P53A-0987
A Balloon-Borne Telescope System for Planetary Atmosphere and Plasma Studies
A telescope floating in the polar stratosphere can continuously monitor planets for more than 24 hours. Thin, clear and stable air of the stratosphere makes it possible to observe planets in a condition free from cloud with fine seeing and high atmospheric transmittance. Moreover, a balloon-borne telescope system is less expensive compared with a huge terrestrial telescope or a direct planetary probe mission. Targets of a balloon-borne telescope system will extend over various atmospheric and plasma phenomena on almost all the planets, i.e., a sodium tail of Mercury, lightning, airglow and aurora in the atmospheres of Venus, Jupiter and Saturn, escaping atmospheres of the Earth-type planets, satellite-induced luminous events in the Jovian atmosphere, etc. The first target is global dynamics of the Venusian atmosphere by detecting cloud motion in UV and NIR imagery. A decoupling mechanism and a pair of control moment gyros (CMGs) are mounted at the top of the gondola. The decoupling mechanism isolates the gondola from a balloon and also transfers an excess angular momentum of the CMGs to the balloon. The attitude of the gondola is stabilized at a constant sun azimuthal angle so that a solar cell panel faces to the sun. A 300 mm F30 Schmidt-Cassegrain telescope is installed at the bottom of the gondola. DC/DC converters, a PC, a high voltage power supply for a piezo-electrically moving mirror and digital video recorders are contained in a sealed cell. The azimuthal angle is detected by a sun-sensor. A PC processes sensor output to control DC motors used in the decoupling mechanism and CMGs with an accuracy in azimuthal attitude of about 0.5 deg. The two-axis gimbal mount of the telescope is controlled by the same PC, guiding an object within a field-of-view of a guide telescope. Residual tracking error is detected by a position sensitive photomultiplier tube and corrected by the two-axis moving mirror installed in the optical system. The optical path is divided into three paths with different colors: the first one with wavelengths less than 450 nm, the second one with 550-630 nm, and the last one more than 750 nm. The first and last paths are utilized for imagery of UV and NIR with bandpass filters and analog and digital CCD video cameras, respectively. The second path is for tracking error detection. The first experiment was scheduled in June, 2007 at Sanriku Balloon Center (SBC), Japan, but it was postponed until late August because of delay in final testing of the system. As of submission of this abstract the gondola has been ready for launch but has not yet been launched. The result of experiment will be presented.
P53A-0988 [WITHDRAWN]
NExT and EPOXI (DIXI), the next steps in Comet Exploration
The results of NASA's successful DS-1, Stardust, and Deep Impact explorations of comets Borrelly, Wild 2 and Tempel 1 are making cometary nuclei objects of novel geophysical interest. The unexpected diversity of surface morphology superposed on underlying similarities discovered on these underdense, icy objects suggest that the geophysical processes that operate there go far beyond those that have previously been discussed. Taking advantage of the viability of the Stardust and Deep Impact spacecraft already in heliocentric orbits, NASA will take as the next steps in this exploration by mounting the NExT and EPOXI (DIXI) missions. NExT will use the Stardust spacecraft to re- encounter Tempel 1, the target of the Deep Impact mission, and EPOXI (DIXI) will use the Deep Impact flyby spacecraft to encounter yet another periodic comet to broaden the scientific base for understanding the diversity of surface expressions discovered in the earlier missions. The NExT mission presents some unique challenges that need to be met if its full potential is to be realized. Its primary goal of elucidating the extent and nature of geological changes that occur as the comet ejects material during perihelion passage should be easily achieved. Its secondary goal of mapping the artificial crater and its debris field formed in the Deep Impact mission requires a precise rotational ephemeris for the comet nucleus. We outline research that quantifies the substantial acceleration of Tempel 1's nucleus spin that we have discovered to occur as it passes through perihelion and how we intend to model these changes. This work should ultimately provide a sufficiently accurate rotational ephemeris of the comet nucleus that will enable NExT to observe the Deep Impact crater with high probability.
P53A-0989
Rosetta Lander - Philae: Status after three swing-bys and about 4 years in space
Rosetta is a Cornerstone Mission of the previous Horizon 2000 ESA Programme. It is going to rendezvous with comet 67/P Churyumov-Gerasimenko after a 10 years cruise and to study both its nucleus and coma through an orbiting spacecraft and a landed platform. The latter, named Philae, after the island where the obelisk was found which helped together with the stone of Rosetta to decipher the Egyptian hieroglyphs, has been designed to land softly on the comet nucleus and is equipped with 10 scientific instruments to perform in-situ studies of the cometary material. Philae has been provided by an international consortium with participation of Germany (lead), France, Italy, UK, Finland, Ireland, Hungary and Austria. Rosetta has been successfully launched on March 2, 2004 from Kourou in French Guyana. Philae is operated by the Lander Control Centre (LCC) at DLR, Cologne and the Science Operations and Navigation Centre (SONC) at CNES, Toulouse via ESOC in Darmstadt. Since the launch, (besides commissioning and several checkouts), two planetary swingbys at the Earth (March 2005 and November 2007) and one at Mars (February 2007) have been performed, where the Lander has been operational. Rosetta will reach 67/P Churyumov-Gerasimenko in spring 2014 and start to investigate the comet with remote sensing instruments. Those data will allow the selection of a preferred landing site for Philae. The delivery of the Lander to the surface of the comet is foreseen in November 2014 at a distance of about 3 Astronomical Units (AU) to the sun. One particular challenge of the mission is the landing on currently completely unknown terrain. Little is known about the target comet. The paper will discuss recent results on the nature of comets (e.g. by Deep Impact or Stardust) and their implications on the Philae Lander mission.
P53A-0990
Preliminary Design of MIA (Mercury Ion Analyzer) for BepiColombo Mission
MIA (Mercury Ion Analyzer) has been developed for measurement of ions in the solar wind and in the Mercuryfs magnetosphere on board MMO (Mercury Magnetospheric Orbiter) spacecraft. One of the instrumental challenges is in the wide dynamic range of count rates required for measurement of both large ion fluxes in the solar wind and tenuous plasma in the magnetosphere. Another challenge is how to avoid increasing back-ground noise level of the MCP detector by the large solar UV flux near the sun. We have adopted a top-hat type of electrostatic analyzer and massive numerical calculation has been conducted for seeking the optimum design of the instrument. We are now summarizing the results of MIA development for the PDR (Preliminary Design Review) scheduled by the end of the year. We present the summary of the basic design of MIA in this fall meeting.
P53A-0991
Impact ionization mass spectrometer instrument development for cosmic dust particles
A new instrument is under development to analyze the chemical composition of dust particles in-situ. The CRIA (Cosmic dust Reflectron for Isotopic Analysis) instrument is a mass spectrometer that analyzes the ions generated upon the hypervelocity impact of cosmic dust particles on a solid surface. The large sensitive area of the instrument (40 cm in diameter) makes the instrument capable of measuring the composition of interstellar dust particles that have a low flux. The laboratory prototype of the instrument has been previously tested in laboratory conditions using laser ablation and the Heidelberg dust acceleration facility. The mass resolution of the instrument is approximately m/dm ~ 200. Here we report on the progress of the technical readiness level (TRL) of the instrument. The development is done as part of a graduate level course offered at the Aerospace Engineering department at the University of Colorado. In the class the students design and fabricate the instrument to specified requirement and perform the environmental tests for the applicable TRL level. The details of the class setup are discussed. This project is funded by the Laboratory of Atmospheric and Space Physics (LASP) and the Aerospace Engineering Department at the University of Colorado, Boulder. The instrument concept development was funded by NASA.
P53A-0992
Overview of the Waveform Capture in the Lunar Radar Sounder on board KAGUYA
The Lunar explorer gKAGUYAh (SELENE) spacecraft will be launched on September 13, 2007. The Lunar Radar Sounder (LRS) is one of the scientific instruments on board KAGUYA. It consists of three subsystems: the sounder observation (SDR), the natural plasma wave receiver (NPW), and the waveform capture (WFC). The WFC is a high-performance and multifunctional software receiver in which most functions are realized by the onboard software implemented in a digital signal processor (DSP). The WFC consists of a fast-sweep frequency analyzer (WFC-H) covering the frequency range from 1 kHz to 1 MHz and a waveform receiver (WFC-L) in the frequency range from 10 Hz to 100 kHz. The amount of raw data from the plasma wave instrument is huge because the scientific objectives require the covering of a wide frequency range with high time and frequency resolution; furthermore, a variety of operation modes are needed to meet these scientific objectives. In addition, new techniques such as digital filtering, automatic filter selection, and data compression are implemented for data processing of the WFC-L to extract the important data adequately under the severe restriction of total amount of telemetry data. Because of the flexibility of the instruments, various kinds of observation modes can be achieved, and we expect the WFC to generate many interesting data. By taking advantage of a moon orbiter, the WFC is expected to measure plasma waves and radio emissions that are generated around the moon and/or that originated from the sun and from the earth and other planets. One of the phenomena of most interest to be obtained from the WFC data is the dynamics of lunar wake as a result of solar wind-moon interaction. Another scientific topic in the field of lunar plasma physics concerns the minimagnetosphere caused by the magnetic anomaly of the moon. There are various kinds of other plasma waves to be observed from the moon such as Auroral Kilometric Radiation, electrostatic solitary wave, fp and 2fp emissions, and solar radio emissions. The first data from the WFC will be obtained in the beginning of November, 2007. In the presentation, we introduce an overview of the WFC onboard KAGUYA as well as the initial results obtained by the receiver.
P53A-0993
VEIL: A New Frontiers Class Mission Concept for Exploring Venus
Comparing the present states of the terrestrial planets can lead to new insights into the evolution of habitable regions in our own and other solar systems. As the terrestrial planet closest in size to Earth, Venus is a particularly interesting analogue when considering the future of our own world. Exploration of Venus, however, presents many challenges due to the extreme environments encountered in the atmosphere and on the surface. Here, we describe VEIL (Venus Exploration In-situ Landers), a design concept for an in-situ mission to Venus developed through NASA/JPL's Planetary Science Summer School (2007). The 2003 NASA New Frontiers Announcement of Opportunity and NASA's 2006 SSE Roadmap were used as guidelines for setting the science goals of the mission and developing the architecture. The science goals for the design presented here focus on surface-atmosphere interactions on Venus. The mission architecture includes two descent probes on a fly-by carrier spacecraft to study two characteristic regions on Venus: tesserae and lowlands. In each area, the probes' goals would be to characterize the composition of the lower atmosphere and the mineral composition of the surface, neither of which have been well quantified. Each probe would house five instruments: a GCMS to measure the composition of the atmosphere, a thermal-infrared imaging spectrometer to study the mineral composition of the surface, a Raman/LIBS spectrometer to characterize the mineral and elemental composition of the surface, visible imagers to characterize cloud and surface morphology, and a meteorology package to obtain temperature and pressure profiles of the atmosphere. The probes are optimized for rapid descent through the upper atmosphere in order to minimize time spent in the hazardous sulfuric acid haze layer, and maximize time spent in the lower atmosphere and on the ground. The probes would be expected to spend a total of an hour and forty-five minutes measuring the properties of the lower atmosphere and the surface. A mission of this type might be a necessary step in the development of a future flagship mission to Venus.
P53A-0994
VIR, the Visible-IR Mapping Spectrometer of Dawn
Dawn Mission, that will visit Vesta and Ceres, will be the first mission visiting the dwarf closer top the Earth, Ceres. Moreover, Dawn will visit Vesta, that is also a very special body, being one of the few asteroids of the main belt that are supposed undergo to a differentiation. Therefore Vesta is an important example of intermediated objects that possibly undergo to a pristine differentiation, might be due to the decay of short lived radioactive elements. Only in situ observation will be able to disentangle the real nature of Vesta and Ceres. Dawn mission is perfectly suited to do that, thanks to its payload, that will permit to study the geology ( thanks to FC, the cameras), the geochemistry ( thanks to the Grand, gamma spectrometer) and mineralogy (thanks to VIR- MS, the imaging spectrometer). Here we will describe the VIR-MS characteristics. VIR-MS is an imaging spectrometer coupling high spectra and spatial resolution in the Visible (0.25-1 micrometer) and IR (0.95-5 micrometers) ranges. We have developed a spectrometer able to cover both Visible and IR regions of the spectrum combining these two spectral ranges in one instrument because diagnostic minerals have absorption bands in the Visible and NIR regions. We will describe VIR and its expected performances in terms of understanding both Vesta and Ceres.
P53A-0995
Vesta Cratering: is it a Record of Primordial Bombardment?
The next-to-be-launched mission Dawn will provide the first, detailed images of Vesta surface and supply crucial informations to constrain its mineralogical and elemental composition through VIR, its imaging spectrometer. Thank to these data, we will be able to study in depth the crater record on the surface of Vesta and get an insight on its place in the context of Solar System history. Vesta is believed, basing on the Hubble observations and the relationship with HED meteorites whose dating is very old, to have underwent early to a substantial differentiation. If this should be the case, we would expect Vesta's surface to have been affected by the early bombardment following the displacement of bodies due to the final phases of Jupiter accretion. In the framework of our studies on the origin of Jupiter, we evaluated the accretion rate during the final phases of Jupiter formation and, through an N-Body code developed on purpose, we evaluated the flux of impactors on Vesta keeping track of their formation zones, which can bear information on their composition. We also evaluated the flux of impactors in the case Jupiter formed earlier than Vesta and underwent to a mild displacement, as hypothesized by the Nice model, and in the case the planet formed later but still radially migrated, to estimate the relative importance of the different processes. We will describe the different scenarios and their implications for the evolution of Solar System to provide a reference frame for future studies of Vesta's cratering history.
P53A-0996
In-Situ Geochronology using Resonance Ionization
We are developing a miniature laser ablation resonance ionization mass spectrometer for in-situ isotopic measurements on Mars and other solid bodies, with a focus on Rb-Sr geochronology. Using a lab instrument built from off-the-shelf components, we have achieved a precision that is within a factor of four of that required to support Rb-Sr geochronology (87Sr/86Sr to ±0.0002 required, ±0.0008 demonstrated). These results were obtained with fewer resonance lasers than anticipated (2 instead of 3) at power levels lower than expected (15 μJ blue & 2 mJ green versus 5 mJ blue & 5 mJ green). Ongoing laboratory work focuses on continuing to increase the precision and accuracy of the instrument, as well as automating the measurement process. New theoretical work on a multi-pass resonance ionization mirror system indicates that it may be possible to reduce power levels for the blue and green lasers even further, reducing their cost, power, and mass requirements. A miniature laser ablation system has been completed, and work is proceeding on a miniature mass spectrometer, both consistent with space flight mass, power, and volume requirements.
P53A-0997
Progress in Life Marker Chip Technology for Detection of Life on Mars
Detection of Life on Mars will rely on detection of biomarkers, physical or chemical structures that can be associated with Life. As a possible payload for the ESA ExoMars rover mission planned in 2013 and other future missions a Life Marker Chip instrument is being developed. This instrument uses immuno-assay techniques to detect the relevant biomarkers. This paper describes the typical targets it will search for, its operating principle and the status of development. 63 biomarker targets have been identified and assays have been developed for a limited subset. Assay development includes use of recombinant DNA techniques to generate the molecular receptors (antibodies). This type of instrument has applications in terrestrial research e.g. sub-glacial lakes as well as planetary exploration. Breadboard demonstrators have been built of the assay system and key components of the micro-fluidics. Results from these breadboards will be presented, along with plans for future development.
P53A-0998
CheMin: A Definitive Mineralogy Instrument on the Mars Science Laboratory (MSL '09) Rover
CheMin is a miniature X-ray diffraction / X-ray fluorescence (XRD/XRF) instrument that has been chosen for the analytical laboratory of MSL. CheMin utilizes a microfocus source cobalt X-ray tube, a transmission sample cell and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D X-ray diffraction patterns and X- ray fluorescence spectra from powdered or crushed samples. The X-ray source utilizes a conventional tungsten cathode and a reflection type cobalt anode. A focusing grid in the tube yields a 50 micron diameter photon source on the anode. The CCD detector is a 600X600 front illuminated frame transfer device having 40 micron square pixels and a deep depletion zone for high QE of 7 KeV X-rays (CoKa). Diffraction data are collected over the range 5-55 degrees 2-theta, with a resolution of 0.32 degrees 2-theta. During the mission, MSL's sample delivery system will provide up to 74 crushed and sieved samples to the CheMin instrument. Samples are delivered through a funnel to one of 26 reusable transmission sample cells on the CheMin sample wheel. Samples are loaded at the top, analyzed, then discarded in a sump by rotating the sample cell to the bottom of the wheel. Samples are analyzed for up to 10 hours during multiple sols. During analysis, sample cells are shaken at sonic frequencies by a piezoelectric actuator that causes convection and granular flow of the powdered material. The result is that all components of the sample are passed through CheMin's ~50 micron diameter beam in random orientations during the course of an analysis. In addition to the 26 reuseable sample cells, CheMin has 6 sealed cells containing XRF and XRD reference standards. These standards can be analyzed at any time to evaluate the health of the instrument or to generate calibrated XRD patterns. For each analysis, CheMin will produce energy-selected 2-D CoKa and CoKb patterns as well as a histogram of X-ray energy vs. number of photons. Diffraction data will be quantified using Rietveld refinement and Fluorescence data will be quantified using a fundamental parameters technique. Downlinked data from Mars will be validated in three ways: First, on-board standards will be used to calibrate unknowns and to control for non- optimal analysis conditions during the lifetime of the mission. Second, laboratory-based CheMin instruments will be used to analyze Mars analog materials. Third, a ray-tracing model has been developed that can simulate the CheMin geometry and corroborate diffraction results from specific sample mineralogies.
P53A-0999
Characterizing the Triboelectric Charging Effect on Sample Transfer for the 2009 Mars Science Laboratory Rover Mission
Understanding how small particles flow in the Martian environment is crucial for the success of the science payload on the 2009 Mars Science Laboratory rover. Triboelectric charges (charges associated with moving particles) result in an increase in particles charges causing them to stick to each other and components of the sample handling system. On Earth, these charges can be minimal due to the amount of water in the atmosphere. These conditions may be worse on Mars where there is virtually no moisture to dissipates electrical charging. We have designed an electrostatics experiment to characterize the amount of electrical charge that might be added on the particles of rocks from drilling and moving them through the sample handling system. Testing was conducted in a simulated Mars environment. Results have provided some groundwork-data regarding the electrical charging nature of processed rocks and minerals as they interact with the construction materials of the MSL sample handling system.
P53A-1000
Robotic Preparation Of Thin Sections For Planetary Applications
A petrographic thin section is a rock, mineral or soil sample, mounted on a glass slide and then ground to ap- proximately 30 μm in thickness and subsequently polished with a fine abrasive, often diamond grit. Thin sections are prepared in order to identify mineral types in a rock, to help to reveal the rock's&p origin and evolution. Current in situ instruments on planetary missions, such as various spectrometers are quite capable, but there is of-ten ambiguity as to the exact mineral composition of geological samples. For example, the composition of lunar mare regolith, the underlying basaltic rock, an impact breccia made from the local regolith, or an impact glass made from melted regolith may be quite similar by optical remote sensing, but the materials can all be distinguished using a petrographic thin section. Thin section preparation is an art and not science. The quality of thin section is assessed by a preparer based on his/hers experience. In order to make the robotic thin section device, the first step is to quantify parameters that control the quality of thin sections. These include the thickness and surface roughness. The next step is to develop a robotic device that could take a rock, cut it and grind it to the desired surface thickness and surface roughness. In the first year of this three year effort, the parameters that determine thin section quality have been determined. The test set up for the sawing of rock and grinding/polishing of thin sections is currently being designed. A study is also underway to determine the best method of supporting the thin section during the grinding and polishing stage.
P53A-1001
Detection of Novel Features and Collection of Opportunistic Science Data with an Onboard Autonomous Rover Science System
The Onboard Autonomous Science Investigation System (OASIS) evaluates science data gathered by a planetary rover. This analysis is used to prioritize the data for transmission, so that the data with the highest science value is transmitted to Earth. In addition, the onboard analysis results are used to identify science opportunities. A planning and scheduling component of the system enables the rover to take advantage of identified science opportunities. We present new system capabilities with an emphasis on the identification of novel geologic features during a traverse. The ability to detect novel features enables the rover to identify rocks that exhibit distinct properties from those in the vicinity, e.g. unusual albedo or orientation. This capability has been integrated into the full system and validated in field testing. In addition, the system has been integrated with the Visual Target Tracking (VTT) capability recently uploaded to the Mars Exploration Rovers. VTT enables the system to robustly track a specified target, typically a rock. By integrating this with the autonomous science system, the rover can approach targets identified onboard, and then acquire targeted measurements both from additional viewing angles as well as from positions in close proximity to the target.
P53A-1002
NASA's New Millennium ST8 Project
NASA's New Millennium Program (NMP) is formulating the Space Technology 8 (ST8) subsystem demonstration mission, which will qualify, on a single spacecraft provided by Orbital Sciences Corporation, four technologies: Thermal Loop, a miniature loop heat pipe system with multiple evaporators; SAILMAST, a gossamer mast; Ultraflex 175, an ultra-lightweight, deployable solar array; and Dependable Multiprocessor, a fault-tolerant COTS processor for onboard science computing. These technologies have been identified by NMP, with input from the space science community, as necessary to enable future NASA space science missions. Examples of previous enabling technologies demonstrated by NMP are the ion engines on Deep Space 1 and the Autonomous Sciencecraft Experiment demonstrated by ST6. The Thermal Loop, provided by NASA's Goddard Space Flight Center will demonstrate that a loop heat pipe with multiple evaporators and condensers can transport large heat loads over long distances without external pumping. It is expected that this technology will enable more precise temperature control decreasing the mass, power, and volume of small remote sensing and surface-based spacecraft. The SAILMAST experiment is a deployable gossamer mast technology, which will validate its load-carrying characteristics by correlating in-flight measurements with analytical predictions. It will enable a new class of missions, which employ solar sail propulsion technology. The Ultraflex 175 will demonstrate the next generation in ultra-lightweight fan-folded flexible solar arrays, providing ultra-high specific power (170-220 W/kg BOL), ultra-compact stowage volume (>33 W/m3), and high deployed stiffness. The result is less mass and volume needed for power generation on future spacecraft. The Dependable Multiprocessor will integrate commercial-off-the-shelf (COTS) processing components and fault-tolerant control algorithms to provide an adaptable, high-performance, on-board science processing platform. It is expected that this experiment will enable more capable, high performance, fault-tolerant, processing to handle, in a variety of planetary and deep space environments, the large science and autonomy data processing loads expected in the future. This work done at JPL under contract with NASA
P53A-1003
NASA's New Millennium ST-9 TRGS Mission
NASA's New Millennium Space Technology 9 (ST-9) Terrain-Relative Guidance System (TRGS) mission is the latest of a series of in-space technology validation activities that began in 1996 with Deep Space 1. TRGS will develop and validate new technology for: 1. Precision-guided landing and, and 2. Hazard detection (HD) and avoidance. Precision guidance is essential to reach landing sites of great scientific interest in rugged terrain and is also necessary for co-locating assets on the surface of other bodies. Hazard detection and avoidance enables landing at sites that will not pose a threat to mission success. The critical new technology enabling precision guidance and hazard avoidance is the use of machine vision methods for image acquisition and processing. It includes means for integrating the processed data with other onboard sensors to perform terrain relative navigation (TRN). The navigation data are input to a guidance subsystem that employs an appropriate flight control subsystem to implement precision guidance and hazard avoidance. The TRN/HD does not depend significantly on the target body and mission. This will benefit several high priority missions defined by the science community including those to the Moon, Mars, Europa, Titan, and Enceladus. ST-9TRGS is an integrated system validation project and part of New Millennium Program effort to identify the technological capabilities needed for future space science missions and the technology advances that require validation in deep space to help provide those capabilities. NASA selected TRGS from five candidate technology capabilities that had been under preliminary consideration. This work done at JPL under contract with NASA
P53A-1004
Electrodynamic-Tether Magnetosphere Interaction From Capture to Low Jovian Orbit of its Spacecraft
An orbiting conductive tether provides a dissipative mechanism in planets that have magnetic field and ionosphere/magnetosphere. The Jovian system is a particularly appropriate place for use of an electrodynamic tether because the magnetic field is intense, the stationary orbit is close to the planet, and moon Io provides a dense plasma torus farther away. The interaction of the tether with the magnetized plasma is analyzed under a variety of conditions, since the spacecraft is captured into an equatorial, highly elliptical orbit with perijove inside the stationary orbit, till the spacecraft reaches a low circular orbit around Jupiter, below the radiation belts. The radiation dose accumulated as the apojove distance is reduced through of sequence of perijove passes, is studied.
P53A-1005
Waves Radiated by an Electrodynamic Tether Over the Jovian Polar Caps
An electrodynamic bare tether could be an alternative source of power for jovian missions such as Juno, which is NASA´s latest proposed mission to Jupiter; Juno, which will be a polar orbiter, is planned to move away from previous use of radioisotope thermoelectric generators to use of solar arrays, required to be very large due to the great distance of Jupiter from the Sun. The radiation impedance for a tether under polar cap conditions, as different from conditions for a Low Earth Orbit [1-2], and conditions for the "tether-like" Io interaction, is determined. For tether parameters appropriate for power generation in a Juno-type mission, total power radiated is calculated. Both the frequence and angular spectra of the radiation is also discussed. References [1] J. R. Sanmartin and M. Martinez-Sanchez, J. Geophysical Research 100, 1677 (1995). [2] J. R. Sanmartin and R. D. Estes, J. Geophysical Research 102, 14625 (1997).
P53A-1006
Results of the Enceladus Flagship Study
With the remarkable Cassini discovery of active water ice plumes emanating from the south pole of Enceladus, this tiny moon has become an exciting possible target for a future Flagship mission. A NASA HQ-directed study was performed by the Goddard Space Flight Center, with science input from a Science Definition Team drawn from the broad scientific community. It was recognized that a Flagship mission to Enceladus must have a significant science return over that which will be achieved by Cassini. Thus, the main science goals are to investigate Enceladus' biological potential, composition, cryovolcanism, tectonics, tidal heating and interior structure. In addition, we wish to understand the Saturn system interaction with Enceladus and other processes that alter the surface. From these science goals, the SDT generated a traceability to measurement objectives, the mission requirements and the broad science mission configuration trade space. In addition engineering work was performed, including trajectory analysis, mission implementation trades and feasibility design studies of three mission concepts: An Enceladus orbiter with soft lander, a single Enceladus orbiter and a Saturn orbiter with soft lander. Both chemical and solar electric propulsion were considered, along with a variety of interplanetary trajectories. In the Saturn system, the use of aeroassist, and gravity assists by Titan, Rhea and Dione flybys were investigated. Other configuration options explored, but not designed in detail, included sample return, dual launch vehicle scenarios and single flybys
P53A-1007
Titan Explorer: A Future NASA Flagship Mission
The Cassini-Huygens mission has provided startling new results at Titan - lakes, dunes, organic aerosol formation in the ionosphere, cryovolcanoes - just to name a view. The science is rich and compelling, but as is usually the case more new questions are raised than old ones answered. We propose a new NASA Flagship class mission, which will explore the Earth-like Organic-rich World of Titan. TITAN EXPLORER is configured as a three element mission: an orbiter, a lander, and a balloon designed to provide a multi-scale study of the intimately coupled interior-surface-atmosphere-magnetosphere system with special emphasis on the production and fate of organics. The full mission complement has 25 instruments ranging from radar altimeters to a surface chemical analysis package. TITAN EXPLORER will orbit Titan for 4 years, returning orders of magnitude more data than Cassini, whose flybys add up to only 4 days. The operations of the balloon and lander are planned to provide data for the first year of the mission. The multi-element nature of the mission presents many options for foreign teaming and cost containment : even an orbiter-only floor mission offers a striking scientific return. The results of the funded NASA study conducted by APL, JPL, Langley, and with science support from SwRI and other institutions are presented in this poster and include the scientific objectives, proposed payload, spacecraft elements and mission design.