What Will It Take To Blow Up Pluto?

“25 billion of your biggest bombs please. I’ll pay credit, thanks!”

"I love the smell of venting volatiles in the morning..."
"I love the smell of venting volatiles in the morning..."

The Pluto debate frustrates me, as you may have noticed. It’s not that I have particularly strong views about whether it should be called a planet or a dwarf planet or a plutoid or pygmy planetoid, it’s that I really don’t care; I actually see Pluto’s “demotion” as exciting progress in the field of Solar System science rather than any derogatory gesture aimed at Pluto. Pluto is still Pluto; it hasn’t been knocked out of orbit, it hasn’t even been “bombed” (unlike our poor old Moon), it’s just being filed under a different category.

A King Amongst Dwarfs

In my opinion, calling Pluto a “planet” was unworkable, especially after a bigger dwarf planet was discovered in 2005 by a team of astronomers led by Dr. Mike Brown. This dwarf planet was named Eris (or 136199 Eris) and at first it seemed like we had gained a tenth planet.

The “ten planets” thing was short lived, however. In recognition that Eris probably represented the beginning of a spate of discoveries of welterweight worlds, the International Astronomical Union (IAU) took a vote in 2006 and decided to redefine what constitutes a planet. Pluto was in the firing line, became a rounding error and was dropped from the planetary club.

Kicked out and nowhere to go.
Kicked out and nowhere to go.

But it wasn’t all bad for the little guy. Pluto was designated king of all “plutoids” (trans-Neptunian dwarf planets) in 2008, meaning another three dwarf planets now orbited the Sun with this designation (Eris, Haumea, and Makemake in addition to Pluto).

In a previous Astroengine article, I made the point (and I’m going to quote myself because I can):

Just so my opinion is known, I don’t care what Pluto is called. If NASA decided to explode Pluto as part of a Kuiper belt clearing project, then yes, I might be a bit annoyed; I’d even start a blog titled “Save Pluto.” But calling Pluto a dwarf planet (or the rather cute plutino) really doesn’t bother me.

I haven’t really thought much about this statement until, today, @PlutoKiller himself (Mike Brown) tweeted, “Seriously, what just happened? The entire discussion is on placing explosives in the solar system. Pluto has not even been mentioned.” I then fired off a reply saying something about building a New Horizons 2 and packing it with plutonium to which @PlutoKiller said, Evil Santa-style: “Just in time for Xmas.”

And then the penny dropped.

Kuiper Belt Cruelness

To be honest, I’m astonished I haven’t thought of this before. Looking at Mike’s Twitter feed should have been enough inspiration, but until I wondered down the bombing Pluto => plutonium enrichment => lets fly a shedload of plutonium to Pluto path, that I asked the question: How much energy is needed to completely destroy Pluto?

Now we’re talking! Time for some Kuiper belt mayhem!

It might seem quiet now...
It might seem quiet now...

I’m not talking about simply bombing Pluto and making a big crater, I’m not even talking about fire bombing all the volatiles out of its frozen surface, I want to remove Pluto from existence. Why do I want to do this? Well, for fun, and because @PlutoKiller himself said so. And it’s Halloween, so why not?

So how much energy is required to do this?

For this gargantuan task, I cheated and looked up the method used by Matt Springer over at Built on Facts to derive how much energy was required by the Star Wars Death Star to shred Earth. In that case, 2.2 × 1032 Joules was needed to totally erase our planet (that’s a week’s-worth of solar output). That’s a lot, right?

Plutoid Killing Equation

Now, energy is energy and mass is mass, let’s give Pluto the same treatment. Using the following equation (known henceforth as the “Plutoid Killing Equation”, or simply PluKE), we can find out how much energy we need to erase Pluto:

The equation that can turn a dwarf planet into dust, as derived by Matt Springer.

This equation is the total gravitational binding energy of a sphere of mass, M and radius, R. G is the Gravitational Constant. For Pluto, a sphere, its vital statistics are:

MPluto = 1.305 × 1022 kg

RPluto = 1.153 × 106 m


G = 6.673 × 10-11 m3 kg-1 s-2

Plugging the numbers into PluKE, we can derive the total energy required to kill Pluto, literally:

EPluto(dead) = 5.914×1027 Joules

Oops, who put those WMDs there?
Oops, who put those WMDs there?

But what does this number mean? This is the bare minimum energy required to match the gravitational binding energy of Pluto. If you want to rip the dwarf planet apart (plus pyrotechnics and speeding debris), you’ll need a lot more energy. However, nearly 6×1027 Joules (that’s a 6 followed by 27 zeros) delivered into Pluto in one second should give the little world a very bad day.

Tsar Very Much

But how can we “deliver” this vast quantity of energy in one second? I suspect that any super-advanced civilization hell-bent of wiping out planets will have a better idea of this than me, but using weapons that are available to modern man might be a good place to start. Forget the uber-powerful death ray emitted by the Death Star, that’s sci-fi. It may not be sci-fact, but how about sending some nuclear bombs to the Kuiper belt?

How many bombs will we need? Ten? Ten dozen? A thousand?

The most powerful nuclear weapon tested was the Soviet 58 MT Tsar Bomba in 1961. So if we know how much energy is released by one of those beasts, we should be able to work out how many we’ll need to send to the unsuspecting Pluto.

1 MT = 1 megaton of TNT = 4.184×1015 Joules

therefore, a single Tsar Bomba has the potential to release an energy of:

58 MT = 58 × 4.184×1015 Joules = 2.427×1017 Joules

We needed 6×1027 Joules to wipe out Pluto, obviously the 2.4×1017 Joules a single bomb can deliver is woefully short of our goal. So how many Tsar Bomba weapons do we need?

(6×1027 Joules) / (2.4×1017 Joules) = 2.5×1010

We need to build 25,000,000,000 nuclear bombs. 25 billion. Ouch.

Obviously, looking at this estimation, it is impossible to destroy a dwarf planet as puny as Pluto using the most powerful weapon known to man. Also, it’s worth keeping in mind that this is the bare minimum of energy that needs to be applied to Pluto to match its gravitational binding energy, so to destroy it, you’ll need a lot more bombs.

There’s also the question of how to distribute the weapons. Would you put them all in one place? Distribute them all around the globe? Perhaps burrow into the centre of the body? I suppose putting all the bombs in one place might be impressive, kicking a chunk of plutoid into space.

Now I must report these findings to @PlutoKiller himself, I fear he won’t be happy with the outcome of my calculations

Space Experts to Discuss Threat of Asteroid Impact

Artist impression of a gravitational tractor deflecting the path of an NEO (Dan Durda/B612 Foundation)

Imagine you’re an astronomer who discovered an asteroid. Happy days, you might be able to name it after yourself (99942 O’Neill has a certain ring to it, don’t you think?). At first you feel little concern, after all, we are getting better at spotting near-Earth objects. But when you get news from another observatory that they had been tracking the same object weeks earlier, your interest is piqued. On the one hand, you didn’t technically discover it, but you did confirm its existence. Unfortunately this is probably the one observation you really didn’t want to make. It turns out that this chunk of rock is heading in our direction. And unlike the Earth-grazers that have come before, this asteroid isn’t going to drift past our planet, it isn’t even going to skip off our atmosphere, it’s going to hit us.

Now imagine you are the president of a nation determined to stop the asteroid from hitting Earth. What do you do? Naturally you’d call your team of oil drillers scientific advisors to present your options. One space scientist suggests sending a rocket to the asteroid, strapping it on in the hope it might be nudged out of harms way. The astronomer who made the discovery of the killer asteroid is having a nervous break down in the corner of the room. Your military advisor is urging you to attach a nuclear warhead to your most powerful rocket, in an attempt to obliterate the target. The Secretary of State is calling for restraint; we need to collaborate with other nations, blasting nuclear missiles in to space would violate all kinds of international treaties, wars have been started for less, perhaps someone else has a better idea…?

Although I doubt we’ll ever be fully prepared to act swiftly and decisively in the event of discovering a civilization-ending asteroid, we can at least try. Defending the planet against the ever-present threat of impact is one of the most critical abilities we must develop as a race, ensuring the long-term future of our species. Fortunately, a team of scientists, engineers, policy makers and lawyers (lawyers?) are teaming up to confront this problem…
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Apollo Astronaut Highlights Threat of Asteroid Impact

In a renewed attempt to bring the concern about a potential asteroid strike to the world’s attention, former Apollo 9 astronaut Rusty Schweickart briefed UN officials on Tuesday about a report entitled “Asteroid Threats: A Call for Global Response.” The report has been drawn up by the International Panel on Asteroid Threat Mitigation (IPATM), formed by space explorers and scientists in an effort to put a contingency plan into action to limit the devastation caused by a theoretical impact.

The key point here is that the IPATM is not predicting an immediate catastrophic asteroid collision, it merely wants the UN to recognise there is a danger out there and to enact procedures to save lives and possibly remove the threat all together…
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