OSIRIS-Rex Spacecraft Brings Back Sample from Asteroid Bennu

What’s in Today’s Article?

• Why in News?
• About OSIRIS-Rex
• About Asteroids
• Classification of Asteroids
• About Asteroid Bennu
• Why Bennu was Chosen as the Target Asteroid?
• News Summary

Why in News?

• OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer), the first US mission to collect a sample from an asteroid, returned on Earth with material from asteroid Bennu.
• So far, Japan is the only other country to similarly bring asteroid samples to the Earth.

About OSIRIS-REx:

• OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is a NASA (National Aeronautics and Space Administration) asteroid-study and sample-return mission.
• The mission was launched in September, 2016. The spacecraft reached asteroid Bennu in 2018.
• Objective: To obtain a sample of at least 60 gm from Bennu and return the sample to Earth for a detailed analysis.
• In October 2020, the spacecraft contacted the surface of the asteroid successfully and fired a burst of nitrogen gas meant to stir rocks and soil.
  • Once the surface was disturbed, the spacecraft’s robotic arm captured some samples.
• NASA had also confirmed that shortly after the spacecraft made contact with the surface, it fired its thrusters and “safely backed away from Bennu”.

About Asteroids:

• Asteroids are small, rocky objects that orbit the Sun.
• Although asteroids orbit the Sun like planets, they are much smaller than planets. They are also known as planetoids or minor planets.
• There are millions of asteroids, ranging in size from hundreds of kms to several feet across.
• In total, the mass of all the asteroids is less than that of Earth's moon.

Classification of Asteroids:

• Asteroids lie within three regions of the solar system:
• Asteroid Belt:
  • Asteroid belt is the region between Mars and Jupiter.
  • This region contains the majority of known asteroids and is estimated to have 1 to 2 million asteroids larger than 1 km in diameter and millions of smaller ones.
• Near-Earth Asteroids:
  • Near-Earth asteroids (NEAs) circle closer to Earth than the Sun.
  • About 10,000 NEAs have been discovered to date. And over 1,400 have been classified as Potentially Hazardous Asteroids or PHAs.
  • Astronomers employ the Torino Scale for categorizing the impact hazard associated with PHAs.
• Trojan Asteroids:
  • Asteroids share an orbit with a larger planet.
  • The Trojan Asteroids do not collide with the parent planet because they are located in places known as Lagrange points where the gravitational pull of the Sun and the planet are balanced.
  • Jupiter has the largest number of Trojan asteroids discovered to date.
  • Neptune, Mars and Earth also have Trojan asteroids.

About Asteroid Bennu:

• Bennu is a B-type Near-Earth Asteroid.
  • B-type asteroids are a relatively uncommon type of carbonaceous asteroid.
• Because of its high carbon content, the asteroid reflects about four per cent of the light that hits it, which is very low.
  • Earth reflects about 30 per cent of the light.
• There is a slight possibility that Bennu might strike the Earth in the next century, between the years 2175 and 2199.

Why Bennu was Chosen as the Target Asteroid?

• Bennu is a "time capsule" from the birth of the Solar System.
  • Scientists believe that it is 4.5 billion years old.
  • It hasn’t undergone drastic changes since its formation and, therefore, it contains chemicals and rocks dating back to the birth of the Solar System.
• In particular, Bennu was selected because of the availability of pristine carbonaceous material, a key element in organic molecules necessary for life.

News Summary:

• On September 24^th, NASA’s first asteroid samples, fetched from asteroid Bennu, were dropped by Osiris-Rex into the USA’s Utah desert by the OSIRIS-Rex spacecraft.
• Engineers estimate the canister holds 250g of material from Bennu, plus or minus 100g.
  • It will take a few weeks to get a precise measurement.
• These samples carried by the OSIRIS-REx mission are important because asteroids such as Bennu can act as a "time capsule" for our solar system's earliest history.
• The asteroid sample will help researchers learn about how our planet and solar system formed, as well as the origin of organics that may have led to life on Earth.
• This was NASA's third sample return from a deep-space robotic mission.
  • The Genesis spacecraft dropped off bits of solar wind in 2004, but the samples were compromised when the parachute failed and the capsule slammed into the ground.
  • The Stardust spacecraft successfully delivered comet dust in 2006.
• On the other hand, Osiris-Rex spacecraft is already chasing the asteroid Apophis, and will reach it in 2029.

Q1) Which is the largest Asteroid?

The largest asteroid is called Ceres. It is about one-quarter the size of the moon and orbits the sun between Mars and Jupiter in a region called the asteroid belt. Unlike most asteroids, Ceres is spherical in shape.

Q2) What is a Meteoroid?

A meteoroid is a small rocky or metallic body in outer space. Meteoroids are distinguished as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide.

Source: NASA capsule carrying first asteroid samples lands on Earth | phys.org