Session
Technical Session II: Mission Lessons I
Abstract
On September 10, 2011, two identical spacecraft were launched from the Kennedy Space Center Space Launch Complex-17B on their 4-month, low-energy trajectory to the moon. The primary objective of the Gravity Recovery and Interior Laboratory (GRAIL) mission was to collect a global gravity map of the moon with a resolution approximately 1000 times better than existing knowledge. Lockheed Martin had the responsibility of designing, developing, assembling, testing, launching, and operating the twin spacecraft. With a dry mass of 200.6 kg each, these GRAIL spacecraft were among the lightest ever to be selected for a NASA Discovery-class mission. This paper discusses some of key trade studies performed and the resulting design features of these two small spacecraft. Among the areas of discussion are the following: • Spacecraft architecture and its significant heritage from Experimental Small Satellite #11 (XSS-11) • Increasing the delta-v capability required for the lunar orbit insertion • Solar array sizing for the science collection phase • Mounting position for the Ka-band antenna, one of the key components of the science instrument • Launch configuration trade study: stacked design vs. side-by-side design • Spacecraft similarity trade study: mirror image buses vs. identical buses with a rotated science orientation • Limited redundancy approach and its associated fault protection This paper also discusses some of the on-orbit performance during GRAIL’s primary mission including: • Spacecraft performance and anomalies • Science results from the primary mission • Analysis performed to justify and gain approval for a 6-month extended mission Not only have the GRAIL spacecraft returned a wealth of scientific data, but they paved the way for future Lockheed Martin small satellite applications including an entry in NASA’s Rapid Spacecraft Development Office (RSDO) catalog.
Presentation Slides
Small Spacecraft Design for the GRAIL Mission
On September 10, 2011, two identical spacecraft were launched from the Kennedy Space Center Space Launch Complex-17B on their 4-month, low-energy trajectory to the moon. The primary objective of the Gravity Recovery and Interior Laboratory (GRAIL) mission was to collect a global gravity map of the moon with a resolution approximately 1000 times better than existing knowledge. Lockheed Martin had the responsibility of designing, developing, assembling, testing, launching, and operating the twin spacecraft. With a dry mass of 200.6 kg each, these GRAIL spacecraft were among the lightest ever to be selected for a NASA Discovery-class mission. This paper discusses some of key trade studies performed and the resulting design features of these two small spacecraft. Among the areas of discussion are the following: • Spacecraft architecture and its significant heritage from Experimental Small Satellite #11 (XSS-11) • Increasing the delta-v capability required for the lunar orbit insertion • Solar array sizing for the science collection phase • Mounting position for the Ka-band antenna, one of the key components of the science instrument • Launch configuration trade study: stacked design vs. side-by-side design • Spacecraft similarity trade study: mirror image buses vs. identical buses with a rotated science orientation • Limited redundancy approach and its associated fault protection This paper also discusses some of the on-orbit performance during GRAIL’s primary mission including: • Spacecraft performance and anomalies • Science results from the primary mission • Analysis performed to justify and gain approval for a 6-month extended mission Not only have the GRAIL spacecraft returned a wealth of scientific data, but they paved the way for future Lockheed Martin small satellite applications including an entry in NASA’s Rapid Spacecraft Development Office (RSDO) catalog.
