DAY 3 - July 18, 1969
TV Transmission of crew entering Eagle
Time Start: 055:09:00
The crew of Apollo enter the Lunar Module Eagle for the first time, and make an unplanned television transmission of their activities. The camera is performing extremely well and shows the interior of the lunar lander with unprecedented clarity.
TV transmission from the spacecraft begins at 055:09:00 showing the crew maneuvering the CM forward hatch into its storage bag within the CM cabin
Flight Plan Updates
After finishing their work in the Lunar Module, Armstrong and Aldrin return to the Command Module and close the hatches. They put the spacecraft back into the Passive Thermal Control roll, then update their Flight Plan at Houston's request. As the crew settle down for the night, they spot a curious flashing object in the distance and discuss it with Mission Control. Apollo 11 continues its outward coast, leaves the Earth's sphere of gravitational dominance and passes into the Moon's domain
Having completed his star sightings, Mike continues through P52 to a point in the program where Noun 93 is presented on the DSKY's three registers. These three numbers represent the angles through which the three gimbals that support the platform need to be rotated (or torqued) in order to restore its proper orientation. While these numbers are on the DSKY, Mission Control can view them, thanks to telemetry. In this case, the angles are 0.111° in X, 0.128° in Y and 0.014° in Z. The star angle difference was 0.01°, this being the difference between two angles; the actual angle between the two stars and the same angle, but as measured by Mike's sightings.
In the context of CSM operations, Delta-H refers to where on a planet's horizon Mike is taking his marks. One of Mike's tasks has been to carry out his own set of navigation sightings as they coast between two worlds. This is in case radio communication with Earth is lost. Mike's navigation uses P23 in the computer and the technique involves using the sextant to take angle measurements between a star and a planet's horizon. However, Earth's horizon is fuzzy, thanks to the atmosphere (and the Moon's is somewhat rough). Based on the P23 sightings he has already done on Earth's horizon and the state vectors that were derived from those, Mission Control can determine how far off the computer's mathematical model of Earth his sightings were. In other words, at what height in the atmosphere was he marking and how does that compare to where the computer thinks Earth's horizon is?
The Service Module has four spherical tanks that cryogenically store the reactants for the fuel cells; two each for hydrogen and oxygen. The oxygen tanks also supply the breathing air for the crew. In order to pack sufficient quantity of these normally gaseous substances into the tanks, they are kept under both very high pressure and very cold temperature. This puts them into a supercritical state that is often described as being neither gas nor liquid, but rather a dense fog. The tanks are extremely well insulated but heat does slowly leak in. On one level, this is not a problem because heat is required to maintain the high pressure within a tank and keep its contents supercritical. However, a side effect of the heat leakage is that the contents near the walls become less dense as they warm up when compared to the contents at the centre. This has an effect on how a tank's quantity is measured.
Each tank uses a capacitance probe that runs across its diameter in order to measure its reme. This consists of two conducting tubes, one inside the other. The tank contents act as a dielectric that affects how electrical charge is stored between those two tube, a property known as capacitance. For accuracy, the density of the contents needs to be constant so periodically, they have to be stirred. For this, each tank has two small fans installed that can be switched on to remove any stratification and homogenise the contents and this is what Mike is being asked to do.
It is well known that the stirring of an oxygen tank on Apollo 13 led to the tank's catastrophic rupture and the aborting of that mission. Service Modules after Apollo 13 had an extra tanks for each reactant, partly to give more resiliency but mostly because those missions were extended and required more consumables.
060:45:46 Armstrong: Do you have any idea where the S-IVB is with respect to us?
The crew have noticed an unexplained flashing object out of the window, which appears to be catching the sunlight as it tumbles. Neil is wondering whether it is the abandoned third stage of the Saturn launch vehicle.
The answer from Mission Control indicates that the mystery object is highly unlikley to be the S-IVB stage, given its great distance from Apollo 11. Although the object's identity was never resolved, it is quite possible that it is one of the SLA panels which covered the Lunar Module during launch.
- Aldrin, from 1969 Technical debrief: "Of course, we were seeing all sorts of little objects going by at the various dumps and then we happened to see this one brighter object going by. We couldn't think of anything else it could be other than the S-IVB. We looked at it through the monocular and it seemed to have a bit of an L shape to it."
- Armstrong, from 1969 Technical debrief: "Like an open suitcase."
- Aldrin, from 1969 Technical debrief: "We were in PTC at the time so each one of us had a chance to take a look at this and it certainly seemed to be within our vicinity and of a very sizeable dimension."
- Armstrong, from 1969 Technical debrief: "We should say that it was right at the limit of the resolution of the eye. It was very difficult to tell just what shape it was. And there was no way to tell the size without knowing the range or the range without knowing the size."
- Aldrin, from 1969 Technical debrief: "So then I got down in the LEB and started looking for it in the optics. We were grossly mislead because with the sextant off focus what we saw appeared to be a cylinder."
- Armstrong, from 1969 Technical debrief: "Or really two rings."
- Aldrin, from 1969 Technical debrief: "Yes."
- Armstrong, from 1969 Technical debrief: "Two rings. Two connected rings."
- Collins, from 1969 Technical debrief: "No, it looked like a hollow cylinder to me. It didn't look like two connected rings. You could see this thing tumbling and, when it came around end-on, you could look right down in its guts. It was a hollow cylinder. But then you could change the focus on the sextant and it would be replaced by this open-book shape. It was really weird."
- Aldrin, from 1969 Technical debrief: "I guess there's not too much more to say about it other than it wasn't a cylinder."
- Collins, from 1969 Technical debrief: "It was during the period when we thought it was a cylinder that we inquired about the S-IVB and we'd almost convinced ourselves that's what it had to be. But we don't have any more conclusions than that really. The fact that we didn't see it much past this one time period - we really don't have a conclusion as to what it might have been, how big it was, or how far away it was. It was something that wasn't part of the urine dump, we're pretty sure of that."