Navigation Ground Data System Engineering for the Cassini/Huygens Mission

Abstract

The launch of the Cassini/Huygens mission on October 15, 1997, began a seven year journey across the solar system that culminated in the entry of the spacecraft into Saturnian orbit on June 30, 2004. Cassini/Huygens Spacecraft Navigation is the result of a complex interplay between several teams within the Cassini Project, performed on the Ground Data System. The work of Spacecraft Navigation involves rigorous requirements for accuracy and completeness carried out often under uncompromising critical time pressures. To support the Navigation function, a fault-tolerant, high-reliability/high-availability computational environment was necessary to support data processing. Configuration Management (CM) was integrated with fault-tolerant design and security engineering, according to the cornerstone principles of Confidentiality, Integrity, and Availability (CIA). Integrated with this approach are security benchmarks and validation to meet strict confidence levels. In addition, similar approaches to CM were applied in consideration of the staffing and training of the System Administration team supporting this effort. As a result, the current configuration of this computational environment incorporates a secure, modular system that provides for almost no downtime during tour operations. NomenclatureCIA = Confidentiality, Integrity, and Availability CIS = Center for Internet Security CISscan = CIS internal host security scanner CM = Configuration Management DOS = Denial of Service attack DSN = Deep Space Network DR = Disaster Recovery ECC = Emergency Control Center GDS = Ground Data System GCC = Goldstone Communications Complex HP-UX = Hewlett-Packard (Unix System V based OS) for Hewlett-Packard computers

Orbit Control Operations for the Cassini-Huygens Mission

“…Interaction between all of these components is constant with the requirement for fast and consistent product turn-around using a reliable ground data system. 4 Overall, the three primary objectives for Cassini Navigation are to 1. Estimate and predict the state of the spacecraft, major satellites and the planets;…”

Computer Security as an Engineering Practice: A System Engineering Discussion

“…It would then orbit Saturn nearly three hundred times over thirteen years, conducting hundreds of targeted flybys of Saturn's largest moons during its mission lifespan, finally coming to a fiery end in Saturn's atmosphere in September of 2017. This operational effort would be conducted on a network of computer systems having a requirement for no more than two minutes of unplanned downtime ASTESJ ISSN: 2415-6698 a year (99.9995% availability) [2]. For a network that could not be upgraded (except in minor incremental steps) during the length of the entire 13-year Saturn orbital tour, maintaining and keeping such a computer network secure, as well as supporting backwards compatibility (and obsolescent hardware) would be a challenging problem.…”

“…The Ground Data System for Navigation is constructed in the manner of a classic Development and Operations model with development and production networks of several hundred servers and workstations. This network is used by teams of engineers working, often under critical time pressures, with rigorous requirements for accuracy [2].…”

Orbit Determination Processes for the Navigation of the Cassini-Huygens Mission

“…This fault-tolerant, eight terabyte, high-availability disk array is devoted to the OD team for daily operations and file deliveries to the other parts of the navigation team. 17 Built on top of this software is the JPL navshell system that helps automate and tie together essential pieces of the ODP and other software tools into an efficient, robust, and flexible system. Deep space navigation, particularly the OD operations of Cassini at Saturn, cannot easily be automated due to the complex dynamical environment in which the S/C flies; however several of the sub-processes are automated.…”