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Saving Lives in Serenity: Can a Fanboy and Physics Change a Movie?

The views expressed are those of the author and are not necessarily those of Scientific American.

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I was late to Firefly. Nearly ten years after the show first aired and then was subsequently cancelled, I holed up in my room, coffee and external hard drive in hand, aiming to blaze through one of the most beloved sci-fi series.

A mix of science fiction and “spaghetti-western” genres, Firefly was wonderful. It certainly awakened the fanboy in me, and I quickly understood why my girlfriend envied me for being able to watch the series for the first time.

It all ended abruptly, due to early cancellation, with the last episodes of Firefly barely answering any central questions or exploring the rich universe that had been so lovingly crafted by creator Joss Whedon. It was to my delight to learn that in 2005 there was a full-length movie in response to public (and private) outcries for more of Serenity and her crew.

Watching Serenity let me spend a bit more time in the ‘verse, and the film thankfully resolved a number of outstanding loops just craving to be closed. But the forced end of Firefly also forced Joss Whedon’s hand. He put in scenes that would only have appeared in a last hurrah like Serenity. One scene in particular shook me, like the unexpected sight of a Reaver ship. It’s a scene that drove me to NASA forums and technical reports, glass manufacturers, my calculator, and eventually to this post.

Needless to say, if you haven’t seen Firefly or Serenity, the ensuing discussion is spoiler-laden (and you should go watch them!).

You Can’t Take This Guy From Me

Late in Serenity, after crash-landing at the mysterious base of “Mr. Universe,” pilot Hoban “Wash” Washburne meets his end at the tip of a Reaver spear. The immediacy of the violence, and his wife Zoe’s touching reaction, kept my mouth agape well into the next few minutes of the film. One of my favorite characters just died, as Firefly died. I couldn’t stand it. I had to be sure.

What if the Reaver spear couldn’t plausibly make it through the forward windows of Serenity? The movie may have been set in the future, but we too have built spacecraft with windows, and they are made to withstand impacts. If I could prove that a modern shuttle window (assuming that a future window would be even better) could withstand the impact that killed Wash, I could have the ultimate in fanboy closure: the movie is “wrong,” and my version of the story lives on.

Objects In Space

In terrestrial situations, a speck of paint is less than harmless. In space, it’s deadly. Travelling at a blistering 9,000 meters per second in orbit, the equations deem it lethal. It becomes a “hypervelocity” bullet.

Our spacecraft obviously must account for this deadly debris. Tens of thousands of pieces of extraterrestrial trash litter the orbit of Earth [PDF], meaning that a shuttle’s final impact could come from an errant hex nut. Shuttles today are outfitted with shielding to prevent such disasters, and feature two-and-a-half inch thick windows—the thickest pieces of glass ever produced in the optical quality for see-through viewing.

The largest impact to a shuttle window occurred when a fleck of paint struck STS-92—a flight to the International Space Station. A shuttle window has never been penetrated by a hypervelocity impact, but it doesn’t have to be. A deformation large enough could eventually cause window failure upon repeated take-offs and re-entries.

After engineers examined the crater in the window, the shape that best explained the damage was a sort of miniaturized plate. Based on the size and the speed (9 km/s!) of the fleck that hit STS-92, I calculated that the window weathered an approximately 5,000 pounds per square inch impact, creating more than enough damage to warrant a window replacement. And such replacements from serious impacts are commonplace. Robert Lee Hotz notes in the Wall Street Journal that “NASA shuttle engineers have replaced the spacecraft’s debris-pitted windows after almost every flight since 1981, at a cost of about $40,000 per window.”

That little fleck of paint was almost a catastrophe. Based on the thickness of the orbiter’s forward facing windows and the basic strength of the glass, made of fused silica, the windows of STS-92 could have resisted a pressure of 8,000 pounds per square inch—nearly three times that of a crocodile bite (amazing in two respects). Still, it was a close call.

The shuttle windows are tough, to be sure, surviving nearly 1,400 impacts intact over 43 sampled missions, but are they strong enough to save Wash? Tiny particles are elevated to terrifying status because of their ridiculous speeds, not their mass. Conversely, the Reaver spear that killed Wash was larger, but moving much more slowly. A few assumptions and some physics equations would determine if I could save him.

I Am A Leaf on the Wind…

To get the general dimensions of the spear that killed Wash, I had to (unfortunately) go back to the scene in question, excruciatingly slowing down an emotional moment to be replayed over and over. Based on some general size comparisons with other objects in the scene, I’d put the tip of the spear no larger than a quarter.

Diving back into Serenity, I used an earlier Reaver chase scene to guesstimate the spear size and speed. If Reavers shoot spears slow enough to be dodged (which they do), the spear that kills Wash can’t be moving much faster than a Major League fast-ball, putting the upper limit on speed around 100 miles per hour (45 m/s). This is orders of magnitude slower than the hypervelocity impacts that a shuttle deals with, but the spear is thousands of times more massive than a fleck of paint. Assuming it’s fashioned out of a metal, and given its size, I’d guess it’s around 100-200 pounds (45-90 kg).

Kinetic energy is easy enough to calculate, as is pressure. The kinetic energy of a moving object is one-half of its mass multiplied by the square of its velocity. This equation gives the Reaver spear a frightening 101,250 newtons of force at the low end. The pressure exerted by the spear is then equal to the force divided by the area it is acting on. Making the tip of the spear the size of a US quarter, the resulting pressure is a ludicrous 31,800 psi—nearly three times the pressure at the bottom of the Mariana Trench. This is over six times the force of the largest recorded impact to a space shuttle window, and almost four times the maximum pressure a shuttle window can take before deforming and failing.

The math doesn’t lie—Wash didn’t stand a chance.

…Watch How I Soar

I thought I had found the perfect fanboy out. The windows in Serenity looked flimsy and thin, surely not something a space-faring craft would be outfitted with. If the windows were anything like what we use to traverse the ‘verse today, perhaps all that would have happened is a jolt of fright from a deflected Reaver spear, or so I hoped.

But even delving through a hundred page NASA technical report[PDF] on impact shielding couldn’t ease my psyche.

Now, this is at its core a fanboy rant. No matter what I found, Wash dies in the movie. It’s part of the larger story and serves as a plot point, not a meaningless killing-off. But I selfishly wanted closure; I needed to resolve the dissonance between a character’s death and the fact that we know he wouldn’t have died if the networks saw better numbers from Firefly.

Maybe this is a testament to the enduring qualities of the show. To create characters important enough, and in only fifteen short stories, to warrant hours of research and calculation that ultimately proves useless in the larger story is an outcome of a great narrative. It’s typical of a the fan base that will still pack a Comic-Con panel ten years after the airing of the show.

I fell headlong into a rich universe of content, only fleetingly illuminated. I guess my desperate attempt to change the story is a compliment to the creators. It’s a love that keeps the show alive, makes Firefly a home.

“Love. You can learn all the math in the ‘Verse, but you take a boat in the air that you don’t love, she’ll shake you off just as sure as the turning of the worlds. Love keeps her in the air when she oughta fall down, tells you she’s hurtin’ ‘fore she keens. Makes her a home.”–Capt. Malcolm Reynolds


Featured drawings courtesy of award-winnings manga artist and TED fellow Sara E. Mayhew. You can purchase custom drawings at her Etsy shop here.

Update (1/11/13):
Based on the astute observations of readers, the original version of this post skipped a step when calculating impact forces (in Newtons). As such, I have stepped back and calculated impact energies of the Reaver spear and orbital debris instead (in Joules). In terms of energy, the fleck of paint that hit STS-92 struck the shuttle with 3,700 times less energy than a Reaver spear would. Based on the allowable damage to a shuttle window, a Reaver spear with this amount of energy could pierce the shuttle’s crew cabin and thermal shielding, let alone its windows. This comparison is more aligned with how NASA characterizes impacts, has more empirical support based on reports, and still ends up at the same conclusion (unfortunately).

Kyle Hill About the Author: Kyle Hill is a freelance science writer and communicator who specializes in finding the secret science in your favorite fandom. Follow on Twitter @Sci_Phile.

The views expressed are those of the author and are not necessarily those of Scientific American.

Comments 19 Comments

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  1. 1. diducthat 12:35 pm 01/10/2013

    Plenty of LOLs from a fellow fan. It is likely though, that in the ‘verse of the series, the ship was made of materials a bit more advanced than ours (despite looking like a wreck).

    For example the window might be made of diamond and the spear would have to hit at a cleaving angle to shatter it. It might be made of graphene laminates, which could absorb the energy by stretching.

    More likely, in the future I would imagine that there would be no windows at all. The window effect, only existing for our psychological comfort, could be achieved with lenses and very high resolution displays. We are already approaching this capability.

    Still fun speculating.

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  2. 2. bgaulke 12:50 pm 01/10/2013

    While two and a half inches may be the thickest optically clear glass ever produced, leaded glass for radiation shielding is made in thicknesses up to at least six inches and see-through viewing is certainly possible. After all, that’s the whole point of using glass in radiation shielding. Cheers

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  3. 3. JasonAW3 4:30 pm 01/10/2013

    There is one important point that was overlooked.

    The windows on a Firefly have an extreme angleto the verticle, which in this case, would multiply the effective thickness of the glass by a ratio directly related to the angle of travel of the spear. Assuming that a 60 degree slope of armor on an old T-34 Russian tank from WWII effectively doubled the efective thickness of the armor, (Making it quite a bit harder for the Germans to take out on the battlefield) then the extreme slope of the glass should multiply the effective thickness by at LEAST a factor of 3, thus, 2.5 inches on Quartz Glass suddenly becomes, effectively, 7.5 inches of Quartz Glass, PLUS the extreme angle of the glass on the cockpit of the ship would act to deflect the spear, much the same way that the Russian tanks deflected the German 88mm rounds.

    I’m not saying that the spear wouldn’t put one heck of a groove in the glass, (requiring a change of pans for everyon in the cockpit, I’d imagine) but it shouldn’t be ably to penetrate, unless it entered at a 45 degree angle to horizontal, which, from the film, it didn’t.

    Just sayin’


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  4. 4. nutbastard 4:52 pm 01/10/2013

    1. They just crash landed the ship, so it’s possible the glass was weakened somehow by the impact.

    2. Ships in the firefly universe may not rely on something as primitive as mechanical durability to deal with space debris. They do have artificial gravity aboard Serenity, so perhaps the same system deflects small particles.

    3. I know it’s cold out there in the Black but Serenity IS a budget ship with no guns and completely unfit for combat, so it makes sense that they wouldn’t make the windows any thicker than they had to, especially if #2 is true.

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  5. 5. silentnights 6:25 pm 01/10/2013

    Based on past experiences with windows in the verse, we know of at least one window that survived a few bullets from Jayne’s favorite weapon Bertha. The episode was #6 “Our Mrs. Reynolds”.

    From Wikipedia “After breaking into the bridge, Kaylee and Wash find that the ship is headed straight for an electric net. Book explains, with a mysterious knowledge of criminal activity, that the net will restrain the craft but kill everyone inside. Jayne shoots the structure with his favorite gun, shorting it out, and Serenity passes through the net unharmed. After disabling the net, Jayne fires at the window of the net’s crew compartment, causing it to rupture and killing the net’s two operators.”

    Bertha appears to be of at least the strength of a Beretta .50 cal which produces around 55,000 PSI. Jayne had already fired a number of shots from Bertha inside a pressure suit (in order to have air to actually use the weapon) so the air pressure had probably dropped by that point possibly decreasing the PSI produced by the weapon. I’m not a mathematician by trade so I can’t produce solid numbers but this theory may still save Wash!

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  6. 6. sladest 7:29 pm 01/10/2013

    physics aside, the series’ continued existence would be no guarantee that Wash would have survived Joss Whedon.

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  7. 7. daviey42 7:37 pm 01/10/2013

    I have oft maintained to my friends that the only real way in which the USS Enterprise D is superior to the Firefly class Serenity or the Millenium Falcon is the Enterprise’s lack of windows on the bridge. Wash would never have died had he been piloting something from the Trek ‘verse. Sadly, existing in the wrong continuum as he did, he died. When he died, so did my man-crush. He had such powerful arms.

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  8. 8. ChezaOtsr 7:45 pm 01/10/2013

    Silentnights, Jayne’s favorite gun is VERA, not BERTHA.

    No matter what the results tell us, Whedon himself said he would not have killed anyone off if FOX would have allowed him to wrap it up on TV at the recent Comic-Con anniversary panel.

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  9. 9. grumfan 10:28 pm 01/10/2013

    Gah, Gunpowder carries its own chemical oxidizer, so bullets don’t need oxygen to function.. Not only do Gunpowder weapons work without atmosphere, they actually work better without atmosphere.

    The bullets achieve a higher velocity before exiting the barrel,and they don’t slow down due to air resistance or get blown off target by the wind, or drop below the target due to gravity.

    Dangit! I’m sure this single technical issue, had it been handled correctly, would have kept FireFly on the air!

    (Yeah, yeah, I know. …. )

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  10. 10. nutbastard 11:16 pm 01/10/2013

    “Jayne’s favorite gun is VERA, not BERTHA.”

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  11. 11. Kanddak 11:39 pm 01/10/2013

    We’re missing a step here. An object moving at 45 m/s with a mass of 45-90 kg has a kinetic energy of 4.6e4-9.1e4 J.
    Where does the 101250 N force come from?

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  12. 12. murraydevine 12:19 am 01/11/2013

    No no no!
    That’s not how science works!
    The spear penetrated the window and killed wash. Observable fact.
    This means that any calculations you come up with to disprove this fact ‘theoretically’ are trumped by the sheer fact that it DID. Even if you work out that it’s impossible, you have to assume that you don’t have enough data to establish why it did.

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  13. 13. DamienFox 5:02 am 01/11/2013

    Congrats man, Nathan Fillion tweeted about this. Also- nice work trying to save Wash, sorry it couldn’t happen. And absolute best ending quote for this blog.

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  14. 14. karpar 9:27 am 01/11/2013

    There’s no getting around murraydevine’s point that direct observation tells us that Wash died, but here’s a wrinkle: Given the transit time we see between planets, Serenity has to travel far faster than the shuttle ever does, which means debris hitting her would be moving at far greater speeds than anything the shuttle and other purely orbital ships have to contend with. That would have to mean that her glass is rated to significantly higher impact force, or that some secondary system is working against the impacts. As nutbastard pointed out, though, there’s no way of knowing how badly damaged the ship (and the glass, or the secondary systems, or whatever) was after the crash landing, and plenty of parts on her were well past their warranties and just waiting for the right combination of circumstances to crap out. It’s a shame, but there its is.

    And how come no one put any effort into proving that Book didn’t die? Sure, he was not a young man, and he’d been shot at least once, potentially by a high-caliber aircraft-mounted weapon, but… he’s got God on his side, right? Right?

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  15. 15. misscleocallmenow 12:12 pm 01/11/2013

    You’re looking at the wrong constraint. The real constraint is the reaver. That 45-90kJ of energy had to come from somewhere – the reaver’s throwing arm. That’s an expenditure of 10,000 to 20,000 calories in maybe a second. By my careful calculations, the reaver’s arm would have burst into flame trying to throw such a heavy spear so fast.

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  16. 16. bucketofsquid 2:52 pm 01/11/2013

    I think the one thing we can all agree on is that the doofus that canceled the series needs to be flogged. Well, that and also we all need to learn to cuss in Mandarin.

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  17. 17. TeslaBoy 4:32 pm 01/11/2013

    The people to blame for Firefly being canceled are the people that didn’t watch it when it was “alive.” They are the who caused it to disappear!

    Wait a minute. That would include me. Never mind.

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  18. 18. Sunju 11:10 pm 01/11/2013

    @murraydevine Science works within the laws and limitations of REALITY. This is a work of fiction in a universe that may or may not follow the laws and limits of our own. At the very least the realm of imagination is, in no way, limited by time or production. Many tv shows, books, comics, and other works of the imagination have been retconned in order to follow a different path or to correct glaring shortsighted “facts”. As Wash dieing was part of a fictitious event, made for our entertainment, it is perfectly reasonable for someone to apply real science, which is different from yours, in order to change an unwanted outcome. It’s called make believe for a reason.

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  19. 19. greygoose 12:19 pm 01/14/2013

    What difference does it make. You’ve missed the point. This can all be resolved as its been done before. This sequence is just a dream or premonition by Inara. It scares Wash enough that he is prepared when this premonition comes to fruition. WASH LIVES!!!!

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