HOUSTON—The Ad Astra Rocket Co. has completed a 30-month NASA contract to continue advancing its Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept with the potential to reach Mars ...

By Isabella Kwai The engine shuddered to life around half past noon local time on Sunday, and with a guttural roar, the 92-foot-tall Spectrum rocket lifted slowly away from its launch tower ...