WOODLAND HILLS, Calif., July 13, 2005 (PRIMEZONE) -- Key navigation aids from Northrop Grumman Corporation (NYSE:NOC) supplied the precise spacecraft-orientation information critical to the success of NASA's Deep Impact mission, a seven-month journey to comet Tempel 1 and the first space mission to probe beneath the surface of a comet and reveal the secrets of its interior.
The Deep Impact spacecraft consisted of two craft that separated when they reached the comet. Scalable space inertial reference units (scalable SIRUs(TM)) from Northrop Grumman were on both spacecraft. During the journey to Tempel 1, the scalable SIRUs provided the navigation information used by the spacecraft to make several course-correction burns. These burns put the dual spacecraft on a collision course to the comet.
The scalable SIRU utilizes Northrop Grumman's exclusive hemispherical-resonator gyros, which to date have accumulated more than 4,500,000 hours of operation in over 50 systems in space without a mission failure.
"Much like a wine glass which rings when it is struck, the hemispherical-resonator gyro is a precisely machined glass hemispherical shell mounted within the spacecraft that is forced to ring by an electrical field," said Lawrence Linick, program manager for the Deep Impact program at Northrop Grumman. "Any rotation of the spacecraft containing the gyro will change the frequency or pitch of this ring. This change in pitch can then be detected within the gyro to determine the exact orientation of the spacecraft in space. This orientation information is then provided by the scalable SIRU to the space vehicle in order to guide it in its mission. The ringing vibration is so minute that it creates virtually no internal stress and fatigue effects in the gyro, leading to its unmatched reliability."
The "fly-by" craft flew by the comet and recorded data and images of the impact, crater formation and comet interior. The second craft, the "impactor," separated from the fly-by craft and was propelled into the comet's path when it reached Tempel 1. Cameras and an infrared spectrometer on the fly-by spacecraft, along with ground-based observatories, studied the icy debris and interior material formed by the impact.
The fly-by spacecraft survived the encounter with Tempel 1, and NASA is examining using the spacecraft for another mission.
"This is one of the most significant navigation and guidance achievements in human history, enabled to a large extent by our scalable SIRUs," said Linick. "The team working on these units has been together for over five years, but many were new to the team when the Deep Impact program started in 2000."
"Our scalable SIRU was selected for its inherent precision performance and high reliability, which is central to this type of space-based mission," said Gorik Hossepian, vice president of situational awareness systems at the company's Navigation Systems Division. "The inherent ultra high-reliability, high-performance, radiation-tolerant features of the hemispherical-resonator gyros and the dual redundant features of the SIRU makes this the ideal inertial-reference unit for missions such as Deep Impact."
Northrop Grumman delivered the scalable SIRUs to Ball Aerospace in Boulder, Colo. in early 2004. Ball Aerospace designed and built the Deep Impact spacecraft under contract to NASA's Jet Propulsion Laboratory. It is NASA's eighth Discovery mission.
Headquartered in Woodland Hills, Calif., Northrop Grumman's Navigation Systems Division -- part of the company's Electronic Systems sector -- supplies situational-awareness products for international and domestic defense and commercial markets and offers integrated avionics, navigation and positioning systems and sensors for space and high-value platform products, navigation-grade and tactical-grade inertial systems, fiber-optic gyro systems designed to customer requirements, underwater fiber-optic sensors, identification friend-or-foe transponders and interrogators, cockpit displays and computers, and logistic support products and services.