shown above, have managed to lose 70lbs/31.75kgs, saving weight any which way.
9. "APOLLO 13 - all BBC's TV original re-entry & splashdown footage – part 4 of 5"
11. "Apollo 15 Splashdown"
12. ASTP - Apollo Splashdown & Recovery
17. Ivanov, N.M. and Lysenko, L.N., Ballistika i navigatsiya kosmicheskikh apparatov
(Spacecrafts Ballistics and Navigation), Moscow: Drofa, 2004, p.422. (In Russian)