Final Great Observatory arrives at launch site

Posted: March 9, 2003

The SIRTF spacecraft is scheduled for launch April 15. Photo: Lockheed Martin Space Systems/Russ Underwood
NASA's Space Infrared Telescope Facility arrived in Florida last week to begin a month-long period of final preparations before being attached to its Delta 2 booster for launch in mid-April.

The transport from its Lockheed Martin manufacturing facility in California to the Kennedy Space Center in Florida ended Thursday as the spacecraft was placed in its new processing facility at the Hangar AE clean room in the Cape Canaveral industrial area.

"We are very pleased to have completed integration and testing of NASA's latest space observatory," Lockheed Martin SIRTF program manager John Straetker said. "Environmental and other comprehensive tests done here in Sunnyvale have confirmed that SIRTF is a healthy observatory, ready for integration with the launch vehicle. We look forward with anticipation to the upcoming launch."

SIRTF will undergo a number of tests and checkout activities in the clean room, including inspections and final checks of the satellite's delicate infrared telescope and its scientific complement of three instruments and optical hardware.

Workers move SIRTF into Hangar AE at Cape Canaveral. Photo: NASA-KSC
Fueling of the craft's attitude control system responsible for orientation control will also occur over the coming weeks as highly pressurized nitrogen gas is loaded aboard for the cold-gas thrusters. Four reaction wheels are also on the spacecraft for pointing control as well.

Electronics and communications testing will be part of the final processing flow in addition to the other activities. An integrated test between NASA's Deep Space Network's three ground stations located around the world is also on the schedule before launch.

Once officials are confident SIRTF is ready for its journey into space, the satellite will be attached to its payload adapter and taken via a short drive to Space Launch Complex 17B, where the Delta 2 that will launch the craft is already waiting.

The SIRTF spacecraft will be mated to the Delta 2 in early April, and its protective payload fairing will be added a few days later. The final major spacecraft preparation activity is to fill it with 90 gallons of cryogenic liquid helium used to chill the infrared telescope instruments for maximum science return.

The Delta 2 rocket's first stage for the SIRTF mission is hoisted atop pad 17B last month. Photo: NASA-KSC
Stacking of the maiden Delta 2-Heavy launcher began on February 24 with first stage erection onto the platform, followed by the attachment of its nine 46-inch solid rocket motors designed for the Delta 3 program. SIRTF's launch will be the first use of these more powerful boosters on a Delta 2. Second stage stacking is scheduled this week for March 12, completing the large portion of rocket assembly.

Launch is set for the pre-dawn hours of April 15 from Cape Canaveral, and the satellite will arrive on-station in heliocentric orbit shortly thereafter, essentially trailing Earth as it orbits the Sun.

From there, the cutting edge spacecraft will get to work in its potential five-year mission, gathering images and data in the infrared wavelength of objects and regions throughout the Universe.

The final cornerstone member of the revolutionary Great Observatories program will join the Hubble Space Telescope covering visual observations and the Chandra X-ray Observatory responsible for the X-ray wavelength. The Compton Gamma Ray Observatory was de-orbited in 2000 after its mission was complete.

All told, SIRTF is the end product of decades of research and planning that has led to a number of mission and design changes, one of which was to change the expected launch vehicle from the Space Shuttle to an expendable booster.

An artist's concept of SIRTF at work. Credit: NASA/JPL

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