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A sophisticated interplanetary spacecraft, Cassini–Huygens was launched on 15 October 1997. After achieving orbit at Saturn in 2004, Cassini collected science data throughout its four-year prime mi...

Cassini is one of the most sophisticated interplanetary spacecraft that humans have ever built and launched. Since achieving orbit at Saturn in 2004, Cassini has collected science data throughout i...

Telemetry data from three 445 N engine burns of the Cassini spacecraft are used to characterize the high-g slosh characteristics of bipropellants in cylindrical tanks with spherical end domes. Comp...

The 2001 Mars Odyssey spacecraft represents the third generation of aerobraking designs, following Magellan's pioneering aerobraking demonstration at Venus and Mars Global Surveyor's planned operational aerobraking at Mars. Aerobraking provides significant advantages for interplanetary spacecraft by reducing the size of the required propulsion system and propellant load, thereby allowing larger payloads for the same launch mass. However, aerobraking is not without risk; relatively small command errors or brief inattention to the highly variable atmospheric dynamics can lead to disaster. This paper describes how the 2001 Mars Odyssey aerobraking design and operations managed the inherent aerodynamics-related risks of aerobraking. We describe the configuration changes Odyssey used during aerobraking orbits and how the operations team managed those configurations. We present a detailed vehicle dynamics model derived for Odyssey's aerobraking safe-mode configuration, as well as the predicted attitude response during aerobraking safing events. Contingency procedures were developed before aerobraking and included an option to "pop-up" out of the atmosphere if aerobraking operations began to endanger spacecraft health and safety. We describe the criteria and decision-making process for commanding pop-up maneuvers. Finally, flight results from Odyssey's aerobraking experience are presented including an assessment of the aerodynamic sating approach in response to the highly variable atmospheric conditions.

The effects of the sporadic meteoroid environment on interplanetary spacecraft have an important impact on mission design. A reformulation is described of the Divine interplanetary meteoroid model, called the meteoroid engineering model (METEM), that is capable of estimating many ofthoseeffects. METEM and the original Divine modelitisbasedonmadeuseofthenewmeteoroiddataobtainedsincethe1970s,whentheoriginalNASAmeteoroid models were developed, to provide a comprehensive phase space description of the environment. METEM allows detailed estimatesofthemeteoroids’ directionalityand variationwithdistancefromthesun.Itincorporatesseveral different meteoroid populations, each population being described in terms of a distribution function in velocity phasespace. These distribution functionsare integrated along a spacecraft trajectory to give the meteoroid e uence asa function of velocity and anglerelativeto a specie edsurface.METEMpredictionsofmissionmeteoroid e uences are explicitly compared with those of the standard NASA models for three representative trajectories (an inner solarsystem,Helios-likemission;a missionat1 AU; anda Cassini-like,outersolarsystemmission ). In addition,the METEMmodelisused toestimatetheangularvariationsin themeteoroide uenceexpectedalongthesetrajectories, a unique feature of this new class of models that provides additional insights into how a spacecraft can bedesigned to protect it from meteoroids.

A shock spectra/impedance method for loads predictions is used to estimate member loads for the Viking Orbiter, a 7800-lb interplanetary spacecraft that has been designed using transient loads analysis techniques. The transient loads analysis approach leads to a lightweight structure but requires complex and costly analyses. To reduce complexity and cost, a shock spectra/impedance method is currently being used to design the Mariner Jupiter Saturn spacecraft. This method has the advantage of using low-cost in-house loads analysis techniques and typically results in more conservative structural loads. The method is evaluated by comparing the increase in Viking member loads to the loads obtained by the transient loads analysis approach. An estimate of the weight penalty incurred by using this method is presented. The paper also compares the calculated flight loads from the transient loads analyses and the shock spectra/impedance method to measured flight data.

As the application of sequential filters has grown, the need has arisen to evaluate the sensitivity of these filters to mismodeling of the random process. A numerically reliable square-root algorithm is developed for calculating the covariances of estimates from a sequential filter which incorrectly models process noise. Mismodeling is restricted to the correlation time and standard deviation of a random process represented as a first-order Gauss-Markov sequence. Using a computer program which employs this algorithm, a sensitivity analysis was performed for several types of earth-based tracking data from an interplanetary spacecraft.

Scientific findings from interplanetary spacecraft radio propagation experiments, particularly Mariner 5 data

Dynamic instability of rolling high drag planetary entry vehicles at subsonic speeds, noting angle of attack divergence in computerized entry simulation

Study of protection requirements for resistance of meteorite penetration damage for various interplanetary spacecraft systems

Algorithm for trajectory analysis in closed loop terminal guidance of solar electrically thrusted interplanetary spacecraft

Analytical technique for unmanned spacecraft sizing for planetary missions, considering scientific objectives, characteristics and requirements

Digital computers for interplanetary spacecraft, comparing centralized and decentralized approaches for implementing onboard functions

Nuclear solid core rocket engine performance for interplanetary orbital launch of spacecraft by multiorbit injection