SAN FRANCISCO — Buoyed by recent launch contracts with NASA and the U.S. Department of Defense, suborbital launch services provider UP Aerospace of Denver is accelerating development of a larger version of its SpaceLoft rocket.

“We expect SpaceLoft Heavy development to be complete with the first flight targeted in about 18 months,” UP Aerospace President Jerry Larson said. “Our launch facilities at Spaceport America were originally sized and designed for SpaceLoft Heavy so we will need very little infrastructure modifications.”

SpaceLoft Heavy would be similar in design to SpaceLoft but with a capability to lift 225 kilograms to altitudes of 115 kilometers and lighter payloads to as high as 300 to 400 kilometers, hesaid.The current SpaceLoft vehicle can carry roughly 40 kilograms to 115 kilometers.

UP Aerospace recently won two contracts for SpaceLoft launches. In September, the Pentagon’s Operationally Responsive Space (ORS) Office awarded the company a contract for a SpaceLoft launch to take place in 2012 from Spaceport America near Las Cruces, N.M. UP Aerospace said the mission will be its first dedicated launch for the Pentagon and will carry the payload to an altitude of 115 kilometers.

“We are currently preparing for many contracted launches and a very busy next few years at Spaceport America,” Larson said in an interview during the International Symposium for Personal and Commercial Spaceflight Oct. 19-20 in Las Cruces. “The [Defense Department] has purchased the first of what we believe to be a series of payload demonstration launches out of the ORS office.”

In October, NASA’s Office of Chief Technologist Launch Opportunities Program awarded UP Aerospace a contract to integrate technology payloads and launch them on up to eight SpaceLoft flights. The contract reserves two SpaceLoft launches with options for six additional flights in 2012 and 2013.

The NASA two-year task order award is valued at $4.7 million if all options are exercised, Larson said.

Next year alone has the potential of doubling the number of contracted launches that UP Aerospace has done at Spaceport America in the past six years, Larson said.

Leonard David has been reporting on space activities for nearly 50 years. He is the 2010 winner of the prestigious National Space Club Press Award and recently co-authored with Apollo 11’s Buzz Aldrin the book “Mission to Mars — My Vision for Space...