Blessed with perfect weather for a space shot and a smooth-as-silk countdown, a Lockheed Martin Atlas 2AS rocket blasted off Thursday night to deliver a Japanese communications satellite into a record-setting high orbit designed to economize the payload's precious fuel supply.

The Atlas 2AS rocket lifts off with Superbird 6. Photo: ILS

As its liquid engines and solid-propellant boosters flashed to life at 8:45 p.m. EDT (0045 GMT), mechanisms holding the half-million pound rocket let go to allow the vehicle to swiftly depart pad 36A at Cape Canaveral Air Force Station, Florida.

Meteorologists predicted three days in advance that conditions would be absolutely ideal for the launch, a rarity for the usually unpredictable Florida weather. But the forecast held true to its word, and clear skies permitted spectators at the launch site to follow the rocket's ascent for several minutes.

A half-hour after liftoff, the launcher deployed its cargo to cap the 71st consecutive successful Atlas mission dating to 1993.

"I want to say congratulations to the Atlas team -- Mike Gass, Jim Sponnick, Adrian Laffitte -- unbelievable, 71 out of 71 launches successful for Atlas," said Mark Albrecht, president of the International Launch Services firm that markets Atlas and Russian Proton rockets.

"The Atlas team -- you guys are only as good as the last launch. You're real good tonight! Thank you one more time for an outstanding effort."

The Atlas lights up the night as viewed from the Cape Canaveral press site. Photo: Steven Young/Spaceflight Now

Weighing just under 7,000 pounds, the smaller-sized Superbird 6 communications satellite took full advantage of what Atlas had to offer by soaring into a supersynchronous transfer orbit.

The highly elliptical orbit stretches from 104 miles at its closest point to Earth to a remarkable high point, or apogee, of 76,024 miles. The inclination is 26.25 degrees to the equator.

Planners opted to send the satellite into such an orbit -- 50,000 miles farther away from Earth than typical -- to make more efficient use of onboard propellant during upcoming space maneuvers.

"The higher the apogee altitude, the lower the velocity at apogee. Therefore, it is much easier from a velocity requirement standpoint to reduce the inclination," said Mike Jensen, ILS vice president for technical operations.

"For all of our missions Atlas provides a dedicated launch service to our customers. Therefore, we tailor the mission design to maximize the benefit to the customer. In this case, it's to reduce the overall velocity requirement and therefore maximize the on-orbit lifetime for the customer (by conserving the fuel supply)."

Superbird 6 will perform more than a half-dozen engine burns between Sunday and May 5 to arrive in a circular geostationary orbit 22,300 miles above the equator and remove the orbital inclination.

The craft will deploy its appendages and undergo testing through the end of May. Controllers expect to place the satellite into service from its operational location at 158 degrees East longitude in mid-June.

Built by Boeing Satellite Systems, the craft will be renamed Superbird A2 once it begins a decade-plus lifetime.

Space Communications Corp. of Tokyo will operate the satellite, using it to replace the aging Superbird A spacecraft launched in 1992.

An artist's concept of Superbird 6 in orbit. Credit: Boeing Satellite Systems

Manufactured upon the Boeing 601 satellite platform, Superbird 6 is equipped with both Ku- and Ka-band transponders to provide a wide-range of services for Japan, Australia, Micronesia, Hawaii, Taiwan, Korea and New Zealand.

"This satellite carries a payload with 23 active Ku-band and four Ka-band transponders for high-data-rate communications that will provide television news gathering, distance learning, Internet access, VSAT and other services to customers throughout the Asia-Pacific region," said David Ryan, president of Boeing Satellite Systems.

This becomes Space Communications Corp.'s fifth satellite in space, joining the Superbirds A, B2, C and D.

SCC officials have not yet settled on future plans for Superbird A once it is relieved by Superbird 6.

"We have a remaining few years on Superbird A. We are looking for other opportunities to use this satellite," said Kazuhiko Aoki, the Superbird 6 program manger from SSC.

The spent air-lit solid rocket boosters are jettisoned from the Atlas 2AS rocket. Photo: ILS TV

Thursday's launch was the third Atlas in three months, a pace that has kept workers busy at Cape Canaveral.

"We are focusing one vehicle at a time," launch director Adrian Laffitte said. "As soon as we finish this, we are running right into the other flow."

The next launch is an Atlas 2AS on May 19 with a U.S. cable television satellite, called AMC-11, from pad 36B.

The 30th and last Atlas 2AS will follow in late June with a classified National Reconnaissance Office payload in the final launch from pad 36A.

One further pad 36B liftoff is scheduled in early 2005 using the last Atlas 3 vehicle.

The Atlas 2- and Atlas 3-series rocket families are being retired in favor of the next-generation Atlas 5 that flies from Complex 41.