APOD: The Eagle Rises (2022 Jul 30)

Comments and questions about the APOD on the main view screen.
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APOD: The Eagle Rises (2022 Jul 30)

Post by APOD Robot » Sat Jul 30, 2022 4:06 am

Image The Eagle Rises

Explanation: Get out your red/blue glasses and check out this stereo view from lunar orbit. The 3D anaglyph was created from two photographs (AS11-44-6633, AS11-44-6634) taken by astronaut Michael Collins during the 1969 Apollo 11 mission. It features the lunar module ascent stage, dubbed The Eagle, rising to meet the command module in lunar orbit on July 21. Aboard the ascent stage are Neil Armstrong and Buzz Aldrin, the first to walk on the Moon. The smooth, dark area on the lunar surface is Mare Smythii located just below the equator on the extreme eastern edge of the Moon's near side. Poised beyond the lunar horizon is our fair planet Earth.

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RocketRon

Re: APOD: The Eagle Rises (2022 Jul 30)

Post by RocketRon » Sat Jul 30, 2022 5:41 am

Amazing view. Not many folks will have seen that !

I've always wondered how did they calculate the dynamics of rising off the moons surface and catching up/docking with the lunar orbiter.
There would only be a small margin of error for that to succeed ?. And a large possibility of missing ??
If they were a degree or 2 off on the takeoff, or a few minutes too late, their paths may never intersect ???

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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by orin stepanek » Sat Jul 30, 2022 12:44 pm

6633.jpg
The Eagle Rises; going home! 8-)
as17-149-22859c41.jpg
Kinda; sorta; look no more than a Box Kite! :roll:
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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by johnnydeep » Sat Jul 30, 2022 3:23 pm

RocketRon wrote: Sat Jul 30, 2022 5:41 am Amazing view. Not many folks will have seen that !

I've always wondered how did they calculate the dynamics of rising off the moons surface and catching up/docking with the lunar orbiter.
There would only be a small margin of error for that to succeed ?. And a large possibility of missing ??
If they were a degree or 2 off on the takeoff, or a few minutes too late, their paths may never intersect ???
All the more impressive - and daring - when you consider that the computer assistance capability back then sucked :-)
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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by Supernovice » Sat Jul 30, 2022 3:29 pm

In his excellent book Carrying the Fire, Michael collins annotates this photo with the following: "The best sight of my life: Neil and Buzz returning."

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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by alter-ego » Sat Jul 30, 2022 3:52 pm

Cross your eyes to see the Hasselblad stereo view.
Apollo 11 Stereo View.jpg
It's amazing to me. As a kid, I loved going to my grandparents' house to use their wooden stereo viewer to look at the old B&W stereo cards of steam engines, trains, and industry. Now I'm at my computer screen looking at a color stereo "card" of the Apollo 11's Eagle above the moon with Earth rising!
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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by Ann » Sat Jul 30, 2022 4:53 pm

Click to play embedded YouTube video.

This is an amazing, incredibly moving video.

And the Earth is the only place in the Universe that has ever featured Johann Sebastian Bach.

Among other things.

Ann
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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by MarkBour » Sat Jul 30, 2022 11:09 pm

RocketRon wrote: Sat Jul 30, 2022 5:41 am Amazing view. Not many folks will have seen that !

I've always wondered how did they calculate the dynamics of rising off the moons surface and catching up/docking with the lunar orbiter.
There would only be a small margin of error for that to succeed ?. And a large possibility of missing ??
If they were a degree or 2 off on the takeoff, or a few minutes too late, their paths may never intersect ???
Great to imagine those steel-nerved space men!
Astronauting has, at least thus far, been a very hazardous profession.

Thinking about your comment, I did some web surfing and ended up at this document:
NASA Technical Memorandum TM X-58040 "Apollo Lunar Descent and Ascent Trajectories"
https://www.hq.nasa.gov/alsj/nasa58040.pdf

John C. Houbolt worked out the main concept and Floyd Bennett and Thomas Price provided further study.

The mission planning documentation shows a lot more attention given to the descent to the lunar surface than to the ascent from the surface. The way they had things worked out, the landing was the harder part. And it had abort contingencies in its planning, which is one of the reasons it shows much more planning evidenced in the documentation. For the ascent phase, there is no abort option!

Happily, for Apollo 11, nothing weird happened on touchdown, so Tranquility Base was sitting straight and solid on a good horizontal surface. And the ascent module engine fired smoothly and ascent went beautifully according to plan. If I read it correctly, once they got into lunar orbit near the Command Module and in the right orbital parameters in the right plane, then they had some propellant to spare in their RCS system and docking was easily managed.

The most unnerving part that happened (that I read in the documents) was during the final phase of the landing, about 400 feet off the surface:

As they were clearing West Crater and approaching the intended landing area, a voltage problem caused an alarm to sound on the guidance computer. It continued to perform priority calculations and everything was okay, but the alarm distracted the crew momentarily. By the time they were reoriented and looking at their landing surface, they had moved over a rough, rocky area. At that point, Armstrong took manual control and flew past the rough terrain. By the time he landed, fuel was getting low.

Another thing I learned while looking around these docs --

James Meador set about to calculate/estimate where the Eagle might have crashed back down to the lunar surface, to see if its remains could be located. In this paper: https://arxiv.org/abs/2105.10088 he came to the surprising conclusion that it is very likely still orbiting the moon!
Last edited by MarkBour on Sun Jul 31, 2022 5:06 am, edited 1 time in total.
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Re: APOD: The Eagle Rises (2022 Jul 30)

Post by Chris Peterson » Sun Jul 31, 2022 1:55 am

RocketRon wrote: Sat Jul 30, 2022 5:41 am Amazing view. Not many folks will have seen that !

I've always wondered how did they calculate the dynamics of rising off the moons surface and catching up/docking with the lunar orbiter.
There would only be a small margin of error for that to succeed ?. And a large possibility of missing ??
If they were a degree or 2 off on the takeoff, or a few minutes too late, their paths may never intersect ???
It's actually not a very difficult problem, given how simple and reliable Newtonian and Keplerian theory is. The orbiter passed over the lander on every orbit, and both the orbiter and the lander had the ability to control their positions with a wide enough range that it made the timing of the ascent pretty easy to manage. Either craft could raise or lower its orbit slightly to speed up or slow down, allowing them to match their positions.
Chris

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RocketRon

Re: APOD: The Eagle Rises (2022 Jul 30)

Post by RocketRon » Mon Aug 01, 2022 5:09 am

Didn't I read that 'engine fire button' didn't initially work on their 1st ascent attempt.
Dismantle the switch and bodge and try again next time ...

They also did some prior practice catch-up-and-dock in orbits around earth previously ??
Just to make sure it could be done.
But the parameters for lifting off the moon could only be estimated, no practices up there.