New US rocket launch delayed

Company launch officials said the blast-off, originally due for Saturday, had been put back because of engine concerns.

The Delta 4, which contains a new first stage and main engine, is seen as the key to Boeing's future in the launch industry.

It is a direct competitor to the new Atlas 5 rocket, built by Lockheed Martin, and the new 10-tonne variant of the European Ariane 5 rocket, due to make it maiden flight at the end of the month.

The Delta 4 will take off from Space Launch Complex 37 at Cape Canaveral, carrying a Eutelsat communications satellite.

Stiff competition

A successful debut is critical, both for Boeing as it attempts to win commercial launch contracts, and for its major customer, the US Air Force.

The Delta 4 is one of two new US rockets being introduced in 2002.

The other is the Lockheed Martin Atlas 5 that successfully debuted on 21 August, launching a Eutelsat television broadcasting satellite.

The Delta 4 and Atlas 5 are in direct competition for the lucrative US national security market in launching large military satellites.

Boeing won the first round of the competition by obtaining 19 of the 28 launch contracts awarded by the US Air Force in 1998.

Having won the major share of these contracts, a trouble-free launch of the Delta 4 is essential for continued confidence in the Boeing rocket series.

Technological improvements

The Delta 4 has been designed to be more swiftly assembled than its predecessors, with its preparation time on the launch pad being reduced from 20 to 10 days.

The Delta 4 comes in several variants based around its new first stage, called the Common Booster Core (CBC).

The rocket's second stage is an expanded version of the second stage used in the Delta 3 rocket.

Additional boosters can be used to supplement the first stage.

The most powerful version of the rocket involves three CBC's strapped together to form the so-called Delta 4 heavy.

It will be able to place a payload of 13 tonnes into a trajectory towards geostationary orbit.

New components

The Delta 4 rocket passed a mission rehearsal on 14 October.

However, some rocket analysts are cautious about the maiden flight, pointing out that the Delta 4 represents a big leap in technology involving many components that have never flown before.

The successfully flown Atlas 5 shares about 80% of its components in common with the reliable Atlas 3 rocket.

A much greater proportion of the Delta 4 is completely new.

In particular, its main engine, the RS-68, has no flight history and is the first new, powerful liquid-fuelled rocket to be developed in the US for more than 20 years.

Europe's new 10-tonne Ariane 5 is set to launch from the Kourou spaceport in French Guiana on 28 November.