Proposed solution(s) to an on-going issue.

submitted by Tom_Bombadil from self.AskSaidIt

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[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (14 children)

I'm sorry... that was a very argumentive statement to make. I realized my mistake soon after making that comment, and meant to edit it into some kind of question that would spark discussion. But I never got to it. So I hope you'll forgive me and allow me to ask a question: How did you come to conclude that it's impossible to land a spacecraft on its thruster?

[–]Tom_Bombadil[S] 2 insightful - 1 fun2 insightful - 0 fun3 insightful - 1 fun -  (13 children)

Do you think that a human could fly and land a rocket on it's main thruster with out computer aided guidance?
Relying solely on a pilot's skill, and gumption?

Space X managed to fly a rocket straight up into the air, and then land it back on it's own foot print, which was a major feat.
Here's a few space x landing scenes.

Notice example 4 and try to imagine the instability of landing a rocket. Do you believe that any person could ever make the required flight corrections while sitting on the top of this rocket? Because to land the "lunar module" the onlty thing that could slow the descent is a rocket, because there is no atmosphere (so no parachutes, or wings).

Top quality 2010's grade sensing and computing still produced failures. There is zero margin for human error.

It is an impossible feat.

If this was possible, then we'd have rocket powered aircraft that landed on landing pads somewhere on the planet. Those do not exist in 2019, because it is folly.

Note that the landing platforms are all on level landing pads, or the deck of a large ship.

The probability of fortuitously landing on a firm level surface on the moon are close to zero.

The probability of landing in some portion of a loose gravel crater is extremely high.

Yet we're expected to believe that NASA landed 6/6 successful missions on the moon, and then took multiple series of perfect photographs?

It was impossible feat in the 60's.

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (12 children)

Oh wow. Those rockets do look quite unstable. They're very tall and have those short legs, those would be hard to land under human control. I wonder why number 4 exploded.

But the lunar module looks quite stable to me. It's short, and its legs stick out.

And according to this article, the lunar module DID have computer assistance:

On final descent, Armstrong noted that the automatic landing system was guiding Eagle toward the boulder-strewn floor of a crater the size of a football field (”West Crater,” not shown below). Armstrong took manual control and skimmed over the crater, landing in a flat plain beyond. Eagle had only about 30 seconds’ worth of fuel left at touchdown.

Do you have any other reasons why landing a lunar module would be impossible, other than the instability of SpaceX rockets?

[–]Tom_Bombadil[S] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (11 children)

The fundamental challenge to landing is the inherent instability of landing any/every rocket.

Can you name a single rocket type aircraft that a human has ever landed on Earth; and walked away from? I'd like to see a video of this if you can find one.

Every person to ever take a flight in a rocket landed by some other means.
The rocket was abandoned at some point in flight, and the pilots parachuted down, etc. The pilots never landed using the thruster. Ever.

The obvious reason for this is landing a rocket propelled craft by controlled thruster descent was literally impossible, at the time.

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (10 children)

I found a video, but first: Why are rockets inherently unstable? Are jets and propellers inherently stabler?

[–]Tom_Bombadil[S] 3 insightful - 1 fun3 insightful - 0 fun4 insightful - 1 fun -  (9 children)

Aircraft use wings for lift and stability.

There's no atmosphere on the moon, so wings are useless for stability. Beyond the rocket power there's no stabilizing forces. It's 100% thruster controlled.

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (8 children)

Oh, so you mean like how if you use the thrusters to rotate a spaceship it keeps turning until you manually cancel the rotation? (or turn on a killrot autopilot)

[–]Tom_Bombadil[S] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (7 children)

Manually cancelling the rotation of a freely floating object would be close to impossible.

[–][deleted] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (6 children)

I suppose I can agree with you about that. I've tried it myself in Pioneer and Orbiter and I can bring the rotation close to zero but I'm always still drifting just a bit.

Here's the closest thing I've found to a rocket powered vehicle that somebody landed on Earth. However, it's also powered by a jet that gimbals. I wish I could fly one. [Wikipedia article on said vehicle](https://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle

[–]Tom_Bombadil[S] 1 insightful - 1 fun1 insightful - 0 fun2 insightful - 1 fun -  (5 children)

I've seen that gimbal contraption. dangerous as heck, and he's barely keeping it together.
I think I read somewhere that it was a terrifying experience.

Also, there not appear to be sufficient thrust going on there, and it looks like there's a propeller on the underside (like a upside down helicopter). This could be a hoax video intended to appear like a

Notice the designed horizontal distribution of this vehicle. It's nothing like the ladder, yet it's teetering with instability.

Imagine traveling thousands of miles an hour; careening blindly towards the moon.

Then rotating the craft around perfectly and engaging the thrusters in perfect opposition against the momentum of the craft (and the increasing gravity of the moon on approach).

Perfect control of the craft in all rotational directions; flying completely blind.

Then gently landing the lander on uneven surfaces, but without any negative incident; 6/6 times, within 3 years... Impossible. ;-)