Volume 10, Number 5 • September/October 2002 • Technology Transfer

Software of the Year Selected

The DAC software has been used to predict the aerodynamic characteristics of the X-38 in the transitional regime and the significant increments associated with interaction of its ACS thrusters and the oncoming freestream. Artwork courtesy of Johnson Space Center.

NASA has selected two software innovations that save significant money and time over more traditional methods as co-winners of its 2002 Software of the Year Award. Each team of developers will receive an award of $50,100 from the NASA Administrator. Other government agencies, private industry and academia have adopted both software design tools.

The DSMC Analysis Code (DAC) software package, developed at NASA Johnson Space Center in Houston, models the flow of low-density gases over flight surfaces. DSMC stands for Direct Simulation Monte-Carlo and is a simulation method. The software provides insight into the interaction of spacecraft and rarified environments, such as those encountered during a spacecraft entry into an atmosphere at high altitudes.

DAC was used to provide information to help optimize and verify maneuvers of spacecraft that orbited Mars after they were slowed by repeatedly skimming through that planet’s atmosphere (also called aerobraking), instead of relying on thrusters for deceleration. The technique allowed the spacecraft to be lighter, reducing launch costs.

Another application is analysis of plume impingement—the effects of firing thrusters by one spacecraft on another spacecraft nearby. An early use of the software was analyzing the effect of space shuttle thruster firings as the vehicle approached the Russian space station Mir during the Shuttle-Mir program. This has led to significant changes in docking procedures and venting operations aboard the International Space Station.

DAC is in use at most NASA Centers and within the US military, and is beginning to be employed by the aerospace industry for advanced applications involving high-altitude vehicles. In addition, the unique flow-solvers adapted to DAC allow the software’s use in applications in which the object within the flow field is very small, such as MEMS (micro-electromechanical systems) and nanotechnology devices.

The DAC team is led by Gerald J. LeBeau and includes Forrest E. Lumpkin, Katie A. Jacikas and Phil C. Stuart of Johnson, and Richard G. Wilmoth and Christopher E. Glass of NASA Langley Research Center in Hampton, VA.

The NASA Software of the Year co-winner, Cart3D, is an aerodynamic simulation tool on which work began in 1992 at NASA Ames Research Center in Moffett Field, CA. This software package provides designers and engineers with an automated, highly accurate computer-simulation suite that streamlines the conceptual and preliminary analysis of new and existing aerospace vehicles.

Cart3D provides a revolutionary approach to computational fluid dynamics—the computer simulation of how fluids and gases flow around an object. Before the advent of this software, the basic computational tool, the grid layout used in analyzing designs of airplanes and spacecraft, had to be hand-generated and required months or even years to produce for complex models. Cart3D automates grid generation to a remarkable degree, enabling even the most complex geometries to be modeled 100 times faster than before.

Simulations generated by Cart3D help identify and fix problems in military transport aircraft and helicopters. Cart3D’s novel approaches allow simulation of complex geometries in fields other than aerospace, ranging from astrophysics to computer science, to electromagnetics. The software is in wide use by universities and corporations, as well as most NASA Centers and other government agencies, for a plethora of applications.

Cart3D was developed jointly by Michael Aftosmis and John Melton of Ames, and Professor Marsha Berger of the Courant Institute, New York University.

Each year, the NASA Chief Engineer sponsors the NASA Software of the Year competition, an international competition for the largest award for software excellence, with technical support from the agency’s Inventions and Contributions Board. The Software of the Year Award is one of the Space Act Awards.

More information about the winners may be found at http://icb.nasa.gov/swoy2002/ Q

For more information, contact John Ira Petty at Johnson Space Center, phone: 281/483-5111 or Victoria Steiner at Ames Research Center,  phone: 650/604-9000. Please mention you read about it in Innovation.

NASA Official: Jonathan Root • Web Design: Printing & Design Office, NASA Headquarters • Credits