In the summer of 1998, Hollywood offered up not one, but two blockbuster films about asteroids hurtling towards Earth.
Released on May 8 of that year, Deep Impact, directed by Mimi Leder, told a story of humanity facing a cataclysmic threat from a deadly asteroid, prompting the U.S. government to build a network of underground shelters for just a select few. Michael Bay’s Armageddon, arriving in theaters seven weeks later on June 30, saw a ragtag team of oil drillers, led by Bruce Willis, embark upon a dangerous mission to save the planet from an incoming, humanity-snuffing asteroid by blowing it up with a nuclear bomb buried in its center.
Now, 25 years after their original releases — and just eight months after DART, the first-ever NASA mission to successfully deflect an asteroid's trajectory in deep space — Yahoo Entertainment has been wondering: Was there any truth in this fiction?
As several NASA scientists tell us, Armageddon's depiction of blowing up an asteroid by planting a nuclear bomb in its core is unrealistic. Their colleagues say that Deep Impact's portrayal of a massive tidal wave wiping out the East Coast is far-fetched.
Here's what else some of the leading minds in asteroid science had to say.
Which film is more scientifically accurate?
Phil Plait, an American astronomer who has worked with NASA on the Hubble telescope, says Deep Impact is by far the most “science-based” of the two.
In fact, he says, some scenes in the film aren’t far off from reality. There's one moment when scientists tether a spaceship to the threatening comet before planting nuclear bombs in its core, hoping the explosion diverts it from its collision course. Nuclear bombs aside, that method is strikingly similar to one used back in September 2016, when the Philae Lander became the first man-made structure to land on the surface of a comet to retrieve images and data.
Seth Jacobson, a planetary scientist and assistant professor at the University of Michigan, agrees that Deep Impact is the more science-based film, but says, “It's not clear to me why burying a bomb in an asteroid would be a good strategy in the first place. This just wouldn’t happen.”
Plait agreed that "the biggest mistake in most asteroid movies" is characters believing that it's a good idea to blow up an asteroid. "In reality, the better thing is to make sure it never hits us," as was accomplished with the recent DART mission through the use of a kinetic impactor — a spacecraft that worked like a big slingshot to redirect its course.
Besides, "blowing up asteroids is harder than most people think," notes William Bottke, head of the Department of Space Studies at the Southwest Research Institute.
Even if one succeeded at using a nuclear bomb to blow up an asteroid, he says, the heat from the blast would vaporize material on the surface and expand violently, ultimately pushing on the rock and turning it from a very, very fast asteroid, or "bullet," to a deadly "shotgun blast."
And then there was the late Jay Melosh, an American geophysicist who specialized in impact cratering, who proposed a way to deflect asteroids without bombs.
"He argued we could fly to the asteroid and use a large optical surface to concentrate solar energy onto a small point on the asteroid," Bottke says. "This would vaporize the rock instantaneously in a fashion not so different from using the sun and a magnifying glass to burn a piece of paper. By carefully choosing your spots, you could create a rock comet and slowly move the asteroid onto a different trajectory."
"The more grounded these movies are in scientific realism, the better," he says. "But I also understand the need to make these movies dramatic and entertaining."
Did the underground shelters make sense?
Deep Impact famously highlighted social inequities by building a network of underground shelters available only to the mega-rich, but Bottke says it’s likely a fool’s errand anyway.
“For very large impacts, the ejected material from the blast can produce firestorms far from the event, and long-term global cooling from the small particles that stay entrained in the atmosphere,” he explains. It may also have an impact on agriculture, which depends on the sun, water and healthy soil for seeds to grow, which “could easily lead to worldwide famine.”
Underground shelters could maybe save humanity in theory, but it all depends on "how big the comet is and where it hits," says Plait. "If you know where the impact will be and put the shelter far away and heavily fortified, then... maybe?"
If the comet were a so-called "planet killer," like the plummeting Chicxulub impactor that wiped out dinosaurs, there will undoubtably be changes to the atmosphere that will last years, which impacts all animals on Earth.
"However, with some foresight, it might be possible to survive, subsurface, through that period," Jacobson notes. "We know that many small animals did just that because humans are the evolved descendants of survivors of the Chicxulub impact."
Should we be worried about planet-killing asteroids?
No one should be losing sleep over it, say the experts. "There are no large asteroids heading for Earth within our lifetimes," says Chodas. "A large impact is exceedingly unlikely, and NASA and other institutions around the world are working to reduce the concern even more, as better asteroid search telescopes come online."
That includes the NEO Surveyor mission, set to launch in Sept. 2027, which aims to find at least two-thirds of the near-Earth objects larger than 460 feet, or "the ones which could potentially cause regional devastation if any should impact Earth," he explains.
Not to mention that a species-ending comet would become public very early on, which means transparency would be demanded from citizens on a global scale, giving us more than enough time to prepare — unlike in Deep Impact, when the world had roughly a year before impact, and in Armageddon, which had only 18 days.
But if we've learned anything from such Hollywood storylines, it’s that time is always of the essence.
“If we have decades [to prepare], which is most likely, scientists and policy makers from around the world will come up with an action plan,” notes Bottke. “The asteroid will become the most studied celestial object in history, and a plan will be developed to carefully nudge it onto a trajectory that misses Earth. If we have a few years, the only option would be to use nuclear weapons," attached to a kinetic impactor, "for deflection.”
Of course, this is all hypothetical, says Chodas. "We have already found more than 95% of the asteroids capable of doing this. And they are not headed for Earth anytime soon."
Finally, say the scientists: At the end of the day, if Hollywood can get people excited about science, it's a good thing, inaccurate or not.
"A lot of scientists today, including me, were inspired by shows like Star Trek," says Plait, "even though the science can be dodgy."
Still, adds Bottke, accuracy goes a long way. And all it takes is "a little bit of script work," something planetary scientists, who are " giant nerds who love science fiction," would happily sign up for. "The audience also responds positively," he adds, "when they feel the filmmakers have tried to get things right."