Asteroids

These are rocky objects that orbit the Sun, much smaller than planets. They are also called minor planets. According to NASA, 9,94,383 is the count of known asteroids, the remnants from the formation of the solar system over 4.6 billion years ago.

Asteroids are divided into three classes.

1. 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.
2. 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.
3. 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). 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 an Earth Minimum Orbit Intersection Distance (MOID) of 0.05 au or less and an absolute magnitude (H) of 22.0 or less are considered PHAs.

A recent study at National Aeronautics and Space Administration has found out that asteroid 16 Psyche, which orbits between Mars and Jupiter, could be made entirely of metal and is worth an estimated 10,000 quadrillion US dollars.

1. Asteroid 16 Psyche is located 370 million kilometers away from earth between Mars and Jupiter and has a diameter of 140 miles.
2. It was discovered in the year 1853 by the Italian astronomer Annibale de Gaspard and was named after the ancient Greek goddess of the soul, Psyche.
3. Unlike most asteroids that are made up of rocks or ice, scientists believe that Psyche is a dense and largely metallic object thought to be the core of an earlier planet that failed formation.
4. Psyche’s shape is like a potato which takes about five earth years to complete one orbit of the sun but only a bit over 4 hours to rotate once on its axis.

The latest study through the Hubble Space Telescope and ultraviolet observation gives a clearer picture of Psyche’s composition. The Hubble Space Telescope was launched into low Earth orbit in 1990 and remains in operation.

It was found that Psyche could be a unique asteroid composed of iron and nickel almost completely which is similar to earth's core. The iron alone would be worth more than 10,000 quadrillion US dollars. Scientists noted that the manner in which Psyche reflected ultraviolet light was very similar to the way iron reflects sunlight.

NASA’s Psyche mission: The primary target of the Psyche mission to be launched in 2022 by NASA is to study this asteroid completely and confirm the assumptions being made by the scientists.

Psyche mission will be the first mission to investigate this metallic asteroid. Psyche spacecraft will land on the asteroid in early 2026. As the composition of Psyche is very similar to earth’s own core, its study will also give an insight to earth’s violent history of collisions and accretion that created it.

OSIRIS-REx

NASA’s OSIRIS-REx spacecraft briefly touched asteroid Bennu, from where it is meant to collect samples of dust and pebbles and deliver them back to Earth in 2023.

What is the OSIRIS-REx mission?

OSIRIS-Rex stands for Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer.

1. This is NASA’s first mission meant to return a sample from the ancient asteroid.
2. Launched in 2016, it reached its target in 2018.
3. The departure window for the mission will open up in 2021, after which it will take over two years to reach back to Earth.

Asteroid Bennu:

The asteroid was discovered by a team from the NASA-funded Lincoln Near-Earth Asteroid Research team in 1999.

Scientists believe that it was formed in the first 10 million years of the solar system’s formation, implying that it is roughly 4.5 billion years old.

1. Because of Bennu’s age, it is likely to contain material that contains molecules that were present when life first formed on Earth, where life forms are based on carbon atom chains.
2. Because of its high carbon content, the asteroid reflects about four per cent of the light that hits it, which is very low when compared with a planet like Venus, which reflects about 65 per cent of the light that hits it. Earth reflects about 30 per cent.
3. It classified as a Near Earth Object (NEO), might strike the Earth in the next century, between the years 2175 and 2199.

Hayabusa 2

Japan Aerospace Exploration Agency (JAXA) has decided to make a crater on asteroid 1999 JU3 (Ryugu) to collect underground samples. This is part of the Hayabusa 2 mission launched in December 2014, to explore asteroid 1999 JU3 (Ryugu). The purpose of drilling is to collect samples for possible clues to the origin of the solar system.

Hayabusa 2

• Hayabusa 2 was launched in December 2014 and is planned to complete a mission of six years.
• It arrived at Ryugu in July 2018 and will spend 18 months studying the asteroid before making its return to Earth in December 2020.
• The mission builds on the original Hayabusa mission that was launched in 2003 and successfully linked up with asteroid Itokawa in 2005.
• It returned samples to Earth in 2010 marking the first time sample materials from an asteroid were brought back to Earth.