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NASA NTRS2002

Following the water, the new program for Mars exploration

In the wake of the loss of Mars Climate Orbiter and Mars Polar Lander in late 1999, NASA embarked on a major review of the failures and subsequently restructured all aspects of what was then called the Mars Surveyor Program--now renamed the Mars Exploration Program. This paper presents the process and results of this reexamination and defines a new approach which we have called "Program System Engineering". Emphasis is given to the scientific, technological, and programmatic strategies that were used to shape the new Program. A scientific approach known as "follow the water" is described, as is an exploration strategy we have called "seek--in situ--sample". An overview of the mission queue from continuing Mars Global Surveyor through a possible Mars Sample Return Mission launch in 2011 is provided. In addition, key proposed international collaborations, especially those between NASA, CNES and ASI are outlined, as is an approach for a robust telecommunications infrastructure. c2002 Published by Elsevier Science Ltd.

Water↗

NASA NTRS2002

Mars sample return, updated to a groundbreaking approach

A Mars Sample Return (MSR) mission is a goal of the Mars Program. Recently, NASA and JPL have been studying the possibility of a Mars Sample Return some time in the next decade of Mars exploration. In 2001, JPL commissioned four industry teams to make a fresh examination of MSR architectures. Six papers on these studies were presented at last year's conference. As new fiscal realities of a cost-capped Mars Exploration Program unfolded, it was evident that these MSR concepts, which included mobility and subsurface sample acquisition, did not fit reasonably within a balanced program. Therefore, at the request of NASA and the science community, JPL asked the four industry teams plus JPL's Team X to explore ways to reduce the cost of a MSR. A NASA-created MSR Science Steering Group (SSG) established a reduced set of requirements for these new studies that built upon the previous year's work. As a result, a new 'Groundbreaking' approach to MSR was established that is well understood based on the studies and independent cost assessments by Aerospace Corporation and SAIC. The Groundbreaking approach appears to be what a contemporary, balanced Mars Exploration Program can afford, has turned out to be justifiable by the MSR Science Steering Group, and has been endorsed by the Mars science community at large. This paper gives a brief overview of the original 2001 study results and discusses the process leading to the new studies, the studies themselves, and the results.

Mars sample return↗

NASA NTRS2012

Autonomous Onboard Science Data Analysis for Comet Missions

Coming years will bring several comet rendezvous missions. The Rosetta spacecraft arrives at Comet 67P/Churyumov-Gerasimenko in 2014. Subsequent rendezvous might include a mission such as the proposed Comet Hopper with multiple surface landings, as well as Comet Nucleus Sample Return (CNSR) and Coma Rendezvous and Sample Return (CRSR). These encounters will begin to shed light on a population that, despite several previous flybys, remains mysterious and poorly understood. Scientists still have little direct knowledge of interactions between the nucleus and coma, their variation across different comets or their evolution over time. Activity may change on short timescales so it is challenging to characterize with scripted data acquisition. Here we investigate automatic onboard image analysis that could act faster than round-trip light time to capture unexpected outbursts and plume activity. We describe one edge-based method for detect comet nuclei and plumes, and test the approach on an existing catalog of comet images. Finally, we quantify benefits to specific measurement objectives by simulating a basic plume monitoring campaign.

comets↗

NASA NTRS1972

Multiple asteroid flyby opportunities in the 1970's and 1980's.

Trajectory characteristics are described for several representative multiple asteroid flyby (MAF) missions possible in the 1970's and early 1980's, many of which are constrained to include a flyby of Ceres, the largest asteroid. It is shown that flybys of three or four asteroids are possible with spacecraft having a delta-V capability of less than 1 km per sec. The major technical problems associated with MAF missions are due to the small size and poorly known orbits of aster oids. These factors make acquisition, guidance, and science measurements difficult, especially for the very small asteroids. Yet, MAF missions are expected to provide a significant increase in knowledge of basic properties of asteroids and to lay the groundwork for more sophisticated rendezvous and sample return missions.

Brooks, D. R.↗

NASA NTRS1979

Spacecraft attitude and articulation control systems for future planetary missions

Comparative evaluations of the major types of control systems, such as three-axis-active, spin-stabilized, dual spin, and momentum basis, are performed to determine their applicability for planetary missions in the early 1990s. The key requirements that determine control system selection are science functional, mission orbital, and vehicle configuration characteristics. Five functional groups are given for preliminary control system selection: (1) preliminary survey; (2) detailed remote observation; (3) close scrutiny - deep space; (4) close scrutiny - near sun; (5) sample return. Requirements affecting the selection of attitude/articulation control methods, comparison of the performance capabilities of competing control concepts, criteria for selecting competing methods, comparison of relative complexity, and identification of hardware needs and trends that may affect control system selection are considered.

Mcglinchey, L. F.↗

NASA NTRS1991

Crustal heterogeneity of the moon viewed from the Galileo SSI camera: Lunar sample calibrations and compositional implications

Summaries are given of the spectral calibration, compositional parameters, nearside color, and limb and farside color of the Moon. The farside of the Moon, a large area of lunar crust, is dominated by heavily cratered terrain and basin deposits that represent the products of the first half billion years of crustal evolution. Continuing analysis of the returned lunar samples suggest a magma ocean and/or serial magmatism model for evolution of the primordial lunar crust. However, testing either hypothesis requires compositional information about the crustal stratigraphy and lateral heterogeneity. Resolution of this important planetary science issue is dependent on additional data. New Galileo multispectral images indicate previously unknown local and regional compositional diversity of the farside crust. Future analysis will focus on individual features and a more detailed assessment of crustal stratigraphy and heterogeneity.

Pieters, Carle M.↗

DOE OSTI2014

Efficiencies and Optimization of Weak Base Anion Ion-Exchange Resin for Groundwater Hexavalent Chromium Removal at Hanford

The U.S. Department of Energy’s (DOE’s) contractor, CH2M HILL Plateau Remediation Company, has successfully converted a series of groundwater treatment facilities to use a new treatment resin that is delivering more than $3 million in annual cost savings and efficiency in treating groundwater contamination at the DOE Hanford Site in southeastern Washington State. During the production era, the nuclear reactors at the Hanford Site required a continuous supply of high-quality cooling water during operations. Cooling water consumption ranged from about 151,417 to 378,541 L/min (40,000 to 100,000 gal/min) per reactor, depending on specific operating conditions. Water from the Columbia River was filtered and treated chemically prior to use as cooling water, including the addition of sodium dichromate as a corrosion inhibitor. Hexavalent chromium was the primary component of the sodium dichromate and was introduced into the groundwater at the Hanford Site as a result of planned and unplanned discharges from the reactors starting in 1944. Groundwater contamination by hexavalent chromium and other contaminants related to nuclear reactor operations resulted in the need for groundwater remedial actions within the Hanford Site reactor areas. Beginning in 1995, groundwater treatment methods were evaluated, leading to the use of pump-and-treat facilities with ion exchange using Dowex™ 21K, a regenerable, strong-base anion exchange resin. This required regeneration of the resin, which was performed offsite. In 2008, DOE recognized that regulatory agreements would require significant expansion for the groundwater chromium treatment capacity. As a result, CH2M HILL performed testing at the Hanford Site in 2009 and 2010 to demonstrate resin performance in the specific groundwater chemistry at different waste sites. The testing demonstrated that a weak-base anion, single-use resin, specifically ResinTech SIR-700 ®, was effective at removing chromium, had a significantly higher capacity, could be disposed of efficiently onsite, and would eliminate the complexities and programmatic risks from sampling, packaging, transportation, and return of resin for regeneration.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS2017

New Developments in NASA's Rodent Research Hardware for Conducting Long Duration Biomedical and Basic Research in Space

Animal models, particularly rodents, are the foundation of pre-clinical research to understand human diseases and evaluate new therapeutics, and play a key role in advancing biomedical discoveries both on Earth and in space. The National Research Councils Decadal survey emphasized the importance of expanding NASA's life sciences research to perform long duration, rodent experiments on the International Space Station (ISS) to study effects of the space environment on the musculoskeletal and neurological systems of mice as model organisms of human health and disease, particularly in areas of muscle atrophy, bone loss, and fracture healing. To accomplish this objective, flight hardware, operations, and science capabilities were developed at NASA Ames Research Center (ARC) to enhance science return for both commercial (CASIS) and government-sponsored rodent research. The Rodent Research Project at NASA ARC has pioneered a new research capability on the International Space Station and has progressed toward translating research to the ISS utilizing commercial rockets, collaborating with academia and science industry, while training crewmembers to assist in performing research on orbit. The Rodent Research Habitat provides a living environment for animals on ISS according to standard animal welfare requirements, and daily health checks can be performed using the habitats camera system. Results from these studies contribute to the science community via both the primary investigation and banked samples that are shared in publicly available data repository such as GeneLab. Following each flight, through the Biospecimen Sharing Program (BSP), numerous tissues and thousands of samples will be harvested, and distributed from the Space Life and Physical Sciences (SLPS) to Principal Investigators (PIs) through the Ames Life Science Data Archive (ALSDA). Every completed mission sets a foundation to build and design greater complexity into future research and answer questions about common human diseases. Together, the hardware improvements (enrichment, telemetry sensors, cameras), new capabilities (live animal return), and experience that the Rodent Research team has gained working with principal investigator teams and ISS crew to conduct complex experiments on orbit are expanding capabilities for long duration rodent research on the ISS to achieve both basic science and biomedical research objectives.

Shirazi, Yasaman↗

NASA NTRSDate not supplied

NASA Institutional Scientific Collection and Biospecimen Sharing Program at Ames Research Center

For decades, NASA and their international partners have flown and conducted non-human biological experiments in space to understand the effects of spaceflight and address potential biological hazards. It is imperative to understand the basic science and health risks associated with spaceflight, along with developing countermeasures, as humanity ventures back to the Moon, and then to Mars and beyond. Sending organisms into space is a costly endeavor which makes space-flown biological specimens a valuable resource. To enable maximum scientific return, samples not required by the Principal Investigators are harvested, preserved and archived in NASA’s Institutional Scientific Collection (ISC) at Ames Research Center (ARC). These specimens are collected according to well-established SOPs that maintain their quality and integrity. To enable new discoveries, the samples are then made available to the international scientific community through NASA’s Biospecimen Sharing Program (BSP). The NASA ISC currently stores over 32,000 specimens from Shuttle, International Space Station and ground-based investigations. Tissues are predominantly from mice and rats, though samples are also available from bacteria and quail. The specimens include tissues from all biological systems including musculoskeletal, neurosensory, reproductive, respiratory, circulatory, and digestive and are stored at -80°C, -20°C, +4°C, or ambient. Descriptive metadata is available for all samples. Historically, these tissues have been used for a wide range of analyses, including histology, genomics, and transcriptomics. Also available through the ISC are tissue from NASA’s Space Radiation Laboratory. To study the effects of space radiation, researchers irradiate biological specimens and unused samples are made available through the LSDA. These biospecimens and data are made available through the public Life Sciences Data Archive (LSDA) website to promote basic discovery, pre-clinical and clinical science. Visit the NASA ISC-BSP website for more information. Websites: https://lsda.jsc.nasa.gov/ ; https://www.nasa.gov/ames/research/space-biosciences/isc-bsp

Space Flown Biospecimens↗

NASA NTRSDate not supplied

NASA Institutional Scientific Collection and Biospecimen Sharing Program at Ames Research Center

Space Flown Biospecimens↗

NASA NTRS2000

Lay and Expert Perceptions of Planetary Protection

As space scientists and engineers plan new missions to Mars and other planets in our solar system, they will face critical questions about the potential for biological contamination of planetary surfaces. In a society that places ever-increasing importance on the role of public involvement in science and technology policy, questions about risks of biological contamination will be examined and debated in the media, and will lead to the formation of public perceptions of planetary-contamination risks. These perceptions will, over time, form an important input to the development of space policy. Previous research in public and expert perceptions of technological risks and hazards has shown that many of the problems faced by risk-management organizations are the result of differing perceptions of risk (and risk management) between the general public and scientific and technical experts. These differences manifest themselves both as disagreements about the definition (and level) of risk associated with a scientific, technological or industrial enterprise, and as distrust about the ability of risk-management organizations (both public and private) to adequately protect people's health and safety. This report presents the results of a set of survey studies designed to reveal perceptions of planetary exploration and protection from a wide range of respondents, including both members of the general public and experts in the life sciences. The potential value of this research lies in what it reveals about perceptions of risk and benefit that could improve risk-management policies and practices. For example, efforts to communicate with the public about Mars sample return missions could benefit from an understanding of the specific concerns that nonscientists have about such a mission by suggesting areas of potential improvement in public education and information. Assessment of both public and expert perceptions of risk can also be used to provide an advanced signal of aspects of planetary exploration and protection that may be particularly sensitive or controversial and that could prove problematic from a risk-management standpoint, perhaps warranting a more stringent risk-management approach than would otherwise be the case based on technical considerations alone. The design of the study compares perceptions and attitudes about space exploration relevant to a Mars sample return mission between three respondent groups: (1) members of The Planetary Society, a group representing individuals with a strong interest in space-related issues, (2) a group of university-aged students, representing a population relatively sensitive to environmental hazards, and (3) a group of life scientists outside of the space research community. Members of The Planetary Society received the survey as part of a special issue of The Planetary Report on planetary protection, which contained a number of background articles on planetary protection and related topics. A synopsis of the issue was prepared as an introduction to the survey for the other two groups.

Race, Margaret S.↗

NASA NTRS2003

Planetary protection and the search for life beneath the surface of Mars

The search for traces of extinct and extant life on Mars will be extended to beneath the surface of the planet. Current data from Mars missions suggesting the presence of liquid water early in Mars' history and mathematical modeling of the fate of water on Mars imply that liquid water may exist deep beneath the surface of Mars. This leads to the hypothesis that life may exist deep beneath the Martian surface. One possible scenario to look for life on Mars involves a series of unmanned missions culminating with a manned mission drilling deep into the Martian subsurface (approximately 3Km), collecting samples, and conducting preliminary analyses to select samples for return to earth. This mission must address both forward and back contamination issues, and falls under planetary protection category V. Planetary protection issues to be addressed include provisions stating that the inevitable deposition of earth microbes by humans should be minimized and localized, and that earth microbes and organic material must not contaminate the Martian subsurface. This requires that the drilling equipment be sterilized prior to use. Further, the collection, containment and retrieval of the sample must be conducted such that the crew is protected and that any materials returning to earth are contained (i.e., physically and biologically isolated) and the chain of connection with Mars is broken. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

NASA Discipline Exobiology↗

NASA NTRS2011

Life Science on the International Space Station Using the Next Generation of Cargo Vehicles

With the retirement of the Space Shuttle and the transition of the International Space Station (ISS) from assembly to full laboratory capabilities, the opportunity to perform life science research in space has increased dramatically, while the operational considerations associated with transportation of the experiments has changed dramatically. US researchers have allocations on the European Automated Transfer Vehicle (ATV) and Japanese H-II Transfer Vehicle (HTV). In addition, the International Space Station (ISS) Cargo Resupply Services (CRS) contract will provide consumables and payloads to and from the ISS via the unmanned SpaceX (offers launch and return capabilities) and Orbital (offers only launch capabilities) resupply vehicles. Early requirements drove the capabilities of the vehicle providers; however, many other engineering considerations affect the actual design and operations plans. To better enable the use of the International Space Station as a National Laboratory, ground and on-orbit facility development can augment the vehicle capabilities to better support needs for cell biology, animal research, and conditioned sample return. NASA Life scientists with experience launching research on the space shuttle can find the trades between the capabilities of the many different vehicles to be confusing. In this presentation we will summarize vehicle and associated ground processing capabilities as well as key concepts of operations for different types of life sciences research being launched in the cargo vehicles. We will provide the latest status of vehicle capabilities and support hardware and facilities development being made to enable the broadest implementation of life sciences research on the ISS.

Robinson, J. A.↗

NASA NTRS2012

Investigations Using Laboratory Testbeds to Interpret Flight Instrument Datasets from Mars Robotic Missions

The Astromaterials Research and Exploration Science Directorate at the NASA Johnson Space Center (JSC) has laboratory instrumentation that mimic the capabilities of corresponding flight instruments to enable interpretation of datasets returned from Mars robotic missions. The lab instruments have been and continue to be applied to datasets for the Moessbauer Spectrometer (MB) on the Mars Exploration Rovers (MER), the Thermal & Evolved Gas Analyzer (TEGA) on the Mars Phoenix Scout, the CRISM instrument on the Mars Reconnaissance Orbiter Missions and will be applied to datasets for the Sample Analysis at Mars (SAM), Chemistry and Mineralogy (CheMin) and Chemistry & Camera (ChemCam) instruments onboard the Mars Science Laboratory (MSL). The laboratory instruments can analyze analog samples at costs that are substantially lower than engineering models of flight instruments, but their success to enable interpretation of flight data depends on how closely their capabilities mimic those of the flight instrument. The JSC lab MB instruments are equivalent to the MER instruments except without flight qualified components and no reference channel Co-57 source. Data from analog samples were critical for identification of Mg-Fe carbonate at Gusev crater. Fiber-optic VNIR spectrometers are used to obtain CRISM-like spectral data over the range 350-2500 nm, and data for Fephyllosilicates show irreversible behavior in the electronic transition region upon dessication. The MB and VNIR instruments can be operated within chambers where, for example, the absolute H2O concentration can be measured and controlled. Phoenix's TEGA consisted of a calorimeter coupled to a mass spectrometer (MS). The JSC laboratory testbed instrument consisted of a differential scanning calorimeter (DSC) coupled to a MS configured to operate under total pressure (12 mbar), heating rate (20 C/min), and purge gas composition (N2) analogous to the flight TEGA. TEGA detected CO2 release at both low (400-680 C) and high (725-820 C) temperature and an endothermic reaction in concert with the high temperature release. The high-temperature thermal decomposition is consistent with calcite, dolomite, or ankerite, (3-6 wt.%) or any combination of these phase based upon laboratory testbed experiments. Recent laboratory experiments suggest that the low temperature CO2 release was caused by a reaction between calcium carbonate and hydrated magnesium perchlorate; although, CO2 release by the oxidation of organic materials and Fe-/Mg-rich carbonates cannot be ruled out. MSL landed in Gale crater on August 5, 2012. Although numerous analog samples have been analyzed on the JSC laboratory testbeds, no SAM, CheMin, or ChemCam analyses have been acquired by MSL to date. The JSC SAM laboratory testbed consists of a thermal analyzer coupled with a MS configured to operate under total pressure (30 mbar), heating rate (35 C/min), and purge gas composition (He) analogous to the flight SAM. The CheMin and ChemCam laboratory testbeds were developed and built by inXitu, Inc. and Los Alamos National Laboratory, respectively, to acquire datasets relevant to the MSL CheMin and ChemCam flight instruments.

Ming, D. W.↗

NASA NTRS2018

Intra-EVA Space-to-Ground Interactions when Conducting Scientific Fieldwork Under Simulated Mars Mission Constraints

The Biologic Analog Science Associated with Lava Terrains (BASALT) project is a four-year program dedicated to iteratively designing, implementing, and evaluating concepts of operations (ConOps) and supporting capabilities to enable and enhance scientific exploration for future human Mars missions. The BASALT project has incorporated three field deployments during which real (non-simulated) biological and geochemical field science have been conducted at two high-fidelity Mars analog locations under simulated Mars mission conditions, including communication delays and data transmission limitations. BASALT's primary Science objective has been to extract basaltic samples for the purpose of investigating how microbial communities and habitability correlate with the physical and geochemical characteristics of chemically altered basalt environments. Field sites include the active East Rift Zone on the Big Island of Hawai'i, reminiscent of early Mars when basaltic volcanism and interaction with water were widespread, and the dormant eastern Snake River Plain in Idaho, similar to present-day Mars where basaltic volcanism is rare and most evidence for volcano-driven hydrothermal activity is relict. BASALT's primary Science Operations objective has been to investigate exploration ConOps and capabilities that facilitate scientific return during human-robotic exploration under Mars mission constraints. Each field deployment has consisted of ten extravehicular activities (EVAs) on the volcanic flows in which crews of two extravehicular and two intravehicular crewmembers conducted the field science while communicating across time delay and under bandwidth constraints with an Earth-based Mission Support Center (MSC) comprised of expert scientists and operators. Communication latencies of 5 and 15 min one-way light time and low (0.512 Mb/s uplink, 1.54 Mb/s downlink) and high (5.0 Mb/s uplink, 10.0 Mb/s downlink) bandwidth conditions were evaluated. EVA crewmembers communicated with the MSC via voice and text messaging. They also provided scientific instrument data, still imagery, video streams from chest-mounted cameras, GPS location tracking information. The MSC monitored and reviewed incoming data from the field across delay and provided recommendations for pre-sampling and sampling tasks based on their collective expertise. The scientists used dynamic priority ranking lists, referred to as dynamic leaderboards, to track and rank candidate samples relative to one another and against the science objectives for the current EVA and the overall mission. Updates to the dynamic leaderboards throughout the EVA were relayed regularly to the IV crewmembers. The use of these leaderboards enabled the crew to track the dynamic nature of the MSC recommendations and helped minimize crew idle time (defined as time spent waiting for input from Earth during which no other productive tasks are being performed). EVA timelines were strategically designed to enable continuous (delayed) feedback from an Earth-based Science Team while simultaneously minimizing crew idle time. Such timelines are operationally advantageous, reducing transport costs by eliminating the need for crews to return to the same locations on multiple EVAs while still providing opportunities for recommendations from science experts on Earth, and scientifically advantageous by minimizing the potential for cross-contamination across sites. This paper will highlight the space-to-ground interaction results from the three BASALT field deployments, including planned versus actual EVA timeline data, ground assimilation times (defined as the amount of time available to the MSC to provide input to the crew), and idle time. Furthermore, we describe how these results vary under the different communication latency and bandwidth conditions. Together, these data will provide a basis for guiding and prioritizing capability development for future human exploration missions.

Beaton, Kara H.↗

NASA NTRS1974

Options for Mars exploration

The many possible post-Viking 1975 Mars mission options are explored. These include small atmospheric probe/landers (adaptations of the Venus Pioneer to Mars), repeat Vikings with and without science changes, long-life orbiters to provide coverage of both hemispheres for a full Martian year, small rovers deployed from the Viking lander with ranges of up to 1 km from it, large autonomous rovers, Mars sample-return missions and, finally, missions to the satellites of Mars, including sample return. The examination includes energy requirements and time frames.

Pritchard, E. B.↗

NASA NTRS2009

The International Space Station Urine Monitoring System (UMS)

A device capable of making in-flight volume measurements of single void urine samples, the Urine Monitoring System (UMS), was developed and flown on seven U.S. Space Shuttle missions. This device provided volume data for each urine void from multiple crewmembers and allowed samples of each to be taken and returned to Earth for post-flight analysis. There were a number of design flaws in the original instrument including the presence of liquid carry-over producing invalid "actual" micturition volumes and cross-contamination between successive users from residual urine in "dead" spots". Additionally, high or low volume voids could not be accurately measured, the on-orbit calibration and nominal use sequence was time intensive, and the unit had to be returned and disassembled to retrieve the volume data. These problems have been resolved in a new version, the International Space Station (ISS) UMS, that has been designed to provide real-time in-flight volume data with accuracy and precision equivalent to measurements made on Earth and the ability to provide urine samples that are unadulterated by the device. Originally conceived to be interfaced with a U.S.-built Waste Collection System (WCS), the unit now has been modified to interface with the Russian-supplied Sanitary Hygiene Device (ASY). The ISS UMS provides significant advantages over the current method of collecting urine samples into Urine Collection Devices (UCDs), from which samples are removed and returned to Earth for analyses. A significant future advantage of the UMS is that it can provide an interface to analytical instrumentation that will allow real-time measurement of urine bioanalytes allowing monitoring of crewmember health status during flight and the ability to provide medical interventions based on the results of these measurements. Currently, the ISS UMS is scheduled to launch along with Node-3 on STS-130 (20A) in December 2009. UMS will be installed and scientific/functional verification completed prior to placing the instrument into operation. Samples collected during the verification sequence will be returned for analyses on STS-131 (19A) currently scheduled for launch in March 2010. The presence of a UMS on ISS will provide the capability to conduct additional collaborative human life science investigations among the ISS International Partners.

Feeback, Daniel L.↗

NASA NTRS2016

Developing Atmospheric Retrieval Methods for Direct Imaging Spectroscopy of Gas Giants in Reflected Light I: Methane Abundances and Basic Cloud Properties

Reflected light spectroscopy and photometry of cool, directly imaged extrasolar giant planets are expected to be performed in the next decade by space-based telescopes equipped with optical wavelength coronagraphs and integral field spectrographs, such as the Wide-Field Infrared Survey Telescope (WFIRST). We are developing a new atmospheric retrieval methodology to help assess the science return and inform the instrument design for such future missions, and ultimately interpret the resulting observations. Our retrieval technique employs an albedo model coupled with both a Markov chain Monte Carlo Ensemble Sampler (emcee) and a multimodal nested sampling algorithm (MultiNest) to map the posterior distribution. This combination makes the global evidence calculation more robust for any given model, and highlights possible discrepancies in the likelihood maps. Here we apply this methodology to simulated spectra of cool giant planets. As a proof-of-concept, our current atmospheric model contains 1 or 2 cloud layers, methane as a major absorber, and a H2-He background gas. This 6-to-9 parameter model is appropriate for Jupiter-like planets and can be easily expanded in the future. In addition to deriving the marginal likelihood distribution and confidence intervals for the model parameters, we perform model selection to determine the significance of methane and cloud detection as a function of expected signal-to-noise, in the presence of spectral noise correlations. After internal validation, the method is applied to realistic reflected-light spectra of Jupiter, Saturn, and HD 99492 c, a likely observing target. We find that the presence or absence of clouds and methane can be determined with high accuracy, while parameters uncertainties are model-dependent.

spectroscopy↗