Thread: Ask me about Space

SAO, You little ninja. I'm here typing away at this long post.

Originally Posted by SwordArtOnline

It would just burn up and spread through the sun, so scientists wouldn't do it as there's no scientific benefit from it. If it was possible to send nuclear waste to the sun, it would still be cheaper to bury it in an asteroid thick enough to shield the waste from outside interference, or leave it at a Lagrange point, or in Jupiter. Even ejecting the waste from the solar system probably takes less fuel than throwing it into the Sun. (Source: many hours of Kerbal Space Program )

EDIT: Chart of fuel costs from Earth to various points in the Solar System. Based on these numbers and without using 'gravitational slingshot' maneuvers around Venus and Jupiter to save fuel, sending something from Earth's surface to the Sun takes over 208 km/s delta-V, but ejecting an object from the Solar System takes only 18.15 km/s. That's ~11.5 times more delta-V to send waste into the Sun than to eject it from the solar system, which means a lot more than 11.5 times more fuel (you need more fuel to carry more fuel, so you get diminishing returns). Ejecting something from the Solar System into the great black beyond is a pretty sure way of making sure nobody will look for it or find it.

You'd have to be dealing with something a lot more dangerous than radioactive waste to want to destroy it so thoroughly that throwing it into a star is your only option.

She asked what would happen IF you dropped nuclear waste waste into the sun, not what a pain in the butt (and wallet) it would be TO drop the world's nuclear waste into the sun. But you are 110% Correct, SAO it would be a huge pain financially to do so and a massive engineering challenge. Particularly since nuclear waste is HEAVY elements. (And there's a lot of it.)

But of course, your many hours of Kerbal Space Program would also tell you that you don't sun-dive From earth orbit, you transfer out to a higher orbit around the sun, then burn retrograde there, or use a planetary gravity assist. It takes longer but you use less DV. I don't think it matters what orbit or gravity assist you use though, just getting the entire world's nuclear waste into LEO is gonna be much more effort than its worth just to bury it underneath the salt flats or something.

Originally Posted by SwordArtOnline

It would just burn up and spread through the sun, so scientists wouldn't do it as there's no scientific benefit from it. If it was possible to send nuclear waste to the sun, it would still be cheaper to bury it in an asteroid thick enough to shield the waste from outside interference, or leave it at a Lagrange point, or in Jupiter. Even ejecting the waste from the solar system probably takes less fuel than throwing it into the Sun. (Source: many hours of Kerbal Space Program )

EDIT: Chart of fuel costs from Earth to various points in the Solar System. Based on these numbers and without using 'gravitational slingshot' maneuvers around Venus and Jupiter to save fuel, sending something from Earth's surface to the Sun takes over 208 km/s delta-V, but ejecting an object from the Solar System takes only 18.15 km/s. That's ~11.5 times more delta-V to send waste into the Sun than to eject it from the solar system, which means a lot more than 11.5 times more fuel (you need more fuel to carry more fuel, so you get diminishing returns). Ejecting something from the Solar System into the great black beyond is a pretty sure way of making sure nobody will look for it or find it.

You'd have to be dealing with something a lot more dangerous than radioactive waste to want to destroy it so thoroughly that throwing it into a star is your only option.

Originally Posted by JadeGreen

SAO, You little ninja. I'm here typing away at this long post.



She asked what would happen IF you dropped nuclear waste waste into the sun, not what a pain in the butt (and wallet) it would be TO drop the world's nuclear waste into the sun. But you are 110% Correct, SAO it would be a huge pain financially to do so and a massive engineering challenge. Particularly since nuclear waste is HEAVY elements. (And there's a lot of it.)

But of course, your many hours of Kerbal Space Program would also tell you that you don't sun-dive From earth orbit, you transfer out to a higher orbit around the sun, then burn retrograde there, or use a planetary gravity assist. It takes longer but you use less DV. I don't think it matters what orbit or gravity assist you use though, just getting the entire world's nuclear waste into LEO is gonna be much more effort than its worth just to bury it underneath the salt flats or something.

Wow.You guys sure do know a lot. I didn't know playing that game could teach you that much.I still haven't tried it from the time I found out about it. >.>" But thanks for answering my question. ^^

Ah, it was late at night (like it is now) and I completelymessed up. The numbers are just wrong - as long as you don't mind hitting the Sun at 616 km/s, even a simple Hohmann transfer to the Sun takes 38km/s from Earth surface, not 208km/s delta-V (which would circularize your orbit over the Sun).

Originally Posted by JadeGreen

you transfer out to a higher orbit around the sun, then burn retrograde there, or use a planetary gravity assist. It takes longer but you use less DV.

I totally forgot about the bi-elliptic transfer - if you do a bi-elliptic transfer up to Neptune's orbit and back down it comes in under 22.7 km/s, but it takes about 62 years to reach aphelion and a few more decades to come back to the Sun. The figure for ejecting from the Solar System is 18.15 km/s. You can get the dV cost for sundiving down close to 18.15 km/s by going out even further, provided that your spacecraft survives long enough to make a burn at the aphelion.

So, assuming our spacecraft can survive for 62 years, it's only 25% more expensive to sundive than to eject from the Solar System, not orders of magnitude as I originally said. That's still completely ignoring gravity assists.

That's what I get for trying to be smart on the Internet.