time – the titan mare...
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TiME – The Titan Mare Explorer Ellen Stofan
Proxemy Research P.O. Box 338
Rectortown VA 20140 540-364-0092
Ralph LorenzJHU Applied Physics
Laboratory 11100 Johns Hopkins Road
Laurel, MD 20723 443-778-2903
Jonathan LunineCRSR
Cornell University 402 Space Sciences Bldg.
Ithaca NY 14853 607-255-5911
Edward B. Bierhaus, Ben Clark
Lockheed Martin, PO Box 179 MS S8110,
Denver, CO 80201 [email protected]
Paul R. Mahaffy NASA Goddard Spaceflight
Center, Greenbelt, MD 20771
Mike Ravine Malin Space Science
Systems, San Diego CA 92191 [email protected]
Abstract—The Titan Mare Explorer (TiME) is a Discovery-class mission concept that underwent a detailed Phase A study in 2011-2012. The mission would splashdown a capsule on Titan’s ethane sea Ligeia Mare as early as the summer of 2023, and would spend multiple Titan days performing science measurements and transmitting data directly back to Earth. This paper reviews briefly the mission concept.
TABLE OF CONTENTS
1. INTRODUCTION ................................................. 1 2. SCIENCE OBJECTIVES AND PAYLOAD .............. 1 3. TARGET : LIGEIA MARE ................................... 2 4. MISSION CONCEPT ........................................... 3 5. SAILING ON TITAN ............................................ 5 6. SUMMARY ......................................................... 6 REFERENCES ......................................................... 6
1. INTRODUCTION
The Titan Mare Explorer (TiME) is a mission concept originally proposed to the Discovery Scout Mission Capability Enhancement (DSMCE) program in 2007, to explore the new mission possibilities that might be enabled by Advanced Stirling Radioisotope Generators (ASRGs). The concept was seen to have considerable appeal and was proposed successfully to the Discovery-2010 call, and underwent a detailed Phase A study between May 2011 and June 2012. This paper summarizes some results.
978-1-4673-1813-6/13/$31.00 ©2013 IEEE
Figure 1. Artist’s concept of the TiME capsule on the surface of a Titan sea.
2. SCIENCE OBJECTIVES AND PAYLOAD
Science Objectives
Titan’s hydrocarbon lakes and seas became a potential target of interest for future exploration as soon as they were observed by the Cassini Radar in 2007 [1]. After the Cassini mission to Saturn ends in 2017, many aspects of the lakes and seas of Titan will remain unknown, including their detailed composition, depths, physical properties, and shore characteristics. All of these are critical to understanding Titan’s active methane cycle. Titan’s lakes and seas are also an important astrobiological target, in that it cannot be ruled out that further chemistry beyond that observed in the atmosphere by Cassini may take place on the surface, yielding prebiotic molecules impossible to form in the gas phase. The only way to understand Titan’s methane cycle and climate, its lakes and seas, and these speculative possibilities of its prebiotic chemistry are through in-situ chemical analysis and observations at a sea surface.
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TiME science objectives are: 1) measure the sea chemistry to determine its role as a source and sink of methane and its chemical products, 2) measure the sea depth to help constrain organic inventory 3) constrain marine processes including sea circulation and the nature of the sea surface 4) determine sea surface meteorology 5) constrain prebiotic chemistry in the sea.
The science objectives of TiME are directly responsive to goals from the 2003 Solar System Decadal Survey, including understanding volatiles and organics in the solar system, through TiME measurements of organics on an-other planetary object, and understanding planetary processes, through TiME’s first in situ measurements of a hydrological cycle beyond Earth. It is also responsive to the 2011 Planetary Science Decadal Survey themes of ‘Planetary Habitats’ and ‘Workings of Solar Systems’. Both Decadal surveys have identified Titan as key to understanding habitability in our solar system.
Instrument Payload
The payload comprises three principal instruments: a Mass Spectrometer, a camera suite, and a Meteorology and Physical Properties Package.
The mass spectrometer, to be provided by Goddard Space Flight Center, would on several occasions throughout the mission, acquire samples of sea liquid and volatilize them for study in a quadrupole mass analyzer. Acquiring Titan materials for analysis is far simpler for a liquid surface than a solid surface. The ability to ingest liquid at ambient temperature and seal it for subsequent heating required an innovative thermal design. Extensive design and testing of the inlet system was performed in Phase A, and successful sampling of cryogenic liquids was performed [2]. In addition, the function of valve seats over multiple operations and with particulate-laden liquids was demonstrated. The mass range and sensitivity of the instrument would substantially exceed that of the (GSFC) Huygens mass spectrometer which operated on the surface of Titan in 2005, and would accurately characterize the organic composition of the sea as well as isotopic ratios and noble gases. The camera system from Malin Space Science Systems comprises two camera heads and a single electronics unit. A descent camera would image the atmosphere and surface during parachute descent, while a surface camera would be deployed on a small mast after splashdown (Figure 1). In addition to searching for shoreline features and observing clouds and atmospheric scattering, the surface camera would study the sea surface and near-surface. Night-time observations would be conducted with separately-commandable above- and below-waterline illumination. The Meteorology and Physical Properties Package (MP3) combines above- and below-the-waterline measurements with simple sensors managed by a common electronics box. Air temperature, pressure, wind speed and direction, and methane humidity would be recorded simultaneously with vehicle dynamics, liquid temperature, turbidity and gross composition (via dielectric
constant measurements). These contemporaneous measurements would allow exploration of the air-sea exchange processes on Titan, such as the wind speed associated with different wave heights, or the evaporative cooling of the sea surface. The turbidity and methane humidity measurements were implemented with novel fiber-coupled instrumentation, allowing the optoelectronic components to be retained inside the comfortably warm capsule interior. One other measurement system was a down-looking echo sounder, able to measure the depth of the sea as well as potentially detect layering or suspended sediments. Phase A development activities for MP3 included the demonstration of sonar transducer performance in cryogenic liquids.
In addition to the three instruments, scientific data would be obtained from engineering systems. The Inertial Measurement Unit (IMU) would measure the entry deceleration history and thus permit the recovery of the polar atmospheric density profile from ~1000km down to the mid-stratosphere. The IMU would also be a sensitive means of detecting waves on the sea surface.
Similarly, the radio link would permit propagation studies and measurement of capsule motion. Specifically, ranging and Doppler information (possibly supplemented by VLBI / D-DOR (Very Long Baseline Interferometry / Differential-One-way-Ranging) would be used to determine on the ground the location of the capsule, and thus its drift in response to winds and ocean currents.
3. TARGET : LIGEIA MARE
The target of the TiME mission is Ligeia Mare (Figure 2), the second-largest and best-mapped of Titan’s three seas.
It is important to draw a distinction between the three seas (Punga, Ligeia and Kraken, ‘PLK’) and the hundreds of smaller lakes that have been observed on Titan. The lakes may be somewhat seasonally-ephemeral and may have a more volatile methane-rich composition than the seas which are large, deep and persistent, and most probably have an ethane-rich composition (e.g., [3]).
The preponderance of seas in the northern hemisphere is thought to be the result of the astronomical configuration of Titan’s seasons in the current epoch [4], which has the result that the northern summer is less intense but longer in duration than that in the south. This results in a longer ‘rainy season’ in the north, such that methane and ethane accumulate there. This seasonal configuration lasts several tens of thousands of years, much like the Croll-Milankovich cycles that play a part in the Earth’s ice ages and the Martian polar layered terrain [4]. This picture of a drying south and accumulating north is consistent with the ria coastlines of PLK which suggest valleys being flooded by rising sea levels, and with the kidney-shaped outline, shallow (and possibly declining) depth of Ontario Lacus in the south.
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Figure 2. Ligeia Mare has a complex shoreline, as well as island archipelagos, whose morphology suggests the sea level has been rising [5]. A flooded valley network at lower left has a rectilinear configuration suggestive of tectonic control.
The energetics of the climate system are such that one or a few meters of liquid might migrate from south to north (or vice versa) during the seasonal cycle of 29.5 Earth years [1]. However, the scaling relationship between the horizontal extent of lakes on Earth and their depth (roughly 1m depth per km of extent, to within an order of magnitude) suggests that Ligeia should have a central depth of the order of 300-400 m, and thus it can be confidently expected to have essentially the same depth and extent in 2023 as it does today (and indeed, a recent Cassini observation of Ligeia in 2012 shows no measureable change in shoreline from when it was first observed in 2007 [6]). In addition, the radar return from the central region of Ligeia indicates a depth of at least 10 m (e.g., [7]).
Simulations [8] show that, if Titan had a rigid crust, the eccentricity of Titan’s 16-day orbit around Saturn would cause a tide in Ligeia with a range at the eastern and western arms of about 1m. For a 300m central depth, this would correspond to tidal currents reaching about 1cm/s. In fact, because the solid body (and liquid water interior) of Titan itself deforms in response to the changing tidal potential, the tidal range of the surface liquids, and thus the corresponding tidal currents, will be lower than this by a factor of a few (< 1 mm/s).
4. MISSION CONCEPT
Mission Architecture - Enabling Factors
Achieving a science mission in the outer solar system within the Discovery cost envelope required innovative design as well as tight science focus. It should be noted that the Discovery-2010 opportunity (with Step 1 proposals solicited in summer of 2010, and Phase A studies completed by summer 2012) was the first Discovery opportunity that permitted radioisotope power, with Advanced Radioisotope Stirling Generators (ASRGs) provided as Government Furnished Equipment (GFE) to proposers if they were technically ready, with a $20M ‘tax’ to cover ASRG-related costs. First, a long-duration mission on the surface of Titan requires radioisotope power. The Titan surface environment is an efficient heat sink at ~94K, and thus heat must be supplied to maintain thermal balance. (As a point of comparison, the Huygens probe, with a 5cm thick layer of foam insulation, cooled at a rate of about 350W after landing [9]. In principle, either thermoelectric or Stirling radioisotope sources could be used: both provide heat as well as electrical power, although a Stirling system with heat:power ratio (i.e. conversion efficiency) of ~20% is better matched to Titan surface needs than a thermoelectric system with 5%.
An enabling aspect of the mission within the Discovery cost envelope is the simple surface operations and the use of Direct-to-Earth (DTE) communication – TiME has no communications relay orbiter. The simple surface operations consist of a preset data acquisition cadence, interleaved with data downlink to Earth. DTE communication from Ligeia Mare at 80oN is easiest in northern summer: midsummer is in 2017, while the equinox is in 2024. In the nominal 2023 summer mission at Ligeia, the Earth and Sun climb about 20o above the horizon, and are visible with a healthy 10o elevation for more than a quarter of each Titan day.
Flight System
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A unique and innovative vehicle architecture evolved over the early (DSMCE and pre-proposal) development of the TiME concept, culminating in a single flight element, drastically reducing cost and complexity. During the cruise to Titan, the vehicle operates as a regular spacecraft, maintaining periodic communication with Earth and conducting maneuvers as needed to target the vehicle to its entry point. The vehicle enters Titan’s atmosphere directly from its interplanetary trajectory, without slowing to enter into Saturn orbit. Despite this hyperbolic arrival, the entry speed is actually very similar to that of (Saturnocentric) Huygens, since the arrival time can be chosen such that Titan, in its orbit around Saturn, is moving away from the capsule. Entry, Descent and Splashdown (EDS)
The capsule/heatshield shape allows the use of heritage hypersonic aerodynamic data. With an entry velocity and angle similar to those for Huygens, TiME’s entry into the Titan atmosphere is unchallenging aerothermodynamically and is well within the capabilities of several heritage thermal protection materials used on recent Mars missions [10].
A significant effort was devoted in the TiME Phase A study to defining a robust descent and surface wind model so that the footprint of splashdown locations could be determined with Monte-Carlo simulations. This model was formulated using four independent Global Circulation Models (GCMs) [11,12] was well as Huygens and ground-based data, and Cassini measurements over some seven years.
Expected splashdown speed is about 6 m/s. Splashdown dynamics were investigated with Hirano-Miura scaling [13], with more than 200 scale model tests into a water tank (Figure 3), and with a Computational Fluid Dynamics (CFD) code. These all confirm that splashdown parameters (taking the horizontal wind into account - see later) are comfortably within the envelope of safe conditions such that no righting mechanism is required (as had to be flown on Apollo [14]) and that the impact deceleration loads are well within the tolerance of the ASRG.
Figure 3. Splashdown! Scale model testing in water was documented with on-board accelerometers and data acquisition, as well as high-speed video.
Power and Thermal Control
The ~1kW of ‘waste’ heat from the two ASRGs is crucial in permitting a mission duration of more than a few hours in the ~94K Titan surface environment. Heat is lost to the environment above and below the ‘waterline’: convective heat transfer coefficients into the atmosphere at Titan conditions are of the order of 1 to a few W/m2/K [9], depending on windspeed, while the coefficient into the hydrocarbon sea is a factor of a few higher. Since these coefficients depend on environmental parameters, the key to a robust thermal design (as for Huygens) is to insulate the capsule. Thus the total series thermal resistance between the capsule interior and the environment is dominated by the engineered and thus known resistance due to the insulation.
On the surface, the principal electrical energy consumer is data downlink (a rule of thumb for energy needs of in-situ science vehicles was developed by Lorenz [15]: 1 bit of science data needs 1 J of energy to obtain and downlink, that relationship approximately holds here too). Although a variety of strategies is possible, a baseline mission plan featured 4-5 downlinks to the DSN in each Titan day. Each downlink would be ~8 hours long, separated by about one Earth day. The ASRG power would be supplemented during these downlink peak power demands by a battery which would be recharged in the intervals between downlinks.
Communication
DTE communication is effected on the sea surface, as is regularly implemented on ships and aircraft on Earth, by a mechanically-steered medium-gain antenna. Radio communication is at X-band, since Ka-band radio waves are significantly attenuated by Titan’s thick atmosphere. Doppler, ranging and VLBI/Delta-DOR information recovered from the radio link would also contribute to measurement of capsule motion and location determination.
Capsule Surface Motion
The capsule, like a floating vehicle on Earth, may move in response to waves. In addition to driving the performance of the antenna gimbal, such motion must also be taken into account in considering the camera resolution and exposure time.
In fact, waves have so far not been observed on Titan’s seas and lakes, although it is thought that this is perhaps because observations by Cassini so far have been during seasons where winds have been predicted to be lower than the wave-generation threshold.
A wave model, adapted to Titan gravity, atmospheric and liquid properties, was developed to evaluate the wave period and height as a function of distance (fetch) and windspeed.
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For an ethane-rich sea, the fully-developed Significant Wave Height (SWH or H1/3, in m) is ~0.2U2, where U is the windspeed in m/s [11, 12], referred to a standard ‘anemometer height’ of 10m. The SWH is a statistical measure, describing the average of the highest one-third of the waves (and is what a visual observer would typically report). For vehicle design, one must consider the probability distribution of waves, which is usually described by a Rayleigh function such that over an interval of N wave periods, the largest wave should be Hmax(N)~H1/3(0.5 ln[N])0.5. Thus if a constant wind of 1m/s (see below) blew, which corresponds to a wave periods of ~5s, the 96 day mission duration corresponds to ~2 million wave periods and hence Hmax(N)~2.7H1/3 and one can confidently expect waves no larger than ~0.55m.
To derive a higher-fidelity estimate of wave motion for the mission, the wind-SWH relationship and the wave height probability function, must in turn be convolved with the predicted probability distribution of wind speeds. These were estimated for the 2023 epoch at Ligeia Mare using several Global Circulation Models (GCMs, [11, 12]), the output of which can be conveniently parameterized by the Weibull distribution, i.e., the cumulative probability P(>U) of encountering a wind speed above U is P(>U)=exp(-[U/C]k. At this location and season, even the strongest GCM winds are enveloped by the Weibull function with C=0.5m/s and shape parameter k=2. The most probable wind speed is ~0.3m/s (below the lowest possible wave generation threshold) and winds are less than 0.7m/s for 99% of the time and never exceed 1m/s.
A floating vehicle has characteristic motions. These motions have natural periods (that are functions of the fluid density as well as well as gravity, the vehicle shape and mass properties). For typical vehicles at Titan, these periods are not very different from the wave periods that force these motions, and thus the highest angular rates of the vehicle (which in turn drive the antenna gimbal performance) are not necessarily associated with the largest (and thus longest period) waves.
To take this period-dependent response into account, a dynamical model must be used to simulate the capsule motion in response to the statistical wave field. Simulations were performed at APL using a commercial ocean vehicle dynamics tool Orcaflex, and higher-fidelity simulations were also performed by Lockheed Martin using a Computational Fluid Dynamics code.
Dynamical simulations of the TiME capsule to occasional waves confirmed the seakeeping characteristics of the vehicle and provided the requirements for the antenna gimbal.
The results of these simulations verified that DTE communication from Ligeia Mare is easily within typical mechanical capabilities.
5. “SAILING” ON TITAN
One of the most appealing aspects of the TiME mission is that it enjoys free mobility by virtue of its environment: it will sail. There is a wide literature on the motion of floating objects in terrestrial seas (a popular account is ‘Flotsametrics’ [16], which describes the rubber toys and Nike sneakers that have crossed oceans after being spilled from cargo ships). Quantitative models are used to predict the drift of icebergs in response to the combination of wind action on their tips and ocean currents on their submerged parts. A detailed investigation was made of the corresponding forces on the TiME capsule, taking the fluid and air density into account: additional empirical effects such as wave slap and Stokes drift were parameterized according to the state-of-the-art in iceberg and debris modeling. The result is that the TiME capsule drifts at approximately one-tenth of the ambient windspeed [17]. Higher-fidelity models could include the effects of tidal and wind-driven currents, but these effects are small.
Figures 4 and 5 show snapshots of a Monte-Carlo simulation of 1000 virtual TiME capsules, delivered according to the results of 6-Degree-of-Freedom entry and descent simulations, and subsequently drifting in response to the changing wind field modeled by a Global Circulation Model. In this season, the drift is predominantly westwards, although a substantial variation in wind direction occurs over one Titan day so the net drift rate over several days is less than the instantaneous translation speed.
Although the drift is only a few cm/second, its persistence results in observable migration over time. Over the surface mission, around half of the simulated capsules have travelled over some 200 km to the edge of Ligeia Mare. This may be compared with the mere 34 km attained over 9 years by the Opportunity rover on Mars.
Simulations were conducted to demonstrate that the capsule can beach safely in a wide range of conditions: the mission continues after landfall. Should the capsule remain fixed, meteorology and imaging observations can continue, and geodetic measurements of Titan’s rotational state can be performed with the radio link. On the other hand, changing wind conditions and the tidal cycle may mean the capsule can be refloated and the adventure would continue.
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Figure 4. For one candidate arrival time and delivery geometry, Monte-Carlo descent simulations showed 99% of splashdowns occurred within an ellipse that fits comfortably within Ligeia. (Different arrival or parachute details will give different results.)
Figure 5. A drift trajectory model moves each virtual capsule by a fraction (here 0.12) of the near-surface windspeed generated by a GCM.
6. SUMMARY
The Titan Mare Explorer (TiME) study demonstrated the feasibility of a focused outer solar system mission within the Discovery-13 envelope of $425M PI-administered cost. The TiME capsule, with ‘free’ roving provided by the wind, is an affordable way to return fundamental science from the surface of an extraterrestrial sea.
REFERENCES
[1] Stofan, E.R. et al., The Lakes of Titan, Nature, 441, 61-64, 2007
[2] Mahaffy, P. et al., Composition of a Cryogenic Sea Studied by the Titan Mare Explorer, Abstract, Titan through Time Conf., 2012
[3] Cordier, D., O. Mousis, J. I. Lunine, P. Lavvas, and V.
Vuitton, An estimate of the chemical composition of Titan’s lakes, Astrophys. J., 707, L128–L131, 2009
[4] Aharonson, O., Hayes, A., Lunine, J. I., Lorenz, R. D.,
Elachi, C., An asymmetric distribution of lakes on Titan as a possible consequence of orbital forcing, Nature Geoscience, 2, 851-854, 2009
[5] Stofan, E. R. et al., Shorelines of Ligeia Mare, Titan. Abstract, 43rd Lunar and Planetary Science Conference, Houston, TX, March 2012
[6] S.W. Wall et al., Have Titan’s north polar lakes changed? (abstract), 400.03, Division of Planetary Sciences Mtg., 2012
[7] Paillou, P., K. Mitchell, S. Wall, G. Ruffie, C. Wood, R. Lorenz, E. Stofan, J. Lunine, R. Lopes, and P. Encrenaz. Microwave dielectric constant of liquid hydrocarbons: Application to the depth estimation of Titan’s lakes, Geophys. Res. Lett., 35, L05202, 2008
[8] Lorenz, R. D. C. E. Newman, T. Tokano, J. Mitchell, B. Charnay, S. Lebonnois, R. Achterberg, Formulation of an Engineering Wind Specification for Titan Late Summer Polar Exploration, Planetary and Space Science, 70, 73-83, 2012
[9] Lorenz, R. D. A Simple Model for Radioisotope Power System performance in the Titan Environment, Journal of the British Interplanetary Society, 63, 9-14, 2010
[10] Dec, J.A. and Braun, R.D., An Approximate Ablative Thermal Protection System Sizing Tool for Entry System Design, AIAA Aerospace Sciences Conf., 2006
[11] Lorenz, R. D., C. Newman and J. I. Lunine, Threshold of wave generation on Titan’s lakes and seas: Effect of viscosity and implications for Cassini observations, Icarus, 207, 932-937, 2010
[12] Lorenz, R. D. and A. G. Hayes, The Growth of Wind-Waves in Titan's Hydrocarbon Seas, Icarus, 219, 468–475, 201
[13] Hirano, Y and K. Miura, Water Impact Accelerations of Axially-Symmetric Bodies, Journal of Spacecraft and Rockets, 7, 762-764, 1970
[14] Lorenz, R. D., Apollo Capsule Capsize Stability during
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Splashdown: Application of a Cavity Collapse Model, Journal of the British Interplanetary Society, 64, 289-295, 2011
[15] Lorenz, R.D. Post-Cassini Exploration of Titan:
Science Rationale and Mission Concepts, Journal of the British Interplanetary Society, 53, 218-234 (2000)
[16] Ebbesmayer, C. and E. Scigliano, Flotsametrics and the
Floating World: How One Man's Obsession with Runaway Sneakers and Rubber Ducks Revolutionized Ocean Science, New York, Harper Collins, 280 pp., 2009
[17] Lorenz, R. D., T. Tokano and C. E. Newman, Winds and Tides of Ligeia Mare: Application to the Drift of the Titan Mare Explorer (TiME) mission, Planetary and Space Science, 60, 72-85, 2012
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Biographies
Ellen R. Stofan is currently Vice President at Proxemy Research. She conducts research on the geology of Venus, Mars, Titan, and Earth, specializing in planetary volcanism and planetary surface processes. She is a co-investigator on the radar sounder on the Mars Express Mission, and an associate member of the Cassini Radar Team. From 1991 through 2000, Dr. Stofan worked at the Jet Propulsion Laboratory, serving as the chief scientist on NASA’s New Millennium Program, the deputy project scientist on the Magellan Mission to Venus, and the experiment scientist on the Spaceborne Imaging-C (SIR-C), an instrument that provided radar images of Earth on two shuttle flights in 1994. She has conducted extensive field studies at volcanoes in Hawaii, California, Sicily and Iceland. She received a Presidential Early Career Award in 1996, a NASA Exceptional Achievement Medal in 1995, a NASA Exceptional Service medal in 1993, and was profiled in the 1994 IMAX film, “The Discoverers.” Dr. Stofan is a co-author with astronaut Tom Jones on the National Geographic book “Planetology: Unlocking the Secrets of the Solar System.”
Ralph Lorenz is a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, with interests in atmospheres, surfaces and their interactions, especially on Titan and Mars. He worked for the European Space Agency on Phase B of
the development of the Huygens probe to Titan, and subsequently built part of the instrumentation of the probe’s Surface Science Package (SSP). Prior to joining APL in 2006, he spent 12 years in various positions at the Lunar and Planetary Laboratory at the University of Arizona, where he led observation planning for the Cassini RADAR investigation, and served on the science team of the New Millennium DS-2 mission to Mars. He is the author of several books, including ‘Spinning Flight’, ‘Titan Unveiled’, and ‘Space Systems Failures. ’He has a B.Eng in Aerospace Systems Engineering from the University of Southampton (UK) and a Ph.D. in Physics from the University of Kent at Canterbury (UK). He is the recipient of 5 NASA Group Achievement Awards.
Jonathan I. Lunine (NAS) is the director of the Center for Radiophysics and Space Research and David C. Duncan Professor in the Physical Sciences at Cornell. Dr. Lunine is interested in how planets form and evolve, what processes maintain and establish habitability, and what are the limits of environments capable of sustaining life.. He is an interdisciplinary scientist on the Cassini Saturn Orbiter, and Huygens Probe.. He is co-investigator on the Juno mission launched in 2011 to Jupiter, and an interdisciplinary scientist for the James Webb Space Telescope.. He is the winner of the Harold C. Urey Prize of the DPS/American Astronomical Society, the Macelwane Medal of the American Geophysical Union (AGU), the Zeldovich Prize in Commission B of COSPAR, and the Basic Science Award of the International Academy of Astronautics. He is a fellow of the AGU and American Association for the Advancement of Science. Dr. Lunine received a B.S. in physics and astronomy from the University of Rochester and an M.S. and a Ph.D. in planetary science from the California Institute of Technology.
Edward ‘Beau‘ Bierhaus is a Staff Research Scientist at Lockheed Martin Space Systems Company. He conducts research on the icy moons of the outer solar system, Mars, the Earth’s Moon, and small bodies. He has also been involved in over ten different mission development efforts, and is currently Co-Investigator in the OSIRIS-REx mission. Ben Clark conceived and developed the x-ray fluorescence spectrometers for the Viking landers. He currently is a co-investigator for the Cassini-Huygens mission, and participated in the Giotto, Stardust and Genesis missions. Dr. Clark introduced the concept of cometary particulates and formation of comet ponds as an enabling step for the abiotic origin of life. He has received the NASA Public Service Medal, the Wright Brothers Award, the Air Force
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Service Medal, and has been selected Inventor of the Year for Martin Marietta Corporation (now Lockheed Martin) and Author of the Year for Martin Marietta Astronautics. Dr. Clark has written more than 130 publications, reports, abstracts and presentations covering instrumentation, planetary missions, radiation, space science, planetary geochemistry, exobiology and other fields of research and development. Paul Mahaffy has over 25 years of experience at Goddard Space Flight Center in the study of planetary atmospheres and development of space-qualified instrumentation. He has developed mass spectrometers that have flown all over the solar system, from the SAM instrument on MSL to Galileo, CONTOUR, MAVEN and LADEE among others. He has a BS from Dordt College and a PhD from Iowa State University. He has served on numerous boards and panels such as Mars Surface Laboratory Science Definition Team, Mars Synthesis Science Definition Team, Mars Strategic Roadmap Federal Advisory Committee, and the NRC Decadal Study Mars Panel (2009–2010). Mike Ravine is the Advanced Project Manager at Malin Space Science systems. He received a BS from Caltech, an MSc from Brown University and a PhD from Scripps Institute of Oceanography. He has been involved with numerous projects, including cameras on the JUNO, MSL and Mars Surveyor missions.
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