Challenges and Opportunities Posed by Impending Close Encounters with Asteroid Apophis

John Junkins

Texas A&M University, College Station, Texas

In 2004, a 400m asteroid named Apophis was discovered after it passed close to Earth, and our early orbit projected another close approach on Friday April 13, 2029. The initial uncertainty was large but contained the Earth near the center of a large uncertainty volume - thus there was some potential for an Earth impact. Subsequent orbit refinements have greatly reduced to the region of uncertainty, now centered on a point about 5.6 Earth radii from the center of the Earth (well inside our 24 hr satellites), with the uncertainty volume shrunk to about +/- 1 Earth radius. So it will be a near miss, we will NOT have a collision with Apophis in 2029. However Apophis' orbit will be heavily perturbed by the 2029 encounter, and the most likely orbit returns for another close encounter on Friday April 13, 2036! The 2036 encounter remains too uncertain to predict an impact (unlikely, but can't be ruled out), but a number of interesting challenges and opportunities have come up as a consequence of these two close encounters. Of course this rock hitting the Earth would not be as devastating to the 65,000 year ago mass extinction that took out the dinosaurs (when a 30km asteroid hit near the Yucatan). However, Apophis impacting Earth would release by far more energy than our largest nuclear weapon and would obviously wreak massive regional devastion and very likely cause very significant global climate change. Mother nature has provided us with a "free long-term challenge" to motivate development of methodology for prediction and mitigation of asteroid collision events. Someday we humans will have to deal with the fact that an asteroid "with our name on it" is discovered , hopefully with many decades to establish the orbit precisely and predict the event with years of warning time. Now is the time to worry about survival of our species when we have to face with this problem!

John L. Junkins holds the rank of Distinguished Professor of Aerospace Engineering at Texas A&M University He also holds the Royce E. Wisenbaker I Chair for Innovation and is the Director of the newly formed Texas A&M Institute for Advanced Study. He is a member of the National Academy of Engineering and has won over a dozen national and international honors. He is the author of about 400 publications including several patents and 7 books. He has directed the research of over 120 graduate students and has 4 generations of PhD students as his technical descendants. He researches dynamical systems and controls broadly and considers applications in guidance, navigation, and control of spacecraft, autonomous air vehicles and robotic systems. Prior to joining Texas A&M in 1985, he held academic appointments at the University of Virginia and Virginia Polytechnic Institute, and was employed at McDonnell Douglas and NASA during the Apollo program. His work has supported over a dozen space missions and a number of terrestial applications. His PhD is from UCLA and his undergraduate studies were at Auburn University.