Moon landing denied. Stephen hawking - Page 13

Nicolas · #**361** (**permalink**) 21-November-2008, 04:16 PM

Quote:

Originally Posted by cjameshuff

Actually, I'm pretty sure the maneuver has a specific name...if I could just remember it...

A Hohmann transfer orbit to LEO from the distance of lunar orbit would have a velocity at apoapsis of only about 188 m/s. A 67 degree change in direction would require a delta v of about 110% of orbital velocity (sqrt((1 - cos(67 degrees))^2 + (sin(67 degrees))^2)), for a total delta v of about 208 m/s.

It's complicated by the fact that the moon is there, but my understanding is that you can get one component of the plane change velocity essentially for free by changing the timing of your burn to break from lunar orbit, dropping the needed delta v down to ~174 m/s. Also, since the moon is rotating so slowly, it doesn't matter that much where you land on it (also why it was more practical for the Apollo missions to use a retrograde lunar orbit than a prograde one), so you could exploit similar mechanics to change inclination on the way in to the moon, land at a high latitude, and cut the needed overall delta-v down even further.

So, doing the plane change at the moon is rather cheap. It imposes stricter scheduling requirements, but that's nothing in comparison to the cost of braking into LEO without aerobraking. The fuel requirements are quite sufficient to make an ISS return rendezvous impractical. It could make sense for a robotic craft with a low-thrust high-Isp engine, no time-sensitive payloads, and the potential for easy refueling and reuse (maybe an asteroid sample return probe), but not for a manned vessel.

OK. I can't do the maths anymore without looking everything up (it's been years since I've done orbital mechanics), but I had a gut feeling that the intersection between the ISS orbital plane and your HTO would be quite close to earth, and your velocity hence large. Apparently it is not.

stutefish · #**362** (**permalink**) 21-November-2008, 04:22 PM

Quote:

Originally Posted by Vallkynn

That's correct, indeed lifting body research started back in apollo era. What puzzles me and is somewhat frustrating is that after so many years of continuous research of lifting bodies, there's no real application of it. After all, if lifting bodies are useless why so many resources were wasted on a useless concept for 40 years? The series M2-F1, M2-F2, M2-F3, HL-10, X-24A and X-24B was used for the Space Shuttle project, but after that, the X-33,X-34,X-37 and X-38 were for what? Are lifting bodies only suited for SSTO concepts?

Actually, it's been pointed out repeatedly in this thread that the Apollo and Orion capsules are, in fact, lifting bodies. Indeed, they're simple, elegant, and subtly sophisticated lifting bodies, supremely suitable for their intended use. If your heartfelt desire is a lifting body, then look no farther than the Orion capsule. It's everything you ask for: A lifting body made with the latest techniques, materials, and components.

NGCHunter · #**363** (**permalink**) 21-November-2008, 05:33 PM

Quote:

Originally Posted by AstroSmurf

I was trying to think of a transfer orbit that would be less concerned with the initial inclination, but quickly found a big problem (for a thought experiment, try going to the Moon from a polar orbit)

1) The launch window becomes immensely critical, as it's no longer possible to launch at any given moment

Bingo, that's what I'm saying. Unless you align your plane you'll be stuck if you need to abort mid-mission because there won't be a return window. Also, launching to the ISS inclination decreases your ability to use the earth's rotation to your advantage in getting to LEO compared to the moon's inclination. That means more delta-V is needed to get to orbit in the first place, I'd have to run the numbers to see exactly how much but every bit helps.

JayUtah · #**364** (**permalink**) 24-November-2008, 01:49 PM

If all you want to do is change the inclination of an orbit, that's a pure delta-v maneuver. Hence it's best done at the apogee. Geostationary transfer orbits generally first set the altitude and then the inclination, so that the change of plane occurs where the spacecraft's velocity (and therefore the required delta-v) is smallest. It's somewhat amusing to think of these payloads diving down out of high-altitude, high-inclination orbits to swoop into their assigned GSO stations.

But yes, the angular difference between the parking orbit plane and the destination orbit plane determines the difficulty and timing of the maneuver. It also says something about the impulse needed to pull off the transfer. Significant changes of plane require the maneuver to be executed smartly.

Real mission design has to consider contingency plans in case something goes wrong. If all we had to think about was the part where everything's rosy, then space travel would be easy and everyone would be doing it. But when you have to design a mission that has one or two viable abort scenarios at each significant change of state, you begin to see that fancy orbital design starts to hurt you. And maybe going to and from the ISS isn't such a win after all.

cjameshuff · #**365** (**permalink**) 24-November-2008, 02:45 PM

Once again, I'm only saying the inclination change is a relatively minor problem compared to the other issues. If the ISS were in an equatorial orbit, only a minor adjustment in plane would be necessary to match it, but it would still be impractical to rendezvous with the station due to the large delta-v needed. There's planning and emergency fallback difficulties, but they are nowhere near the showstopper that the delta-v issue is...if everything goes right, they do work. The ISS rendezvous doesn't...to achieve that delta-v with a manned vehicle and the time constraints that implies requires an impractically large rocket for our current capabilities.

On the subject of inclination changes, one maneuver I've seen suggested is to actually do them in a low altitude pass, ducking into the atmosphere to both drop apoapsis and make an aerodynamic turn to accomplish the inclination change. You could even accomplish this to some degree with an Orion capsule, because, as stated numerous times, it is a lifting body...though I doubt even Vallkynn would suggest a reentry-capable capsule for aerobraking/plane changing maneuvers followed by ISS rendezvous followed by another atmospheric entry in a winged vehicle before finally landing.

NEOWatcher · #**366** (**permalink**) 24-November-2008, 05:28 PM

Quote:

Originally Posted by cjameshuff

On the subject of inclination changes, one maneuver I've seen suggested is to actually do them in a low altitude pass, ducking into the atmosphere to both drop apoapsis and make an aerodynamic turn to accomplish the inclination change.

That sounds like just as much of an energy problem as just changing inclination.
First: slow down to achieve atmosphere penetration.
Second: Speed lost to friction.
So; by the time you make up for those, you could have just changed inclination.

cjameshuff · #**367** (**permalink**) 24-November-2008, 05:54 PM

Quote:

Originally Posted by NEOWatcher

That sounds like just as much of an energy problem as just changing inclination.
First: slow down to achieve atmosphere penetration.
Second: Speed lost to friction.
So; by the time you make up for those, you could have just changed inclination.

It makes more sense in context...adjusting inclination while aerobraking into orbit around Mars, Venus, Titan, or possibly one of the gas giants (or Earth, if you need to enter LEO from a high orbit and change inclination in the process). Loss of velocity being one of the goals of the maneuver, the change in direction being a free bonus.

I do not recall why they wouldn't just adjust trajectory while still at a distance. Perhaps it was meant for multi-payload missions, with orbiters destined for different inclinations, separating on arrival. It seems like a bit of a solution looking for a problem, just thought it was worth mentioning here.

NEOWatcher · #**368** (**permalink**) 24-November-2008, 06:23 PM

Quote:

Originally Posted by cjameshuff

It makes more sense in context...adjusting inclination while aerobraking into orbit...

Yes; that does make more sense, I was reading the part about going from ISS inclination to a moon heading...

Jeff Root · #**369** (**permalink**) 25-November-2008, 03:41 PM

Quote:

Originally Posted by Peter B

Quote:

Originally Posted by Jeff Root

Why do you say that the astronauts would have little opportunity to
explore Mars? Limited payload mass? Limited time on the surface?

Two related reasons. Firstly, my understanding is that most models for
sending astronauts to Mars involve them spending little time on the
surface - as little as a month in some models.

My baseline for humans on Mars is Robert Zubrin's Mars Direct plan.
It would put four astronauts on Mars for 550 days. Transit time is
180 days in each direction, for a total of 360 days in zero-g, which
is much less than the 610 days of an opposition trajectory that gives
a mere 30 days on Mars.

-- Jeff, in Minneapolis

mugaliens · #**370** (**permalink**) 29-November-2008, 03:24 PM

i thought apoll landd on the sun isnt that after all why i dont remember how to spl or punctate wasnt apollo god of sun or sun god child something so whr not name him after planet he landed on like sun why we let threadslike this go on cant spell or puntate i don know why

Please let me know when the above starts sounding familiar...

Let Me Enlighten U · #**371** (**permalink**) 06-December-2008, 06:28 AM

it's sad to me to see how many people have been fooled. i hope you find the truth. i will try my best to bring the truth out and have it shine brightly for all to see.

captain swoop · #**372** (**permalink**) 06-December-2008, 09:02 AM

Fooled about what? and what do you take to be the 'truth'?

Paul Beardsley · #**373** (**permalink**) 06-December-2008, 09:28 AM

Quote:

Originally Posted by Let Me Enlighten U

it's sad to me to see how many people have been fooled. i hope you find the truth. i will try my best to bring the truth out and have it shine brightly for all to see.

It may well be that we are mistaken about many things.

But to my mind, it is much easier to admire the honest hard work of scientists who use evidence and reason to gain an imperfect but workable understanding of the universe than it is to admire the pronouncements of those who indulge in inane fantasies about "revealed truth".

JayUtah · #**374** (**permalink**) 06-December-2008, 02:14 PM

it's sad to me to see how many people have been fooled.

Yes, we highly-trained and experienced aerospace engineers who believe that Apollo was real because we've studied it in great depth, are such a gullible lot. So now that I've read three separate crowing posts in which you promise to "enlighten" us on this and other points, when may we expect the enlightenment to begin?

Nicolas · #**375** (**permalink**) 06-December-2008, 02:42 PM

recommended listening:

Mike Oldfield - The songs of distant earth: "Let there be light".

youtube music video

I thought it was appropriate, as we're all eagerly awaiting the announced enlightenment, and the sampled text is from an Apollo mission.

(No religious context implied whatsoever.)

LaurelHS · #**376** (**permalink**) 06-December-2008, 03:18 PM

That is a surreal and beautiful video.

Let Me Enlighten U · #**377** (**permalink**) 06-December-2008, 04:29 PM

Quote:

Originally Posted by Paul Beardsley

It may well be that we are mistaken about many things.

But to my mind, it is much easier to admire the honest hard work of scientists who use evidence and reason to gain an imperfect but workable understanding of the universe than it is to admire the pronouncements of those who indulge in inane fantasies about "revealed truth".

i admire the hard work of scientist as well. i think mankind has made great progress through science, that is not what is up for debate. what i speak of is how science has also led to the creation of technologies that manipulate people into believing in certain fallacies. not very often, but it has happened in some very few instances.

Nicolas · #**378** (**permalink**) 06-December-2008, 04:45 PM

Can you be a bit more concrete?

JayUtah · #**379** (**permalink**) 06-December-2008, 06:07 PM

what i speak of is how science has also led to the creation of technologies that manipulate people into believing in certain fallacies.

Let's be clear. Are you accusing mainstream science of discouraging believe in pseudoscience by means of mind control?

not very often, but it has happened in some very few instances.

Name the instances and give evidence of your proposed causation.

Let Me Enlighten U · #**380** (**permalink**) 07-December-2008, 04:38 AM

Quote:

Originally Posted by JayUtah

what i speak of is how science has also led to the creation of technologies that manipulate people into believing in certain fallacies.

Let's be clear. Are you accusing mainstream science of discouraging believe in pseudoscience by means of mind control?

not very often, but it has happened in some very few instances.

Name the instances and give evidence of your proposed causation.

all i'm saying is that some people use science to exploit others to their advantage.

JayUtah · #**381** (**permalink**) 07-December-2008, 04:40 AM

You say this has happened "in some very few instances." Name and describe the instances.

Let Me Enlighten U · #**382** (**permalink**) 07-December-2008, 04:41 AM

apollo moon landings = world domination

NickW · #**383** (**permalink**) 07-December-2008, 08:01 AM

world domination?

The only fallacy I am seeing here is non sequitor. Or course, pointing out fallacies is not my strong suit.

Maybe, instead of throwing out these statements you are making, you should start by giving some evidence for your claims, because it will make the conversations that you are having here on BAUT alot easier for all to understand. You are just being vague.

slang · #**384** (**permalink**) 07-December-2008, 10:55 AM

Quote:

Originally Posted by Let Me Enlighten U

apollo moon landings = world domination

Well, umm, yeah. If you're the only two people on a certain world, let's say the moon, then yes, absolutely, you completely dominate the population on that world. Very observant. Not very useful though.

Nowhere Man · #**385** (**permalink**) 07-December-2008, 12:39 PM

Quote:

apollo moon landings = world domination

In other words,

1. Apollo moon landings
2. ????
3. World domination!

Sounds like
1. Collect underpants
2. ????
3. Profit!

And about as valid. You've been asked for explanations and evidence for your various claims. So far, all you've come up with is vague claims like the above and statements that you have the evidence but that to divulge it would put your life at risk. I've read this thread, and you've convinced me...

that you have nothing.

Fred

Let Me Enlighten U · #**386** (**permalink**) 07-December-2008, 04:22 PM

Quote:

Originally Posted by slang

Well, umm, yeah. If you're the only two people on a certain world, let's say the moon, then yes, absolutely, you completely dominate the population on that world. Very observant. Not very useful though.

you were trying to be witty but you failed in this case. world refers to earth so what you said makes no sense.

Nicolas · #**387** (**permalink**) 07-December-2008, 04:23 PM

Verifiable evidence of the claims you made earlier. Nothing more, nothing less.

captain swoop · #**388** (**permalink**) 07-December-2008, 04:23 PM

Let Me Enlighten U

Several warnings have been issued both on the threads and by PM concerning the way you are conducting yourself.

Before you make anymore claims can we have some substansive answers to the questions already posed.
I will refer you again to the [/url=http://www.bautforum.com/about-baut/32864-rules-posting-board.html]Rules For Posting[/url]

Maybe it would be a good idea for the other paricipant in the thread to remind Let Me Enlighten U of the outstanding questions.

Nicolas · #**389** (**permalink**) 07-December-2008, 04:25 PM

As far questions still to be answered/claims still to be given verifiable evidence for:

-the existence of aliens
-the existence of space warping satellites
-your involvement in a top secret space agency
-your involvement in any space agency
-the lethal radiation dose astronauts would have gotten in the CSM/LM
-the inability of the CSM and LM as spacecraft.

That would be such a nice start.

Nicolas · #**390** (**permalink**) 07-December-2008, 04:36 PM

Discussion of LMEU's claims can be continued here:

Let Me Enlighten U's claims

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