Can We Launch Nuclear Waste Into the Sun?

When I look at the Sun, I don’t see a warm life-giving orb, nourishing all living creatures here on Earth. No, I see that fiery ball as a cosmic garbage compactor. A place I can dump all my household garbage, to make room for new impulse purchases.

I mean, the Sun is right there, not doing anything right? It’s hotter than any garbage incinerator, and it’s the gravitational well at the heart of the Solar System. Get me a rocket, let’s blast that waste into oblivion.

Okay, I suspect it’s going to get expensive, so let’s just start with the worst garbage on Earth: nuclear waste. You know, the byproduct of nuclear reactors that generate electricity for many parts of the world. This stuff is highly toxic and it’s going to be around for hundreds of thousands of years.

It’s also pretty dense, maybe it does make sense to get this stuff off Earth and into the Sun? Let’s run the numbers.

Nuclear waste, or radioactive waste, of course, is anything leftover material that still has radioactivity. For the most part, we get this as the leftover material from nuclear power reactors, but it’s also generated by hospitals, and nuclear weapons manufacturing. We’ve got leftover nuclear waste from uranium mining, radium processing, and various civil and military research projects.

Inside this geometric is a demolished uranium mill and its radioactive tailings. Credit: U.S. Department of Energy

For example, when you mine uranium from the ground, you get leftover radium and radioactive rock, soil, and even the water. When you power a nuclear reactor, the spent fuel rods are still highly radioactive and dangerous. In the United States alone, there are hundreds of different sites which are heavily contaminated, over thousands of acres.

According to the World Nuclear Association, OPEC nations generate 300 million tonnes of toxic waste every year. We’re talking about poisonous chemicals, medical waste, coal dust. Really anything that you don’t want anywhere near you, or inside you.

Just to give you a sense of scale, that’s a cube of toxic poisons nearly a kilometer to a side, assuming the stuff is a little more dense than water.

Out of this, only 97,000 tonnes of nuclear waste is generated across the planet every year. This is radioactive wastes of all types. That’s only .03% of all the toxic waste.

But for the purpose of our calculations, I’m going to zero in on the most toxic, most radioactive material we’re dealing with: the high-level waste produced by nuclear reactors. Now we’re merely talking about 12,000 tonnes per year, or 12% of the nuclear waste showing up on our planet every year.

Now, let’s look at launch costs. Most rocket companies are going to charge you $10,000 to $20,000 per kilogram to blast a payload into Low Earth Orbit. The best deal on the market right now is SpaceX at around $4,000 USD per kilogram. And if they get the Falcon Heavy flying this year, it could bring the price down to around $2,500 per kilogram.

If all we wanted to do was blast all this waste into Low Earth Orbit, the calculations are pretty simple. 12,000 tonnes is 12 million kilograms. Multiply that by $2,500 per kilogram, and you get 30 billion dollars. You’re looking at 240 Falcon Heavy launches per year. Almost a launch every single day carrying a payload of high-level nuclear waste. Out of sight, out of mind.

SpaceX Falcon Heavy rocket poised for launch from the Kennedy Space Center in Florida in this updated artists concept. Credit: SpaceX

That’s a lot of money, but in theory, the world could afford it if they wanted to stop having wars, or something. If they wanted to blast off all the nuclear waste, it would be more like 250 billion. Again. An incomprehensible amount of money, but still within the realm of possibility, assuming that SpaceX gets the Falcon Heavy launching, lofting payloads of nuclear waste 50 tonnes at a time.

But this is Low Earth Orbit, and we don’t want to go there. Anything in LEO still experiences friction from the Earth’s atmosphere, and eventually it’s going to return back to Earth. Imagine regular meteor showers of highly radioactive plutonium. That would be bad.

It would be more safer to launch this stuff into Geostationary Orbit, where the television satellites are broadcasting from. Material in this orbit can be expected to hang around for a long long time.

You’re looking at twice the price to blast off to GEO, so go ahead and double your costs to put that stuff safely out into space. 60 billion dollars for high-level waste. 500 billion for all the nuclear waste.

I’m sure SpaceX will give you a volume discount. And there might be smarter orbits where the waste has totally decayed into something safer by the time it re-enters the Earth’s atmosphere. What I’m saying is, there might be some cost savings.

Let’s say we’ve run all these numbers, and the cost is still worth it. But here’s the problem, rockets fail on a regular basis. They explode on the launch pad, or on their way to orbit. One bad explosion could spray highly toxic plutonium across a huge swath of the planet.

SpaceX Falcon 9 rocket moments after catastrophic explosion destroys the rocket and Amos-6 Israeli satellite payload at launch pad 40 at Cape Canaveral Air Force Station, FL, on Sept. 1, 2016. Credit: USLaunchReport

For one rocket, there’s a pretty low risk. Rockets are about 95% reliable, which means that 1 in 20 is going to fail somehow. If you’re only launching 240 rockets, you’re looking at 12 failure, some of which will be detonations on the launch pad, or explosions at a high altitude. At that rate, we’re guaranteed that it’ll always be cloudy with a chance of plutonium rain somewhere on Earth.

If having thousands of tonnes of nuclear waste hanging over your head makes you nervous, then you’re going to want to hear about more, permanent options. Let’s crash that stuff into the Sun.

It turns out, blasting it into the Sun is much much more expensive. Here’s why: You’d think that just blasting your waste into space means that it would just fall into the Sun, but your waste is still orbiting the Sun at the Earth’s velocity – 30 m/s sideways.

In order to actually get it to drop into the Sun, you need to cancel out the orbital velocity. In other words, you need to give your rocket about 31.7 m/s in velocity, to account for the atmosphere drag of Earth, and then cancel out the orbital velocity.

NASA’s New Horizons spacecraft needed 16.1 m/s to reach Pluto, so you’re talking about double the velocity.

To be fair, New Horizons and other spacecraft use gravitational slingshots to steal velocity from Jupiter and other planets, so it’s possible you could perform some complicated trajectory sweeping past the various planets to get the change in velocity you need. I haven’t done the math, but let’s just assume, there could be savings.

If you don’t cancel out that motion, your nuclear waste is going to just orbit the Sun forever, like an asteroid of garbage.

There’s another path you could take. Instead of trying to drop down into the Sun, you fly outwards until you’ve almost escaped the pull of the Sun. Where the angular momentum, that sideways motion, is almost zero. Cancel that out with a little thrust, and then let the Sun’s gravity pull your waste back down to its doom.

It’ll take hundreds or even thousands of years, but there would be cost savings. Then you only need to gain about 16.5 m/s in velocity.

The Falcon Heavy, once operational, will be the most powerful rocket in the world. Credit: SpaceX

Rockets need to carry more of their payload as fuel if they’re going to gain higher velocities. A Falcon Heavy can carry more than 54 tonnes to Low Earth Orbit, but only 2.9 tonnes to Pluto.

In other words, using the most efficient trajectory, you’d still need about 20 times more rockets to blast your fuel into the Sun. In other words, multiple your costs by a factor of 20.

$1.2 trillion to launch the high-level waste into the Sun on a trajectory that takes a long long time.

The bottom line is that blasting our nuclear waste off into space, into the Sun, is just too expensive – by several orders of magnitude. Not to mention incredibly dangerous for the inevitable rocket failures that will compound the problem.

No, we need to learn how to recycle nuclear waste, to make it less toxic. We need to be willing to spend the resources to properly clean up contaminated sites, and we need to careful consider the long term consequences of how we generate our energy. Not just with nuclear power, but with any polluting form of energy generation.

But you know what idea I like even better? I agree with Jeff Bezos when he says that we’re eventually going to want to move all heavy industry and manufacturing off Earth and out into space.

We could take our manufacturing off-planet to reduce environmental risks. NASA/Denise Watt

Instead of cleaning the waste out of our environment, let’s mine it, refine it and manufacture it out in space in the first place. Then we can send the products back to Earth, and skip most of the pollution.

Now I’ve done the numbers, what do you think? Still worth it to launch nuclear waste into space? Let me know your thoughts in the comments.

23 Replies to “Can We Launch Nuclear Waste Into the Sun?”

  1. The other possibility is that what we now consider waste may be a required input to some future technology. In other words nuclear technology and research are not dead, although they appear so. The future is very difficult to predict.

  2. I chaired a seminar on this in Glasgow in 1979, continued the research and published 2 papers in the Journal of the British Interplanetary Society in 1983, followed by one in the Journal of Practical Applications in Space in Spring 1990 (Vol.1 No.3). For the first paper, a top astrodynamicist, the late Prof. Archie Roy, evaluated the disposal options and concluded that direct launch out of the Solar System was the best ‘fire and forget’ option, using a mass driver in Low Earth Orbit. Big savings were possible by launching only the vitrified blocks and returning the steel containers for resuse. With STS-derived Heavy Lift boosters, at 1980 production rates, 1 launch per 3 days could keep pace with all the world production of High Level radioactive waste. In our second JBIS paper (Sept. 1983) the late John Braithwaite and I outlined ‘Project Starseed’, in which we used the booster tanks to build what Prof. Gerard O’Neill called ‘construction shacks’, then turned his scenario around to build solar powersats at the Earth-Moon L2 point, then use the residues to build space habitats at L5. 10 years of the programme would give you enough powersats to meet all the world’s energy needs, enough hull material for 50 Island One habitats and enough volatiles to make 6 of them habitable. At O’Neill’s invitation I gave a poster paper on it at the 1985 Space Manufacturing Conference in Princeton.
    Nobody has ever faulted the scenario, which has only two problems. In 1977 dollars the cost of space disposal would be 25 times that of burial, though the costs would be reclaimed from the powersat revenues. But the real problem is that (although NASA assured us that the canisters could be made robust enough to survive booster explosions and be recovered at sea) quite simply, people are too scared of rockets. When burial, the safest option, meets so much opposition, space disposal could never be politically acceptable.

    1. Woah! The article was totally tongue in cheek but you’re actually serious aren’t you?

      Please tell me you’re not in a position of power anywhere.

      1. Personally I found Duncan Lunan’s insights very interesting and will be seeking out his papers on the subject. Nothing wrong with speculation grounded in science – what would our descendants say if we did not explore all the options?

  3. Surely this can be done, but the cost is too prohibitive. Better to find a reasonably safe burial site below the earth’s surface and let the stuff work its way down to the earth’s core (a la China Syndrome)

  4. I have never understood why the high level nuclear waste can’t be the core of a Combined Heat & Power plant ( it presumably gives off lots of heat?)

  5. Why not just bury it all on the far side of the moon? Oh, wait, we all know how that would turn out!

  6. I’ve read many a sci-fi scenario for first contact, including the interstellar equivalent of a chain letter but imagine if an alien craft arrives and it’s just a garbage scow full of pitchblende tailings.

  7. If we’re launching vitrified blocks of high-level nuclear waste, at Solar System escape velocity (see my previous message), the harmful stuff will have turned to lead before any of it passes even the nearest stars. So the outside of the block should have moulded instructions to cut it into thin slices and mount them facing the sun. That way, the legacy of our probably brief flirtation with nuclear fission can be our gift to the Galaxy of thousands of beautiful, abstract stained-glass windows!

  8. I like the idea of putting the waste in the Earth’s core. Seems to be the safest way. It also would make sense to me to use the same corridor that would lead to the Earth’s core as a foundation in the construction of a space elevator. Piggybacking these two projects could make affordable the utilization of more space-bound projects.

  9. I think it is going to be as expensive to boost material into space that becomes the waste you are now generating in orbit, as it would be to boost the waste into orbit after manufacturing processes are done with it.

    And then, you are back to an early step in your “modest proposal” of having all this waste in orbit, where you don’t really want it to be.

    I’m not sure you have gained anything.

    If you are thinking more in terms of manufacturing on the moon, you solve the orbiting waste problem, and you can likely find some of your raw materials locally, saving the cost of boosting them from Earth — but what you DO need to carry to the Moon is going to be much more expensive, in terms of transport costs, than it would have been putting it into orbit. And then you have to get your finished product back to market. So manufacturing in space is not going to be economical until the transport costs drop by an order of magnitude or more — that may or may not be possible in the foreseeable future, but I note the last time we developed a spacecraft to regularly make cargo runs too and from space efficiently and economically, it became the single most expensive way to put a given mass of cargo into orbit ever devised.

    But on the specific topic of nuclear waste — as long as rockets sometimes blow up or other wise fail to make orbit, it’s a non-starter. A favor Mr. Niven’s elegant solution involving a fence and a sign.

  10. Here we go again. As you correctly point out rockets fail and a payload of highly radioactive material would be a disaster in a failed launch. This is why NASA wet to such great lengths to harden its PU-238 RTGs for missions like New Horizons and other deep space missions that require sustained electrical power beyond the distance at which solar power is feasible.

    Article could have also addressed the size and mass of spent fuel bundles which would be real challenges even for the most powerful rockets.

    Finally, how about a better headline, like “Putting nuclear waste on rockets to send to the sun is a bad idea.”

  11. with manned vehicles the % of succes go way way up.
    – Soyuz last incident was about 45 years ago.

  12. “Instead of trying to drop down into the Sun, you fly outwards until you’ve almost escaped the pull of the Sun. Where the angular momentum, that sideways motion, is almost zero. Cancel that out with a little thrust, and then let the Sun’s gravity pull your waste back down to its doom.”

    That’s not the way it works. Getting into a higher orbit requires you to go faster. Higher orbits go faster than low orbits. Lowering orbits require you to go slower. Both of these use fuel. So using a lot of fuel to get into a higher orbit doesn’t suddenly make it easy to go slower, it makes it harder. Every meter per second you add to get into a higher orbit is a m/s you have to cancel to get back to a lower orbit. This is like saying “the best way to slow down from 20 mph is to first speed up to 100mph.”

      1. Plugging my own paper in January’s The Physics Teacher journal, and unfortunately you have to pay for access, but the abstract is here:…38B
        “Slow down or speed up: lowering periapsis vs. escaping from a circular orbit”.

        In the article I show that a bi-elliptic transfer into the Sun does require less delta-v than the more direct “slow down and fall in” method.

        But while we are comparing unrealistic solutions, it’s even cheaper to crash the nuclear waste onto Venus – about 2.5 km/s delta-v from a 1 A.U. heliocentric orbit, “more feasible, but still a terrible idea for reasons that students can discuss!”

  13. If a space elevator gets off the ground how would your calculations change? Would it still be infeasible?

  14. I’m not a miner or a geologist, so I’ve always wondered why we can’t do this….
    Nuclear material is sourced, i.e. dug, from the Earth, it’s processed and refined to make it useful. The spoil from the extraction processes is stored somewhere, probably back in the holes from which it was dug. Why not mix the spoil from new mining with the nuclear waste from previous mining, before putting it back into the Earth? i.e, put used nuclear material back where it came from, in a concentration equal to, or less than, the original.

  15. Rockets require tens of thousands of tons of fuel. ~90% of the mass of a typical rocket is propellant. The COST of launching is secondary; perhaps even a moot point here – we need to consider the disposal system’s energy burned in the overall EROI (Energy Return On Investment).

    Add the
    1] actual rocket fuel consumed
    2] the fuel associated with manufacturing and delivering that rocket fuel,
    3] manufacturing and delivering rocket booster metals and other materials, etc.
    4] the fuel consumed mining,
    5] refining,
    6] transporting &
    7] storing uranium, and
    8] fuel used in hauling the waste,
    9] cleaning up after rocket launch pollutants (all aspects including CO2 and toxic chemical impact costs),
    10] cleaning up after fuel manufacturing
    11] power plant decommissioning.

    And still, this would be just the more obvious parts of an equation.

    EROI: look at the numbers for the overall energy expenditure INTO the system vs. the lifetime energy OUTPUT of the reactor.

    In business, if you’re continuously losing money (net) due to operating costs, it ain’t a business in the end. With energy, if you’re burning more than you’re creating, it ain’t energy.

    We want to whittle these questions down to easy ones like ‘how much would it cost?’ Let’s not be hoodwinked into reducing this question to one of upfront cash. In reality, the system is one that includes feedback loops that likely make the entire rocket-powered nuclear disposal scheme an ENERGY loser compared to other methods. I.e., after doing the bigger picture math, burning natural gas directly to generate electricity would likely result in a higher overall EROI than fission + rockets. (Yes, a space elevator scheme would have a significantly impact on those numbers.) Let’s try the same math on lithium, steel, plastics etc. in the electric vehicle production chain to see the true energy use of ‘cleaner’ cars. It’s not a matter of environmentalism; when we’re talking energy, it’s (Energy Delivered / Energy Required To Deliver) that counts. Otherwise, no net energy is being produced, and that’s the function of a nuclear reactor.

  16. Returning the waste to the earth is the only solution (along with stop producing it of course)
    To do this it must be buried in proximity to a subduction zone so it is pushed deep into the mantle and recycled. There are numerous such zone on dry land as well as under water. Obviously dry land sites are easier and safer. the downward plunging side of subduction zones are relatively stable as opposed to the upthrusting side. The technology for bores of sufficient diameter and depth exists or is readily developed from existing technology.

Comments are closed.