OSIRIS-REx Mission

• NASA has launched a spacecraft to an asteroid Bennu in 2016 and use a robotic arm to pluck samples that could better explain our solar system's formation and how life began.
• The mission, called Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer, or OSIRIS-REx, is the first U.S. mission to carry samples from an asteroid back to Earth.
• After traveling three years, OSIRIS-REx will approach the Bennu , near Earth asteroid designated 1999 RQ36 in 2018.
• Once within three miles of the asteroid, the spacecraft will begin six months of comprehensive surface mapping.
• The science team then will pick a location from where the spacecraft's arm will take a sample. The spacecraft gradually will move closer to the site, and the arm will extend to collect more than two ounces of material for return to Earth in 2023.
• RQ36 is approximately 1,900 feet in diameter or roughly the size of six football fields.
• The asteroid, little altered over time, is likely to represent a snapshot of our solar system's infancy. The asteroid also is likely rich in carbon, a key element in the organic molecules necessary for life

Why Bennu

• For this mission most accessible asteroids for a spacecraft to reach are located between 1.6 AU and 0.8 AU. The ideal asteroid has an Earth-like orbit with low eccentricity and inclination. At the time of the mission’s asteroid selection in 2008, there were over 7,000 known NEOs, but only 192 had orbits that met these criteria.
• Asteroids with small diameters rotate more rapidly than those with large diameters. With a diameter less than 200 meters, an asteroid spins so rapidly that the loose material on its surface (regolith) can be ejected from it. The ideal asteroid has a diameter larger than 200 m so that a spacecraft can safely come into contact with it and collect a sufficient regolith sample. Size of bennu is more than 200 m.
• Asteroids are divided into different types based on their chemical composition. The most primitive asteroids are carbon-rich and have not significantly changed since they formed nearly 4 billion years ago. These asteroids contain organic molecules, volatiles, and amino acids that may have been the precursors to life on Earth.

Analysis:

• Bennu is classified as a potentially hazardous asteroid, or PHA. There is a small (1 in 2,700) chance that Bennu will hit Earth late in the 22nd century. If Bennu did hit Earth, it would release the energy equivalent of 1,450 megatons of TNT, creating an impact crater about 5 kilometers (about 3 miles) in diameter. That’s over 70,000 times more energy than was released by the atomic bomb that fell on Hiroshima.
• Bennu crosses the Earth's orbit every six years, and it gets closer every time. In fact, during a flyby in 2135, the asteroid could hit a special orbit-altering "keyhole" that could send it on a collision course with Earth later in the century.
• Although this mission has little to do with this less-than-likely collision. However, his mission will help scientists get a better understanding of Bennu's orbit.

By: Vishal