# Accuracy in space

1. Nov 8, 2005

### dev_arora_13

my question is about the availability of present technology

is it possible to screw a nut & bolt very ,very pricisely in space.
each of them will be of 10000kg and about 0.7km
most important-they will be rotating at a speed of 0.5 RPM

2. Nov 8, 2005

### Labguy

That's the strangest question I have ever seen..
But, yes, we could screw the nut onto the bolt in space. What we can't do is get them into space in the first place..

3. Nov 8, 2005

### turbo

Actually, we could get them into space using present technology. For low Earth orbit, the Russian Energia has a payload of close to 200,000 pounds and the Saturn V maxes out at about 285,000 pounds.

4. Nov 8, 2005

### Labguy

It's not the weight, it's the size. The OP said 0.7 km, which is 2296.587927 feet long. That would be a tough liftoff...:uhh:

5. Nov 8, 2005

### DaveC426913

I'm not sure what you mean by "very precisely". Can you give some examples of putting them together imprecisely? You mean like, banging together?

It seems to me that the biggest problem you'd have putting them together would be orbital mechanics. Their CoMs are in slightly different orbits. This is the problem the first apollo Soyuz docking missions had.

6. Nov 8, 2005

### Staff: Mentor

Along the lines of what Labguy mentioned - the size mentioned here is rather impractical. No engineer in his or her right mind would design a structure requiring a 700 m nut or bolt!

Last edited: Nov 8, 2005
7. Nov 8, 2005

### Staff: Mentor

Just speculation, but perhaps the OP is talking about docking and the nut and bolt are just analogies for the spacecraft and station. Just a wild guess, though....

8. Nov 8, 2005

### Staff: Mentor

That sounds reasonable. On the other hand, something the size of 700m is not going to be launched in one piece for earth's surface, but rather it will be assembled on orbit.

Just do the calculation on air resistance at typical launch velocities!

Also a large structure would have much smaller docking ports.

9. Nov 8, 2005

### turbo

Oops! I jumped on the trivial mass problem. I guess we could make a 0.7 km bolt that would pop into shape like a shock-corded tent pole, but why on earth would the nut need to be 0.7 km in its largest dimension? Again though, if it needed to be a nut with 0.7 km of threaded contact area (more of a long threaded tube) we could engineer something that would fold down to a launchable size. A single monolithic cast and machined object? Nope - we can't do it.

Perhaps the OP can enlighten us as to why the question was posed in this way?

10. Nov 9, 2005

### Danger

Anything that requires a nut and bolt that big should probably be welded instead.

11. Nov 12, 2005

### Nereid

Staff Emeritus
Or velcro! :tongue:

12. Nov 12, 2005

### tony873004

lol... that's just what I was thinking. A nut and a bolt are nice general solution to fastening two things together. No need to re-invent the wheel. There's lots of sizes available.

But at 0.7km, you are re-inventing the wheel. It would probably be better to weld a stop onto a non-threaded shaft.

13. Nov 13, 2005

### pervect

Staff Emeritus
What is this nut supposed to be made of, anyway?

If it is 350 meters in radius, and 100 meters thick (about 1/7th of it's diameter, which seems to be in the right ballpark) it will have a volume of 38,484,510 meters^3. With a mass of 10,000 kg, that's a density of .0002 kg/m^3.

Water has a density of 1000 kg / m^3, air at standard temperature and pressure has a density of 1 kg/m^3. This nut has a density that's much lower than that of air!

Steel would have a density of about 8000 kg / m^3, or perhaps a little less.