Scientists fine-tune odds of asteroid Bennu hitting Earth through 2300 with NASA probe's help

NASA scientists believe that if the possibility of Bennu, an asteroid hitting Earth in a few years is keeping you awake at night you can now rest easier.OSIRIS-REx, the OSIRIS spacecraft of the agency, spent over two years orbiting this space rock. Experts studying possible space rock impacts with Earth were able to get a detailed view of the asteroid and fine tune their models of Bennu’s future.Scientists behind new research are now confident that the asteroid's total probability of impact through 2300 is only 1 in 1,750. NASA reported that estimates made before OSIRIS REx reached the space rock put the cumulative probability for a Bennu-impact between 2175-2199 at 1 in 2,700. NASA stated that while it is a higher risk than previous estimates, it is still a small change to an already minimal risk.Related: NASA spacecraft leaves Bennu asteroid to bring parts to EarthContinue reading: OSIRIS-REx team creates Bennu photosOSIRIS-REx captured an image of Bennu, the asteroid. (Image credit: NASA/Goddard/University of Arizona)Although technically, this is a slight increase in risk, the scientists behind the research don't believe it will have any significant impact. Asteroid trajectory calculations can be improved by the research, which could help reduce concerns about possible impacts from other asteroids."The impact probability went up just a bit, but it's still not a significant difference, the impact probability remains pretty much the same," Davide Farnocchia (lead author), who works at NASA's Center for Near Earth Object Studies, California, stated during a news conference on Wednesday, August 11. "I believe that the overall situation has improved."Precision is importantOverall, I believe that the situation has improved. Davide Farnocchia is the study's lead author.OSIRIS-REx, also known as Origins Spectral Interpretation and Resource Identification, Security-Regolith Explorer, was launched in September 2016 by OSIRIS-REx. It was then placed in orbit around the asteroid Bennu, December 2018.The spacecraft spent almost two-and-a-half years studying the space rock orbiting it, hovering above and inspecting every aspect of the rock.Dante Lauretta (University of Arizona planetary scientist), said that the trajectory of the spacecraft was "really amazing" and was compared to a hummingbird. He is also the principal investigator of OSIRIS-REx, and was an author of the new research. We were able go into orbit, and we were also able leave orbit. This allowed us to see a wide range of angles.The spacecraft kept track of its position relative to Earth and the asteroid throughout that period. The new research team was able to refine their understanding of the movement and location of the space rock for almost two and a quarter years using this data.October 2020 was the culmination of the spacecraft's trip to the asteroid. OSIRIS-REx took a sample from Bennu for its safekeeping. The spacecraft and its valuable cargo left the asteroid in May and returned to Earth. OSIRIS-REx will deposit a sample capsule on September 2023. This delivery will allow scientists to examine asteroid material with all the advanced equipment available in terrestrial laboratories.Scientists don't have to be able to access the sample material in order to study the two-and-a-half years of spacecraft observations. Add to that the work of astronomers who observed Bennu from ground before OSIRIS/REx existed, and scientists now have 20 years worth data on a single space rock.Asteroid trajectories are always uncertain in scientists' models. This is because a variety of forces pull at the space rock as it moves around the inner solar system. Even though the models of Bennu’s future paths are improved, that uncertainty is still present. However, OSIRIS-REx observations allowed scientists to significantly reduce their uncertainty about Bennu’s fate.The researchers were able, among other things, to account for tiny orbital changes caused by forces such as radiation from the sun, relativity's impact, and gravity of hundreds more large asteroids that are whizzing around the area.These factors affect all objects in the solar system, but only to a small degree. The team was able to examine the impact of Bennu's two unique characteristics: the plumes that shoot off the asteroid regularly and the rock's interaction to the spacecraft.Scientists were especially concerned about the Yarkovsky Effect, which is caused by constant temperature fluctuations as regions of an asteroid pass in or out of daylight. This gently pushes the asteroid.Farnocchia stated that the Yarkovsky effect on Bennu is equal to three grapes in weight. "That's what drives the motion of Bennu into future because this acceleration persists, its effect builds up, and it becomes very important by the time you reach 2135."It is difficult to predict Bennu's future course after 2135, despite all the best efforts of scientists. Bennu will pass Earth in September that year. It won't be close enough to cause an impact but close enough for Earth's gravity to push the asteroid along its path. The trajectory of Bennu over the next decade and century will be determined by how that dance unfolds.NASA released a statement regarding the new research, saying that Bennu's impact probability through 2300 is 1 in 1,750. The most alarming date within that time frame is Sept. 24, 2182. Even on that day, Bennu’s impact probability is just 1 in 2,700.Beyond BennuScientists are concerned about Bennu, but it's not the only space rock. The planetary defense program aims to identify all asteroids that could potentially have an impact on Earth. NASA reports that one aspect of this work is to find as many near-Earth asteroids possible. To date, scientists have cataloged over 26,000.Scientists need to be able calculate the trajectory of a space rock in order to identify which asteroids could pose a threat. This trajectory is based on observations of an asteroid's location, but scientists know for years that factors such as the Yarkovsky Effect may affect their calculations.According to researchers, the new OSIRIS-REx data that quantifies the three-grape-heavy Yarkovsky Effect should help scientists understand how this effect affects the trajectory of other asteroids.Farnocchia stated that it was the first time she had been able to test her models on an asteroid trajectory at levels never before attempted. "These results can be applied to any other asteroid and they are extremely accurate.This research was described in a paper published in Icarus on Tuesday, August 10, 2010.Send Meghan Bartels an email at, or follow her Twitter @meghanbartels. Follow us on Facebook and Twitter @Spacedotcom