Delta IV Heavy launches with DSP-23 – mission success

by Chris Bergin

A United Launch Alliance (ULA) Delta IV Heavy has lifted off for only the second time, carrying the Defense Support Program Satellite (DSP-23) from Cape Canaveral Air Force Station’s SLC-37B. Launch was slightly delayed to 8:50pm Eastern, following a short delay at T-5 minutes. covered the launch as a live event through to spacecraft seperation, with extensive background, live updates, images and free launch video, available on the links below (read more).

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ULA claim mission success, following spacecraft separation 6hrs 20mins after after launch.

‘Following the Delta IV Heavy test flight three years ago, the hard work and dedication of the team to prepare to launch our first operational mission was phenomenal,’ said Mark Wilkins, ULA vice president, Delta Programs.


‘We appreciate the support from our Air Force customer in achieving this milestone, and ULA is pleased to welcome the Delta IV Heavy as a member of our operational vehicle family.’ 

‘The success of this launch today is due to the thousands of people who have worked so hard on this program,’ said Lt. Col. Joe Coniglio, DSP program manager for the U.S. Air Force Space and Missile Center. ‘We are standing on the shoulders of giants and thank the entire team for getting us to mission success.’

Mission background:

The Delta IV Heavy is the largest vehicle in the EELV (Evolved Expendable Launch Vehicle) family, consisting of three strapped together Common Booster Cores (CBCs), each powered by a Pratt & Whitney Rocketdyne RS-68 main engine, with cryogenic upper stage mated to the top of the middle CBC, powered by a Pratt & Whitney Rocketdyne RL10B-2 engine.

The debut of the giant Delta IV-H occurred on its demo flight at the end of 2004. However, the vehicle suffered fuel sensor problems – due to vacuum pockets in the fuel lines – during first stage flight, leading to the strap-on and the core CBC shutting down prematurely. The second stage ran out of propellant before it could compensate for the problems during first stage flight.

Thanks to data gathered during the demo flight – which was only carrying a dummy payload – engineers believe they have corrected the issue via increased pressure in the fuel lines and modified flight software.

Tonight’s launch was orginally set to take place back in late 2005, later delayed to April of this year – before a LO2 leak at the pad during a tanking test at the end of February caused a major delay while repairs to the launch table were conducted.

‘While securing the DSP-23/Delta IV launch vehicle after the Wet Dress rehearsal held on Feb. 28 , two structural cracks were observed in the metallic Launch Table,’ noted a USAF release, following an investigation.

‘The cracks appeared on the bottom of the launch table’s starboard and center bays; roughly underneath the liquid oxygen servicing equipment for the starboard and center booster cores. There was no damage to the heavy launch vehicle.

‘Based on findings to date, the investigation team has determined that a liquid oxygen leak inside the launch table most likely led to the fracturing of the low carbon construction steel plates from cryogenic temperatures. The origin of the leak appears to be from the vacuum jacketed liquid oxygen propellant lines inside the launch table, which are used to fill the booster tanks.’

The Block 3 5,250 pounds (2,386 kilograms) Air Force Space Command-operated DSP satellites are a key part of North America’s early warning systems. In their 22,300 mile geosynchronous orbits, DSP satellites help protect the United States and its allies by detecting missile launches, space launches and nuclear detonations.

DSP satellites use an infrared sensor to detect heat from missile and booster plumes against the earth’s background. In 1995, technological advancements were made to ground processing systems, enhancing detection capability of smaller missiles to provide improved warning of attack by short-range missiles against US and allied forces overseas.

DSP satellites used to be been launched via a Titan IV booster and inertial upper stage combination. However, one DSP satellite was launched using the space shuttle on mission STS-44 (November, 24, 1991). DSP-23 debuts the use of the EELV Delta IV-H.

‘The Northrop Grumman-built DSP satellites have been the spaceborne segment of North American Aerospace Defense Command (NORAD’s) Tactical Warning and Attack Assessment System since 1970. DSP satellites use infrared sensors to detect heat from missile and booster plumes against the Earth’s background,’ said ULA’s Dan Marin, Director of the Delta EELV Program.

‘Air Force Defense Support Program satellites provide early detection and warning of missile launches and nuclear explosions to National Command Authorities and operational commands.

‘United Launch Alliance is proud to launch DSP-23, the last satellite of this constellation that has been the cornerstone of North America’s early warning system for more than 35 years. I congratulate the entire Delta team for their significant efforts that resulted in achieving this milestone.’

DSP’s effectiveness was proven during Desert Storm, when DSP detected the launch of Iraqi Scud missiles and provided warning to civilian populations and coalition forces in Israel and Saudi Arabia.

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