Washington

Alterations to the plane set to carry NASA's SOFIA telescope are holding up the project. Credit: NASA

The first flight of a long-awaited airborne telescope developed by German and US scientists will take place two years later than planned, NASA officials have admitted. Take-off is now scheduled for late 2004 or early 2005.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) was conceived as a follow-on to the Kuiper Airborne Observatory, which ended a productive 20-year career in 1995. The $500-million project will use a German-built telescope the same size as the Hubble space telescope (2.5 metres in diameter) mounted in a converted Boeing 747.

The aircraft will fly three or four times a week from NASA's Ames Research Center in California, with a planned lifetime of 20 years. Cruising at altitudes of around 12,500 metres, above almost all of the infrared-absorbing water vapour in the atmosphere, SOFIA will study star and planet formation as well as the interstellar medium.

But modifying the airplane, which can stay aloft longer than a conventional 747, has needed more manpower and money than the company doing the job — Raytheon Aircraft Integration Systems in Waco, Texas — had bargained for. Faced with projected cost overruns of tens of millions of dollars, NASA has decided to delay the first flight by two years.

“We're not particularly happy about it,” says Ken Ledbetter, director of the Flight Programs Division at NASA's Office of Space Science. But for an agency that is struggling to complete a series of missions started in the 1990s, it was the best available option. NASA science chief Ed Weiler even told a recent meeting of the National Research Council's Space Science Board that, were it not for the German involvement, he would have considered cancelling the project.

→ http://sofia.arc.nasa.gov