Sending things into the sun

In the book “Everything You Know Is Wrong” by Paul Kirchner, there is an entry about why sending nuclear waste into the sun would not be a good way to get rid of it and it says:

“Most people would assume that a waste-laden rocket could be fired through the earth’s gravitational field toward the sun, and that it would then be captured by the sun’s gravitational field and be pulled to its doom. Actually, the whole mess would simply pick up the Earth’s own orbital speed of 66,500 mph and go into its own orbit around the sun, never falling into that cosmic fusion reactor.”

Why is this so? We can land things on planets, but not the sun? Can someone explain this?


0f course we could shoot a rocket into the Sun. It wouldn’t be quite as simple as just aiming at the sun and firing it off, but with the right trajectory and appropriately timed braking thrust, it could be done.

Also the amount of energy needed to brake a payload sufficiently to fall into the sun is greater than the amount needed to chuck it out of the solar system entirely.

Presumably it is possible to do a ‘braking slingshot’ around a planet?

And if anything goes wrong a la ‘Challenger’ all that nuclear material blows up in our atmosphere. Whee!

My original post was not about specifically sending nuclear waste into the sun but the explanation about why it couldn’t be done. I have no desire to send nuclear waste into the sun.

I find it impossible to believe that you couldn’t fire a rocket fast enough in the opposite direction of the earth’s path so that it would fall into the sun.

You can fire a rocket into the Sun, but it’d be difficult. Basically, all you need to do is shoot it at 30 km/s in the direction opposite the Earth’s orbit.

On the other hand, if you shoot it at about 15 km/s in the same direction as the orbit, it’ll be at escape speed, and also never be seen again.

The excerpt which cmonidareya quotes does not say that it’s impossible, just that it’s more difficult than most people think. A lot of people think that it’s just a matter of getting it out of Earth’s gravitational field and into the Sun’s field, and just let it drop. The problem is that it’s already in the Sun’s field, and if you just get it away from Earth, it’s still in an orbit similar to Earth’s, and likely to come entirely too close for comfort in the future.

It’s not impossible, it’s just difficult. Imagine throwing a baseball off the back of a moving truck: unless you throw faster than the truck is moving, the ball is still going to be travelling in the same direction as you (albeit a bit slower). Unless you can propel the rocket fast enough to cancel solar orbital velocity, you’re not going to be able to get inwards.

Assuming that you don’t even attempt any deceleration, what would happen if you dropped a large amount of nuclear waste straight into the sun at a very high speed? I kind of doubt that it would actually begin orbiting. I mean, the sun isn’t made out of ether or anything. Wouldn’t a fast-moving chunk of material be slowed down enough through friction to be unable to escape?

Friction with what?

I think that’s the scary part.

Other than that, I’m all for it!

Presumably he was thinking of the Sun’s corona. Or maybe the solar wind?

Okay, work with me here…

We, the earth, are like a person on a truck that’s going 90 miles an hour around in a circle. In the exact center of the circle, there is a tree.

Now, intuitively, if I’m stading in the back of the truck, I can throw a baseball and make it hit the tree. It may not be easy. I may have to do a lot of math to figure out the exact angle to throw it. But I DO NOT have to implant a little rocket engine on the baseball, and then throw it out the back of the truck at the exact same speed as the truck (thus “deorbiting” it) and then have the rocket motor push it straight inwards. Also no need to somehow stop it or slow it down right before it hits the tree. I can throw the ball in such a way that the curving path it takes (which is the vector sum of the initial throw velocity when it leaves my hand and the perpendicular orbital velocity of the truck) will smack it right into the tree. Again, maybe this will take some differential equations to figure out. But it seems quite possible.

In short, it comes down to this: there is no reason to require any kind of thrust either establishing or deestabishing any kind of orbit around either the earth or the sun. Send that sucker screaming into the sun as fast as you want, so long as its path of travel brings it deep into the sun - preferably through the center. As long as it passes into the corona (or deeper) it’s going to vaporize and turn into plasma. This will then be easily caught by the sun’s gravatational and/or electromagnetic fields. Intuitively I cannot see any way that plasma has enough structural cohesiveness or especially inertia to punch all the way through something as massive as the sun.
Am I mistaken here? Are my assumptions about the behavior of objects in orbit faulty?
I mean, I can still buy the cost and safety arguments. The cost of launching it might be prohibitive. Getting stuff off earth ain’t cheap! And certanly we don’t want a shuttle full of plutonium blowing up in either the upper or lower atmosphere. I just don’t buy the idea that we have to de-orbit the earth or/and orbit the sun for something like this to work. Both of those things require thrust on the vehicle thing being chucked into the sun, which seems to be the lynchpin of the “too costly” argument. I think a properly computed initial push of velocity should be enough. Certanly once it’s in earth orbit we should be able to give it an initial push in just exactly the right direction and it’d fall in on some kind of curved path.

If we can sling Voyager around Jupiter, we can surly manage that…

Well, I’m assuming that hitting the sun wouldn’t really be that difficult, and one it’s there, the nuclear waste isn’t going to escape back into orbit.

It’s kind of ironic. I’m reading this thread while listening to my Pink Floyd Echoes CD. The song “set the controls for the heart of the sun” just came on. If that isn’t an omen, I don’t know what is.

How are you going to “Send that sucker screaming into the sun” without attaching a great big rocket engine to it?

The problem is, we are already orbiting the sun at a fairly high velocity, and that velocity is always at right angles to the direction you want the object to go to hit the sun. Unless your throw completely (or nearly so, the sun is a big target) cancels that initial velocity, the object will be moving “sideways” as it travels towards the sun, putting it into an elliptical orbit that doesn’t hit it. If you throw the object with a speed less than your orbital velocity, you can’t hit the sun no matter what angle you throw at. And it’s a lot easier to throw the object in the opposite direction out of the solar system entierly.

Well, in principle you could use some sort of mass accelerator on earth or in orbit to give it the necessary velocity without the need for a rocket. In practice …

Of course, a little bit. Say, your truck is going around that circle at 90mph (132ft/sec) at a distance of 100 feet. The centrifictional acceleration on your body relative to the truck is, what, v^2/r, or 132^2/100, which is 174 ft/s^2. It seems you’re being pressed up against the side of the truck with over five times your body weight. How are you going to get up to throw the ball at the tree?

A recent solar flare (, science and space, solar “tadpoles” item) released 1 billion megatons of energy. That’s a trillion Hiroshima weapons, or a quadrillion tons of TNT, ouch my brain hurts, from a single solar flare.

I doubt that any rocket would reach the sun before being vaporized and sent back out as a plasma. If, however, you could decelerate it so that it fell towards the north or south pole of the sun, then the rocket would be vaporized and blasted up (or down) and away from the earth.