The first Delta 4 rocket is scheduled to launch Saturday. Photo: Justin Ray/Spaceflight Now

Boeing's next-generation Delta 4 rocket blasts off from Cape Canaveral this weekend on its debut launch to shape its destiny in the fiercely competitive commercial marketplace and prove reliability to the vehicle's major backer -- the U.S. Air Force.

Powered by the first new U.S. liquid-fueled rocket engine developed in a quarter-century, the inaugural Delta 4 is scheduled to launch at sunset Saturday on a 37-minute flight to deliver the W5 telecommunications satellite into Earth orbit for Paris-based operator Eutelsat. The available launch window extends from 5:38 to 6:49 p.m. EST (2238-2349 GMT).

A successful introduction is vital for Boeing's hopes to carve out a slice of the market to launch large commercial satellites. The industry -- currently dominated by Europe's Arianespace and the Russian/American venture International Launch Services -- is overpopulated with more available rockets than payloads to carry.

What's more, the U.S. Defense Department is counting on Delta 4 to launch nearly two-dozen missions over the next few years to loft satellites that are crucial to the military and intelligence-gathering community.

"Any first launch is important," said Dan Collins, Boeing's vice president and Delta program manager. "It is important to us and we're working hard to make sure it is successful."

"From a national security standpoint, Delta 4 is critical to our overall strategy for assured access to space, for cost effectiveness," added Air Force Lt. Col. Tony Taliancich of the Evolved Expendable Launch Vehicle System Program Office. "There are a lot of implications for this launch coming up."

Evolved Expendable Launch Vehicle
The Delta 4 was developed by Boeing as part of the Air Force's Evolved Expendable Launch Vehicle program to create a new era of American rockets.

EELV's goal is to replace today's versions of Atlas, Delta and Titan boosters with new launchers that are cheaper and have higher reliability for putting payloads into orbit.

The other EELV rocket -- Lockheed Martin's Atlas 5 -- flew a flawless maiden voyage on August 21.

Boeing won the majority of initial Air Force EELV launches, which were awarded in October 1998. After some restructuring of the manifest and the addition of a Delta 4 test flight paid for by the Air Force, Boeing has 22 government EELV missions and Lockheed Martin has 7.

"Both Lockheed and Boeing have been extremely responsive partners. They have been committed," Taliancich said.

"Boeing has clearly demonstrated the willing commitment to drive down the cost of the vehicle, to build up reliability, to invest in the future of the system. And because of that, we clearly awarded a significant number of DOD payloads for their efforts. We are confident in the system as it has come along and its ability to meet our needs in the future."

A DSCS satellite during pre-flight testing at manufacturer facilities. Photo: Lockheed Martin

The first Air Force EELV mission, scheduled for February aboard the second Delta 4 rocket, will place a Defense Satellite Communications System spacecraft into orbit.

Assuming the maiden Delta 4 is successful, engineers will take a couple months to thoroughly pick through the data before clearing the path to the second launch.

"We are confident we will get this first inaugural launch off successfully and that we will have somewhere around two-and-a-half months that we will need to get through the data review of the first mission, make sure everything is good, and then move on to the DSCS mission," Collins said.

To ensure military payloads have a ride to space, Atlas 5 and Delta 4 are capable of backing up each other, allowing the government to switch a satellite to the other rocket if one is grounded.

Although the Air Force has paid Lockheed Martin to prepare for launching DSCS on an Atlas 5, the switch wouldn't automatically happen if the first Delta 4 fails.

"There would have to be a significant emotional event. We're committed to flying on Delta 4," Taliancich said. "But it is prudent to make sure we understand all the options in the time frame necessary to respond to whatever conditions might occur.

"It would take a lot to force any kind of re-evaluation of our decision to fly on Delta 4."

Can Delta 4 survive a failure?
"This is not a make or break launch for The Boeing Company or Boeing Expendable Launch Systems or the Delta program," said Will Trafton, president of Boeing Launch Services, which markets the Delta and Sea Launch rockets.

"If there is a failure we will investigate it, we will come up with corrective actions and we will go launch the vehicle again.

"The customer community, both on the military side and commercial, are looking for success. If there is a failure you have to look at what caused the failure and how long are you looking at to get back to flight."

Delta 4 has a strong early manifest with six launches planned over the next year -- two commercial flights and four EELV missions, including one from Vandenberg Air Force Base in California. Through 2007, some 27 launches are booked.

For Boeing Launch Services as a whole, 95 missions are scheduled on Delta 2, 3 and 4 and Sea Launch through 2007.

Boeing Launch Services' fleet of rockets. Photo: Boeing

"As I look down the road from the (Boeing Launch Services) standpoint, we are in good shape. We have our customers lined up. They are behind us," Trafton said.

"This is a company that is going to be in the launch business a long time. We all talk about the launch business maybe contracting, some kind of fallout over this tremendous competition that is going on. I just want to assure everyone in this room that when we get down to one or two left standing, if it comes to that some day, Boeing is going to be one of the companies standing," Trafton recently told reporters at Cape Canaveral.

"We feel like we are looking at a very bright future."

This is the first in a series of stories that will preview the upcoming Delta 4 launch. Look for a technical overview of the rocket, tour of the Delta 4's Cape launch pad, detailed description of the first launch and much more throughout the week. And, of course, we will provide the most thorough live coverage of Saturday's countdown and launch.