A Colorado-built booster rocket is the last of its kind to travel into space when it blasted off from a California launch Wednesday.
The Titan IV rocket carries a spy satellite for the federal government during the country's final such launch.
Littleton based Lockheed Martin Space Systems has built 527 rockets at its Waterton Canyon facility in the past 46 years, including rockets used for the Gemini and Casini programs.
Many Lockheed workers in Colorado say they're sorry to see the Titan program end, but know it's been worthwhile.
A Titan program manager calls today's launch "a critical mission for the United States of America."
Liftoff is set for 12:04 p-m Mountain time.
The Gemini Four mission during the mid-1960s included the first "extra vehicular activity" for the country's manned space flight program.