The Space Infrared Telescope Facility (SIRTF) was originally scheduled to be launched on April 17 -- then postponed to April 27 -- aboard a Delta II rocket from the Cape Canaveral, Florida.

The delay gives engineers enough time to change one of the nine solid rocket motors attached to the Delta II rocket, which had "multiple delaminations within the layers of material that comprise the engine-nozzle exit-cone liner," NASA said in a statement.

"There simply is not enough time to remove and replace the rocket motor to support a SIRTF launch in advance of the Mars Exploration Rover-B launch window," said Karen Poniatowski, Assistant Associate Administrator for Launch Services at NASA Headquarters, Washington.

The Mars Exploration Rovers are scheduled to be launched also on Delta II rockets on June 6 and June 25.

The first of the two Mars missions was originally scheduled for May 30, but rescheduled to June 6 because of a possible problem with cabling on the spacecraft.

The mission of the 1.2-billion SIRTF, planned to last for five years, will complete the range of US space telescopes that include the Hubble Space Telescope, the Compton Gamma Ray, and the Chandra X-ray Observatories.

Researchers will use the new four metre (13 feet) long telescope to study planets and stellar fragments that surround certain stars, in the hope of finding a planet similar to Earth with favorable conditions for life.

The SIRTF's infrared sensors will allow it to see further into the universe than ever before, according to NASA.

The telescope, with an 85-centimeter (33.5-inch) diameter lens, whose mission could last up to five years, is equipped with three scientific cryogenic cooling instruments.

It has an infrared array camera to study near-to-mid-infrared rays, an infrared spectrograph that breaks light into wavelengths similar to a prism, and a multi-band imaging photometer that operates at far-infrared wavelengths to study cool, dusty objects.

SPACE.WIRE