NASA’s OSIRIS-Rex

Context: NASA’s OSIRIS-Rex spacecraft has set a new milestone in cosmic exploration by entering orbit around an asteroid, Bennu, the smallest object ever to be circled by a human-made spaceship.

Significance:

OSIRIS-Rex is the first-ever US mission designed to visit an asteroid and return a sample of its dust back to Earth. The $800 million (roughly Rs. 5,600 crores) unmanned spaceship launched two years ago from Cape Canaveral, Florida and arrived December 3 at its destination, some 70 million miles (110 million kilometres) away.

What next?

The plan is for OSIRIS-REx to orbit Bennu through mid-February, using a suite of five scientific instruments to map the asteroid in high resolution to help scientists decide precisely where to sample from.

• Then, in 2020, it will reach out with its robotic arm and touch the asteroid in a maneuver Rich Kuhns, OSIRIS-REx program manager with Lockheed Martin Space Systems in Denver, described as a “gentle high-five.”
• Using a circular device much like a car’s air filter, and a reverse vacuum to stir up and collect dust, the device aims to grab about two ounces (60 grams) of material from the asteroid’s surface, and return it to Earth in 2023.

About the mission:

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

OSIRIS-REx is the third mission in NASA’s New Frontiers program, which previously sent the New Horizons spacecraft zooming by Pluto and the Juno spacecraft into orbit around Jupiter.

Why was Bennu chosen?

Bennu was selected for a the OSIRIS-REx mission from over 500,000 known asteroids, due to it fitting a number of key criteria. These include:

Proximity to Earth: In order for OSIRIS-REx to reach its destination in a reasonable timeframe, NASA needed to find an asteroid which had a similar orbit to Earth.

Size: Small asteroids, those less than 200m in diameter, typically spin much faster than larger asteroids, meaning the regolith material can be ejected into space. Bennu is around 500m in diameter, so rotates slowly enough to ensure that the regolith stays on its surface.

Composition: Bennu is a primitive asteroid, meaning it hasn’t significantly changed since the beginning of the Solar System (over 4 billion years ago). It is also very carbon-rich, meaning it may contain organic molecules, which could have been precursors to life on Earth.

Additionally, Bennu is of interest as it is a Potentially Hazardous Asteroid (PHA). Every 6 years, Bennu’s orbit brings it within 200,000 miles of the Earth, which means it has a high probability of impacting Earth in the late 22nd Century.

Sources: et.