In our new series, A Scientist Responds, we’re dredging up the great and terrible disaster flicks of days past—and we’re making scientists watch them. Today’s movie: 1998’s asteroid thriller, Deep Impact. The scientist: io9’s resident geophysicist, Mika McKinnon.

The Movie: Deep Impact


Deep Impact is a tale of comets, politics, total destruction, and the increasingly poor decisions of hormonal teenage astronomer Leo Biederman (played by a young, pre-Hobbit Elijah Wood). When Biederman discovers a giant comet that poses an imminent threat to Earth, a team of astronauts attempt to nuke the comet into oblivion. After this plan goes (unshockingly) awry, Deep Impact turns away from rah-rah patriotism toward the disturbing politics of who President Beck (the always-reassuring Morgan Freeman) will save to rebuild in the smoldering wreckage of civilization. But don’t worry: after repeatedly demonstrating what a terrible idea it is to allow hormonal high school students to make life-or-death choices, Leo proves that with even more terrible life choices, he can at least save the girl by outrunning a tsunami on a motorbike.

Deep Impact: Everything will be okay as long as teenagers are still getting it on.

The Science

Deep Impact actually features something close to a realistic look at how our society might face a major impact event — although in our world, it’d probably be much, much worse. Here’s how some of the the scenarios the movie shows us might play out in real life:

Premise #1: A massive comet is about to hit the planet and kill everything on it. How often does this happen, really?


Thankfully, asteroid impacts follow a, “The worse it is, the less likely it is to happen” inverse intensity verses frequency relationship: small no-big-deal impacts happen all the time, while large devastating catastrophes happen extremely rarely.

Small impact events happen all the time; large impact events happen less frequently. Image credit: Stephen A. Nelson.

Tiny impact events are a daily occurrence, with dust burning up as fleeting shooting stars every night, and explosive events in the upper atmosphere happen every few months. A city-flattening airburst event like a slightly-larger and worse-positioned Chelyabinsk meteor or the 1908 Tunguska explosion only happen about once every few centuries, with personal odds of witnessing one approaching 1% over a lifetime. Impact-induced extinction events happen even less frequently, decimating life on the planet once every 10 to 100 million years. This is so infrequent that the odds of an impact during our lifetimes is so rare we don’t even have a good colloquial description for it — but the planet-wide devastating consequences mean your personal odds of death from an impact event are somewhere between 1:250,000 and 1:700,000. For context, that’s less likely than death by venomous sting, and more likely than death by fireworks accident.


Verdict: Possible — but extremely unlikely within our lifetimes.

Premise #2: A comet is going to crash into the Earth and kill us all, and there’s not much we can do.

Given the level of technology in 1998 when Deep Impact premiered, Secretary of the Treasury Alan Rittenhouse had it entirely correct when he bemoaned, “What difference does any of it make anymore?” Even now, over a decade and a half later, our progress on even tracking potential hazardous impactors with enough lead-time to do anything about them is downright abysmal, and the lack of technology to do absolutely anything to save our planet is even more depressing.


Unfortunately, humans are terrible at dealing with high intensity, low-frequency events, and declare that they’re totally going to win the lottery but will never suffer from catastrophe. Consequently, our funding to identify and track potential impactors, and our research on mitigating them, is crap. All-sky surveys are slowly tracking most things big enough to wipe out the planet even if city-killers can still sneak terrifyingly close with impunity, and private organizations are doing their best to fill in the technology gap for developing techniques to actually do something about saving our planet if only we can get enough lead-time. If this lack of serious preparation freaks you out and you want to help change it, check out B612 Foundation’s Sentinel Mission.

Verdict: Highly plausible — this is pretty much exactly how doomed we are.

Premise #3: The giant comet headed towards us was not picked up by any of the agencies or researchers deep-scanning the skies, but a teenager with his backyard telescope did spot it.


The American military can’t even keep the orbits of their clandestine spy satellites secret from amateur astronomers for long; a massive comet coming to destroy the planet would absolutely be noticed by everyone else, and the construction of the Messiah spacecraft would’ve been photographed in detail long before the President’s speech.

Why would astronomer Marcus Wolf need to protect his night vision with red lights since he doesn’t need observations to make orbital determinations anyway?

The deeper problem though seems to be that astronomers in this movie don’t actually look at stars. This is remarkably clear when teen astronomer Leo Biederman spontaneously decides the field of view for his telescope is greater than 10 degrees, the distance covered by two fists held at arm’s length, and manages to find Alpha Centauri, a star not visible in the northern hemisphere. It doesn’t get any better when we switch off to his doomed mentor, Dr. Marcus Wolf. By the time Wolf performs the world’s fastest, tidiest orbital determination on virtually no data while munching on pizza before bolting off to make an instantaneous report on a comet that wouldn’t arrive for over two years, I’ve already written him off as an alien from another dimension utterly lacking in night-vision rods in his eyes, an understanding of orbital mechanics, and common sense.


While we’re at it, although “extinction events” are absolutely a thing, and even “species-level extinction events,” no self-respecting scientific paper has called them “E.L.E.” or “Ellie” even after this movie came out. If an overly-enthusiastic investigative journalist is going to confuse a civilization-ending cometary impact for a Presidential sex scandal, they’re going to need to be more oblivious.

Verdict: No. Just no, not likely at all, and it makes me weep soggy tears for hard-working astronomers everywhere.

Premise #4: Comet Wolf-Biederman is bright and blue and surrounded by a halo of dust with a long, beautiful tail of chaos to endanger the spaceship. It’s pretty much distilled awesome, right?


Wolf-Biederman has an albedo so bright, it may actually glow instead of just reluctantly reflect sunshine.

Eh. Sure, it’s good enough. I’m willing declare President Beck forgot his high school geometry classes when he declared a three-dimensional volume is equivalent to a two-dimensional area during his scare-fest news conference, and I’m willing to make similar allowances for political reporter Jenny Lerner confusing a comet’s coma, the nebulous envelope surrounding the nucleus, and its tail, the long trail of dust and gas pushed away from the sun by radiation pressure and the solar wind. All of that gets trumped by watching the lander successfully harpoon the comet when Rosetta and its little lander Philae were but a dream-in-development and had not yet made it off the planet.


Comet harpoons have moved from science fiction to flat-out science since 1998.

More confusingly, Wolf-Biederman is possibly the brightest, highest-albedo comet that has ever existed. I can handle the lovely, artistic blue as an ion tail (even though it’s pointing in entirely the wrong direction as real comet tales point away from the sun, not away from the direction of travel), but how is a dirty mess of dust, ice, and rock possibly that damn shiny?!


Verdict: Big-strokes accurate-ish, but the details fall apart.

Premise #5: Fake NASA snapped together a spaceship propelled by nuclear blasts to land on an asteroid and blow it to smithereens. Doesn’t real-life NASA also have a nuke-powered Orion prototype?


We don’t have the technology and couldn’t get it developed, tested, and reliable within a year, but the history of spacecraft development had taken a different route it may have been possible.

In their infinite wisdom, NASA recycled the name of the original nuclear-powered Project Orion for their “Hey, we’re going to Mars!” Orion spacecraft that relies on traditional chemical rockets. The two have nothing in common, and I’ve never found a persuasive rational for deliberately courting the unnecessary and oddly common confusion. The closest NASA comes to the nuclear-powered spacecraft business is loading tiny reactors onto the rare rover or satellite where solar won’t cut it, and even then they’re trying awfully hard to find alternatives.

That said, Deep Impact got the mechanics of taxiing astronauts to the futuristic nuclear spacecraft in a separate vehicle entirely correct: a nuclear-powered spacecraft would only be good to go in space itself, not bouncing along on a string of explosions in our thick and fragile atmosphere. They even recycle the concept of old Skylab grid-floors, where astronauts could lock in and stabilize themselves with specially-shaped cleats. And hey, I, too, would side with token old-timer astronaut Spurgeon Tanner in his declaration that he’d rather get home glowing in the dark from firing up their radioactive engines with damaged shielding, then slowly freeze, starve, or suffocate by staying put while Earth in annihilated.


Verdict: Plausible alternate future, if history had taken a different path.

Premise #6: The mission failed, splitting the comet in half so instead of one impact, we now have two to worry about. Would we really be that bumblingly incompetent?


We love our nukes, and somehow think they’d be the solution to everything, but even carting the entire planetary nuclear stockpile into space in an asteroid-destroying/nuclear-disarmament anti-apocalypse double-play can’t overcome the basic physics of momentum. Sure, we might be able to break pieces off a comet or asteroid, but that just means we have more pieces to slam into the planet and directly squash people instead of indirectly kill them through global firestorms, ejecta, dust in the upper atmosphere, and the resulting climate chill and prolonged intense Greenhouse Effect.


If we actually want to save our planet from annihilation-by-impact, we’re going to need a lot more warning and a lot more lead-time to slowly alter its orbit through gravity-tugs, imbalanced solar pressure, embedded rockets, or a million other ideas that are currently more fiction than fact. Blowing shit up will just add to our problems.

Diamond encrusted drill bit? Check. Astronaut-drillers? Check. Cometary gravity strong enough to leave the drill platform at a strange, severe angle? Uh...

Re: the astronauts impersonating miners, I am totally unsurprised they could figure out drilling with half a year of mission training. It’s unfortunate yet sadly not unprecedented in spaceflight that they mixed up the metric and imperial measurement systems. Even more plausibly, like every borehole geophysicist on the planet experiences eventually, their probe got hopelessly stuck in an inconvenient location.


Verdict: Depressingly plausible — our puny nukes are useless.

Premise #7: Everywhere looks like Southern California, and the logistics of transportation are strangely simple, almost as though envisioned by someone who has never lived in the eastern United States.

Look, somehow Richmond, Virginia sprouted hills, Missouri lost its forests, the journey from DC to Cape Code takes under 2 hours in heavy, gridlock traffic, and it just keeps getting worse. I don’t even care anymore.


Verdict: Implausible — but who actually cares about setting anyway?

Premise #8: The smallest comet fragment impacts the Atlantic Ocean off the eastern seaboard, triggering a massive tsunami that swamps the coast.


A tsunami is a rapidly-rising wall of water that doesn’t look at all like the graceful cresting waves on tsunami warning signs.

Yes, the graphics are, indeed, lovely! We get a nice draw-down of the trough arriving before the crest (although, Dear Hollywood, the odds are 50/50 the crest will arrive first and our heroes will have no warning of their impending doom...) and a huge wall of rapidly-rising water that doesn’t crest. But it’s only one wave. A real tsunami is a whole series of waves, like incredibly devastating ripples in pond triggered by a catastrophically huge pebble carelessly tossed in by the Lord High Director of Impending Doom. Not only that, but the first wave isn’t necessarily the biggest one, especially since nasty constructive interference effects of advancing and retreating waves can spike that tsunami even higher.


The scale of an impact tsunami is far larger, but they still shoal by the same mechanics. Image credit: International Tsunami Information Center.

But you know what it really gets right? Even though he never uses the term, President Beck successfully describes how a tsunami shoals as it enters ever-shallower water, bunching up into a steep, tall hill. He doesn’t inform us, or doesn’t know, that a tsunami also slows down as they shoal. While that monster propagated at the speed of a jet airplane in open ocean, it slows down to highway speeds as it approaches shore. In some ways, it’s almost, sort of, kinda, somewhat plausible a kid on a motorcycle with good reflexes and a hilly destination for a vertical refuge might be able to out-ride a tsunami if he was very, very lucky and had a very good bike.

Verdict: Surprisingly plausible.

Premise #9: The astronauts sacrifice themselves to give the planet a last-minute reprieve, vaporizing the final, bigger comet-chunk into puppies, rainbows, shooting stars, and pure joy. President Beck remains in office despite ruthlessly abandoning his citizens to their doom, and speaks rousingly of rebuilding in the wake of catastrophe. Sure, a few people died including our intrepid journalist, but a happy ending like this is totally plausible!


Ahahahahahhahahahahahahaha hah ah aha ha ha ha...

Wait, you’re serious?


Impending doom is such a romantic setting for newlywed teenage orphans.

Okay. So, all that comet-dust. It’s still the same mass, just in bitty pieces now, right? That shit still causes problems when it enters the atmosphere on that kind of scale. Worse, even a pathos-enhanced suicide-run explosion of the same number of nukes that split the comet before isn’t going to be able to totally decimate the comet to bite-sized pieces: some of those fragments are going to be legit city-destroying impactors scattering localized destruction below. Shockwaves, airbursts, flash-burns, direct impact... No way is this a Happily Ever After moment.

But ignore that and the rest of the physical sciences: We’ve just wiped out every major population center on the eastern seaboard at the very least, and probably a lot more damage in all those ignorable foreign-places around the rest of the Atlantic. Next, we’re looking at a population that was left anticipating the End of Days for months, stripped of all hope, explicitly abandoned by their political leaders, then somehow saved by the vagaries of plot. Society is resilient, but that’s a massive shock to assume that American culture will come out the other side still singing praises of the red, white, and blue. Whatever happens next, I can’t imagine it’ll be pretty.


Verdict: Brain-bendingly implausible.

The Judgement

Deep Impact is a surprisingly plausible doomsday scenario, although verging on overly-optimistic at times. Slap some red filters on any light that comes near an astronomer, make the tsunami significantly more scary, and add in some post-apocalyptic Mad Max collapse of society, and you might have a fairly realistic look at what will happen if we keep delaying investing in asteroid detection, tracking, and interception plans.