Right now and probably until mid-century, humankind will be helpless to defend itself against “killer asteroids,” those monstrously large chunks of space rock that can pulverize a country and even the planet.

This defenselessness was proven at the International Academy of Astronautics “2019 Planetary Defense Conference” in Maryland that took place from May 2 to 7. The geniuses from NASA, the Federal Emergency Management Agency (FEMA) and the European Space Agency (ESA) developed and conducted a simulation experiment to test our defenses against a huge asteroid hurtling toward the planet.

The asteroid in this simulation was a hypothetical one given the designation 2019 PDC. This asteroid was discovered on March 26, 2019 with a projected impact on April 29, 2027.

Despite an advanced warning of eight years and despite the asteroid being reduced in size by the impact of three kamikaze space probes that sought to deflect it off course, a 60 meter-wide fragment plunged into the atmosphere at a speed of 19 kilometers per second (43,000 mph) to explode in the air over New York City’s Central Park. The horrific blast unleashed 20 megatons of energy and completely obliterated the Big Apple.

The city, however, had been evacuated but the damage inflicted by the explosion on the surrounding terrain, as well as on the world’s ecology, was immense.

Now imagine if this asteroid were of the same type and almost the same size as the one that smashed into the Atlantic Ocean off Yucatan, Mexico some 66 million years ago. The Chixulub impactor, which caused the extinction of the dinosaurs, is estimated to have had a maximum diameter of some 80 meters.

But what if the next impactor were larger than Chixulub?

Steinn Sigurðsson, a professor in the Department of Astronomy and Astrophysics at Penn State University, believes an impact powerful enough to wipe out all life on Earth's surface will launch large amounts of rock into orbit around the Sun.

He contended that most of these bits and pieces will end up falling back onto our shattered planet, potentially bringing life back with them. That’s microbial life, by the way.

"This is peculiarly reassuring," said Sigurðsson at the Breakthrough Discuss conference at the University of California, Berkeley last month.

"If you have a sterilizing impact -- if you have a beyond dinosaur killer, something that’s going to flash fry the entire planet -- there is a significant probability that some biota is ejected and returns to the planet, hopefully gently, fast enough to reseed the planet," he pointed out.

The existence of these "space refugees" is supported by computer simulations conducted by Sigurðsson and his colleagues. The simulations tracked the trajectories of rock, or ejecta, blasted off the Earth and into orbit around the Sun.

Sigurðsson and his team followed the simulated ejecta's orbital evolution for 10 million years. They chose this time span "because there's a meme in the literature that you might keep biota viable (inside a rock in space) for about 10 million years," said Sigurðsson. "Beyond that, you're pushing your luck."

Surprisingly, the simulation showed less than 0.1 percent of the ejecta making it to the outer Solar System, to the realm of the potentially habitable Jupiter moon, Europa, and the Saturn satellites, Enceladus and Titan, both of which may also be capable of supporting life.

In addition, a few percent of ejected rocks escaped our solar system entirely, raising the possibility that life from Earth or Mars may have seeded worlds circling other stars, said Sigurðsson.