To Mars By A-Bomb

[Crush]

Or we get the Alcubierre Drive working, and suddenly stars will be weeks and months away, not centuries and millenias. I don't know about you, guys - but i have a good feeling about this

Sorry to rain on your parade, but the Alcubierre drive is unlikely to ever exist. It requires large amounts of matter with negative mass. Most accepted models of physics don't even allow particles with negative mass to exist, and in those where its existence is possible, it is in form of particles which do not interact with normal matter and thus are impossible to collect and utilize.

Edited May 6, 2013 by Crush

[Holo]

Sending up our entire nuclear arsenal into space and nuking it repeatedly?

No way that could possibly go wrong.

Nope, none at all.

[Rune]

I'd rather wait another hundred years to get to mars safely than do it in 20 years and risk an EMP over earth...

I'd rather work out the science so there's no EMP. And we could have gotten there 20, or 40 years ago with this thing. Not that I would advocate using an Orion for going to Mars, there are better alternatives for such a short trip.

Sending up our entire nuclear arsenal into space and nuking it repeatedly?

No way that could possibly go wrong.

Nope, none at all.

Have you bothered examining the concept before jumping to a sensationalist conclusion? You might be surprised. For example, you don't want to use standard nukes as pulse units.

Rune. And of course, nuclear stuff glows green in the dark.

Edited May 6, 2013 by Rune

[Holo]

I know, I was exaggerating, but still. If that thing crashes...

[Rune]

I know, I was exaggerating, but still. If that thing crashes...

...then it's safer than any other nuclear drive, since making a bomb go off is an incredibly difficult thing requiring very precise mechanisms and timing. An operating reactor, on the other hand, can spill a lot of harmful stuff if it's blown up. Like say, the one you would need to operate a VASIMIR for a manned vessel, to get a much lower isp and lots of orders of magnitude less thrust/weight ratios.

[Spanier]

Project Daedalus ftw!

It's "just" about 500m high and has an equivalnet diameter, it's a two stage fusion vessel, that could reach Barnard's star within 50 years with it's top-speed exceeding 12%c.

Problem: it needs gargantuan masses of He3

[Rune]

Project Daedalus ftw!

It's "just" about 500m high and has an equivalnet diameter, it's a two stage fusion vessel, that could reach Barnard's star within 50 years with it's top-speed exceeding 12%c.

Problem: it needs gargantuan masses of He3

Yeah, and someone figuring out how to make inertial confinement fusion with lasers work. The last results from NIF are pretty much discouraging form what I've heard. I found this recently, however. If you buy what they are selling, it sounds neat and close to work:

http://msnwllc.com/Papers/FDR_JPC_2012.pdf

Rune. Fusion is turning out to be hard.

[nyrath]

Project Daedalus ftw!

It's "just" about 500m high and has an equivalnet diameter, it's a two stage fusion vessel, that could reach Barnard's star within 50 years with it's top-speed exceeding 12%c.)

Yes, and it has just enough fuel to delta-V to 12%c. It does not have any fuel to slow down.

So it goes streaking through the Barnard's Star system at 12%c. Take your pictures and get your scientific readings fast, you don't have a long time.

Yeah, and someone figuring out how to make inertial confinement fusion with lasers work. The last results from NIF are pretty much discouraging form what I've heard. I found this recently, however. If you buy what they are selling, it sounds neat and close to work:

http://msnwllc.com/Papers/FDR_JPC_2012.pdf.

Yes, magneto-inertial-fusion. So crazy it just might work. It is sort of a hybrid approach combining inertial confinement with magnetic confinement.

http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Inertial_Confinement--Magneto_Inertial_Fusion

As is often the case, it has fantastic Isp (like 5,000 seconds) but pathetic thrust (like 14 kiloNewtons).

What is interesting is that you can use it on Earth for electrical power generation. Just direct the exhaust through a magnetiohydrodynamic generatior, and you have a fusion power reactor.

[Rune]

Hey, Nyrath, while we are at it, I always wondered why you didn't have Bussard's fusion engine concept up on your page. You have something on hydrogen-boron fusion, I know, but honestly this is a way cooler way to go about it. Basically, they use one Polywell reactor to directly drive relativistic electron beams to heat the propellant (which is simple, since the output of a Polywell is extremely high voltage current). Here's the paper, well worth a read, especially the QED/ARC SSTO section (payload fraction 0.14 with dry weight fraction 0.48, just so you get an idea):

http://www.askmar.com/Fusion_files/From%20SSTO%20to%20Saturns%20Moons.pdf

As the title says, from SSTO to Saturn's moons. Sounds like a sci-fi wet dream. Seriously, they even consider airbreathing versions, and the lower isp's are regeneratively cooled, so no radiators...

Rune. If Polywell pans out, of course.

Edited May 8, 2013 by Rune

[nyrath]

Hey, Nyrath, while we are at it, I always wondered why you didn't have Bussard's fusion engine concept up on your page. You have something on hydrogen-boron fusion, I know, but honestly this is a way cooler way to go about it. Basically, they use one Polywell reactor to directly drive relativistic electron beams to heat the propellant (which is simple, since the output of a Polywell is extremely high voltage current).

I was hesitant since there is still some question about the viability of the Polywell fusor.

[Rune]

I was hesitant since there is still some question about the viability of the Polywell fusor.

Well, there are a lot of questions about pretty much every hypothetical engine you have in there. Some are even 100% ass-pulling by sci-fi authors, as you well acknowledge in their entries. And didn't you use to have an entry on the (proven) impossible Bussard ramjet? So I don't think that is a good enough reason!

On the other hand, I'm glad to see it didn't go under your radar.

Rune. On the third hand, it's a shame I couldn't show you something you hadn't seen already ^^'

[nyrath]

Sometimes it is a case of so many propulsion systems, so little time.

You should see the gigabytes of data in my "to be added" folders.

[Rune]

Sometimes it is a case of so many propulsion systems, so little time.

You should see the gigabytes of data in my "to be added" folders.

That sounds more plausible . Anyway, your site, your say. Don't take it as a complaint! I will still love it.

Rune. I think I would like to see them indeed.

[Drunken Hobo]

You gotta love a technology from the 50's that is still the best bet for interstellar travel.

To be fair, the best way to get around Earth still uses 1930s technology!

How exactly does nuclear pulse propulsion work anyway? Most of the damage from a nuclear bomb comes from the movement of the air, but in space there's obviously no medium to transfer the energy. Is it "just" the radiation pressure from the blast, or is the bomb wrapped in a medium that is vapourised to provide usable thrust?

[nyrath]

How exactly does nuclear pulse propulsion work anyway? Most of the damage from a nuclear bomb comes from the movement of the air, but in space there's obviously no medium to transfer the energy. Is it "just" the radiation pressure from the blast, or is the bomb wrapped in a medium that is vapourised to provide usable thrust?

http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Orion

It is a nuclear shaped charge.

Most of the _blast_ from a nuclear bomb comes from the movement of the air. A nuclear detonation is a huge burst of x-rays. In an atmosphere, it heats the air, creating blast.

In the nuclear pulse unit, allowing the x-rays to radiate in all directions would waste 90% of the bomb's energy, only 10% would hit the pusher plate. So the bomb is encased in a thick shell of x-ray opaque material with a hole oriented in the direction of the pusher plate. On top of the hole is a channel filler which converts the x-rays into heat. On top of the channel filler is a slab of propellant. The propellant is vaporized by the heat and projected at the pusher plate.

By using the shaped charge, about 85% of the bomb's energy hits the pusher plate.

[Drunken Hobo]

http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Orion

It is a nuclear shaped charge.

Most of the _blast_ from a nuclear bomb comes from the movement of the air. A nuclear detonation is a huge burst of x-rays. In an atmosphere, it heats the air, creating blast.

In the nuclear pulse unit, allowing the x-rays to radiate in all directions would waste 90% of the bomb's energy, only 10% would hit the pusher plate. So the bomb is encased in a thick shell of x-ray opaque material with a hole oriented in the direction of the pusher plate. On top of the hole is a channel filler which converts the x-rays into heat. On top of the channel filler is a slab of propellant. The propellant is vaporized by the heat and projected at the pusher plate.

By using the shaped charge, about 85% of the bomb's energy hits the pusher plate.

Interesting stuff. I wondered how the directional casing would survive the blast. The obvious answer - it doesn't! It only needs to survive for a few ms to be effective.

[nyrath]

Interesting stuff. I wondered how the directional casing would survive the blast. The obvious answer - it doesn't! It only needs to survive for a few ms to be effective.

Got it in one. The casing does not survive, but it survives long enough.

Interesting stuff? Heh, you don't know the half of it.

The Orion propulsion unit is a nuclear shaped charge optimized for propulsion.

What if you optimized it as a weapon?

You'd have the dreaded Casaba Howitzer, a directed energy weapon that shoots spears of nuclear flame.

http://www.projectrho.com/public_html/rocket/spacegunconvent.php#id--Nukes_In_Space--Nuclear_Shaped_Charges

I'd like to find more information about this but the blasted thing is still classified after all these years.

[Temstar]

Awww yes the Casaba Howitzer. I bet someone from the air force was looking at how to build a battleship out of Orion and suddenly this lightblub comes on and he just thinks to himself "hang on, we're already shooting little nukes out of the back of this thing, why not load a couple of more and fire them out of the side of the ship at the bad guys?"

[Djsnowboy267]

http://www.youtube.com/watch?v=TOBgPZFFlFY

This is a documentary talking about abandoning the Earth with an interplanetary ship to escape a neutron star headed into our system. It mentions the Orion project at around 19:30

Not sure if somebody has posted this already, I only quickly browsed through to check.