Cassini Trajectory Design Description
The Cassini mission to Saturn will start a second phase in the exploration of the Saturnian system
flybys↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Kinetic and Transport Modeling for Entry Flows in Hydrogen-Helium Atmospheres
Several different thermochemical models for H2/He mixtures are used to simulate a 1-D shock in a viscous CFD code at conditions relevant for hypersonic entry into the ice and gas giants. These models range from a 6-species, 1-temperature (1-T) model, to more complex 17 and 25-species state-to-state (StS) models. Corresponding radiance profiles for each of these models are then computed using a radiation code, and results are compared to experimental data from the NASA Ames Electric Arc Shock Tube (EAST) facility. Overall, the 6-species model with a quasi-steady state (QSS) solver for atomic H and modified ionization rates, along with the 17 and 25-species StS models, are found to reproduce the magnitude of the radiance seen in the EAST experiments reasonably accurately. Two additional changes to the modeling of species diffusion fluxes are also investigated: the exclusion of a ∇W term, as well as the inclusion of Soret/ Dufour effects. It is determined that these changes to the transport modeling have a negligible impact on the flowfield and therefore the radiance predictions for the H2/He shock conditions considered in this study.
Outer planets↗
First Results from the Descent Imager/Spectral Radiometer (DISR) Experiment on the Huygens Entry Probe of Titan
The Cassini-Huygens mission was launched on October 15, 1997, and arrived in Orbit around Saturn in July, 2004. The Huygens Probe was released from the Cassini Orbiter on December 24, 2004 and entered Titan s atmosphere on January 14, 2005. Here we give the first results from the Descent Imager/Spectral Radiometer (DISR) instrument aboard the Huygens Probe during its descent into the atmosphere of Titan. Measurements were made by several different optical systems and sensors.
Tomasko, M. G.↗
The extension of the Cassini spacecraft/Titan probe to the exploration of Neptune/Triton
NASA and ESA are planning a mission named 'Cassini' to place a spacecraft in Saturn orbit and deposit an atmospheric probe into the atmosphere of Titan. It is expected that the upcoming close flyby of Neptune and Triton by Voyager 2 will increase future scientific interest in more intensive exploration of that system. The purpose of this paper is to examine the feasibility of the extension of the Cassini spacecraft and Titan Probe designs to this expected future scientific need for longer-term orbital observations of Neptune and its satellites and for in situ exploration of the suspected Triton atmosphere with a probe vehicle.
Wercinski, Paul F.↗
Integration of Spacecraft Telemetry into Navigation Operations for the Cassini-Huygens Mission
The Cassini orbiter is the largest and most complex interplanetary spacecraft ever built. Since attaining orbit around Saturn in the summer of 2004, Cassini, along with its Huygens probe, have been continually improving our understanding Saturn, its satellites, its enigmatic rings system, and of the solar system. One of the hallmarks of the Cassini- Huygens Project is the close working relationship between the many teams required to operate such a sophisticated spacecraft. Their ingenuity has enabled them to find new and different ways to improve their processes during Cassini's prime 4-year orbital tour. This paper will discuss the relationship between Cassini's Navigation and Spacecraft Teams and the work required to properly configure Cassini's telemetry system for Navigation. A detailed explanation of how the Navigation Team utilizes spacecraft telemetry and analysis demonstrating the benefits will also be provided. Finally, telemetry requirements for Navigation for future missions will be addressed.
AACS↗
Cassini / Huygens Science Instruments
The Cassini spacecraft will bring eighteen scientific instruments to Saturn. After it is inserted into Saturn orbit, it will seperate into a Saturn Orbiter and an atmospheric probe, called Huygens, which will descend to the surface of Titan.
Cassini↗
A First Look at Orbit Determination for the Cassini Mission, Part 2: Saturn Tour
This paper completes the presentation of the first round of orbit determination analysis accomplished as part of Cassini navigation studies. The thrust of the analysis was to characterize operational orbit determination accuracy to first order for selected phases of the mission. The previous paper, Part 1, covered early phases from inner solar system cruise through the approach to Saturn and delivery of the Huygens probe to Titan. Part 2 resumes chronologically where Part 1 left off, covering the tour phase after delivery of the Huygens probe.
Cassini mission orbit determination Saturn Titan↗
Cassini/Huygens Science Instruments, Spacecraft, and Mission
The Cassini spacecraft will take 18 scientific instruments to Saturn. After launch and a seven-year cruise, Cassini will arrive at Saturn and separate into a Saturn orbiter and an atmospheric probe, called Huygens, which will descend to the surface of Titan. The orbiter will orbit the planet for four years, making close flybys of five satellites, including multiple flybys of Titan. Communication with Earth is at X-band; the maximum downlink rate from Saturn is 166 x 10(exp 3) bps. Orbiter instruments are body mounted; the spacecraft must be turned to point some of them toward objects of interest. The orbiter carries 12 instruments. Optical instruments provide imagery and spectrometry. Radar supplies imaging, altimetry, and radiometry. Radio links contribute information about intervening material and gravity fields. Other instruments measure electromagnetic fields and the properties of plasma, energetic particles, and dust particles. The probe is spin stabilized. It returns data via an S-band link to the orbiter. The probe's six instruments include sensors to determine atmospheric physical properties and composition. Radiometric and optical sensors will produce data on thermal balance and obtain images of Titan's atmosphere and surface. Doppler measurements between probe and orbiter will provide wind profiles. Surface sensors will measure impact acceleration, thermal and electrical properties, and, if the surface is liquid, density and refractive index. This design will enable Cassini to determine the composition; the physical, morphological, and geological nature; and the physical and chemical processes of the atmospheres, surfaces, and magnetosphere of the Saturnian system. This paper briefly describes the Cassini mission and spacecraft and, in somewhat more detail, the scientific instruments.
Jaffe, Leonard D.↗
Planetary missions
The scientific and engineering aspects of near-term missions for planetary exploration are outlined. The missions include the Voyager Neptune flyby, the Magellan survey of Venus, the Ocean Topography Experiment, the Mars Observer mission, the Galileo Jupiter Orbiter and Probe, the Comet Rendezvous Asteroid Flyby mission, the Mars Rover Sample Return mission, the Cassini mission to Saturn and Titan, and the Daedalus probe to Barnard's star. The spacecraft, scientific goals, and instruments for these missions are noted.
Mclaughlin, William I.↗
Touring the Saturnian System
The Cassini mission to Saturn employs a Saturn Orbiter and a Titan probe to conduct an intensive investigation of the Saturnian system. The Cassini orbiter flies series of orbits incorporating flybys of the Saturnian satellites called the Satellite Tour.
Cassini↗
Cassini: A mission to Saturn and Titan
The Cassini spacecraft that will carry out a detailed exploration of the Saturnian system is described. The spacecraft is composed of a Saturn orbiter and a Titan atmospheric probe called Huygens. The scientific objectives and investigations developed for the accommodation phase of the mission are discussed. The preferred trajectories available for transit to Saturn are discussed along with Titan specific features of the tour of the Saturnian system.
Matson, Dennis L.↗
Cassini Attitude Control Operations - Guidelines Levied on Science to Extend Reaction Wheel Life
The Cassini spacecraft was launched on October 15, 1997 and arrived at Saturn on June 30, 2004. It has performed detailed observations and remote sensing of Saturn, its rings, and its satellites since that time. Cassini deployed the European-built Huygens probe, which descended through the Titan atmosphere (Saturn's largest moon) and landed on its surface on January 14, 2005. The Cassini mission has recently been approved by NASA to continue through September of 2017. This 7-year extension is called the Solstice mission and it presents challenges to the spacecraft operations team and its ability to maintain the health of the spacecraft. To keep the spacecraft healthy for 7 more years, the spacecraft team must carefully manage hydrazine use (about 48% of the 132 kg launch load remains as of January 2011). A vital part of conserving hydrazine is to use the reaction wheel assembly (RWA) control system for precise pointing and slews wherever possible. In any given week, the Cassini spacecraft is commanded to use RWA control about 99% of the time, with about 1% of the time requiring reaction control system (RCS) thruster control (to perform Delta V course corrections or to bias the RWA momentum). Such extensive use of the RWA hardware throughout the mission requires that the RWAs be operated in a way that minimizes degradation in the RWA electronics, DC motor, and spin bearing for each reaction wheel. Three consumables in particular have been identified for the RWAs: (1) Total number of revolutions for each RWA. (2) Time spent at very low wheel speeds. At these low speeds, good elasto-hydrodynamic (EHD) film lubrication may be compromised. (3) Total number of on/off power cycles. The second of these consumables, minimizing the time spent at very low wheel speeds, is especially important to keep the spin bearing healthy and well-lubricated. These consumables are actively managed by the attitude control operations team throughout the mission. One vital management technique is to predict individual RWA momentum (given the pointing and slews that are needed to collect the best science) and to bias the RWA momentum in a way that reduces both the total number of revolutions as well as the time spent below EHD wheel speed. Another strategy to protect RWA health is to alter the planned pointing of the spacecraft (which can affect science collection) so that the RWA consumables are conserved. This paper focuses on why this second technique is needed, and discusses how guidelines have been developed by the attitude control team which affects the planned science pointing, so that science data can be most optimally collected while still minimizing RWA consumable usage.
interplanetary trajectory↗
Common Probe Design Study and Follow-On Activities
The Common Probe Study was funded by the NASA's Planetary Science Division in the Science Mission Directorate in 2018 to investigate the feasibility of a common aeroshell design for atmospheric probe missions at Venus, Jupiter, Saturn, Uranus, and Neptune. The study involved 4 NASA Centers: Ames Research Center, Goddard Space Flight Center, Langley Research Center, and the Jet Propulsion Laboratory. The common aeroshell design that was studied was a 400 kg, 1.5 m diameter, 45-degree sphere cone shape with a high density heatshield material (Heatshield for Extreme Entry Environments Technology, or HEEET) and a parachute system to extract the descent vehicle. This size of aeroshell could accommodate a descent vehicle of 0.75 m diameter, which could encompass both Tier 1 and Tier 2 science instruments at each of the 5 destinations. Study methodology: First, a notional payload of instruments for each destination was defined based on the top priority measurements indicated by the Planetary Science Decadal Survey. Steep and shallow entry flight path angles (EFPA) were defined for each planet based on qualification and operational g-load limits for current, state-of-the-art instruments. Interplanetary trajectories were then identified that bounded the EFPA range.Next, 3-DoF simulations for entry trajectories were run using the entry state vectors from the interplanetary trajectories. Conical ribbon parachutes were sized based on heatshield separation dynamics. Aero-heating correlations were used to generate stagnation point convective and radiative heat flux profiles. High fidelity thermal response models for various TPS materials were used to size stagnation point thicknesses, with margins based on previous studies. Backshell TPS masses were assumed based on scaled heat fluxes from the heatshield and also from previous mission concepts.Based on these analyses, we have found that the common design is applicable for atmospheric probe missions for 4 out of the 5 destinations. Because of the unique gravity well for Jupiter, the entry environments are more severe resulting in heat loads an order of magnitude higher than for the other destinations.The next step is to determine what follow-on activities NASA should engage in. A questionnaire for the atmospheric probe community has been developed, with a focus on what size of aeroshell should be further analyzed (smaller or same diameter), and what incentives would make using such an aeroshell, if assembled and available, desirable to mission proposers.Preliminary results from this questionnaire will be presented.
Hwang, Helen H.↗
Outer planet mission analysis overview
Mission analysis work provides for off the Pioneer spacecraft probe flight schematics to Uranus, Saturn and Jupiter.
Swenson, B. L.↗
Entry into outer planet environments. II - Performance of volume reflecting hyperpure silica heat shields
The performance of hyperpure silica heat shields that backscatter incident radiation in the depths of the material, i.e., a volume reflecting heat shield, is mapped for probes entering the atmospheres of Saturn and Uranus. Three models of each atmosphere are considered; the warm, nominal, and cool models. The most recent thermophysical and optical properties of hyperpure silica are employed. Detailed incident radiative spectra and the effects of ablation on radiative and convective heating obtained from benchmark flowfield solutions are used. In-depth material response is examined and results are presented in terms of the peak rear-face temperature as a function of initial thickness for each atmosphere. Results are compared with carbon phenolic heat-shield requirements.
Howe, J. T.↗
NASA takes stock
The history of NASA activities and achievements in the past decade is reviewed with consideration given to the Apollo expeditions and the post-Apollo planetary exploration. Progress in spaceborne astronomy and in satellite communications is characterized as revolutionary. It is also noted that Landsat alone may eventually repay the United States for the cost of the entire space program. Special attention is given to the Shuttle program which will be the key to all operations in space for the next decade including the Galileo mission to Jupiter (1982) and the Space Telescope (1983). Future missions could include a Venus orbiter with imaging radar to finally penetrate the cloud cover of the planet and to map its surface; a rover or sample return expedition to Mars; a Saturn orbiter combined with a probe of its Titan satellite, and an examination of Halley's Comet. Finally the next decade should bring the data needed to make a 'go' or 'no go' decision on the concept of SPS that would beam solar energy into earth stations.
Frosch, R. A.↗
Impact of lunar and planetary missions on the space station
The impacts upon the growth space station of several advanced planetary missions and a populated lunar base are examined. Planetary missions examined include sample returns from Mars, the Comet Kopff, the main belt asteroid Ceres, a Mercury orbiter, and a saturn orbiter with multiple Titan probes. A manned lunar base build-up scenario is defined, encompassing preliminary lunar surveys, ten years of construction, and establishment of a permanent 18 person facility with the capability to produce oxygen propellant. The spacecraft mass departing from the space station, mission Delta V requirements, and scheduled departure date for each payload outbound from low Earth orbit are determined for both the planetary missions and for the lunar base build-up. Large aerobraked orbital transfer vehicles (OTV's) are used. Two 42 metric ton propellant capacity OTV's are required for each the the 68 lunar sorties of the base build-up scenario. The two most difficult planetary missions (Kopff and Ceres) also require two of these OTV's. An expendable lunar lander and ascent stage and a reusable lunar lander which uses lunar produced oxygen are sized to deliver 18 metric tons to the lunar surface. For the lunar base, the Space Station must hangar at least two non-pressurized OTV's, store 100 metric tons of cryogens, and support an average of 14 OTV launch, return, and refurbishment cycles per year. Planetary sample return missions require a dedicated quarantine module.
Source record↗
Saturn/Titan Rendezvous: A Solar-Sail Aerocapture Mission
A low-mass Titan orbiter is proposed that uses conservative or optimistic solar sails for all post-Earth-escape propulsion. After accelerating the probe onto a trans-Saturn trajectory, the sail is used parachute style for Saturn capture during a pass through Saturn's outer atmosphere. If the apoapsis of the Saturn-capture orbit is appropriate, the aerocapture maneuver can later be repeated at Titan so that the spacecraft becomes a satellite of Titan. An isodensity-atmosphere model is applied to screen aerocapture trajectories. Huygens/Cassini should greatly reduce uncertainties regarding the upper atmospheres of Saturn and Titan.
Matloff, Gregory L.↗