In Brief
Years ago, Entrepreneur and CEO of SpaceX Elon Musk warned that life on Earth will go extinct if we don't become a multi-planetary species and colonize Mars. But precisely how imminent are these mass-extinction events? Exactly how pressing is it to colonize Mars? Could the Moon be a better first step?

The Path Towards Extinction

If we stay on Earth, some believe, humans will cease to exist. In an article published in June, Elon Musk warned of this cosmic inevitability: that life on Earth will go extinct if we don’t become a multi-planetary species. There are two paths, Musk wrote: “One path is we stay on Earth forever, and then there will be some eventual extinction event. I do not have an immediate doomsday prophecy, but eventually, history suggests, there will be some doomsday event. The alternative is to become a space-bearing civilization and a multi-planetary species, which I hope you would agree is the right way to go.”

Survival, compounded by fear, are ostensibly the primary motivations for humans to become a multi-planetary species. And though hypothetical mass-extinction events like asteroid impacts or nuclear war may crease our brows, we have advanced technologies—or strong theories about how to make such technologies—in order to safeguard the future of humanity. How pressing, then, is it to colonize Mars?

Super Solar Flares

Over the past few years, scientists and futurists have become increasingly concerned about the possibility of super solar flares (SSF). An ordinary solar flare is a normal part of our star’s sunspot-cycle, causing spikes of cosmic radiation. An SSF, however, is a massive solar flare. A star releases a blast of energy equivalent to 475 billion nuclear bombs in just a few hours or seconds, Scott Fleming, astronomer and archive scientist at the Mikulski Archive for Space Telescopes (MAST), told Futurism. Their energy is released in the form of X-rays, gamma rays, radio waves, visible light, and ultraviolet radiation.

For a long time, scientists didn’t think they were a big deal, but new discoveries about them has changed the expert opinion. Over the past few years, the Kepler space telescope has found evidence that distant, Sun-like stars have frequent flare activity. And scientists began to wonder what would happen if a SSF happened in our Sun, prompting new research.

If an SSF were to occur, the first thing to go would be the electrical infrastructure. That means cell phones, computers, automobiles, artificial lights — technologies upon which our society is now totally dependent — will cease to function, potentially throwing global civilization into a tailspin…and, quite literally, a new dark age.

A SSF could affect the environment, too. It could ravage what’s left of the ozone layer, which would cause widespread damage to ecosystems and trigger mass extinction, according to a study about the phenomenon published earlier this year. At first, such an event would allow warm gases to escape the atmosphere and cool the planet. But later, Earth would have little protection from its near-constant bombardment of ultraviolet rays, allowing them to descend to the surface where they would irradiate the planet.

At the poles, where ozone holes have grown since the 1970s, frigid seas would rapidly absorb carbon dioxide, reducing the amount of available oxygen in the ocean and making Earth’s water far more acidic. That kind of change would threaten phytoplankton, which make up the base of the food web. Scarcity would work its way up the food chain like a short line of dominoes.

But the real danger lies in the remote possibility of a second subsequent major flare that occurs before our ozone has fully recovered from the first, according to the study. Without an ozone layer to protect us, the UV radiation from a second SSF would cause DNA to mutate so dramatically that it could damage fertility and alter physiological functions. Even extremophiles could perish (though, admittedly, this scenario is even less likely than just one SSF).

So far, humans haven’t witnessed a SSF from our Sun in part because they aren’t so frequent, and our civilization has only existed for a few thousand years but unstable atoms trapped in tree rings show that bonafide SSFs have struck Earth before.

And despite their dramatic effects, researchers are still unsure exactly how often these catastrophic events happen. But according to the same study, Kepler data about the frequency of flares from other stars over the past 400,000 years helped researchers understand how often SSFs occur in stars that are very much like our Sun. That information led them to estimate that the Sun would probably emit a SSF every 20 million years (other analyses of the limited data available on Earth suggest that SSFs occur every 26 to 62 million years).

If the last SSF happened in the year 775, and if we (generously) assume that they happen every 20 million years, we could be waiting for a very long time until the next one. If people like Musk are looking for a rationale for off-world exploration, SSFs are not the most convincing motive.

But the story doesn’t end here. Although a full-powered SSF is not expected in the near future, a weaker yet destructive solar flare is highly likely in this millennium, the Astrophysical Journal paper concludes. “We hypothesized that the overall losses could exceed the world’s current GDP for certain superflares,” the study authors write. An event like that might not extinguish our species in a catastrophic blaze, but instead dismantle our society by destroying our economy and restrict our access to the resources that are necessary for our survival.

Yet, in order to understand the nature of SSFs, astrophysicists need to know exactly how they form from within a star. “It involves a lot of chaotic activity, the Sun’s magnetosphere and its churning atmosphere,” said Fleming. “It’s like a boiling pot of water combined with a slinky.” Without knowing the interior of our Sun with more certainty, researchers don’t see how we could predict a SSF more than about a week in advance. So it’s possible that SSFs present more of a risk than scientists currently predict.

What About Other Earth-Ending Threats?

The threat of SSFs may not be enough to drive us off-world, but there are other apocalyptic scenarios that might be more motivating. Brian Wilcox, Principal Investigator of Robotics and member of the NASA Advisory Council on Planetary Defense (NACPD), has spent much of his career tracking asteroids and comets to assess whether they might threaten Earth.

“It became apparent in my studies that, really, the asteroid problem was not as serious as some people appear to be claiming it is, in the narrow sense that we are mapping all the large objects in the inner solar system,” Wilcox tells Futurism. “It’s estimated that 98 percent of the one-kilometer objects in the inner solar system have been located, and that before long we’ll have located them all.”

As we confirm locations and trajectories of asteroids, Wilcox said, collisions between those objects and Earth that we are unable to prevent become increasingly less likely. When scientists identify a possible asteroid threat, they know within seven minutes if it’s on track to collide with Earth (that’s because of the physics and timing of Earth’s orbit, combined with the charted trajectory of the asteroid). “Either you get hit or you don’t,” he added. Instead of an unknown threat, we have quantifiable evidence that the vast majority of asteroids found to travel through the inner solar system are not on a path to collide with Earth. So to date, it seems that we have little to worry about.

Should a celestial object end up on a trajectory towards Earth, there are a few plans in place to stop it. Earlier this year, NASA began to design the Double Asteroid Redirection Test (DART), a spacecraft intended to launch a huge object at an asteroid in order to adjust its course. Lasers might be able to do something similar. NASA and FEMA also have effective (albeit unnerving) evacuation plans for low-probability but high-consequence impacts.

To that end, Wilcox isn’t worried about asteroids. Supervolcanoes, however, are a slightly different story. Erupting once every 100,000 years or so makes them “roughly one order higher in magnitude of probability [than an asteroid impact],” said Wilcox.

A supervolcano could have a devastating effect, should one erupt. It would spew enough dust and other particles into the atmosphere to block out sunlight, halting photosynthesis and leading to mass starvation, Wilcox said. And it’s not yet possible to predict when (or if) supervolcanoes will erupt. “If you go to the National Park Service, they won’t be able to tell you if [Yellowstone] has spent itself and won’t ever explode, or not,” Wilcox said.

We know Yellowstone explodes every 620,000 years, but, as with SSFs, human civilization hasn’t been around long enough to witness such an event. The last known supervolcano erupted 75,000 years ago in Indonesia and, evidence shows, ejected the equivalent of 175,000 dump trucks’ worth of scaldingly hot material into the atmosphere.

However, in Wilcox’s mind, neither of these examples truly provide sufficient motivation to leave Earth. In fact, he believes that even something like a pandemic wouldn’t justify heading to Mars.

Fleeing to Mars, he argued, won’t preserve our species. “If pandemic disease were our main concern, then the fastest way to protect ourselves would be to establish asteroid settlements from the terraformed interiors of asteroids, which could provide a habitat for 7,000 people,” Wilcox explained.

Not only are asteroids easier and cheaper than a Martian colony to build; they provide safety in the form of distance. It takes months to years to fly from Earth to Mars, it would take even longer to get to the asteroid belt. That’s longer than the incubation time for diseases — by the time the astronauts arrived at their new home, the most virulent diseases affecting them would no longer be infectious. “The hope is that medical science would progress enough for us to develop a test and prevent the infected from moving into space settlements,” Wilcox said.

If we have to get off Earth, the Moon seems to be a particularly viable option. We can mine rocket fuel on its surface, and transit is quicker, too. Tubes from ancient lava flows offer humans a protected place to construct our colonies, where we could terraform an area shielded from SSF radiation.

So, Is Mars Our Best Bet?

If we’re worried about SSFs, Mars initially appears to be a promising option for colonization. The Red Planet is roughly twice the distance from the Sun as Earth, so less radiation from the Sun would reach its surface.

But in fact, Mars would be far more dangerous for humans if an SSF were to occur. Mars has no magnetosphere, and its atmosphere was blown away by solar flare activity 4 billion years ago. In the event of an SSF, on Earth we’d at least have our atmosphere, our “bulletproof vest,” to protect us from radiation; on Mars, we’d be naked and vulnerable.

Additionally, transit to Mars will be remarkably dangerous. To this end, Wilcox thinks there are better alternatives. “If humanity is going to live and work in space, we have to learn to live and work in space,” says Wilcox. One good place to start might be going right next door. “Before going all the way to Mars, you could practice living and working in space on the Moon,” Wilcox told Futurism. Wilcox argues that we must test the technology required to colonize Mars before putting astronauts months away from hope of viable rescue, putting their lives at risk.

So in the end, visiting Mars may yield new knowledge, and open new means to embrace our pioneering spirit. But to simply survive, to live, it may be better to stay on Earth for now.