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Why the sun is a poor dumping ground for nuclear waste (2010)

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Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#61

Post by joe_the_user »

leni536 wrote: post #32

> To reach the Sun you need to subtract 100 percent of Earth’s orbital velocity; to reach solar escape velocity you need only add 41 percent to it. You could send the waste with near solar escape velocity to travel on a really long ellipsis trajectory, at the furthest point you can get rid of the remaining kinetic energy with minimal fuel and let the waste fall back straight into the Sun. Subtracting Earth's orbital…

Your "trick" doesn't change any of the conservation of angular momentum considerations in the article.

To "get rid of the remaining kinetic energy" would only result in the object getting escape velocity relative to earth. The object would never have "stopped" relative to it's orbit around the sun but even at it's further point would be traveling with fairly close to the same angular velocity as the earth (as described in the article etc).

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#62

Post by notahacker »

aqme28 wrote: post #24

I always thought the biggest reason was that if a rocket carrying nuclear waste exploded in our atmosphere, it would be catastrophic. It's a lot less risky to just bury it underground and pray it never leaks.

Also cheaper.

The author acknowledges the existence of that argument, but then insists that the "real objection" is difficulties in orbital trajectories. I'll believe that's the real objection if we start considering sending nuclear waste on a comparably simple orbital journey into outer space.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#63

Post by cryptoz »

MichaelCrawford wrote: post #52

Sometimes rockets fail. I mean like they blow up on launch. When the Shuttle was first commissioned, my concern at the time was that America's most reliable rocket was the delta, which failed every thirty launches. When it's nuclear waste, it's not good enough just to have launch insurance.

> When the Shuttle was first commissioned, my concern at the time was that America's most reliable rocket was the delta, which failed every thirty launches.

You were right to be concerned. The shuttle had "a 40% vehicular failure rate and a flight failure rate of 1.5%", killing more people than any other space vehicle. [1]

[1] http://www.forbes.com/sites/carolpinchefsky/2012/04/18/5-hor...

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#65

Post by CompelTechnic »

joe_the_user wrote: post #61
leni536 wrote: post #32

> To reach the Sun you need to subtract 100 percent of Earth’s orbital velocity; to reach solar escape velocity you need only add 41 percent to it. You could send the waste with near solar escape velocity to travel on a really long ellipsis trajectory, at the furthest point you can get rid of the remaining kinetic energy with minimal fuel and let the waste fall back straight into the Sun. Subtracting Earth's orbital…

Your "trick" doesn't change any of the conservation of angular momentum considerations in the article. To "get rid of the remaining kinetic energy" would only result in the object getting escape velocity relative to earth. The object would never have "stopped" relative to it's orbit around the sun but even at it's further point would be traveling with fairly close to the same angular velocity as the earth (as describ…

I'm about 80% sure leni536 is right, from playing Kerbal Space Program.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#66

Post by joe_the_user »

kavalec wrote: post #41

Use the Jules Verne solution: a cannon. A solar powered mass-driver could sling a steady stream of pellets from Earth orbit into Solar non-orbit using existing technology. That being said, burying it deep near the the start of a plate subduction zone makes at least as much sense.

What does "Solar non-orbit" mean?

What would happen, if you managed to make sure all this stuff got escape velocity, is you would wind-up with a bunch of junk (literally) in an orbit around the sun that would inherently pass through Earth's orbit - as long as it doesn't have solar escape velocity, once a thing is moving on pure momentum, it is in orbit and since the orbit fairly closely an ellipse so the object will return. As the article mentions, probably not when the earth return to the point. But if you keep throwing stuff "out there", the chances of a return are naturally going to increase.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#67

Post by benjoffe »

joe_the_user wrote: post #61
leni536 wrote: post #32

> To reach the Sun you need to subtract 100 percent of Earth’s orbital velocity; to reach solar escape velocity you need only add 41 percent to it. You could send the waste with near solar escape velocity to travel on a really long ellipsis trajectory, at the furthest point you can get rid of the remaining kinetic energy with minimal fuel and let the waste fall back straight into the Sun. Subtracting Earth's orbital…

Your "trick" doesn't change any of the conservation of angular momentum considerations in the article. To "get rid of the remaining kinetic energy" would only result in the object getting escape velocity relative to earth. The object would never have "stopped" relative to it's orbit around the sun but even at it's further point would be traveling with fairly close to the same angular velocity as the earth (as describ…

That "trick" would indeed work and is a well known orbital manoeuvre: http://en.wikipedia.org/wiki/Bi-elliptic_transfer (without the final circularising burn).

This manoeuvre would be preferable to the article's alternative (a Hohmann transfer reducing periapsis to the sun's radius without the final circularising burn) in all cases where the initial semi-major axis (relative to the sun) is roughly greater than 11.94 solar radii (ignoring minor factors that make this case slightly different to the wikipedia example).

edit: to make it clear, I'm talking about a heliocentric bi-elliptic transfer after Earth escape, where the initial orbit is equivalent to Earth's orbit, and the final inner orbit can be imagined as one scraping the surface of the sun, but since the sun would destroy the craft, the final circularising burn is not required (in sloppy terms: hitting the sun on the edge would be easier than hitting it straight on).

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#68

Post by tsotha »

iwwr wrote: post #55

It could be much lower than that if you take roundabout trajectories with gravity assists from Earth, Venus and Mercury. Not having to establish orbit is definitely a plus. Besides, nuclear waste is still mostly unburned fuel which could be reprocessed and burned for power in special reactors.

>Besides, nuclear waste is still mostly unburned fuel which could be reprocessed and burned for power in special reactors.

That was my reaction. Future generations will want to use that stuff for fuel. There's no reason to launch it into space.

Re: Why the sun is a poor dumping ground for nuclear waste (2010)

#70

Post by teraflop »

benjoffe wrote: post #67
joe_the_user wrote: post #61

Earlier quoted context omitted.

Your "trick" doesn't change any of the conservation of angular momentum considerations in the article. To "get rid of the remaining kinetic energy" would only result in the object getting escape velocity relative to earth. The object would never have "stopped" relative to it's orbit around the sun but even at it's further point would be traveling with fairly close to the same angular velocity as the earth (as describ…

That "trick" would indeed work and is a well known orbital manoeuvre: http://en.wikipedia.org/wiki/Bi-elliptic_transfer (without the final circularising burn). This manoeuvre would be preferable to the article's alternative (a Hohmann transfer reducing periapsis to the sun's radius without the final circularising burn) in all cases where the initial semi-major axis (relative to the sun) is roughly greater than 11.94…

The downside, of course, is that your nuclear waste spends an awfully long time in an orbit that crosses, or at least passes very close to, Earth's. Better not lose control of your rocket, or you'll have a politically inconvenient situation on your hands.
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