Due to the gravitational pull of Earth, some objects, like asteroids and meteors, do crash on Earth. These objects include asteroids, comets, stars, planets, meteors, galaxies, and more. 

As long as the objects are not particularly large, such as the asteroid that wiped out all the dinosaurs, they do not pose any threat to Earth. We need some kind of defense system in place to prevent mishaps. 

A single asteroid strike or comet impact on Earth may have wiped out dinosaurs 65 million years ago, but NASA shared another explanation. 'Dinosaurs might have been wiped out 65 million years ago when asteroid or comet impacts caused their extinction, or they may have died out due to multiple comet impacts over one million years, a group of scientists believes. 

Scientists from NASA's Jet Propulsion Laboratory in Pasadena, Calif., said comet showers that occurred over time may have caused extinctions, says Dr. Paul Weissman, one of eight authors. As a result, staying alert and prepared is essential, as any such strike would destroy Earth in unimaginable ways. This could even lead to the extinction of humanity.

A NASA mission titled DART (Double Asteroid Redirection Test) was launched in November 2021 to achieve this goal. Through kinetic impact, DART will explore and demonstrate a method of asteroid deflection in space, which will change an asteroid's motion in space. It is the world's first planetary defense test mission.

'DART demonstrates that a spacecraft can navigate autonomously to an asteroid and intentionally collide with it – a method of deflection called kinetic impact – to deflect it. According to NASA, the test will provide valuable information that could be used to prepare for an asteroid that might pose a threat to Earth, should one be discovered.

An Italian CubeSat, LICIACube, will be released before DART's impact and will capture images of the cloud of material ejected by the impact. The Hera project of the European Space Agency (ESA) will conduct detailed surveys of both asteroids roughly four years after DART's impact, focusing on the crater left by DART's collision and determining Dimorphos' mass precisely.

Since the formation of the solar system, the fraction of the asteroid population that has survived has been subjected to numerous collisions, dynamical events, and thermal events that have shaped their orbits and structures. 

Laboratory experiments cannot replicate low-gravity, low-strength impact conditions, so the observed regime of low-gravity, low-strength impacts remains largely unknown.  A numerical simulation of these impact processes has been impossible up to now because of the very long timescales involved in the growth of craters.

It has been demonstrated that an asteroid can have a very loose internal structure through missions like JAXA's Hayabusa2's artificial impact experiment on Ryugu. In earlier simulations, DART's asteroid target Dimorphos was assumed to have a solid interior.

“The study lead-author Sabina Raducan of the Institute of Physics and the National Centre of Competence in Research PlanetS points out, quoted by techexplorist, that this could drastically change the outcome of the collision between DART and Dimorphous.

Furthermore, the European Space Agency will send a space probe to Dimorphos in 2024 as part of the HERA space mission. The goal of the mission is to investigate the aftermath of the DART probe's impact on Dimorphous.