Aircraft carrying world's largest airborne telescope, suspended on 11t mounting, looks set to make first flight in 2004

L-3 Communications Integrated Systems has successfully installed the massive suspension assembly for the Stratospheric Observatory for Infrared Astronomy (SOFIA) telescope in a heavily modified Boeing 747SP at its Waco, Texas site.

Installation of the structure, weighing around 11,350kg (25,000lb), marks a major milestone towards completion of the SOFIA, which will be the world's largest airborne telescope when it starts operations in late 2004. L-3's work on the joint NASA and German Aerospace Centre (DLR) project is being led by the Universities Space Research Association (USRA), which will also be responsible for operating the aircraft for NASA.

Over the next four months L-3 plans to install the primary mirror assembly, weighing around 2,050kg, and the metering structure, weighing a further 900kg, which holds the secondary mirror assembly. "Physical integration work will go through June 2003, and we should be performing functional testing of the telescope in September," says L-3 SOFIA chief engineer John Fitch.

To reinforce the 747SP to take the telescope, its support structure and the complex door system, encompassing virtually the entire section 46, was rebuilt over a 14-month period, adds Fitch.

Following a four-month ground test phase, SOFIA is set to make its maiden flight in January 2004. Flight tests will last until mid-2004 when the aircraft is due to transfer to NASA Ames where it will be based for observing missions starting from September 2004.

Full scientific operations will not begin until the end of 2004, around three years later than originally planned when the SOFIA project was launched in the 1990s. The delay is attributed to slippages in the telescope timetable at MAN Technologies in Germany, and to deliberate programme slowdowns on both sides of the Atlantic.

When complete, SOFIA will conduct observations from altitudes of a minimum of 41,000ft (12,500m) and above 99% of the infrared-obscuring water vapour in the Earth's atmosphere.

Source: Flight International