How many maximum tons can you lift to orbit?

[Spacescifi]

According to Scott Manley, metallic hydrogen has a specific impulse of 1700 seconds. That is rocket scientist way of saying that such a rocket would go farther per pound of fuel used than our relatively quick exhausted chemical and solid booster rockets.

Nonetheless, the tyranny of the to rocket equation will stiill effect any rocket no matter how powerful so long it cannot create it's own fuel.

Say you want to launch a constitution class star trek starship onto orbit and it weighs 190,000 tons. Theoretically perhaps solid hydrogen staged booster rockets could do it, given how much thrust they give, but maybe even that is too much.

What I want to know is, what is the upper mass ton limit that you can lift to orbit with pure metallic hydrogen, assuming you had engines that would'nt melt?

Also what is the upper ton limit on what you can launch to orbit using pure fusion without a fission reaction, fission whether through nuclear pulse propulsion or nuclear saltwater rockets, or antimatter propulsion staging rockets?

I believe antimatter will require the least staging for launching the enterprise to orbit, but the exhaust would be gamma ray and other radiation, and I am not sure how safe that would be for the planet. Pure metallic hydroge, being an uber chemical reaction, I do not think leaves radiation hazards in it's wake, just a really hot plume.

Launch and starship service life: Although rocket staging is not often seen in visual scifi, it really is the most efficient way to lift heavy loads to orbit. You can lift more through staging than you can without it, no matter if you're using antimatter or not. So if your goal is to lift massive ground built starships into orbit, staging is the way to go. Landing is not ever going to happen unless the ship is light enough and has the fuel reserves to do so. In that sense, any thing you launch into space that massive is a resource you will not get back. Overtime I think the ship's radioactive protection would probably be defeated by cosmic rays, (unless you have 6 foot thick walls on your ship) meaning you would either have to retrofit it in orbit or retire it. Retiring it would be a massive waste of resources, unless you dissassembled it and shuttled it piece by piece back to the surface of a planet.

[RocketSquid]

There is no upper limit from a mathematical perspective. You can just keep adding more boosters and stages. From a practical perspective, it depends on the size of the launch area.

[Ultimate Steve]

1 hour ago, RocketSquid said:

There is no upper limit from a mathematical perspective. You can just keep adding more boosters and stages. From a practical perspective, it depends on the size of the launch area.

Also, you're structurally limited. If your rocket is too big/dense, it will collapse into a black hole.

[magnemoe]

1 hour ago, RocketSquid said:

There is no upper limit from a mathematical perspective. You can just keep adding more boosters and stages. From a practical perspective, it depends on the size of the launch area.

Yes you can just scale up, scaling up let the square cube law work your way. Think sea dragon was 500 ton, you could build that far larger. 
Downside is development cost, an larger rocket is more expensive to develop, build and test, you will also have an very limited numbers of payloads who require an so large rocket. 

[Spacescifi]

42 minutes ago, magnemoe said:

Yes you can just scale up, scaling up let the square cube law work your way. Think sea dragon was 500 ton, you could build that far larger. 
Downside is development cost, an larger rocket is more expensive to develop, build and test, you will also have an very limited numbers of payloads who require an so large rocket. 

 

 

Wow. I assumed enough weight would render lift off impossible.

But that is ONLY so without staging as staging makes you leave used rocket mass behind so the ship becomes ligjter as it ascends.

The irony is that with big enough staged rockets and sufficient thrust, the earth itself could be moved!

[DDE]

39 minutes ago, Spacescifi said:

Wow. I assumed enough weight would render lift off impossible.

But that is ONLY so without staging as staging makes you leave used rocket mass behind so the ship becomes ligjter as it ascends.

The irony is that with big enough staged rockets and sufficient thrust, the earth itself could be moved!

Any amount of weight can be added by sufficient amounts of thrust. Indeed, the square-cube law means rockets scale up quite nicely.

The Earth can be easily moved with continent-sized thrusters firing bits of said continents. The Sun is even easier, with some math having been done for a modestly-sized (a few kilometers long) gamma-ray laser that would induce enormous CMEs.

[Spacescifi]

56 minutes ago, DDE said:

Any amount of weight can be added by sufficient amounts of thrust. Indeed, the square-cube law means rockets scale up quite nicely.

The Earth can be easily moved with continent-sized thrusters firing bits of said continents. The Sun is even easier, with some math having been done for a modestly-sized (a few kilometers long) gamma-ray laser that would induce enormous CMEs.

 

Wow. Although I still think you would need ridiculoulsly high energy levels on that gamma ray laser. In other words, I think more energy than Earth can provide.

A few jupiter mass equivalents of gamma laser blasts would probably work.

Come to think of it... I like both your continent propellant rocket idea and the corona mass ejection star rocket idea.

These ideas are so basic in practice that virtually any scifi faction with starships capable of warp or FTL should be capable of these feats if they were willing to invest the time and resources to do so.

I do not know of any good reason to move a planet other than to move it closer or farther from the sun or a doomsday weapon. Moving a planet is problematic since by the time you have moved it far enough by ejecting continents, you may have less gravity and may even lose the atmosphere needed for life.

Moving a star definitely seems purely like a doomsday thing. Oh you wanna make war with me? I will cause CME'S and bring an ENTIRE sun into your solar system! Sure it may take a century or so (accelerating a star up to relativistic speeds will be anything but easy, but hey, the nearest star is only about 4 LY), but wow, that is some WMD on steroids.

Thanks for the idea, I may use it in my own scifi work someday. I wonder if anyone has already? No stories I am aware of.... good ideas!

 

Edited May 17, 2019 by Spacescifi

[magnemoe]

2 hours ago, Spacescifi said:

Wow. I assumed enough weight would render lift off impossible.

But that is ONLY so without staging as staging makes you leave used rocket mass behind so the ship becomes ligjter as it ascends.

The irony is that with big enough staged rockets and sufficient thrust, the earth itself could be moved!

The trust area in the bottom will only scale with x^2 while volume scales x^3 but this can be solved by having the rocket wider or cone shaped. 
As surface area scales x^2 results in that the body becomes an less and less faction of weight, air resistance become less and less of an factor to but that is already small on large rockets

Sea dragon is the largest rocket to ever been designed on paper. You could buid it larger but would probably needed to use more engines as engines has limits on how big they can be build in practice.

[Flibble]

3 hours ago, Spacescifi said:

Wow. Although I still think you would need ridiculoulsly high energy levels on that gamma ray laser. In other words, I think more energy than Earth can provide.

A few jupiter mass equivalents of gamma laser blasts would probably work.

I don't think you need to add that much energy to the Sun, you just destabilise it a bit and cause it to eject its own mass.

[wumpus]

2 hours ago, magnemoe said:

The trust area in the bottom will only scale with x^2 while volume scales x^3 but this can be solved by having the rocket wider or cone shaped. 
As surface area scales x^2 results in that the body becomes an less and less faction of weight, air resistance become less and less of an factor to but that is already small on large rockets

Sea dragon is the largest rocket to ever been designed on paper. You could buid it larger but would probably needed to use more engines as engines has limits on how big they can be build in practice.

This thread needs more Orion.

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000096503.pdf

(no idea why the pdf is so bad on an allegedly 2000 paper (that references at least one other 2000 paper).

http://www.projectrho.com/public_html/rocket/enginelist.php

https://www.amazon.com/Project-Orion-Story-Atomic-Spaceship/dp/0805059857

Orion was beyond kerbal.  It was basically E.E. doc Smith level rocketry that could be built with 1960s tech (quite possibly easier than now, you could probably find welders familiar with welding battleships together during the 1960s.  That's a skill that would come in handy in building an Orion).

[DDE]

5 hours ago, Spacescifi said:

Although I still think you would need ridiculoulsly high energy levels on that gamma ray laser.

Apparently a mile-long self-critical fission reactor could do the trick.

5 hours ago, Spacescifi said:

Moving a star definitely seems purely like a doomsday thing.

Nope. How are you going to keep it in the middle of a Dyson shell, or guide stars into a deconstructor facility?

5 hours ago, Spacescifi said:

These ideas are so basic in practice that virtually any scifi faction with starships capable of warp or FTL should be capable of these feats if they were willing to invest the time and resources to do so.

They can’t. Most don’t have widespread bioengineering, or sensors that can see past 100 m, or ships that move faster than 10 m/s 

[RocketSquid]

5 hours ago, Spacescifi said:

 

Wow. Although I still think you would need ridiculoulsly high energy levels on that gamma ray laser. In other words, I think more energy than Earth can provide.

A few jupiter mass equivalents of gamma laser blasts would probably work.

Come to think of it... I like both your continent propellant rocket idea and the corona mass ejection star rocket idea.

These ideas are so basic in practice that virtually any scifi faction with starships capable of warp or FTL should be capable of these feats if they were willing to invest the time and resources to do so.

I do not know of any good reason to move a planet other than to move it closer or farther from the sun or a doomsday weapon. Moving a planet is problematic since by the time you have moved it far enough by ejecting continents, you may have less gravity and may even lose the atmosphere needed for life.

Moving a star definitely seems purely like a doomsday thing. Oh you wanna make war with me? I will cause CME'S and bring an ENTIRE sun into your solar system! Sure it may take a century or so (accelerating a star up to relativistic speeds will be anything but easy, but hey, the nearest star is only about 4 LY), but wow, that is some WMD on steroids.

Thanks for the idea, I may use it in my own scifi work someday. I wonder if anyone has already? No stories I am aware of.... good ideas!

 

And a more advanced civilization could produce a shkadov thruster, using a gargantuan mirror to make the star’s light output asymmetrical and turning the whole thing into a slow and steady photon drive, then use the CME thrusters for fast (from the perspective of a multiple million year project) maneuvering. 

[Thor Wotansen]

The easiest way to move a planet is a gravity tractor, which would be fairly trivial, since we have a nice convenient moon.  All we need is a nice beefy fusion torch on the front and back of the moon and we just fire it for a day when it's in line with Earth's prograde direction.