International Space Agencies – Missions and Discoveries

NASA’s OSIRIS-REx lands on Asteroid Bennu

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Asteroids, Bennu

Mains level : NASA's feat of landing on an asteroid

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.

The OSIRIS-REx mission

  • OSIRIS-REx stands for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer. This is NASA’s first mission meant to return a sample from the ancient asteroid.
  • The mission is essentially a seven-year-long voyage and will conclude when at least 60 grams of samples are delivered back to the Earth.
  • As per NASA, the mission promises to bring the largest amount of extraterrestrial material back to our planet since the Apollo era.
  • The mission was launched in 2016, it reached its target in 2018 and since then, the spacecraft has been trying to match the velocity of the asteroid using small rocket thrusters to rendezvous it.
  • This week, the spacecraft’s robotic arm called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), made an attempt to “TAG” the asteroid and collected a sample.

About Bennu

  • Bennu is a B-type asteroid, implying that it contains significant amounts of carbon and various other minerals.
  • It was discovered by a team from the NASA-funded Lincoln Near-Earth Asteroid Research team in 1999.
  • 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. Earth reflects about 30 per cent.
  • Around 20-40 per cent of Bennu’s interior is empty space and 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.

Why are scientists studying asteroid Bennu?

  • Bennu is an asteroid about as tall as the Empire State Building and located at a distance of about 200 million miles away from the Earth.
  • Scientists study asteroids to look for information about the formation and history of planets and the sun since asteroids were formed at the same time as other objects in the solar system.
  • Another reason for tracking them is to look for asteroids that might be potentially hazardous. It is also relatively close to the Earth.
  • It is for these reasons that scientists are interested in gathering information about this particular asteroid.
  • Significantly, Bennu hasn’t undergone drastic changes since its formation over billions of years ago and therefore it contains chemicals and rocks dating back to the birth of the solar system.

How do chemicals and rocks offer scientists clues about the solar system?

  • 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.
  • Even so organic material like the kind scientists hope to find in a sample from Bennu doesn’t necessarily always come from biology.
  • It would, though, further scientists’ search to uncover the role asteroids rich in organics played in catalyzing life on Earth.

Back2Basics: Asteroid

  • 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 of 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.
  • 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).
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