rocket, the largest in the u.s. inventory, orion thundered space today for a crucial 4.5-hour test flight. orion circled the globe twice. reaching an altitude of 3600 miles, 14 times higher than the international space station. in the most nerve-wracking moment, orion re-entered earth's atmosphere of a blazing speed, generating temperatures of 4,000 degrees. the advanced heat shield designed to keep astronauts safe appeared to have performed tuawlessly. >> main chute deployed. >> reporter: the enormous parachutes that slowed orion for a gentle splash-down in the pacific also passed with flying colors. ( applause ) >> it was also really, really cool. >> reporter: mark geyer is the top nasa official in charge of the orion program. what's the big-picture significance of this mission? >> it's the beginning of showing that, you know, the united states is getting back to exploring the solar system. and orion has the systems that