How Much Anti-Matter Would it Take to Move Venus?

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Discussion Overview

The discussion revolves around the hypothetical scenario of using antimatter to alter the orbit of Venus, exploring the feasibility of such an event as a plot device in a science fiction narrative. Participants examine the energy requirements, potential effects of an antimatter explosion, and alternative methods for achieving similar outcomes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that changing Venus's orbit would require millions of tons of antimatter, emphasizing the need to consider both energy and momentum in such calculations.
  • Another participant provides calculations indicating that to match Venus's kinetic energy, approximately 1.7 x 10^16 kg of antimatter would be necessary, noting that much energy would be lost to heat and gamma radiation rather than effective orbital change.
  • Some participants discuss the implications of the explosion's proximity to Venus's surface, suggesting that a significant portion of gamma radiation could transfer momentum to the planet.
  • There is a proposal that other celestial events, such as the passage of a rogue planet or a cosmic string, could serve as alternative plot devices to achieve the desired orbital changes without relying solely on antimatter.
  • Concerns are raised about the effectiveness of nuclear weapons compared to celestial impacts in altering planetary orbits, with references to historical events like the K-T boundary extinction event.
  • One participant suggests that even if an explosion does not directly move Venus, it could indirectly affect its orbit through interactions with other celestial bodies.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of using antimatter for orbital changes, with some supporting the idea while others propose alternative scenarios. The discussion remains unresolved regarding the best approach to achieve the desired narrative outcomes.

Contextual Notes

Participants highlight limitations in their calculations, such as the dependence on specific assumptions about energy transfer and the nature of the explosion. There is also an acknowledgment of the complexities involved in momentum transfer and energy dissipation.

Who May Find This Useful

Writers and creators interested in science fiction, particularly those exploring realistic scientific principles in their narratives, may find the discussion valuable for developing plot devices related to planetary manipulation and antimatter. Additionally, those curious about the physics of celestial mechanics and energy interactions could benefit from the technical insights shared.

Holywar
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im a non-scientifically trained individual, who is toying with the idea of writting a sci-fi novel. I tend to prefer sci-fi that is based on realistic principles, and realistic results as that helps me maintain the "suspension of disbeleif" so key in making a good story.

Ive also always been tremendously supportive of sceintific efforts and the scientific community, so getting a chance to talk to the "eggheads" is pretty cool in and of itself. :)

Anyways, As a plot device, i want a ship, carrying a load of anti-matter to loose containment right inside the atmopshere of Venus, say 80 miles up. I am looking to blow maybe 60% of the cloud cover off the planet, crater it, and push into a slightly ellpiptical orbit, requiring a massive amount of international resources to move the planet correctly or destroy it so that it doesn't screw up the solar system.

Anyways, as a rough estimate how much anti-matter would this take to accomplish, and are there any other effects that such a large explosion would cause that i should be cognacent of?
 
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To change the orbit substantially you need of order millions of tons of antimatter. Calculate the kinetic energy of Venus and you get an idea of the energy needed to change an orbit: a non-negligible fraction of that. Note also that if you don't also change the momentum of Venus, the orbit will also be unchanged.
 
Just to tune in with vanadium, here are some numbers:

energy equivalent of 1kg of mass (which is liberated when half a kg of antimatter reacts with normal matter): 9 10^16 J or 90 PJ. (peta-joule).

Mass of venus: http://en.wikipedia.org/wiki/Venus

5 10^24 kg

orbital velocity of venus: 35000 m/s

kinetic energy of venus: 1/2 m v^2 = 3 10^33 J

This is equivalent to the annihilation of 3 10^33 / 9 10^16 = 3.4 10^16 kg, so you'd need to annihilate half of that (1.7 10^16 kg) of antimatter.

As a reference, the Earth ocean contains about 1.3 10^9 km^3 of water, or 1.3 10^21 kg of water. So you'd need about 1/100000 of the Earth ocean of anti-matter to have something comparable to the kinetic energy of venus. Now, of course, 1% will already have an influence, but don't forget that much energy will not go into "orbit changing" but rather in heat and most in intense gamma radiation. You will get a terrible gamma flash, better do this out of sight (or at least put on strong sunglasses).

So you'd need of the order of a millionth of the Earth's ocean of anti-matter do do your feat...
 
vanesch said:
Now, of course, 1% will already have an influence, but don't forget that much energy will not go into "orbit changing" but rather in heat and most in intense gamma radiation.
If the explosion happens close to the surface of venus, then nearly half the gammas will transfer momentum to the planet. A mass on the order of about 10^19 kg will make a momentum transfer on the order of 1% of venus' orbital momentum.
 
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Holywar said:
im a non-scientifically trained individual, who is toying with the idea of writting a sci-fi novel. I tend to prefer sci-fi that is based on realistic principles, and realistic results as that helps me maintain the "suspension of disbeleif" so key in making a good story.

Ive also always been tremendously supportive of sceintific efforts and the scientific community, so getting a chance to talk to the "eggheads" is pretty cool in and of itself. :)

Anyways, As a plot device, i want a ship, carrying a load of anti-matter to loose containment right inside the atmopshere of Venus, say 80 miles up. I am looking to blow maybe 60% of the cloud cover off the planet, crater it, and push into a slightly ellpiptical orbit, requiring a massive amount of international resources to move the planet correctly or destroy it so that it doesn't screw up the solar system.

Anyways, as a rough estimate how much anti-matter would this take to accomplish, and are there any other effects that such a large explosion would cause that i should be cognacent of?


Is the actual plot device the altered orbit of Venus? If so, then you'd be well served to come up with an alternative, as pointed out by others- antimatter won't cut it.

What if a small black hole goes whinging by? Or a cosmic string sideswipes the planet? Or an Oort cloud/Kuiper belt object comes loose and smacks into Venus?
 
Alternatively, a friend of mine is currently creating a role-playing game in which a rogue planet passes through the Solar System, dissrupting orbits. If you send one of these through your story, you could have it pass close to Venus when Venus is on the far side of the Sun, and no ither planets are near. This, however, will not give you the cratering or loss of cloud-cover (which I'm guessing might be important to your plot, am I right?).
 
Well that was illuminating.

Its interesting that a substance that is to be a hundred times more than powerful nuclear fission by weight is somehow "less" in raw power than say a space rock that smacks into the side of an celestial body. At least in terms of effecting momentum. I could certainly imagine the creation of a nuclear weapon so powerful that it could peterb the planets orbit, but i guess by the reasoning here that would be false.

The main plot device needs to be something that effects the orbit sufficantly and meets a few criteria.

1. It must be man made, or man-caused.
2. It must somehow blow enough atmo-shpere off the planet that it becomes more usable. Not habitable mind you, but enough that it brakes the greenhouse effect to more manageable levels and makes the planet worth utilizing by a Type 1.1 or 1.2 Civilization.
3. This event must have in some way perturbed its orbit in a fashion that requires a massive enginnering effort to eventually correct. It should not be something that results in the death of the planet within say a few months, but could cause problems years down the road.

Maybe a miscalculated mining asteroid moved incorrectly of sufficant size?
 
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Gokul43201 said:
If the explosion happens close to the surface of venus, then nearly half the gammas will transfer momentum to the planet. A mass on the order of about 10^19 kg will make a momentum transfer on the order of 1% of venus' orbital momentum.

Note that you are talking about 10^19 for the momentum balance (I didn't check it, suppose your numbers are right), while I was talking about 10^16 (thousand times less) for the energy balance. 10^19 is 1% of the Earth ocean...
 
Holywar said:
Well that was illuminating.

Its interesting that a substance that is to be a hundred times more than powerful nuclear fission by weight is somehow "less" in raw power than say a space rock that smacks into the side of an celestial body. At least in terms of effecting momentum. I could certainly imagine the creation of a nuclear weapon so powerful that it could peterb the planets orbit, but i guess by the reasoning here that would be false.

Indeed, have a look at the "standard" hypothesis for the K-T boundary extinction (end of the dinosaurs) 65 million years ago: the impact of a meteorite http://en.wikipedia.org/wiki/Alvarez_hypothesis

The impact is estimated to be energetically equivalent to a few million of the most powerfull thermonuclear weapons ever build (Tsar Bombas), and it didn't significantly change the orbit of the earth.

Nukes are peanuts compared to celestial bodies (unless they are celestial bodies themselves, such as supernova).
 
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  • #10
Even if the explosion is not powerfull enough to directly move a planet, it could do it by changing an orbit of another body which would pass near the planet (and causing it to crash into the planet).
Here is an idea: a new minor planet is discovered. It has highly eccentric orbit, which comes as close to the Sun as Venus's. It will pass very close to Venus after some years. Scientists see this as an opportunity to perform some experiments, so they send a spacecraft which attaches itself to the minor planet. However some experiments go wrong and the spacecraft explodes, slight changing the minor planet's orbit: just enough that it crashes into Venus...
 

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