Press Release

Unison’s Dual Direct Ignition System Ignites the First Atlas V Centaur Upper Stage

By SpaceRef Editor
September 6, 2002
Filed under , ,

Unison’s New Ignition System Makes Inaugural Launch on the Maiden Flight of the Atlas V


Unison Industries announced that its new Dual Direct Spark Ignition System
(DDSI) successfully lit the Pratt & Whitney RL10A-4-2 engine used on the
Lockheed Martin Atlas V Expendable Launch Vehicle’s Centaur upper stage. The
Atlas V launched from Cape Canaveral’s Complex 41 at 6:05PM EDT on August
21, 2002. Just four-and-a-half minutes later, Unison’s DDSI ignited the
Centaur’s first RL10A-4-2 main engine start after the separation of the
first stage. Twenty-four minutes after liftoff, Unison’s DDSI re-ignited the
RL-10A-4-2 engine for a four-minute, fourteen-second burn that propelled the
payload, the Hot Bird 6 satellite, to a supersynchronous orbit around the

Hot Bird 6 is an Alcatel Spacebus 3000B3 satellite carrying 29 Ku-band and 4
Ka-band transponders. The satellite will deliver 600 television and 475
radio services to homes across Europe, North Africa, and the Middle East.
The Atlas V Centaur upper stage is powered by one Pratt & Whitney RL10A-4-2
engine that burns liquid oxygen and liquid hydrogen. The Centaur engine,
using Unison’s Dual Direct Spark Ignition System, is capable of being
restarted in space and can sustain multiple firings separated by coast
phases. The engine delivers 22,300 pounds of thrust.

Unison started its DDSI development efforts in 1994 with Pratt & Whitney and
Lockheed Martin on the RL10E-1 Atlas Reliability Enhancement Program funded
by the US Air Force. The new solid-state DDSI increases the reliability of
the Centaur upper stage by delivering multiple firings to allow heavier
payloads to be placed in orbit. The DDSI, a derivative of Unison’s Direct
Spark Ignition Single-Channel System, features two electrically and
hermetically redundant solid-state ignition circuits for enhanced
dependability. Unison’s Norwich, New York facility has produced the Direct
Spark Ignition Single-Channel System since 1959. The Single-Channel ignition
system has achieved a perfect track record in 636 upper stage firings.
Unison remains committed to supporting the space transportation industry
through its research and development efforts under NASA’s Space Launch
Initiative. As part of this new initiative, Unison is exploring new
propulsion and ignition options for second-generation reusable launch

Unison, a wholly-owned subsidiary of GE Engine Services, Inc., is a world
leader in the design and manufacture of electrical components, sensors, and
systems for aircraft, industrial, marine, and space uses. Headquartered in
Jacksonville, Florida, Unison operates manufacturing facilities and
logistics centers worldwide. Additional information a

bout Unison is
available at .

SpaceRef staff editor.