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    OSIRIS-REx spacecraft starts its two-year-long journey back to Earth.

    About OSIRIS-REx

    • It is the first U.S. mission to collect a sample from a near-Earth asteroid, called Bennu (formerly 1999 RQ36) and return it to Earth for study.
      • Scientists will use the asteroid samples to study the formation of the solar system and of habitable planets such as Earth. 
      • Analyzing the sample will help scientists understand the early solar system, as well as the hazards and resources of near-Earth space
    • It was built by Lockheed Martin and launched in 2016.
    • The spacecraft contains five instruments meant to explore Bennu including cameras, a spectrometer and a laser altimeter.


    The OSIRIS-REx name is an acronym of the mission objectives, which are: 

    • Origins: Return and analyze a pristine carbon-rich asteroid sample. 
    • Spectral Interpretation: Provide ground truth or direct observations for telescopic data of the entire asteroid population.
    • Resource Identification: Map the chemistry and mineralogy of a primitive carbon-rich asteroid.
    • Security: Measure the effect of sunlight on the orbit of a small asteroid, known as the “Yarkovsky effect” – the slight push created when the asteroid absorbs sunlight and re-emits that energy as heat. 
    • Regolith Explorer: Document the regolith (layer of loose, outer material) at the sampling site at scales down to the sub-centimetre.

    Sample Collection and Return 

    • Touch-And-Go Sample Acquisition Mechanism (TAGSAM) – an articulated robotic arm with a sampler head to collect a sample of Bennu’s surface. 
    • OSIRIS-REx Sample Return Capsule (SRC) – a capsule with a heat shield and parachutes through which the spacecraft will return the asteroid sample to Earth.

    Image Courtesy: CSA


    • The spacecraft found traces of hydrogen and oxygen molecules – part of the recipe for water and thus the potential for life – embedded in the asteroid’s rocky surface.
    • In October 2020, the spacecraft briefly touched asteroid Bennu, from where it collected samples of dust and pebbles.
    • A sample of primordial rock is now on its way to Earth, where scientists will analyze it to learn about the origins of our solar system and life on Earth.
    • When the spacecraft finally returns in September 2023, it will bring back the largest sample collected by a NASA mission since the Apollo astronauts collected samples of Moonrock. 


    • Asteroids, sometimes called minor planets, are rocky, airless remnants left over from the early formation of our solar system about 4.6 billion years ago.
    • The current known asteroid count is: 1,080,514.
    • Most of this ancient space rubble can be found orbiting the Sun between Mars and Jupiter within the main asteroid belt. 
    • Asteroids range in size from Vesta – the largest at about 329 miles (530 kilometers) in diameter – to bodies that are less than 33 feet (10 meters) across. 
    • The total mass of all the asteroids combined is less than that of Earth’s Moon.
    • Those like Bennu contain natural resources such as water, organics and metals. 
    • Future space exploration and economic development may rely on asteroids for these materials. 

    Image Courtesy: Socratic

    Asteroid Bennu

    • It is a skyscraper-sized asteroid some 320 million km from Earth.
    • It is named after an Egyptian deity
    • The asteroid was discovered by a team from the NASA-funded Lincoln Near-Earth Asteroid Research team in 1999.
    • It likely broke off from a much larger carbon-rich asteroid about 700 million to 2 billion years ago. 
    • Because its materials are so old, Bennu may contain organic molecules similar to those that could have been involved with the start of life on Earth.
    • It likely formed in the Main Asteroid Belt between Mars and Jupiter, and has drifted much closer to Earth since then. 
    • There is a slight possibility that Bennu, which is classified as a Near Earth Object (NEO), might strike the Earth in the next century, between the years 2175 and 2199.

    Near Earth Object (NEO)

    • NEOs are comets and asteroids nudged by the gravitational attraction of nearby planets into orbits which allow them to enter the Earth’s neighbourhood.


    • Comets are frozen leftovers from the formation of the solar system composed of dust, rock and ices
    • They range from a few miles to tens of miles wide, but as they orbit closer to the sun, they heat up and spew gases and dust into a glowing head that can be larger than a planet. 
    • This material forms a tail that stretches millions of miles.

    Sources: IE