Could you travel using nuclear bombs?

[Audun Nilsen]

I have two scenarios. 

One; imagine that, at the same time as the engine of your ship is ignited, there is also a device detonated inside the ship. If timed correctly, the difference between the two would equal out, right? For now, there's one huge problem and that's making sure the aim is correct, because, if you collide with an asteroid or something, you'd just spin out of control, but if you could measure the trajectory perfectly, there would be nothing in the way of that, if space, truly, is a vacuum which could accommodate fast travel. Next, there's the slowing down. Once the blast has burned out, you would naturally slow down, but the process of slowing down an object from something in the area of the speed of light would take immensely long, but you can calculate how long you go by adjusting the strength of the device according to distance. If there is some kind of resistance in space, fine, and if not, you can fire an engine in the nose end of the ship and initiate the stopping sequence that way. If there is only miniscule mass the stopping force would have to be on a par with the start force, and, again, if you detonate outside and inside at exaclty the same time, then you won't have a problem, right? Relative to ... the sides of the "ship", your pod hasn't moved at all. In short, dead accuracy is the way to go.

Two; imagine a huge construction with several hundred stories of tunnels with rails in them, which all contained a smaller pod except the one in which you have the astronauts, and imagine also that the pods of this Matryoshka ship has springs in both ends and, when the ship speeds up or slows down, the springs lessen the impact, and reduce G-forces to an acceptable minimum. The challenge as I see it here, is not just accuracy, but sheer size, since the force of, even, a jet engine in a vacuum would be immense and, so, you'd need 100s, maybe 1.000s of pods. I'm sure that having vacuum inside the tunnels would help, since that would lessen the immediate impact, but it would make the length of the tunnels a great deal bigger.

[zapatos]

If a nuclear bomb is detonated in your ship you will not have to worry about any of the other details.

[Ken Fabian]

 

4 hours ago, Audun Nilsen said:

At the same time as the engine of your ship is ignited, there is also a device detonated inside the ship. If timed correctly, the difference between the two would equal out, right?

I don't understand what kind of beneficial "difference would equal out" effect you expect to occur. I don't seen how anything would be gained from detonating anything inside a spaceship.

Designs exist for nuclear pulse rockets, such as "Orion" that detonate nuclear bombs behind a deflection plate with shock absorbers. Other kinds of nuclear pulse spacecraft have been proposed. Like above ground nuclear testing, proponents insist there is insufficient evidence that this could have harmful consequences in Earth's atmosphere. Not convinced this is a safe space technology, in or out of the atmosphere, but others may disagree.

[Audun Nilsen]

 

 

G-forces, dude. You'd equal out G-forces.

[Samantha Priss]

12 hours ago, Audun Nilsen said:

I have two scenarios. 

One; imagine that, at the same time as the engine of your ship is ignited, there is also a device detonated inside the ship. If timed correctly, the difference between the two would equal out, right? For now, there's one huge problem and that's making sure the aim is correct, because, if you collide with an asteroid or something, you'd just spin out of control, but if you could measure the trajectory perfectly, there would be nothing in the way of that, if space, truly, is a vacuum which could accommodate fast travel. Next, there's the slowing down. Once the blast has burned out, you would naturally slow down, but the process of slowing down an object from something in the area of the speed of light would take immensely long, but you can calculate how long you go by adjusting the strength of the device according to distance. If there is some kind of resistance in space, fine, and if not, you can fire an engine in the nose end of the ship and initiate the stopping sequence that way. If there is only miniscule mass the stopping force would have to be on a par with the start force, and, again, if you detonate outside and inside at exaclty the same time, then you won't have a problem, right? Relative to ... the sides of the "ship", your pod hasn't moved at all. In short, dead accuracy is the way to go.

Two; imagine a huge construction with several hundred stories of tunnels with rails in them, which all contained a smaller pod except the one in which you have the astronauts, and imagine also that the pods of this Matryoshka ship has springs in both ends and, when the ship speeds up or slows down, the springs lessen the impact, and reduce G-forces to an acceptable minimum. The challenge as I see it here, is not just accuracy, but sheer size, since the force of, even, a jet engine in a vacuum would be immense and, so, you'd need 100s, maybe 1.000s of pods. I'm sure that having vacuum inside the tunnels would help, since that would lessen the immediate impact, but it would make the length of the tunnels a great deal bigger.

How are you going to get something big enough to withstand nuclear blasts into space? What do you have in mind that could handle this?

Wouldn't using moderated fission electricity to produce a highly accelerated jet work better?

[dimreepr]

34 minutes ago, Samantha Priss said:

How are you going to get something big enough to withstand nuclear blasts into space?

With a big bomb, like we do now.

[Audun Nilsen]

Gee, I don't know, I was keen on getting some feedback on the principle itself, really, but I suppose you could build a massive tower, a space elevator or build the labs themselves in space, havesting asteroids and moon rock. I guess you could haul parts with a space jet too.

 

A fission reactor produces about 3000 times less power than a Tsar Bomba and about 4.000.000 times more than jet fuel:

 209 200 000 000 megajoule

            82 000 000 megajoule

                                 5 megajoule

If a spaceship could go 35.000 km/h wiht jet fuel, a fission engine could reach 0.1 speed of light, which is the same as the NASA ship under construction and the fastest Orion.

[dimreepr]

1 minute ago, Audun Nilsen said:

Gee, I don't know, I was keen on getting some feedback on the principle itself, really, but I suppose you could build a massive tower, a space elevator or build the labs themselves in space, havesting asteroids and moon rock. I guess you could haul parts with a space jet too.

 

A fission reactor produces about 3000 times less power than a Tsar Bomba and about 4.000.000 times more than jet fuel:

 209 200 000 000 megajoule

            82 000 000 megajoule

                                 5 megajoule

If a spaceship could go 35.000 km/h wiht jet fuel, a fission engne could reach 0.1 speed of light, which is the same as the NASA ship under construction and the fastest Orion.i

5

Did you read the link nuclear pulse rockets?

Quote

Efficient directional explosives maximized the momentum transfer, leading to specific impulses in the range of 6,000 seconds, or about thirteen times that of the Space Shuttle main engine. With refinements a theoretical maximum of 100,000 seconds (1 MN·s/kg) might be possible. Thrusts were in the millions of tons, allowing spacecraft larger than 8×10⁶ tons to be built with 1958 materials.^[3]

 

[Audun Nilsen]

Spoiler

 

Spoiler

 

I haven't found that converter. Feel free.

[Samantha Priss]

1 hour ago, Audun Nilsen said:

A fission reactor produces about 3000 times less power than a Tsar Bomba and about 4.000.000 times more than jet fuel:

 209 200 000 000 megajoule

            82 000 000 megajoule

                                 5 megajoule

If a spaceship could go 35.000 km/h wiht jet fuel, a fission engine could reach 0.1 speed of light, which is the same as the NASA ship under construction and the fastest Orion.

That isn't power that's energy. Tsar Bomba released all of its energy in a fraction of a second.

https://www.quora.com/What-is-the-difference-between-power-and-energy

I think an analogy here is using high explosives to push a bullet. What would happen is it would just wreck your equipment achieving nothing.

Edited March 10, 2019 by Samantha Priss

[Janus]

2 hours ago, Audun Nilsen said:

Gee, I don't know, I was keen on getting some feedback on the principle itself, really, but I suppose you could build a massive tower, a space elevator or build the labs themselves in space, havesting asteroids and moon rock. I guess you could haul parts with a space jet too.

 

A fission reactor produces about 3000 times less power than a Tsar Bomba and about 4.000.000 times more than jet fuel:

 209 200 000 000 megajoule

            82 000 000 megajoule

                                 5 megajoule

If a spaceship could go 35.000 km/h wiht jet fuel, a fission engine could reach 0.1 speed of light, which is the same as the NASA ship under construction and the fastest Orion.

It's not that simple.  For one thing, there is such thing as a maximum theoretical speed that a spaceship could reach using a given propulsion method.   The limits are the practical ones due to how much fuel per kg of rocket mass you need to reach a given speed with any given propulsion method.  This is a function of the exhaust velocity your propulsion method generates.

Modern day chemical rockets generate exhaust velocities in the order of 4.5 km/sec.  

There is an equation for determining final velocity with a given fuel/ rocket mass ratio and exhaust speed. It is known as the "rocket equation."

V_f = V_e ln (MR)

where v_e is the exhaust ratio,  ln means the natural log and MR is the mass ratio (fully fueled rocket mass/ empty rocket mass)

Your 35,000 km/hr = ~9.7 km/s

By rearranging the rocket equation, we can work out what mass ratio we would need to reach it with a modern chemical rocket.

it works out to a mass ratio of ~8.6 , or 7.6 kg of fuel for every kg of rocket.

In the late ''60s and early '70s,  NASA worked on developing a fission-based rocket that used a fission reactor to generate its propulsion(NERVA). It could achieve exhaust velocities of ~ 8.1 km/sec.

Thus NERVA, with the same mass ratio could reach 17.4 km/sec or just twice that of a chemical rocket.  While this does not seem like much of an improvement, it would have made a manned Mars mission practical. Congress however, lost interest in manned space exploration and cut funding to the project.   Even with further development, this type of fission reactor rocket design wouldn't have improved its performance that much to make even a dent in the speed of light.

A newer approach is the fission fragmentation rocket, which actually uses the daughter products of the fission reaction as the exhaust medium. (NERVA just used the reactor to heat a different working fluid)

Theoretically, a Fission fragmentation rocket could achieve exhaust velocities in the order of 3% of the speed of light.  With the same 8.6 mass ratio, this gets you up to ~6.5% of c. not bad, but consider the fact that this means that your rocket has to carry 7.6 kg of fissionable material per ever kg of rocket. And the mass of that rocket would have to take into account all the shielding for this, the superstructure to support it, and a means of keeping your fissionable material from prematurely undergoing fission. (anything thing more than critical mass too closely packed will go BOOM, or at the very least generate enough energy to cripple your ship.) This drives the amount of the rocket that is used for useful payload down even further.

It gets worse if you plan to slow down. Accelerating to 6.5 c and then decelerating back down to 0 requires you to carry 73 kg of fissionable material per kg of ship.

The problem is that you are making linear extrapolations in instances where they don't apply.

[Ken Fabian]

18 hours ago, Ken Fabian said:

I don't understand what kind of beneficial "difference would equal out" effect you expect to occur. I don't seen how anything would be gained from detonating anything inside a spaceship.

 

10 hours ago, Audun Nilsen said:

G-forces, dude. You'd equal out G-forces.

Huh? What you mean is still not clear, but it sounds to me like you expect the occupants to experience less G-force than the overall acceleration of the spacecraft? If so, no - if you get acceleration, that makes (is?) the G-force - and the G-forces the ship and occupant experience will not be "equalled out" by putting the spacecraft in between two nuclear detonations.

The idea of using nuclear pulse rockets has been around a long time but they will operate within the known laws of physics, which doesn't include a means to accelerate without the acceleration.

[Strange]

On 3/10/2019 at 2:31 PM, Audun Nilsen said:

G-forces, dude. You'd equal out G-forces.

How? Please explain in detail how an explosion can counter g-forces. Does that happen on Earth when things explode? Do people feel weightless when a bomb goes off?

[Janus]

On 3/9/2019 at 5:04 PM, Audun Nilsen said:

I have two scenarios. 



Two; imagine a huge construction with several hundred stories of tunnels with rails in them, which all contained a smaller pod except the one in which you have the astronauts, and imagine also that the pods of this Matryoshka ship has springs in both ends and, when the ship speeds up or slows down, the springs lessen the impact, and reduce G-forces to an acceptable minimum.

 

The only effect springs would have would be to lessen the "jerk", or the rate of change from no acceleration to full acceleration; they will not reduce the g forces due to the acceleration itself.   The springs aren't even necessary; all you need to do is to ramp up the acceleration from 0 to full over a period of time rather than doing a sudden transition.