Move over, Bruce Willis: Bong Wie and colleagues are building tools to protect the planet from rogue asteroids.
Bong Wie established Iowa State’s Asteroid Deflection Research Center (ADRC) in April 2008 in order to bring together researchers from around the world to develop technologies that could prevent asteroids from colliding with Earth. Wie, the Vance D. Coffman Chair Professor in Aerospace Engineering and ADRC director, now says that goal has been expanded to include the idea of sending manned missions to asteroids.
This wider focus is a direct result of the 2011 budget proposed by the Obama administration, which eliminates NASA’s Constellation program that would have returned astronauts to the moon. Yet because the same components required for manned lunar missions (i.e., launch vehicle, spacecraft, and mission operation concept) are needed to take astronauts deeper into space, officials are considering instead a sustainable, flexible-path option for developing technologies that could take them to various solar system destinations—including near-Earth objects (NEOs) such as asteroids.
“This is a win-win situation for us,” Wie says. “Our original plan was to use robotics or unmanned missions, but the idea of manned asteroid missions broadens our scope, and it is good for the space program.
“For the last 40 years,” Wie continues, “we have just been exploring close to Earth. Space is like the ocean, and we have been playing near the shore. There is so much more for astronauts to explore in deep space.”
While popular movies such as Armageddon and Deep Impact make the idea of astronauts walking on or blowing up asteroids easy to imagine, Wie emphasizes that the complex technology needed to carry out such missions does not currently exist. Yet another challenge Wie faces in getting support to study and develop deflection techniques is the uncertainty about how real the threat is that an asteroid could strike the Earth.
Lindley Johnson is program executive for the Near-Earth Objects Observation Program at NASA headquarters in Washington, D.C., which to date has focused on cataloging NEOs larger than one kilometer. The risk of an NEO collision that size is remote compared to other risks faced every day. But, Johnson notes, if such an impact did occur, it would be an event having extreme global consequences.
Fortunately, according to Johnson, no asteroids have yet been found to cause concern. However, he adds, thousands of smaller asteroids are more likely to hit Earth, and these could cause localized devastation. The Tunguska Event, for example, occurred on June 30, 1908, when an asteroid from 30 to 50 meters in diameter exploded in the skies above Siberia, flattening trees and killing other vegetation over 2,150 square kilometers. A 100–200 meter asteroid, Johnson estimates, could devastate a region the size of Iowa.
“The frequency of when a 100-meter object could hit us is probably once every several thousand years,” he says, “and a 50-meter object once every several hundred years. Of course, that once could be tomorrow, so we certainly want to be looking at ways to avoid that happening.
“It’s estimated that it will take us at least 5–10 years from the time we know about the object to be able to build the systems, launch the systems, and reach the point in the asteroid’s orbit where we would want to deflect it,” Johnson adds. “It will take quite a bit of thought before we can undertake such a mission—and that is what Bong Wie and the ADRC are all about.”
A planetary defense roadmap
Since establishing the ADRC, Wie has focused his efforts in three areas. First, ADRC associates have attended and organized conferences and workshops to spread the word about the threat posed by asteroids and the complex engineering and technology issues involved in deflecting or disrupting them. Next, Wie has sought to bring together a community of scientists and engineers to develop a roadmap for an effective planetary defense system. Finally, the ADRC has sought grants to support research to find the best possible engineering solutions for asteroid deflection.
The first official ADRC activity was to organize and sponsor an asteroid deflection research symposium in Arlington, Virginia, in October of 2008. Attendees included researchers from the Air Force Research Laboratory, Defense Intelligence Agency, Defense Threat Reduction Agency (DTRA), Department of Homeland Security, Lawrence Livermore National Laboratory, NASA, the National Research Council, Sandia National Laboratories, and the U.S. Air Force, as well as from industry and academia.
Discussions ranged from which agency or organization might be responsible for deflecting or disrupting an asteroid to what types of technology might provide the best means for doing so. Technologies discussed by the conferees included antimatter devices, gravity tractors, kinetic impactors, nuclear explosions, and solar sails.
Since that first symposium, Wie has participated in the National Research Council’s Committee to Review Near-Earth Object Surveys and Hazard Mitigation Strategies, as well as given a presentation at an asteroid deflection workshop sponsored by DTRA, NASA, and the National Nuclear Security Administration.
A groundbreaking grant
The ADRC received its first research grant in December 2008, when the NASA-supported Iowa Space Grant Consortium (ISGC) awarded a three-year, $340,000 grant to Wie and his multidisciplinary research team. The grant’s objectives included support for initial research in the ADRC, as well as providing seed money for efforts to obtain additional grants.
“Asteroid mitigation is a timely and compelling topic,” said ISGC director William Byrd in awarding the grant. “I don’t know of any other competitively awarded grants from NASA in this area. So with the ADRC already established, this is fertile ground for getting in early and developing a strength and expertise that addresses a high-priority technical challenge.”
For the research part of this project, Wie has assembled a team that includes Iowa State electrical and computer engineering professor emeritus John Basart; Ames Lab scientist Alfred Kracher; Quang Lam of Orbital Sciences Corporation; Brent Barbee of Emergent Space Technologies, Inc.; Robert Adams from the NASA Marshall Space Flight Center; and Yvonne Pendleton of NASA’s Ames Research Center. This group, says Wie, is charged with developing a baseline space system concept that includes the types of launch vehicle, spacecraft, and technology needed to deflect an asteroid.
“With any mission of this type,” Wie explains, “the first step is to determine what kind of launch vehicle and spacecraft is needed. For example, with the Apollo missions the goal was to determine how to transport the astronauts to the moon and back. Development of the large Saturn V rockets accomplished that goal, so then work focused on specific technologies including Apollo guidance, navigation, and control systems.
“With cancellation of the Constellation program,” he continues, “NASA will need to focus on a new heavy launch vehicle design that is both feasible from a technological standpoint and cost effective to build and implement.”
Addressing a global audience
In addition to these domestic initiatives, Wie has also sought opportunities to spread the word about the ADRC to international audiences. He served on the planning committee for the 1st International Academy of Astronautics Planetary Defense Conference held in April of 2009 in Granada, Spain, and presented a technical paper on the ISGC/ADRC research project.
At the 60th International Astronautical Congress in Daejeon, Korea, last October, Wie presented the John V. Breakwell Memorial Lecture, “Astrodynamic Fundamentals for Deﬂecting Hazardous Near-Earth Objects,” as well as technical papers with graduate students Brian Kaplinger and Sam Wagner (below). About 3,000 people from all over the world attended the conference, which had the theme “Space for Sustainable Peace and Progress.”
Student research: two papers
1. A fragmentation strategy
Omaha native Brian Kaplinger started his PhD program in 2009 after working with Bong Wie as an undergraduate in 2007. His conference paper presented in Korea focused on research to determine what would happen if an asteroid were blown up or broke apart while being deflected, for which Kaplinger developed a mathematical model and simulation tool to predict where the fragments would go under various conditions.
“Using the asteroid Apophis as a model, we found that asteroid disruption using nuclear subsurface explosions results in [a] large dispersion of fragments,” he explains. “Instead of one big object striking Earth, we would have a small number of fragments that are still going to impact Earth. However, this option may be the only feasible strategy if all other non-nuclear alternatives were to fail because of a very short warning time for most realistic situations.”
2. Mission to Apophis
A master’s student from Webster City, Iowa, Sam Wagner also began working with Wie as an undergraduate. He presented papers on a preliminary conceptual design for an interplanetary ballistic missile system to deflect or disrupt a near-Earth object, as well as a study of the feasibility of a manned mission to Apophis in 2029. In addition to such advanced mission design studies, Wagner is developing astrodynamic computational algorithms in preparation for his PhD research starting in 2011.