An asteroid on a trajectory to impact Earth could not be shot down in the last few minutes or even hours before impact. No known weapon system could stop the mass because of the velocity at which it travels – an average of 12 miles per second.
Johnson said now that NASA successfully smashed a spacecraft into an asteroid and altered its trajectory, a mission known as the Double Asteroid Redirection Test, or DART, “our emphasis now will turn to getting the NEO surveyor mission developed and launched.”
Nuclear weapon
If executed at the proper distance, the explosion would make the surface of the asteroid rip away into space and push the asteroid firmly away from its current path, experts have said.
There are a variety of deflection techniques that could save Earth from an incoming asteroid. They range from using a large spacecraft's gravity to pull the asteroid off course, to sending up a kinetic impactor to slam into the asteroid, or even using nuclear detonations.
With an asteroid hitting the Earth; dust and smoke rising in the atmosphere prevents sunlight from reaching our world and causes the total temperature to drop. This event can lead to the death of many living things. If an asteroid the size of an apartment hits Earth, this blow could possibly destroy a small city.
“Any asteroid over 1km in size is considered a planet killer,” said Sheppard, adding that should such an object strike Earth, the impact would be devastating to life as we know it, with dust and pollutants kicked up into the atmosphere, where they would linger for years.
An asteroid, named "2019 PDC", was discovered that will come dangerously close to the earth 8 years from now, on April 29, 2027. The space rock is between 330 and 1000 feet in size, somewhere in between the length of 6.5 school buses to the height of two Washington Monuments stacked on top of each other.
An asteroid on a trajectory to impact Earth could not be shot down in the last few minutes or even hours before impact. No known weapon system could stop the mass because of the velocity at which it travels – an average of 12 miles per second.
This could be done by impacting it with a non-destructive projectile, simply tugging the asteroid into a different orbit with a nearby high-mass spacecraft, ablating the asteroid's surface with a high-power laser (or a nearby nuclear explosion), or by placing small rockets on the asteroid's surface.
There is currently no known significant threat of impact for the next hundred years or more.
But assuming every warhead had a megatonne rating, the energy released by their simultaneous detonation wouldn't destroy the Earth. It would, however, make a crater around 10km across and 2km deep. The huge volume of debris injected into the atmosphere would have far more widespread effects.
If a nuclear weapon is exploded in a vacuum-i. e., in space-the complexion of weapon effects changes drastically: First, in the absence of an atmosphere, blast disappears completely. Second, thermal radiation, as usually defined, also disappears.
NASA considers any space rock a potential hazard if it measures at least 460 feet (140 meters) in diameter and orbits within 4.6 million miles (7.4 million km) of Earth. An impact from such a rock could wipe out an entire city and devastate the land around it, according to NASA.
Billions would die, and much of life on the planet would be destroyed. But, scientists believe some would survive. NASA scientists say it would take an asteroid 60 miles (96 kilometers) wide to totally wipe out life on Earth.
It's important to stress that 2023 PDC is a purely hypothetical object and it isn't on course to impact Earth. In fact, currently, there are no large asteroids predicted to hit Earth for the next 100 years.
The last known impact of an object of 10 km (6 mi) or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago. The energy released by an impactor depends on diameter, density, velocity, and angle.
Their experiments showed that blowing up a 200-meter asteroid would require a bomb 200 times as powerful as the one that exploded over Hiroshima in 1945. They also said it would be most effective to drill into the asteroid, bury the bomb, then blow it up—just like in the movie Armageddon.
"If scientists actually knew there was an impending catastrophic collision, some asteroid was heading towards Earth, would they tell you?" "And the answer is yes... Every night we are looking for objects that might be on a collision course with Earth and if we find anything that looks risky, we inform lots of people."
When the 6-mile-wide asteroid that led to dinosaur extinction hit Earth 66 million years ago, the impact also triggered a “mega-earthquake” that lasted weeks to months, new evidence suggests.
The planet Earth has been around for more than 4.5 billion years. And in the course of its history it has been hit by asteroids at least 190 times. But there were three particular occasions when the asteroid was so large and the impact crater it created was so wide, scientists are sure it would have ended humanity!
The good thing is, according to NASA, asteroids larger than 100 meters that can cause local damage hit the Earth about every 10,000 years. Space rocks larger than 1 kilometer that can threaten life on our planet come along only once in a few million years.
Fortunately, given enough time and preparation, it is possible to defend our planet from dangerous asteroids. Small nudges to a near-Earth asteroid's path can have big long-term consequences, turning a direct hit into a near-miss. A myriad of asteroid deflection methods have been proposed over the years.
The largest asteroid to ever hit earth was an asteroid named Vredefort. This absolutely gargantuan asteroid was likely around 12.4 and 15.5 miles across and was traveling between 45,000 and 56,000 mph when it hit the surface.
An asteroid in space has been identified as having a value of approximately $700 quintillion. If NASA were to capture the asteroid and distribute its resources among people, each individual would receive around $93 billion!
A newly discovered asteroid may make a perilously close approach to Earth about 20 years from now, with a roughly 1-in-600 chance that the space rock will collide directly with our planet, officials with NASA's Planetary Defense Coordination Office tweeted.