34

The authors of the paper are Harold A. Hamer, Katherine G. Johnson, and W. Thomas Blackshear. Of these, the name Katherine Johnson might ring a bell with people, as she was one of the protagonists in the 2016 movie Hidden Figures, honouring the women that were instrumental in the early days of the US space program. Katherine Johnson and her colleagues were ...


21

This answer is a guess based on NASA Technical Note D-5869: Description and performance of the Saturn launch vehicle's navigation, guidance and control system (referred to as 'D-5869' below), also the Launch Vehicle Digital Computer pages (referred to as 'LVDC' below) and finally the description in the video in the question (referred to as 'the video' below)....


17

"Could be flown" is a clear yes, "could be flown to a landing" is another story. Most of the points you are listing can be accomplished using the backup system in the LM, the Abort Guidance System (AGS). I'll be using the LM Apollo Operations Handbook Volume I as the main source for all your specific points. An attitude / attitude rate reference is ...


9

The Apollo attitude control system starts from a known orientation established by taking star sightings, then uses gyroscopes to track the change in orientation over time. The problem with gimbal lock is that the system can no longer distinguish the axes of rotation properly, so can't tell how the orientation is changing. The remedy for gimbal lock is just ...


9

I agree with your comment "it's not clear when or if this situation actually occurred." From reading both Klumpp's account and his colleague Don Eyles' book Sunburst and Luminary I do not think we have enough information to know if the situation could have existed on Apollo 11. I think we know it did not exist on Apollo 11, because the radar power supply ...


7

A single axis rotation (SAR) was performed from the initial to final attitude, unless they were avoiding gimbal lock, in which case it was split into two rotations. It has been shown in MIT/IL Report E-1832 that it is convenient to perform attitude maneuvers by simultaneous maneuvers in three axes. However, under certain ...


7

The RD-180 can gimbal each thrust chamber independently, allowing for roll control. Each Chamber assembly is gimballed in two planes for thrust vector control. This feature is implemented through the innovative construction of the gimballing unit on each hot oxygen gasline. Strains developed by the actuator for ...


6

Yes and No. The altitude data presented on the altitude indicator (tapemeter) depends on the mode select switch setting. MODEL SEL switch LGD RADAR: Radar altitude, altitude rate... are displayed. PGNS: LGC-computed altitude, altitude rate... are displayed. AGS: AGS-computed altitude, altitude rate... are displayed. Source: LM Apollo Operations Handbook ...


6

The lunar module had two computers. The 1202 alarm happened on the Lunar Guidance Computer, which did many different tasks -- in fact, the 1202 alarm was a warning that its multitasking system was at risk of being (but not yet completely) overloaded. There also was the Abort Guidance System. Its computer and software were completely different designs than ...


5

According to the mission report, immediately after separation, there was disagreement on the LM's velocity between its primary guidance/navigation system and its abort guidance system: The undocking action imparted a velocity to the lunar module of 0.4 ft/sec, as measured by the lunar module primary guidance system. The abort guidance system disagreed ...


5

The order in which rotations are applied matters. 260 roll around REFSMMAT x followed by 90 pitch around REFSMMAT y is the same orientation as 90 pitch around REFSMMAT y followed by 260 yaw around REFSMMAT z.


4

What I would do is read the book, and where you run in to a concept that doesn't make sense to you, use other resources to better understand that. But bottom line, do what is interesting to you.


4

This depends on how stable your rocket is. If your rocket is aerodynamically stable, meaning its center of pressure is behind its center of mass, the rocket will likely be turned to its velocity vector (zero angle of attack) by aerodynamics alone. A gravity turn is optimized for the least manual maneuvering possible. Any launch trajectory besides a perfect ...


3

I doubt such code exists, intact. The code you are asking for, 1970s or earlier, was written in FORTRAN IV (or earlier), and was highly tuned to work efficiently on one type of computer, specifically, the type of computer the developers of said software happened to use. FORTRAN IV code is in ALL_CAPS and is (nearly) flush left, nearly because columns 1 to 5 ...


2

The language here tends to get in the way a bit. Generally “reaction wheels” are used for pointing: you turn them, then stop turning them once the satellite is pointing as desired. They’re not meant to spin rapidly to soak up a bunch of angular momentum. If you just need to control pointing, a reaction wheel system isn’t going to be able to absorb the ...


1

While there are some commercially available thrusters for Cubesats, any kind of thruster on a Cubesat places you very much in experimental territory. (Additionally, any system that includes liquid or gaseous fuel under pressure will make it significantly harder to get a cubesat approved to be launched, since it's against the usual rules and will need a ...


1

No. The "LM altitude" computed from the Landing Radar slant range is only corrected for the altimeter beam angles, not the vehicle attitude angles. The altimeter beam angles are used by the LGC in the computation of LM altitude from LR slant range output. Source: LMA790-3 -LM APOLLO OPERATIONS HANDBOOK pp. 2.2-25 and 2.2-26 On Figure 2.2-9 you can ...


1

I understand your question can be summarised into, how exactly one knows in Inertial frame where one is moving. I understand there are subtle caveats here. So suppose I know in Inertial frame where I need to fire and onboard can be aligned to this frame using Inertial sensors. Now question is how does one know exact alignment of star sensor to body? and ...


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