ASTEROIDS

Subject: Geography

Context: Prominent astrophysicist has said that Asteroid 2018VP1, a refrigerator-sized space-rock that is on a collision course with Earth.

Concept:

Asteroid 2018VP1:

• Asteroid 2018VP1 has a diameter of about 2 metres, around the size of a small automobile.
• Only 1 in 240 chance that 2018VP1 would impact the Earth. It would likely burn up into a fireball after entering the Earth’s atmosphere before reaching the ground.
• According to NASA, such an event happens about once every year.

Asteroids

• Asteroids are also known as minor planets.
• They are rocky remnants left over from the early formation of our solar system about 4.6 billion years ago.
• Most asteroids are irregularly shaped, though a few are nearly spherical and are known to have a small companion moon (some have two moons).

Classification of Asteroids:

• Main Asteroid Belt: The majority of known asteroids orbit within the asteroid belt between Mars and Jupiter.
• Trojans: These asteroids share an orbit with a larger planet, but do not collide with it because they gather around two special places in the orbit (called the L4 and L5 Lagrangian points). There, the gravitational pull from the sun and the planet are balanced.

Lagrange Points are positions in space where the gravitational forces of a two body system like the Sun and the Earth produce enhanced regions of attraction and repulsion. These can be used by spacecraft to reduce fuel consumption needed to remain in position.

• Near-Earth Asteroids: These objects have orbits that pass close by that of Earth. Asteroids that actually cross Earth’s orbital path are known as Earth-crossers.

Cut off size:

• As per NASA’s Near-Earth Object Observations Programme, asteroids that are 140 metres or larger (bigger than a small football stadium) are of “the greatest concern” due to the level of devastation their impact is capable of causing.
• No asteroid larger than 140 metres has a “significant” chance of hitting the Earth for the next 100 years.

Deflecting Asteroids: Important steps taken so far.

• Double Asteroid Redirection Test (DART): The construction of DART began in 2018, which is scheduled to launch in 2021.

             Aim is to slam into the smaller asteroid of the Didymos system at around 6 km per second in 2022.

• Hera: It is scheduled to launch in 2024, will arrive at the Didymos system in 2027.

          Aim is to measure the impact crater produced by the DART collision and study the change in the asteroid’s orbital trajectory.