How can I destroy a planet with antimatter?

Question

So I found the base of these pesky rebels on this planet and I am tasked with destroying the planet to eliminate the rebels once and for all. Unfortunately, my death star has malfunctioned and has been rendered totally inoperable.

Now, all I have is effectively an unlimited supply of antimatter (which is contained within a permanent magnetosphere within the core of the death star), but no weapon by which to use it and no matter by which to retrieve it without building something.

I can harvest the parts from the death star (which my boss built as an actual clone of the death star from the Galactic Empire from a different universe; but that's another story) but due to the critical failure of the project since my boss obviously had no idea what he was doing when he built this thing, there are no electronic parts and there is no way to actually use any electronic parts, weapons, or any other electrical equipment.

Since there are no electronics, we are also stranded here in space hanging above this planet. I have to destroy this planet before my boss arrives because he's surely to blame it all on me, and also there is a risk those rebels will blow us up too if we don't get them first.

Unlike the other universe which we don't actually have access to, our universe has no magical [force]es, so I can only use science and the laws of physics. I have no process for which to manufacture silicone or any comparable material for electronics, so no electronics are available and no way to make any electronics.

However, there is a fully mechanical particle accelerator on board which is still functional (it's an advanced futuristic prototype requiring no electricity, around the circumference of the death star); as well as plenty of chemicals of every type, so chemical reactions are also possible. But the failure prevented any electronics and there is a permanent gravity EMP surrounding the death star caused by the failure, preventing any electronics from working or flying.

Keep in mind we can't deliver a physical payload since the rebels will see it coming and we have no force field to protect us, they'll kill us before we shoot anything at them. Gravity wells? Black holes? We need a way to covertly destroy the planet without shooting anything at them.

How can I destroy this planet and eradicate these rebels once and for all using my antimatter and any harvested materials or mechanics from this death star replica?

Answer 1

Ditch the Death Star.

1. See about your own escape and that of crew.

2. "Hanging above planet" is a temporary situation unless you are in orbit. If you are not in orbit, you are rapidly proceeding towards the surface of the planet.

3. If you are in orbit, decelerate. You got there somehow. Unget there.

4. The Death Star will proceed towards the surface of the planet.

5. Impact with the planet will probably disrupt the containment of the antimatter, which will begin to react with its surroundings, then the atmosphere.

6. The interaction between antimatter and matter will produce large amounts of heat. Heated matter will expand, throwing unreacted antimatter about. The reaction will accelerate.

7. The atmosphere will heat up to the point of sterilizing the planet.

8. Once the reaction has exhausted itself, it may be possible to return to the planet once it has cooled down. It may take a while.

Answer 2

The answer lies in the containment device - magnetosphere. This means it can be rolled.

Essentially, what you have to do is get your crew to create a 'tunnel' in the ship leading between the magnetosphere and the back of the ship. Then you all push. Really hard. You get it to the back, give it an extra shove, and it's loose from the ship.

If you've given it a large enough shove, you've reduced it's momentum sufficiently that it will now be caught by the gravity well and will de-orbit. (It needs to be a really BIG shove, especially if this is a LOT of antimatter.)

Ultimately, you then sit in orbit until your boss sends the auto club over to tow your busted ship out of orbit, or until the planet explodes, baking you in gamma radiation before the loss of mass flings you out of your orbit into the sun / another planet / open space.

Ultimately, this entire scenario is a really good cautionary tale as to why you shouldn't let your death stars be built by the lowest bidders.

Answer 3

A bomb will do the trick. The gravitational binding energy of a planet is .6 times the gravitational constant times the square of the mass, divided by the radius. So, if we have an planet with about the same mass and radius as Earth, it would require an explosion with an energy of at least 2.2510^32 J. And as an antimatter bomb would be 100% efficient at turning mass into energy, the amount of antimatter that needs to react with matter would be 1.2510^15 kg, which is the mass of several Mount Everests. We will assume that the antimatter is antiosmium, which has a density of 22562 kg/m^3, so it'd be packed into a space of 55.3 km^3.

If it was a perfect sphere, we'd have a ball with a radius of 2.36 km. A head-on collision of an impact velocity of 17 km/s would release 1.81*10^23 J, which is more than enough to cause an extinction event. And that's without getting into the antimatter. With the protective shell, there will be a devastating impact, but as the shell breaks, the antimatter breaks loose and annihilates, releasing an planet-shattering explosion.

Answer 4

Rethink the problem--destroying a planet you are orbiting is suicide. It's also total overkill--the objective is to kill the rebels and that doesn't take anywhere near the energy.

You give no indication of what form your antimatter is in but it's pretty clearly contained in some fashion that you can handle it--if it wasn't the failure of all your electronics would mean it destroyed you.

You also don't indicate the power of that accelerator that does work so I will have to consider two cases here.

Just keep taking containers of antimatter, load them into your accelerator and drop them into the atmosphere. Drop enough of it and the surface will become uninhabitable--and since this the base was built on a planet with a habitable biosphere it's not going to be protected. It's shields might keep it from being bombed, they won't stop it from being cooked.

If your accelerator is too wimpy for this add rope. The package of antimatter is swung on the end of the rope so it's going faster.

This will be slow but it will do the job. No guarantee they can't shoot you while you're doing it, but if you can keep lobbing packages of antimatter at them when you're over the horizon they're going to have quite a time finding you to shoot at.