# Using the Suns gravity for propulsion

1. May 3, 2015

### Scaledriver

Is it possible to use the sun to slingshot vehicles in order to achieve higher velocities?

2. May 3, 2015

### Orodruin

Staff Emeritus
Higher velocities relative to what? And starting from what?

3. May 3, 2015

### Scaledriver

Relative to the Suns position starting from earth.

4. May 3, 2015

### Orodruin

Staff Emeritus
You can never do a slingshot relative to an astronomical body itself. The entire idea behind a slingshot is that the relative velocity between the slingshotting object and the slingshotted object is maintained (after the objects have become well separated). You can do slingshots using planets because they are moving relative to the Sun.

5. May 3, 2015

### Scaledriver

I was curious if a parabolic course through the Suns gravity would produce any increase of velocity.

6. May 3, 2015

### Orodruin

Staff Emeritus
It does, of course, increase the velocity close to the Sun, but this has to do with how gravity works and the loss of potential energy, not with slingshotting. By conservation of energy (and ignoring other astronomical bodies) you will have the same velocity as your original velocity when you reach the radius you started at.

7. May 3, 2015

### Scaledriver

The earth is moving very fast relative to the sun. So initial velocity is high. Why can't that be used as a base to then vector off the Suns gravity and change that potential to a chosen vector?

8. May 3, 2015

### Scaledriver

The earth gives us the speed, the sun can be used to change the direction of the velocity.

9. May 3, 2015

### Orodruin

Staff Emeritus
It is unclear what you mean by this. Yes, the initial velocity relative to the Sun is high. It will still be high when something (like the Earth) returns to the same radius, but it is not a slingshot effect. The slingshot effect is using a large moving object to increase the velocity of a smaller object relative to the frame in which the large object is moving.

10. May 3, 2015

### Scaledriver

I apologize I can envision this I just need to run some computer modeling to see the effects.

11. May 3, 2015

### Drakkith

Staff Emeritus
12. May 3, 2015

### Scaledriver

13. May 3, 2015

### Scaledriver

Compiling and running simulation. I'll let you know if it works.

14. May 3, 2015

### Scaledriver

The "ship". Doesn't even need to have very much propulsion. Most is used for course correction. Human pilot is going to be needed though rf signals wouldn't be able to reach the area I'm going.

15. May 3, 2015

### Scaledriver

This changes all my theories. Using this new data I can build a fully electric space vehicle. Solar powered.

16. May 3, 2015

### Scaledriver

And, because you can also use the rotation of the earth in the same manner I can take off from earth and circle the sun and land again. if the craft is light enough. Which is possible with the current materials.

17. May 3, 2015

### Scaledriver

six months with no gravity would be an issue. Need to recalculate.

18. May 3, 2015

### Orodruin

Staff Emeritus
Please note that Physics Forums is not a place for personal theories. The original question has been answered and the answer is "no". This thread is therefore closed.