ALL SCI-FI

[Bud Brewster]

How a cavorite sphere might be used to take a round trip to the Moon!

We watched First Men in the Moon in the All Sci-Fi's Chatzy Room a few weeks back, and I gained a new respect for it.

However, today I started thinking about the cavorite sphere the characters used to get to the Moon and back to Earth . . . and I realized that Professor Cavor's wondrous anti-gravity device would not work quite as simply as the movie demonstrates.

Here's what I mean.

The reason the sphere shot up into the sky when Cavor closed all the cavorite shutters was because they cut off a large percentage of the Earth's gravity and made the sphere suddenly much less heavy.

Bear in mind that the shutters didn't completely cover the sphere, so the sphere couldn't become totally weightless. However, let's be generous and assume that the weight was cancelled in the manner H.G. Wells described in his novel.

Wells states that the cavorite sphere would make the air above it weightless, causing it to shoot upward, thus sucking up the weightless sphere and sending it racing towards space.

Sadly, that is not what would happen.

Consider this; when you're standing up, the gravity which holds your feet to the floor is not generated only by the one-square-foot area you're standing on.

The gravity which acts on your body also comes from the entire area around you. In fact, a certain amount of the gravity is pulling on you at an angle from all sides — but since it's equally distributed in all directions, it equals out and you don't fall over!

I suspect that Wells' just fudged a bit on the complex science involved in his science fiction novel to keep it from being overly complex for his readers.

As for the 1964 movie, the scene in First Men in the Moon which showed the cavorite sphere blasting straight up through the greenhouse was completely wrong.

Please forgive the long explanation below, but I think you'll enjoy it, because yesterday I realized that a weightless sphere coated in cavorite actually would leave the Earth . . . but for a very different reason than the one used by Wells and Harryhausen!

Buckle up, folks. Here's comes some real science!
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The surface of the Earth is spinning 1,000 mph at the equator, although it's traveling slower as you approach the two poles.

Despite this fact, there is no measurable "centrifugal force" affecting objects on the surface, because the Earth's circumference is 24,000 miles, which means it takes 24 hours (one full day) to make one rotation.

Therefore, even at the equator the surface isn't spinning around fast enough to cause any measurable centrifugal force.

Gravity, of course, keeps all objects on the surface, but if an object (like the cavorite sphere) suddenly became weightless it wouldn't shoot straight UP like the sphere in the movie. It would simply keep going 1,000 mph in the same direction as the Earth's surface and all the objects around it, even though it was no longer held down by gravity!

In short, nothing much would happen.

The sphere would, however, act like a hot air balloon, because the sphere would be lighter than an equal volume of air. But since the sphere is only about 25 feet in diameter, it wouldn’t have much more lift than a weather balloon like this one — and the guy in the photo is having no trouble holding on to it.


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In fact, Cavor could open a shutter on the bottom of the sphere and give it just enough weight to make it hover, rather than rise.

Surprisingly enough, however, the sphere would soon begin to rise up slowly for a completely difference reason.

The reason is inertia.

Inertia causes a moving object to continue along at the same speed and direction it's currently traveling unless it's acted upon by external forces. (Weight is different from mass, and mass is what causes inertia.)

So, even a nearly-weightless object like the cavorite sphere (with one shutter open on the bottom to make it hover) will continue to travel along with the surface of the Earth in a perfectly normal manner.

However, at this point the sphere would begin to do something very abnormal!

Over the next sixty minutes the sphere (and the land it formerly rested on) will travel 1,000 miles as the Earth rotates. No surprise there, right?

But during that time, the sphere would get further from the land below, even though it's NOT actually "floating up like a balloon"!

Here's where things get delightfully weird and wonderful, guys. Stay with me on this, because we're going to the Moon!

The reason the sphere starts to rise up is because the surface of the Earth is going around in a 24,000 mile-wide circle . . . while the suspended sphere is traveling in a straight line — thanks to inertia.

Let's pretend the sphere was being launched in Ecuador, the South American country right on the equator. Soon after it became weightless, it would appear to float upward very slowly.

But what's really happening is that the ground is "rolling down below the object" as the Earth rotates.

(Wait . . . what!?)

Sounds crazy, I know . . . but I can prove it.

Remember, both the sphere and the land under it are traveling 1,000 mph, along with all the air around them. Naturally none of this is apparent to an observer . . . who would also be traveling 1,000 mph.

Now, here comes the really good part.

Eventually the suspended sphere would keep right on traveling in a straight line at 1,000 mph, still positioned directly over the place where it first became weightless. It hasn't moved an inch horizontally from — but it is moving vertically, very slowly.

The sphere just remains inches above the ground, moving in a straight line because of inertia . . . but the ground below it can't actually do that! It rolls along with the rest of Earth's surface, a circular path which is governed by the Earth's round shape!

As the hours pass, the sphere's height above the ground visibly increases . . . but it's only because the ground beneath it is dropping lower and lower!

In about six hours it will be hundreds of miles directly above the launching point, and then it will sail right off into space!

I know that's hard as hell to visualize because it's so damn counter intuitive. So, here's a few visual aids. Study the two images below. These illustrations are showing a launch site in Ecuador, right on the equator.

The first one shows the straight-line path of the floating sphere. Ecuador would rotate toward the East and eventually drop below the horizon, while the sphere would remain above it, getting higher and higher until is passed through the atmosphere, still traveling 1,000 mph.


This second image shows a view from the South Pole, with the Earth turning clockwise and the equator extending around the circumference.

The two blue dots represent the sphere, first at it's starting place on the equator, and then out in space, still traveling at 1,000 mph in a straight line because of inertia.





One of the green dot shows the launching place on the equator, which will move with the rotating Earth and end up where the second green dot is located, well below the sphere's blue dot when the sphere is out in space.

So, the sphere is launched into space by traveling horizontally at 1,000 mph in a straight line until it flies right out of the atmosphere!

Pretty wild, huh?

In Harryhausen's movie, the sphere shot upward, crashed through the greenhouse roof, and soared into the night sky. It looked great . . . but unfortunately that's not what would have happened to the cavorite sphere when it became weightless.

The sphere would just start rising up very slowly until it bumped the glass roof of the greenhouse. I suppose the glass roof would hold it for a while, but finally it would break and release the sphere.

So much for the dramatic lift-off!

But let's amend the scene so that the sphere is sitting on open ground. In that situation the sphere could rise up slowly and, over a period of about six hours, travel higher and higher until it left the atmosphere, the way the images above illustrate.

Once the sphere is in space, its actual forward motion would become more apparent as Cavor and Bedfore gaze out the sphere's portholes and watching the surface of the Earth receding at 1,000 mph.

But how will the sphere get to the Moon if it's going in the wrong direction?

Well, if the Moon happens to be rising on the eastern horizon at the moment the sphere becomes weightless, it would be headed directly towards it — because the Moon would be in the direction the sphere is propelled by the rotating Earth, the moment the ties of gravity released it.





If all this sounds ridiculous, try thinking of the sphere as the stone in young King David's sling when he slew Goliath. If the stone was released from its leather pouch at just the right moment when David whirled it 'round and 'round, inertia would send it zipping off in the direction of Goliath's head, and the giant would come crashing down!

Just for fun, let's assume that the cavorite sphere was launched on the equator at just the right moment to send it racing along parallel to the Earth's surface and headed straight towards the rising Moon on the horizon.

After several tranquil hours of floating along like a balloon, getting further and further from land below, the sphere does what a balloon can't do, which is float right up out of the atmosphere, still traveling 1,000 miles and hour, and still headed straight towards the point in the heavens were the Moon was when the sphere was launched.

Unfortunately, by that time the moon won't there anymore.

That's because the Moon has been traveling 2,288 mph in it's orbit, so it's well past the point in the sky where it was located when the sphere was launched.

Obviously a course correction is need. But how much correction?

Well, let's figure that out mathematically. We must consider how fast the sphere is traveling and how far is it from the Moon. We know both of those facts, of course. The sphere is traveling 1,000 mph, and the distance to the Moon is about 240,000 miles.

The math is so easy I can do it in my head! 24 hours in a day X 1,000 mph = 24,000 miles per day. So, it will take the sphere 10 days to reach the Moon's orbit.

But as I said, the Moon won't be where it was when the sphere was launched.

Therefore, if Cavor and Bedford want to arrive at the point in space where the Moon is located, they'll have to either depart 10 days before the Moon arrives at that point, or they'll have to adjust the velocity of the sphere so that is arrives just when the Moon has returned to that point in it's orbit.

Unfortunately the cavorite sphere can not accelerate, decelerate, or change course like a conventional spacecraft.

Besides that, there's the fact that in the 1964 movie, the cavorite sphere didn't launch from Ecuador, it launched from England. That means it won't be traveling 1,000 mph, it will only be traveling 645 mph — which is the rotational speed of the Earth's surface at that latitude. (I looked it up.)

So, the trip to the Moon will actually take 15 days.

Based on this fact, the sphere needs to launch 15 days prior to the moment when the Moon is rising in the east.

Now that we've figured out how to get the sphere to the Moon, how can we slow the damn thing down and land it without killing the crew!

I gave that a lot of thought . . . and here's what I came up with.

Since the sphere used the complete absence of gravity from all directions to allow the inertia of Earth's rotation to propel it towards the Moon, we have to find a way to use the presence of gravity coming from directly behind it to decelerate the sphere.

If the sphere's shutters were closed on the side facing the Moon during it's approach, while the shutters were open on the side facing the Earth behind it, the gravitational force would slow the sphere to some degree.

But would it be enough?

Well, maybe not — but we can increase the effectiveness of this maneuver by having the sphere schedule its launch date so that the Sun is on the opposite side of the Earth from both the Moon and the sphere.

In other words, the approach should take place during a lunar eclipse, when the Moon is in the Earth's shadow. The alignment of the Sun and the Earth would increase the gravitational pull on the sphere and slow it down.





Ironically, a lunar eclipse takes place in the movie while Bedford and Cavor are on the Moon!

Gentlemen, I certainly can't prove if mathematically, but it seems at least possible that the combined gravitational pull of both the Earth and the Sun behind the sphere — with absolutely no gravitational influence from the Moon ahead of the sphere — might be able to decrease the sphere's 645 mph velocity enough to allow a reasonably soft landing to take place.





As a matter of fact, I sincerely believe that this same arrangement of gravitation forces might actually allow the sphere to lift off and return to Earth!

The sphere would have to leave within a day or so of it's arrival on Moon, while the Earth and the Sun are still close to together in the lunar sky. With the sphere rendered weightless by the closed shutters on the lower side, and all the shutters open on the upper side, the gravity from the Earth and the Sun would actually lift it slowly and draw it back towards the Earth!

What a wild idea! The cavoite sphere would be resting on the surface of the Moon, but it could totally neutralize the Moon's gravity and then be raised up and brought back to Earth by the combined gravity of the Earth and Sun!





Furthermore, the fact that the Sun would not be precisely behind the Earth at this point could actually work to the crews' advantage!

With careful manipulation of the shutters during the return trip, the sphere's flight path could be controlled so that the sun would actually pull the sphere slightly to one side of the Earth, allowing it to brush past the upper atmosphere, slowing it gradually.

Bear in mind that the goal would be to adjust the weight of the sphere with the shutters so that it becomes, in effect, an extremely lightweight object in a slow orbit, skimming the atmosphere as the orbit decays.

As it gradually dips further into the atmosphere — slowing even more — the shutters could be adjusted to make the sphere so light that it drifts slowly towards the ground, a virtual "hot air balloon" that could be raised and lowered at will!

The crew could seek out the wind currents that would take them in the most favorable direction until they reached a suitable region in which to make a gentle landing!

In fact, there's really no reason why the sphere couldn't float around for hours (or even days) while the crew maneuvered it, using wind currents at different levels!

Gentlemen, my description of the entire journey might be a bit overly optimistic, but I think I've actually outlined the manner in which a cavorite sphere could make a round-trip journey to the Moon!
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Is there no man on Earth who has the wisdom and innocence of a child?
~ The Space Children (1958)