Asteroids
- September 7, 2020
- Posted by: OptimizeIAS Team
- Category: DPN Topics
No Comments
Subject: Geography
Context:
Asteroid 465824 2010 FR was expected to cross the Earth’s orbit on September 6.
Concept:
- Asteroids are rocky objects that orbit the Sun, much smaller than planets. They are also called minor planets.
- According to NASA, 994,383 is the count for known asteroids, the remnants from the formation of the solar system over 4.6 billion years ago.
- Asteroids are divided into three classes.
- First, those found in the main asteroid belt between Mars and Jupiter, which is estimated to contain somewhere between 1.1-1.9 million asteroids.
- The second group is that of trojans, which are asteroids that share an orbit with a larger planet. NASA reports the presence of Jupiter, Neptune and Mars trojans. In 2011, they reported an Earth trojan as well.
- The third classification is Near-Earth Asteroids (NEA), which have orbits that pass close by the Earth. Those that cross the Earth’s orbit are called Earth-crossers. More than 10,000 such asteroids are known, out of which over 1,400 are classified as potentially hazardous asteroids (PHAs).
- Potentially Hazardous Asteroids (PHAs) are currently defined based on parameters that measure the asteroid’s potential to make threatening close approaches to the Earth. Specifically, all asteroids with a minimum orbit intersection distance (MOID) of 0.05 au or less are considered PHA.
Threats:
- NASA’s Near-Earth Object Observations Program finds, tracks and characterises over 90 per cent of the predicted number of NEOs that are 140 metre or larger which according to the space agency are of “the greatest concern” due to the level of devastation that their impact is capable of causing.
- No asteroid larger than 140 metre has a “significant” chance of hitting the Earth for the next 100 years.
Measures:
- Over the years, scientists have suggested different ways to ward off such threats, such as blowing up the asteroid before it reaches Earth, or deflecting it off its Earth-bound course by hitting it with a spacecraft.
- Asteroid Impact and Deflection Assessment (AIDA), which includes NASA’s Double Asteroid Redirection Test (DART) mission and the European Space Agency’s (ESA) Hera. The mission’s target is Didymos, a binary near-Earth asteroid, one of whose bodies is of the size that could pose the most likely significant threat to Earth.