Fascinating NASA video explaning in details the Apollo Atmospheric Entry Phase

[MrMoog]

It\'s like porn for space geeks.

It explains in great details everything that happens when they lifted off from the moon all the way back to earth.

It could serves as inspiration to the future reentry and mission planing features.

Part 1:

Part 2:

[Kosmo-not]

I started off with the lunar orbit rendezvous video:

part 1:

part 2:

[MrMoog]

Thanks, I didn\'t see this one.

[Ydoow]

Kosmo-not, in the first video it says that the Ascent stage docks with the orbiting rocket, then the ascent stage is left behind in Orbit around the Moon.

So is the ascent stage still Orbit the Moon??

[Lordherrmann]

Kosmo-not, in the first video it says that the Ascent stage docks with the orbiting rocket, then the ascent stage is left behind in Orbit around the Moon.

So is the ascent stage still Orbit the Moon??

I know I\'m not Kosmonot (or atleast wasn\'t the last time I checked ;D), but as far as I know the Ascent Stage wasn\'t put into a stable orbit so it crashed down.

[Ydoow]

Huh. At 2:48 it says they left it in Orbit. Maybe they didn\'t mean to imply stable orbit?...

[MrMoog]

I know I\'m not Kosmonot (or atleast wasn\'t the last time I checked ;D), but as far as I know the Ascent Stage wasn\'t put into a stable orbit so it crashed down.

What would make an orbit around the moon unstable?

Since there no atmosphere, I thought there was no decay. Does the movement of the moon has a perceptible effect on the orbit?

[Alchemist]

Don\'t forget various sources of perturbations - they can make low orbits to intersect the surface over time.

Liked the videos - a pretty good explanation of some aspects.

BTW, some comparison between Apollo and ?1-?3 flight sequences:

1) Launch window:

Apollo is launched into the plane of the orbit of the Moon

Latitude of Baikonur is too high, so ?3 is launched into orbit with minimal possible relative inclination (then off-plane intercept is done)

2) Ascent:

2 stages of Saturn V used to launch the craft to suborbital trajectory, the third stage (S-IVB) performs circularization burn.

3 stages of ?1 used to launch the craft to suborbital trajectory/unstable prbit, the fourth stage (???? ?) performs circularization burn.

3) TLI:

S-IVB used for TLI

???? ? used for TLI

4) Mid-course operations:

After S-IVB cutoff CSM separates from it, turns around, docks with LM and extracts it. Course corrections are done by CSM engine.

After ???? ? (it works until runs out of fuel) cutoff it\'s separated, then the shroud of ???? ? is thrown off. ???? ? is used for finishing TLI (if necessary) and course corrections.

5) LOI and orbit corrections.

CSM engine is used for Lunar Orbit Insertion

???? ? engine is used for Lunar Orbit Insertion

6) Preparations before landing:

2 astronauts transfer to LM through inner hatch (partial disassembly and reassembly of docking port required), then it\'s separated from CSM

1 cosmonaut performs EVA to get into ?? (the second cosmonaut performs EVA to help him). Then ?? (with ???? ? attached to it) is separated from ??? and slides out of its shroud (then the shroud is separated from ???). ?? deploys its legs and antennas.

7) Landing

LM landing stage is used for deorbiting, breaking and landing.

???? ? is used for deorbiting and killing most of the surface speed, then it\'s separated several km above the surface. ?? engine (???? ?) is used for final phase of the landing. To ensure craft stability on high slopes (up to 30 degrees) nesting solid charges are used

8 ) Ascent & rendezvous:

LM Ascent stage is used to get to Lunar orbit (descent stage left on the surface) and intercept CSM and dock with it (with possibility to use CSM for the rendezvous maneuvering in case of failure)

?? uses it\'s engine (???? ?) to get to orbit (??? - conical support structure with legs and landing equipment - is left on the surface). Then ??? approaches ?? and docks to it.

9) After docking:

2 astronauts transfer back to CSM through inner hatch. Then LM is separated.

The cosmonaut performs EVA to get back to ??? (the second cosmonaut performs EVA to help him). ??? orbital module with ?? docked to it is separated (and possibly deorbited by the RCS of the orbital module).

10) Trans-Earth injection and mid-course actions.

CSM engine used for the injection and correction burns.

??? uses a large engine (with 2 combustion cameras) for TEI burn. For course corrections (and also during rendezvous) a smaller correction engine is used.

11) Reentry and landing

SM is separated from CM before entering the atmosphere. CM enters the atmosphere over Pacific and splashes down.

??? service module (???? ?) is separated before reentry. The capsule enters the atmosphere above Indian ocean, bounces to the space and enters the atmosphere again over USSR (alternatively, it could splash down in the Indian ocean). Before the landing the heat shield is separated, soft landing engines used just before touchdown.

[hebdomad]

You\'ve got to love the use of the early 19th century (18th?) map and the size of the Americas in comparison to the rest of the world.

Just some political/idealogical visual analysis that I found rather amusing... ;P

[PakledHostage]

What would make an orbit around the moon unstable?

Since there no atmosphere, I thought there was no decay. Does the movement of the moon has a perceptible effect on the orbit?

Awesome videos!

I would think that even the Moon\'s interior density distribution would have an effect over a long enough time period? Check out the GRAIL mission. I heard an interview with Dr. Maria Zuber (the GRAIL mission\'s principal investigator) on the CBC\'s 'Quirks and Quarks' program some months ago. She explained that they will be able to measure the Moon\'s density distribution by accurately measuring variations in the distance between the tandem GRAIL spacecraft caused by the Moon\'s mass distribution.

I guess the question is whether or not the effect is strong enough or if it is overshadowed by other effects (like tidal effects)?

[Kosmo-not]

Kosmo-not, in the first video it says that the Ascent stage docks with the orbiting rocket, then the ascent stage is left behind in Orbit around the Moon.

So is the ascent stage still Orbit the Moon??

lol, why are you asking me? I\'m no cosmonaut.

From this article on wikipedia, it says:

Having completed its job, the LM was separated and sent into solar orbit or to crash into the Moon.

[rdfox]

(More necro! Aiee!)

For Apollo 11 and 12, the LM ascent stage was left in lunar orbit, expected to decay and crash into the moon within about ten years, though nobody tracked them and thus we will likely never know when and where they impacted. Starting with Apollo 13, the plan (and, beginning with 14, the actual practice) was to deorbit the ascent stage by remote control after it was discarded, so that it would impact at a known time and location (to within a mile or so), so that the seismometers left on the surface as part of the experiments package could be used to pick up the vibrations from the impact and be analyzed to determine the Moon\'s inner structure, much as is done with earthquakes on Earth.

Likewise, the S-IVB on Apollo 8, 10, 11, and 12 was launched into solar orbit by venting the remaining propellants, but starting with Apollo 13, it too was deliberately crashed into the Moon as a seismic sounding technique. (Had the Lunar Orbiter probes not been deorbited before the Apollo landings began, they would have likely also been used for seismic sounding. Given that most, if not all, of the seismometers are still running with their radiothermal generators providing power, I expect that most unmanned lunar probes are used for that now, given that it\'s considered Good Practice to deorbit them at the end of their missions to prevent clutter in the usable lunar orbits and spurious radio signals.)

[Ydoow]

Hm that answers questions, but how does a Lunar Orbit decay with no atmosphere?

[Kryten]

It happens because the Moon\'s gravity well is very irregular, due to the major changes in elevation and density at the surface.

[Ydoow]

Now THAT\'S interesting, and totally explains why they currently have a satellite orbiting the Moon mapping it\'s gravity