Dr. Joan M. Centrella and Dr. John G. Baker are the 2008 recipients of the John C. Lindsay Memorial Award for Space Science. NASA's Goddard Space Flight Center in Greenbelt, Md., honors one or more of its civil servant space scientists each year with this award, which is the center's highest honor for outstanding contributions in space science. Centrella and Baker will receive their awards on May 30 for their groundbreaking computer simulations, which show what happens when two supermassive black holes collide and merge. Centrella serves as director of Goddard's Gravitational Astrophysics Laboratory. Baker is an astrophysicist with the Numerical Relativistic Astrophysics Group. "Our simulations are achieved by a team of scientists with diverse skills, ranging from building large computer programs to understanding details of Einstein's theory," says Centrella. "We have an outstanding team of both civil servants and contractors," adds Baker. "The Lindsay Award recognizes the contributions of everyone in our group." According to Albert Einstein's general theory of relativity, when two black holes merge, the surrounding space trembles like an earthquake as gravitational waves race outward at light speed. For 30 years, attempts to simulate these dramatic collisions on computers failed because of the complexity of the mathematics, which caused computer codes to crash. But the Goddard team developed a method to translate Einstein's equations into a form that computers can handle. Teams around the world are now using the techniques developed by the Goddard group. Black hole mergers are by far the most powerful events in the universe since the Big Bang. Supermassive black holes reside in the centers of most or all large galaxies, so black hole mergers have played a pivotal role in the construction of galaxies. Understanding these collisions is essential to understanding cosmic evolution. The Goddard group's advances have spurred rapid progress in predicting the observable signatures of these events. Scientists will search for these signatures with sensitive instruments for measuring gravitational waves, such as the National Science Foundation's Laser Interferometer Gravitational-wave Observatory (LIGO), and the space-based Laser Interferometer Space Antenna (LISA), a planned mission of NASA and the European Space Agency. The new calculations impact astronomy in other ways as well, showing that the black hole that results from a merger can receive an enormous kick, which can eject it from a host galaxy. "Theoretical work is rarely honored by the Lindsay Award; most of the awards are presented for observational discoveries made with new NASA missions," notes William Oegerle, director of Goddard's Astrophysics Science Division. "The work by Centrella and Baker is of special importance to NASA, since it is a driving force for the design of the Laser Interferometer Space Antenna, a mission which will detect the gravitational waves from black hole mergers." Centrella and Baker cite the vital contributions of team member Jim Van Meter, who played a leading role in these advances. Centrella grew up in Winsted, Conn. She completed undergraduate coursework at the University of Massachusetts at Amherst. Her doctoral degree is from Cambridge University, United Kingdom. She came to Goddard in 2001. Baker hails from Kansas City, Missouri. He completed his undergraduate work at Northeast Missouri State University (now Truman State University) in Kirksville, Mo., and received his doctorate from Penn State University in 1999. He also moved to Goddard in 2001. Both Baker and Centrella reside in Silver Spring, Md. Last year, Centrella received the NASA Exceptional Scientific Achievement Medal. The NASA administrator awards the medal each year for significant accomplishments that contribute to the agency. The Lindsay Award commemorates the 1962 launch of the first of eight Orbiting Solar Observatories, which was built by John C. Lindsay and others.