1. NASA Spacecraft Provides Insight into Asteroid Bennu’s Future Orbit

    August 11, 2021 -

    In a study released Wednesday, NASA researchers used precision-tracking data from the agency’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft to better understand movements of the potentially hazardous asteroid Bennu through the year 2300, significantly reducing uncertainties related to its future orbit, and improving scientists’ ability to determine the total impact probability and predict orbits of other asteroids.

    The study, titled “Ephemeris and hazard assessment for near-Earth asteroid (101955) Bennu based on OSIRIS-REx data,” was published in the journal Icarus.

    “NASA’s Planetary Defense mission is to find and monitor asteroids and comets that can come near Earth and may pose a hazard to our planet,” said Kelly Fast, program manager for the Near-Earth Object Observations Program at NASA Headquarters in Washington. “We carry out this endeavor through continuing astronomical surveys that collect data to discover previously unknown objects and refine our orbital models for them. The OSIRIS-REx mission has provided an extraordinary opportunity to refine and test these models, helping us better predict where Bennu will be when it makes its close approach to Earth more than a century from now.”

    In 2135, asteroid Bennu will make a close approach with Earth. Although the near-Earth object will not pose a danger to our planet at that time, scientists must understand Bennu’s exact trajectory during that encounter in order to predict how Earth’s gravity will alter the asteroid’s path around the Sun – and affect the hazard of Earth impact.

    Using NASA’s Deep Space Network and state-of-the-art computer models, scientists were able to significantly shrink uncertainties in Bennu’s orbit, determining its total impact probability through the year 2300 is about 1 in 1,750 (or 0.057%). The researchers were also able to identify Sept. 24, 2182, as the most significant single date in terms of a potential impact, with an impact probability of 1 in 2,700 (or about 0.037%).

    Although the chances of it hitting Earth are very low, Bennu remains one of the two most hazardous known asteroids in our solar system, along with another asteroid called 1950 DA.

    Before leaving Bennu May 10, 2021, OSIRIS-REx spent more than two years in close proximity to the asteroid, gathering information about its size (it is about one-third of a mile, or 500 meters, wide), shape, mass, and composition, while monitoring its spin and orbital trajectory. The spacecraft also scooped up a sample of rock and dust from the asteroid’s surface, which it will deliver to Earth on Sept. 24, 2023, for further scientific investigation.

    “The OSIRIS-REx data give us so much more precise information, we can test the limits of our models and calculate the future trajectory of Bennu to a very high degree of certainty through 2135,” said study lead Davide Farnocchia, of the Center for Near Earth Object Studies (CNEOS), which is managed by NASA’s Jet Propulsion Laboratory in Southern California. “We’ve never modeled an asteroid’s trajectory to this precision before.”

    This mosaic of Bennu was created using observations made by NASA’s OSIRIS-REx spacecraft that was in close proximity to the asteroid for over two years. Credit: NASA/Goddard/University of Arizona

    Gravitational keyholes

    The precision measurements on Bennu help to better determine how the asteroid’s orbit will evolve over time and whether it will pass through a “gravitational keyhole” during its 2135 close approach. These keyholes are areas in space that would set Bennu on a path toward a future impact with Earth if the asteroid were to pass through them at certain times, due to the effect of Earth’s gravitational pull.

    To calculate exactly where the asteroid will be during its 2135 close approach – and whether it might pass through a gravitational keyhole – Farnocchia and his team evaluated various types of small forces that may affect the asteroid as it orbits the Sun. Even the smallest force can significantly deflect its orbital path over time, causing it to pass through or completely miss a keyhole.

    Among those forces, the Sun’s heat plays a crucial role. As an asteroid travels around the Sun, sunlight heats up its dayside. Because the asteroid spins, the heated surface will rotate away and cool down when it enters the nightside. As it cools, the surface releases infrared energy, which generates a small amount of thrust on the asteroid – a phenomenon called the Yarkovsky effect. Over short timeframes, this thrust is minuscule, but over long periods, the effect on the asteroid’s position builds up and can play a significant role in changing an asteroid’s path.

    “The Yarkovsky effect will act on all asteroids of all sizes, and while it has been measured for a small fraction of the asteroid population from afar, OSIRIS-REx gave us the first opportunity to measure it in detail as Bennu travelled around the Sun,” said Steve Chesley, senior research scientist at JPL and study co-investigator. “The effect on Bennu is equivalent to the weight of three grapes constantly acting on the asteroid – tiny, yes, but significant when determining Bennu’s future impact chances over the decades and centuries to come.”

    The team considered many other perturbing forces as well, including the gravity of the Sun, the planets, their moons, and more than 300 other asteroids, the drag caused by interplanetary dust, the pressure of the solar wind, and Bennu’s particle-ejection events. The researchers even evaluated the force OSIRIS-REx exerted when performing its Touch-And-Go (TAG) sample collection event Oct. 20, 2020, to see if it might have slightly altered Bennu’s orbit, ultimately confirming previous estimates that the TAG event had a negligible effect.

    “The force exerted on Bennu’s surface during the TAG event were tiny even in comparison to the effects of other small forces considered,” said Rich Burns, OSIRIS-REx project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “TAG did not alter Bennu’s likelihood of impacting Earth.”

    Tiny risk, huge gain

    Although a 0.057% impact probability through the year 2300 and an impact probability of 0.037% on Sept. 24, 2182, are low, this study highlights the crucial role that OSIRIS-REx operations played in precisely characterizing Bennu’s orbit.

    “The orbital data from this mission helped us better appreciate Bennu’s impact chances over the next couple of centuries and our overall understanding of potentially hazardous asteroids – an incredible result,” said Dante Lauretta, OSIRIS-REx principal investigator and professor at the University of Arizona. “The spacecraft is now returning home, carrying a precious sample from this fascinating ancient object that will help us better understand not only the history of the solar system but also the role of sunlight in altering Bennu’s orbit since we will measure the asteroid’s thermal properties at unprecedented scales in laboratories on Earth.”

    More about OSIRIS-REx

    Goddard provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Lauretta is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space Systems in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace in Tempe, Arizona are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers ProgramNASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for the agency’s Science Mission Directorate in Washington.

    For more information about the OSIRIS-REx mission, visit:

    https://www.nasa.gov/osiris-rex

    To view the images discussed during today’s media teleconference, visit:

    https://svs.gsfc.nasa.gov/13906

    More about NASA’s CNEOS and Planetary Defense Coordination Office

    CNEOS computes high-precision orbits for near-Earth objects (NEOs) in support of NASA’s Planetary Defense Coordination Office, to help precisely characterize every NEO’s orbit to improve long-term hazard assessments.

    More information about CNEOS, asteroids, and near-Earth objects can be found at:

    https://cneos.jpl.nasa.gov

    For more information about NASA’s Planetary Defense Coordination Office, visit:

    https://www.nasa.gov/planetarydefense

    For asteroid and comet news and updates, follow @AsteroidWatch on Twitter.

    Karen Fox / Alana Johnson / Josh Handal
    NASA Headquarters, Washington
    301-286-6284 / 202-358-1501 / 202-358-2307
    karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov / Joshua.a.handal@nasa.gov

    Ian J. O’Neill
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-2649
    ian.j.oneill@jpl.nasa.gov

    Rani Gran
    Goddard Space Flight Center, Greenbelt, Md.
    301-332-6975
    rani.gran@jpl.nasa.gov

  2. NASA’s “Tour of Asteroid Bennu” Selected for Prestigious Computer Graphics Film Festival

    August 10, 2021 -

    It’s hard to imagine what the surface of asteroid Bennu might look like – it’s shortest distance from Earth still 250,000 miles away – but the video “Tour of Asteroid Bennu” brings us on a journey to see this landscape up close.

    On August 9 and 11, 2021, the video produced at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will be featured in the SIGGRAPH Computer Animation Festival Electronic Theater – a high honor for those in the graphic visualization field.

    “We’re going up against the best of the best in the graphics industry right now,” said Kel Elkins, lead data visualizer for the project. “And it’s very exciting when something that we create, especially something data driven like this can compete and get accepted on the same level as these other pieces.”

    The Electronic Theater, often likened to the Academy Awards for graphics, highlights empowering and inspirational short video stories created through the use of computer graphics and interactive techniques. “Tour of Asteroid Bennu” will be recognized alongside 36 other short videos in this year’s SIGGRAPH viewing.

    Thanks to laser altimetry data and high-resolution imagery from NASA’s OSIRIS-REx spacecraft, we can take a tour of asteroid Bennu’s remarkable terrain.

    Credits: NASA’s Goddard Space Flight Center This video is public domain and can be downloaded from the Scientific Visualization Studio.

    The story of this video begins in March 2020, just at the start of the pandemic.

    “I remember taking breaks, my lunchtime walk around my neighborhood, and sort of thinking up some shots, like how we would first approach the asteroid,” said Dan Gallagher, producer and writer at NASA’s Goddard Space Flight Center.

    The video, which now has just under one million views on YouTube, utilizes advanced graphics techniques to portray the close-to-home asteroid.

    Unlike the other videos being featured at SIGGRAPH, Gallagher and Elkins used actual scientific data from NASA’s OSIRIS-REx spacecraft to create “Tour of Asteroid Bennu.” OSIRIS-REx, which launched on September 6, 2016, reached the asteroid in 2018 and gathered imagery, lidar, laser ranging, data, and other forms of data while in orbit. The spacecraft even briefly touched down on the asteroid to take a sample in October 2020.

    Depicted by an orange loop around the asteroid, the beginning of the video highlights the location of the spacecraft while in orbit, which is based on actual mission data. The 3D model of the asteroid comes primarily from lidar data, but as the camera takes the viewer in closer to Bennu, the model also incorporates global image mosaics and global brightness maps.

    “We had this idea to do for Bennu what Ernie Wright had done in his Tour of the Moon, which was to take terrain data, and high-resolution imagery and make a really awesome flyover of Bennu and put the camera down as close as we could to the surface and fly it over some of the new features,” Gallagher said.

    The tour of the asteroid covers six sites in depth, stating the name of each site as well as giving a 3D view of the surroundings. According to a behind-the-scenes video diving into the making of “Tour of Asteroid Bennu,” the model of the asteroid began as a low-resolution polygon model, limiting how close the camera could get to the surface. As the OSIRIS-REx mission continued, more data was collected, until the model was composed of five-centimeter resolution tiles.

    “Every time we would get new high-resolution models of the asteroid, we would try pushing the camera in closer and closer in those regions,” Elkins said.

    When zooming into the close up locations or boulders, there are individual tiles with varying resolutions that had to have been combined to keep the levels of detail as the camera is getting closer. Elkins meticulously selected the individual tiles depending on where the camera was looking to stitch together a finalized view of the model at varying vantage points.

    Other videos accepted by SIGGRAPH are artists’ renditions, but with the use of scientific data to create a graphical representation come some limitations. Stitching tiles together leaves some unavoidable imperfections or holes, compared to an artistic assembly.

    “That’s why we’re super excited that our data visualizations were pulled into the same level as some of these other pieces,” Elkins said.

    With the electronic theater viewing date drawing closer, Gallagher reflects on the precedent that “Tour of Asteroid Bennu” sets.

    “I think there’s a big demand in the public.” Gallagher said. “People love exploration, they love novelty. This is a whole new world and it’s a world that can be hard to really fully appreciate in two dimensional photographs. I think that really reflects the hunger that people have for exploration, and it’s a way to explore Bennu remotely through technology, so it’s very exciting to see it reach that level.”

    On August 9 and 11, 2021, “Tour of Asteroid Bennu” will be featured in the SIGGRAPH awards electronic theater. Producer Dan Gallagher and data visualizer Kel Elkins discuss the making of the video, and how data-driven animation is enabling viewers to explore new worlds like Bennu.

    Credits: NASA’s Goddard Space Flight Center

    Erica McNamee,
    NASA’s Goddard Space Flight Center

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