Asteroid impact is not science fiction, Space X helps NASA eliminate the threat

The Chelyabinsk event in Russia shows that the severity and potential likelihood of asteroid impacts are increasing.

According to foreign media reports, NASA Administrator Jim Bridenstine believes that asteroid impacts that could cause mass casualties are not something that only happen in science fiction movies.

Bridenstine explained why the U.S. should strengthen its defenses against asteroid events during the 2019 Planetary Defense Conference in Washington, D.C., where NASA, the Federal Emergency Management Agency (FEMA) and related agencies will conduct a defense exercise simulating an asteroid heading straight for Earth.

"We have to make sure people understand that this is not about Hollywood, this is not about movies," Bridenstine said at the conference. "This is ultimately about protecting the only planet that we know of that can support life, and that's Earth." He also pointed out that the Chelyabinsk event in Russia showed that the severity and potential likelihood of asteroid impacts are increasing.

In February 2013, an asteroid plunged into the atmosphere, leaving a trail about 10 kilometers long over the southern Ural Mountains. It was the largest meteor impact recorded in more than a century since the Tunguska event in 1908, and the shock wave of the airburst injured more than 1,600 people. Its power was estimated to be as strong as 20 Hiroshima atomic bombs. It is estimated that such events occur once every 60 years, but Bridenstine said that such events have occurred three times in the past 100 years.

According to this line of thinking, the next asteroid impact event similar to the Chelyabinsk event may happen in our lifetime. "I wish I could tell you that these events are very rare," Bridenstine said, "but they are not."

The Chelyabinsk incident has made the world realize the threat of asteroid impacts on the Earth, and it has also prompted scientists to update their ideas and response strategies for such events. Bridenstine said that planetary defense is as important as NASA's other goals (such as humans landing on the moon again). NASA is working hard to detect and track 90% of asteroids larger than 140 meters in width near the Earth, which are likely to cause deadly damage if they hit the Earth.

NASA's efforts also include the Double Asteroid Redirect Test (DART) mission. The mission, scheduled to launch in June 2021, includes help from Elon Musk's SpaceX. DART is groundbreaking in that it will be the first time an asteroid is deliberately deflected by crashing an object into it at high speed. The mission will launch from Vandenberg Air Force Base in California on a Falcon 9 rocket in 2021 and is expected to arrive at Didymos, 11 million kilometers from Earth, in October 2022.

The success of the DART mission depends on the so-called "kinetic impactor", which uses a 2.4-meter-long spacecraft with solar electric propulsion to hit an asteroid. The mission's target is the near-Earth binary asteroid system Didymos, which is about 800 meters in diameter. The other body in the binary asteroid is a satellite, which is only 150 meters wide and is "more typical of asteroid size and may pose a more common threat to the Earth."

With the help of onboard cameras and advanced autonomous navigation software, the DART mission spacecraft will deliberately crash into the small satellite at a speed of about 6 kilometers per second, thereby achieving a kinetic impact. The collision will cause the small satellite's speed in its orbit around the main celestial body to change by a few tenths of a percent, enough to be measured with telescopes on Earth. So far, the cost, including launch services, has been estimated at about $69 million.

How to stop an asteroid from hitting Earth?

If an asteroid were headed toward Earth today, humans would not be able to deflect it, but they could mitigate the impact as much as possible and take measures to protect life and property, including evacuating affected areas and relocating critical infrastructure.

Knowing an asteroid's trajectory, size, shape, mass, composition and rotational dynamics will help experts determine the severity of a possible impact event. Of course, the key to mitigating damage is detecting any potential threats as early as possible.

Scientists are currently advancing a mission to prevent an asteroid from colliding with Earth using a refrigerator-sized probe that will test a small, non-threatening asteroid in 2024, the first demonstration of asteroid deflection technology for planetary defense.

The Double Asteroid Redirection Test (DART) will use a kinetic impactor technique to change the orbit of an asteroid by striking it. This impact will only change the asteroid's overall velocity by a small amount, but if prepared in advance of the predicted impact, this small push over time will cause the asteroid to deviate significantly from Earth's orbit.