To Benu Impact Presented by Science at NASA NASA is launching a spacecraft to visit an asteroid and return to tell the tale. A Cyrus Rex is scheduled to blast off from Cape Canaveral on September 8, 2016, on a mission to orbit, map, and collect samples from the asteroid Benu and return to Earth seven years later. Discovered in 1999 by the NASA-funded linear asteroid survey, Benu 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 Benu. So why Benu? Because the asteroid is interesting due to its size and composition, and it is accessible to be sampled. Benu 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 Benu 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 LaRetta of the University of Arizona, principal investigator on the O'Syrus 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 Benu, O'Syrus 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 Benu, its five instruments imaging the asteroid, documenting its lumpy shape and surveying its chemical and physical properties. In July 2020, O'Syrus Rex will approach Benu and execute its touching 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 general high five to the surface. The maneuver may be executed up to three times, and O'Syrus Rex could leave Benu with up to 4.4 pounds of sample material from the asteroid. Researchers will be keen to learn about Benu for another reason. Benu orbits the Sun between Venus and Mars so it crosses Earth's orbit frequently and comes close to Earth every six years. In 2135, Benu will make an especially close approach to Earth just within the Moon's orbit. This will change Benu's orbit, and it is more difficult to predict how much closer it may come to Earth after that close encounter. The Reddha says we need to learn as much about Benu as we can. Predicting a small asteroid like Benu's exact course is somewhat tricky due to the Yarkovsky effect. The dark asteroid absorbs sunlight and then gives it off as heat, which serves as a general thruster that gradually shifts its path. Edward Bayshore, the University of Arizona, deputy principal investigator for O'Syrus Rex, says we'll get accurate measurements of the Yarkovsky effect on Benu by precisely tracking O'Syrus Rex as it orbits the asteroid. If all goes as planned, O'Syrus 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 Benu will land at the Utah Test and Training Range. From there, the capsule and its precious contents will travel 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 Benu and back, go to www.asteroidmission.org. For more on objects in and around our solar system, stay tuned to science.nasa.gov.