Traj and Traj.CGI are computer programs for designing thermal-protection systems (TPSs) for spacecraft that must survive re-entry into planetary atmospheres. Together with a separately developed program denoted FIAT, Traj and Traj.CGI are integral parts of NASA’s Entry Vehicle Integrated Design System. Traj simulates trajectories for a wide variety of spacecraft by use of a three-degreeof- freedom trajectory model coupled with a set of approximate functions for calculating heating effects caused by hypersonic passage through an atmosphere. Included within Traj are equilibrium thermodynamics tables, atmospheric tables for various planets, gravitational data, and aerodynamic data for a large set of spacecraft. Traj.CGI is a common-gatewayinterface code that enables users to gain access to Traj simultaneously through readily available Internet browser software, using dynamically generated Hypertext Markup Language (HTML) pages. Traj.CGI passes data generated by Traj to plotting software packages for immediate browser display or to postprocessing software (e.g., FIAT, which is used to size components of TPSs).
These programs were written by Gary Allen, Mark Loomis, David Olynick, Paul Wercinski, Peter Gage, Ethiraj Venkatapathy, and Michael Wright of Ames Research Center.