 to Bennu Impact, presented by Science at NASA. NASA is launching a spacecraft to visit an asteroid and return to tell the tale. Osiris-Rex is scheduled to blast off from Cape Canaveral on September 8th, 2016 on a mission to orbit, map, and collect samples from the asteroid Bennu and return to Earth seven years later. Discovered in 1999 by the NASA-funded Linear Asteroid Survey, Bennu measures about 1,650 feet across and weighs over 60 million tons. Imagine a boulder the height of the Empire State Building. That's about the size of Bennu. So why Bennu? Because the asteroid is interesting due to its size and composition and it is accessible to be sampled. Bennu is a primitive and carbon-rich asteroid. Primitive asteroids contain material that has not changed significantly since they formed over 4.5 billion years ago. The analysis of any organic material found on Bennu will give scientists an inventory of the materials present at the beginning of the solar system that may have had a role in the origin of life on Earth and potentially elsewhere. Indeed, Dante Loretta of the University of Arizona, principal investigator on the Osiris-Rex mission, says mapping and sampling the space rock can potentially hold answers to the most fundamental questions human beings ask, like where do we come from? To get to Bennu, Osiris-Rex will perform a series of deep space maneuvers, first orbiting the Sun for a year and then using Earth's gravity to be slung towards the asteroid. The spacecraft will spend a year flying in close proximity to Bennu, its five instruments imaging the asteroid, documenting its lumpy shape and surveying its chemical and physical properties. In July 2020, Osiris-Rex will approach Bennu and execute its touch-and-go or tag maneuver. A mechanical arm that functions like a combination sample scoop and pogo stick will be extended from the spacecraft. The spacecraft will slowly approach the asteroid until the sample head at the end of the arm gives a gentle high-five to the surface. The maneuver may be executed up to three times and Osiris-Rex could leave Bennu up to 4.4 pounds of sample material from the asteroid. Researchers will be keen to learn about Bennu for another reason. Bennu orbits the Sun between Venus and Mars so it crosses Earth's orbit frequently and comes close to Earth every six years. In 2135, Bennu will make an especially close approach to Earth just within the Moon's orbit. This will change Bennu's orbit and it is more difficult to predict how much closer it may come to Earth after that close encounter. Loretta says we need to learn as much about Bennu as we can. Predicting a small asteroid, like Bennu's exact course, is somewhat tricky due to the Yarkotsky effect. The dark asteroid absorbs sunlight and then gives it off as heat which serves as a gentle thruster that gradually shifts its path. Edward Beshore of the University of Arizona, Deputy Principal Investigator for Osiris-Rex, says we'll get accurate measurements of the Yarkotsky effect on Bennu by precisely tracking Osiris-Rex as it orbits the asteroid. If all goes as planned, Osiris-Rex will fire its main engines in March 2021 and begin its journey back to Earth. The samples will arrive in September 2023 when a capsule containing bits of Bennu will land at the Utah test and training range. From there, the capsule and its precious contents will go to NASA's Johnson Space Center in Houston, Texas, where hands-on analysis of this ancient asteroid will begin by mission scientists and then by scientists from all over the world. For updates on the mission to Bennu and back, go to www.asteroidmission.org. For more on objects in and around our solar system, stay tuned to science.nasa.gov.