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NASA NTRS2005

Solar System Observations with Spitzer Space Telescope: Preliminary Results

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 microns, and the detection of emission bands in the spectra of several distant asteroids (Trojans) around 10 and 25 microns. The 10 Kuiper Belt objects observed to date have albedos in the range 0.08 - 0.15, significantly higher than the earlier estimated 0.04. An additional KBO [(55565) 2002 AW(sub l97)] has an albedo of 0.17 plus or minus 0.03. The emission bands in the asteroid spectra are indicative of silicates, but specific minerals have not yet been identified. The Centaur/comet 29P/Schwassmann-Wachmann 1 has a nucleus surface albedo of 0.025 plus or minus 0.01, and its dust production rate was calculated from the properties of the coma. Several other investigations are in progress as the incoming data are processed and analyzed.

Cruikshank, Dale P.↗
NASA NTRS2010

Comparison of the Mineralogy of Comet Wild 2 Coma Grains to Other Astromaterials

We propose that Kuiper Belt samples (in this case comet coma grains from the Jupiter family comet Wild 2) are recognizably different from the bulk of materials in outer belt asteroids, because of their different formation positions and times in the early solar system. We believe this despite similarities found between some Wild 2 grains and components of carbonaceous chondrites (i.e. some CAI and chondrules). Kuiper Belt samples must preserve measurable mineralogical and compositional evidence of formation at unique positions and times in the early solar nebula, and these formational differences must have imparted recognizable special characteristics. We hypothesize that these characteristics include: (1) Unique major element compositional ranges of common astromaterial minerals, especially olivine and pyroxene; (2) Unique minor element compositions of major silicate phases, especially olivine and low-Ca pyroxene; (3) Degree and effects of radiation processing -- including amorphous rims, metal coatings, and Glass with Embedded Metal and Sulfides (GEMS); (4) Presence of abundant presolar silicate grains as recognized by anomalous oxygen in silicates; (5) Oxidation state of the mineral assemblage. We are working our way through all available Wild 2 samples, selecting 1-2 non-consecutive viable TEM grids from each possible extracted Wild 2 grain. We especially prefer TEM grids from grains for which complete mineralogical details have not been published (which is to say the majority of the extracted grains). We are performing a basic mineralogic survey by E-beam techniques, to establish the essential features of the extracted Wild 2 grains. We are making a particular effort to carefully and accurately measure minor elements of olivine and pyroxene, as these minerals are widespread in astromaterials, and comparisons of their compositions will serve to place the Wild 2 silicates in contact with asteroids, meteorites and chondritic interplanetary dust particles processing. We are also making a special effort to search for mineralogical products of aqueous alteration, since their presence would reveal that Wild 2 was once internally heated, a result with dramatic implications for models of early solar system primitive bodies. Thus far carbonates are the only potential evidence for aqueous alteration for Wild 2.

Frank, David↗
NASA NTRS2011

Spitzer Evidence for a Late Heavy Bombardment and the Formation of Urelites in {eta}Corvi at Approximately 1 Gyr

We have analyzed Spitzer and NASA/IRTF 2 - 35 micrometer spectra of the warm, ~350 K circumstellar dust around the nearby MS star eta Corvi (F2V, 1.4 plus or minus 0.3 Gyr). The spectra show clear evidence for warm, water- and carbon-rich dust at ~3 AU from the central star, in the system's Terrestrial Habitability Zone. Spectral features due to ultra-primitive cometary material were found, in addition to features due to impact produced silica and high temperature carbonaceous phases. At least 9 x 10(exp 18) kg of 0.1 - 100 micrometer warm dust is present in a collisional equilibrium distribution with dn/da ~ a(exp -3.5), the equivalent of a 130 km radius KBO of 1.0 grams per cubic centimeter density and similar to recent estimates of the mass delivered to the Earth at 0.6 - 0.8 Gyr during the Late Heavy Bombardment. We conclude that the parent body was a Kuiper-Belt body or bodies which captured a large amount of early primitive material in the first Myrs of the system's lifetime and preserved it in deep freeze at approximately 150 AU. At approximately 1.4 Gyr they were prompted by dynamical stirring of their parent Kuiper Belt into spiraling into the inner system, eventually colliding at 5-10 kilometers per second with a rocky planetary body of mass less than or equal to M(sub Earth at approximately 3 AU, delivering large amounts of water (greater than 0.1 % of M(sub Earth's Oceans)) and carbon-rich material. The Spitzer spectrum also closely matches spectra reported for the Ureilite meteorites of the Sudan Almahata Sitta fall in 2008, suggesting that one of the Ureilite parent bodies was a KBO.

Lisse, C. M.↗
NASA NTRS2021

Neptune Odyssey: A Flagship Concept for the Exploration of the Neptune–Triton System

The Neptune Odyssey mission concept is a Flagship-class orbiter and atmospheric probe to the Neptune–Triton system. This bold mission of exploration would orbit an ice-giant planet to study the planet, its rings, small satellites, space environment, and the planet-sized moon Triton. Triton is a captured dwarf planet from the Kuiper Belt, twin of Pluto, and likely ocean world. Odyssey addresses Neptune system-level science, with equal priorities placed on Neptune, its rings, moons, space environment, and Triton. Between Uranus and Neptune, the latter is unique in providing simultaneous access to both an ice giant and a Kuiper Belt dwarf planet. The spacecraft—in a class equivalent to the NASA/ESA/ASI Cassini spacecraft—would launch by 2031 on a Space Launch System or equivalent launch vehicle and utilize a Jupiter gravity assist for a 12 yr cruise to Neptune and a 4 yr prime orbital mission; alternatively a launch after 2031 would have a 16 yr direct-to-Neptune cruise phase. Our solution provides annual launch opportunities and allows for an easy upgrade to the shorter (12 yr) cruise. Odyssey would orbit Neptune retrograde (prograde with respect to Triton), using the moonʼs gravity to shape the orbital tour and allow coverage of Triton, Neptune, and the space environment. The atmospheric entry probe would descend in ∼37 minutes to the 10 bar pressure level in Neptune’s atmosphere just before Odysseyʼs orbit-insertion engine burn. Odysseyʼs mission would end by conducting a Cassini-like “Grand Finale,” passing inside the rings and ultimately taking a final great plunge into Neptuneʼs atmosphere.

Abigail M. Rymer↗
NASA NTRS2002

Organic Solid Matter as a Coloring Agent in Outer Solar System Bodies

Small bodies in the outer Solar System OSS, exhibit a range of color, or slope of the reflectance in the photovisual spectral region, ranging from neutral to very red, sometimes with and sometimes without distinct absorption bands. These objects range in geometric albedo from 0.03 to 1.0, with the higher albedo objects typically showing clear evidence of water ice. Water ice has also been found in a few objects with albedo 0. 1 or less. We explore here the identification of the material or materials that color these icy and non-icy surfaces through scattering models that incorporate minerals, meteoritic material, and organic solids (tholins) produced ID the laboratory by energy deposition in ices and gases. These models must match not only the color in the photovisual region, but the spectral reflectance properties throughout the near-infrared. Among some classes of objects, such as Kuiper Belt objects, the coloring agent may be a single material that is present in greater or lesser abundance, thus accounting for the range in color from neutral to very red. This may also apply to the Centaur objects, the Jovian Trojans, and the outer-main belt asteroids, each taken as a separate class. If so, each class may be colored to varying degrees by a different material, or they all might be colored by a common material that is widespread throughout the OSS, from 3 to 50 AU, and beyond. In this paper, we model the reflectances of "Kuiper Belt objects, Centaurs, Trojans, outer ARAB asteroids, and planetary satellites. Our models show that the reddest surfaces cannot be colored by minerals or meteoritic materials, but can be matched throughout the photovisual and near-infrared by organic solids, specifically certain tholins.

Cruikshank, D. P.↗
NASA NTRS2022

29P/Schwassmann–Wachmann 1: A Rosetta Stone for Amorphous Water Ice and CO↔CO 2 Conversion in Centaurs and Comets?

Centaur 29P/Schwassmann–Wachmann 1 (SW1) is a highly active object orbiting in the transitional "Gateway" region between the Centaur and Jupiter-family comet (JFC) regions. SW1 is unique among the Centaurs in that it experiences quasi-regular major outbursts and produces CO emission continuously; however, the source of the CO is unclear. We argue that, due to its very large size (∼32 km radius), SW1 is likely still responding, via amorphous water ice (AWI) conversion to crystalline water ice (CWI), to the "sudden" change in its external thermal environment produced by its Myrs-long dynamical migration from the Kuiper Belt to its current location at the inner edge of the Centaur region. It is this conversion process that is the source of the abundant CO and dust released from the object during its quiescent and outburst phases. If correct, these arguments have a number of important predictions testable via remote sensing and in situ spacecraft characterization, including the quick release on Myr timescales of CO from AWI conversion for any few kilometer-scale scattered disk Kuiper Belt Objects transiting into the inner system; that to date SW1 has only converted between 50% and 65% of its nuclear AWI to CWI; that volume changes on AWI conversion could have caused subsidence and cave-ins, but not significant mass wasting or crater loss; that SW1's coma should contain abundant amounts of CWI+CO 2 "dust" particles; and that when SW1 transits into the inner system within the next 10,000 yr, it will be a very different kind of JFC.

Centaur 29P/Schwassmann–Wachmann 1(SW1)↗
NASA NTRS1995

To Boldly Go: America's Next Era in Space. Probing the Primordial Constituents of Our Solar System

Dr. France Cordova, NASA's Chief Scientist, chaired this, another seminar in the Administrator's Seminar Series. She introduced NASA Administrator, Daniel S. Goldin, who greeted the attendees, and noted that, from the day people first looked into the sky, they've wondered what was up there, who or what created it, is Earth unique, what shaped the solar system, what is the Kuiper Belt and why is it there, and what are the solar system's building blocks. NASA's missions may discover some of the answers. Dr. Cordova then introduced Dr. Anita Cochran, research scientist at the University of Texas. Dr. Cochran has been searching for some of this information. She is especially interested in finding out when various planets and asteroids were discovered, what their orbits are, when the solar system was formed, and more about the comets in the Kuiper Belt. Are they icy planetisimals that helped form our solar system? Dr. Toby Owen of the University of Hawaii faculty spoke next. He believes that life on Earth exists because comets brought water and a variety of light elements to Earth from the outer parts of the solar system. Without them, we couldn't exist. He noted that noble gases don't mix with other gases. Gases come to Earth via rocks and by bombardment. Ice can trap argon and carbon, but not neon. Dr. Owens concluded with comments that we need 'better numbers for the Martian atmosphere', and it would be good to get samples of material from a comet. The third speaker was Dr. Eugene Shoemaker of the Lowell Observatory and the U.S. Geological Survey. He is credited with discovering more than 800 asteroids and learning about the Oort Cloud, which is believed to be a cloud of rocks and dust that may surround our solar system and be where comets originate. Comet storms reoccur about every 30 million years. Dr. Shoemaker suggested that since we are presently in a period of comet showers, it would be good to get a comet sample. It might provide insight regarding the origin of life. Additional information is included in the original extended abstract.

Source record↗
NASA NTRS2006

Volume Ice Radiolysis in the Outer Solar System

The primary energy flux of charged particle components of the heliospheric and magnetospheric environments of the solar system is primarily carried by highly penetrating energetic particles. Although laboratory experiments on production of organics and oxidants typically only address effects on very thin surface layers, energy deposition occurs on surfaces of icy bodies of the outer solar system to meters in depth. Time scales for significant radiolytic deposition vary from thousands of years at millimeter depths on Europa to billions of years in the meters-deep regolith of Kuiper Belt Objects. Radioisotope decay (e.g., K-40) also contributes to volume radiolysis as the only energy source at much greater depths. Radiolytic oxygen is a potential resource for life within Europa and a partial source of oxygen for Saturn's magnetosphere and Titan's upper atmosphere. Interactions of very high energy cosmic rays with ices at Titan's surface may provide one of the few sources of oxidants in that highly reducing environment. The red colors of low-inclination classical Kuiper Belt Objects at 40-50 AU, and Centaur objects originating from this same population, may arise from volume radiolysis of deep ice layers below more refractory radiation crusts eroded away by surface sputtering and micrometeoroid impacts. A variety of techniques are potentially available to measure volume radiolysis products and have been proposed for study as part of the new Space Physics of Life initiative at NASA Goddard Space Flight Center. The technique of Electron Paramagnetic Resonance (EPR) has been used in medical studies to measure oxidant production in irradiated human tissue for cancer treatment. Other potential techniques include optical absorption spectroscopy and standard wet chemical analysis. These and other potential techniques are briefly reviewed for applicability to problems in solar system ice radiolysis and astrobiology.

Cooper, John F.↗
NASA NTRS2024

StarNAV: An Architecture for Autonomous Spacecraft Navigation by the Relativistic Perturbation of Starlight

Exploration missions to the outer Solar System (e.g., Neptune, Kuiper belt objects) or to the interstellar medium present several challenges for conventional spacecraft designs. One of the greatest challenges is a means for navigation, as Earth-based tracking with the Deep Space Network (DSN) becomes less desirable due to high cost, decreased performance at long ranges, and long light-time delays. Indeed, light time delays at Neptune are over four hours (one way), making control of spacecraft during critical events nearly impossible—and this problem only becomes worse as we move to the Kuiper belt or to interstellar space. The need for autonomous spacecraft navigation is well established and is prominently featured in the 2015 NASA Technology Roadmap (e.g., TA 5.4.2.6 & 5.4.2.8). This has led to investment in various technologies to accomplish this task, with the majority of recent work focusing on optical navigation (OPNAV; TA 5.4.4.1) [1], X-ray pulsar navigation (XNAV; TA 5.6.1) [2], or DSN one-way ranging with the Deep Space Atomic Clock (DSAC; TA 5.4.1.1) [3]. This NIAC study suggests a new (and completely different) way of autonomously navigating a spacecraft anywhere in the Solar System or beyond. We call this new technique StarNAV.

NIAC Phase I↗
NASA NTRS1996

Studies of extra-solar Oort clouds and the Kuiper disk

We are conducting research designed to enhance our understanding of the evolution and detectability of comet clouds and disks. According to 'standard' theory, both the Kuiper Belt and the Oort Cloud are (at least in part) natural products of the planetary accumulation stage of solar system formation. One expects such assemblages to be a common attribute of other solar systems. Therefore, searches for comet disks and clouds orbiting other stars offer a new method for inferring the presence of planetary systems. This project consists of two efforts: (1) observational work to predict and search for the signatures of Oort Clouds and comet disks around other stars; and (2) modelling studies of the formation and evolution of the Kuiper Belt (KB) and similar assemblages that may reside around other stars, including beta Pic.

Stern, S. Alan↗
NASA NTRS2013

DUst around NEarby Stars. The Survey Observational Results

Context. Debris discs are a consequence of the planet formation process and constitute the fingerprints of planetesimal systems. Their solar system counterparts are the asteroid and Edgeworth-Kuiper belts.Aims. The DUNES survey aims at detecting extra-solar analogues to the Edgeworth-Kuiper belt around solar-type stars, putting in this way the solar system into context. The survey allows us to address some questions related to the prevalence and properties of planetesimal systems.Methods. We used Herschel PACS to observe a sample of nearby FGK stars. Data at 100 and 160 micron were obtained, complemented in some cases with observations at 70 micron, and at 250, 350 and 500 micron using SPIRE. The observing strategy was to integrate as deep as possible at 100 micron to detect the stellar photosphere. Results. Debris discs have been detected at a fractional luminosity level down to several times that of the Edgeworth-Kuiper belt. The incidence rate of discs around the DUNES stars is increased from a rate of approx. 12.1% +/- 5% before Herschel to approx 20.2 % +/- % 2. A significant fraction (approx. 52%) of the discs are resolved, which represents an enormous step ahead from the previously known resolved discs. Some stars are associated with faint far-IR excesses attributed to a new class of cold discs. Although it cannot be excluded that these excesses are produced by coincidental alignment of background galaxies, statistical arguments suggest that at least some of them are true debris discs. Some discs display peculiar SEDs with spectral indexes in the 70-160 micron range steeper than the Rayleigh-Jeans one. An analysis of the debris disc parameters suggests that a decrease might exist of the mean black body radius from the F-type to the K-type stars. In addition, a weak trend is suggested for a correlation of disc sizes and an anticorrelation of disc temperatures with the stellar age.

circumstellar matter↗
NASA NTRS2003

Cratering Rates in the Outer Solar System

We use several independent constraints on the number of ecliptic comets (aka JFCs) to determine impact cratering rates from Jupiter to Pluto. Long period comets and asteroids are currently unimportant on most worlds at most sizes. The size- number distribution of comets smaller than 20 km is inferred from size-number distributions of impact craters on Europa, Ganymede, and Triton; while the size- number distribution of comets bigger than 50 km is equated to the size-number distribution of Kuiper Belt Objects. The gap is bridged by interpolation. It is notable that small craters on Jupiter's moons indicate a pronounced paucity of small impactors, while small craters on Triton imply a collisional population rich in small bodies. However it is unclear whether the craters on Triton are of heliocentric or planetocentric origin. We therefore consider two cases for Saturn and beyond: a Case A in which the size-number distribution is like that inferred at Jupiter, and a Case B in which small objects obey a more nearly collisional distribution. Known craters on Saturnian and Uranian satellites are consistent with either Case, although surface ages are much younger in Case B, especially at Saturn and Uranus. At Neptune and especially at Saturn our cratering rates are much higher than rates estimated by Shoemaker and colleagues, presumably because Shoemaker's estimates mostly predate discovery of the Kuiper Belt. We also estimate collisional disruption rates of moons and compare these to estimates in the literature .

Zahnle, K.↗
NASA NTRS2007

Radiolytic Gas-Driven Cryovolcanism in the Outer Solar System

Water ices in surface crusts of Europa, Enceladus, Saturn's main rings, and Kuiper Belt Objects can become heavily oxidized from radiolytic chemical alteration of near-surface water ice by space environment irradiation. Oxidant accumulations and gas production are manifested in part through observed H2O2 on Europa. tentatively also on Enceladus, and found elsewhere in gaseous or condensed phases at moons and rings of Jupiter and Saturn. On subsequent chemical contact in sub-surface environments with significant concentrations of primordially abundant reductants such as NH3 and CH4, oxidants of radiolytic origin can react exothermically to power gas-driven cryovolcanism. The gas-piston effect enormously amplifies the mass flow output in the case of gas formation at basal thermal margins of incompressible fluid reservoirs. Surface irradiation, H2O2 production, NH3 oxidation, and resultant heat, gas, and gas-driven mass flow rates are computed in the fluid reservoir case for selected bodies. At Enceladus the oxidant power inputs are comparable to limits on nonthermal kinetic power for the south polar plumes. Total heat output and plume gas abundance may be accounted for at Enceladus if plume activity is cyclic in high and low "Old Faithful" phases, so that oxidants can accumulate during low activity phases. Interior upwelling of primordially abundant NH3 and CH4 hydrates is assumed to resupply the reductant fuels. Much lower irradiation fluxes on Kuiper Belt Objects require correspondingly larger times for accumulation of oxidants to produce comparable resurfacing, but brightness and surface composition of some objects suggest that such activity may be ongoing.

Cooper, John F.↗
NASA NTRS2019

The HST Lightcurve of (486958) 2014 MU69

We report Hubble Space Telescope (HST) lightcurve observations of the New Horizons spacecraft encounter Kuiper Belt object (KBO) (486958) 2014 MU69 acquired near opposition in July 2017. In order to plan the optimum flyby sequence the New Horizons mission planners needed to learn as much as possible about the target in advance of the encounter. Specifically, from lightcurve data, encounter timing could be adjusted to accommodate a highly elongated, binary, or rapidly rotating target. HST astrometric (Porter et al., 2018) and stellar occultation (Buie et al., 2018) observations constrained MU69's orbit and diameter (21–41 km for an albedo of 0.15–0.04), respectively. Photometry from the astrometric dataset suggested a variability of ≥0.3 mags, but they did not determine the period or provide shape information. To that end we strategically spaced 24 HST orbits over 9 days to investigate rotation periods from approximately 2–100 h and to better constrain the lightcurve amplitude. Until New Horizons detected MU69 in its optical navigation images beginning in August 2018, this HST lightcurve campaign provided the most accurate photometry to date. The mean variation in our data is 0.15 magnitudes which suggests that MU69 is either nearly spherical (a:b axis ratio of 1:1.15), or its pole vector is pointed near the line of sight to Earth; this interpretation does not preclude a near-contact binary or bi-lobed object. However, image stacks do conclude that MU69 does not have a binary companion ≥2000 km with a sensitivity to 29th magnitude (an object a few km in size for an albedo of 0.04–0.15). Our data are not of sufficient signal to noise to uniquely determine the period or amplitude, however, they did provide the necessary information for spacecraft planning. We report with confidence that MU69 is not both rapidly rotating and highly elongated (which we define as a lightcurve amplitude ≥ 0.5 magnitude). Since this paper is being published post fly-by, we note that our results are consistent with the fly-by imagery and orientation of MU69 (Stern et al., 2019). The combined dataset also suggests that within the KBO lightcurve literature there are likely other objects which share a geometric configuration like MU69 resulting in an underestimate of the contact binary fraction for the Cold Classical Kuiper Belt.

S D Benecchi↗
NASA NTRSDate not supplied

NASA’s Space Launch System: New Launch Capability for Artemis Lunar and Deep Space Science Missions

With stacking and integration of the initial Block 1 Space Launch System (SLS) expected to begin in 2020, NASA’s powerful new launch vehicle is ready to take center stage in the agency’s Artemis program to return astronauts to the Moon. Combining the highest launch thrust and largest payload capacity ever developed, SLS also enables a new generation of high-C3 science missions to destinations such as the gas and ice giants, the Kuiper Belt, and even beyond the solar system. Block 1 is only the beginning, as the vehicle has a planned evolution path to progressively more powerful variants. In addition to these block upgrades providing increased lift capability, the vehicle can be configured to fly in crew configuration with the Orion spacecraft or in cargo configuration with payload fairings for launching science mission or large infrastructure, providing a flexible launch option. For Artemis I, the first SLS flight, the Block 1 vehicle in the crew configuration will send an uncrewed Orion spacecraft to lunar orbit for a thorough systems checkout before the crewed Artemis II flight. The Block 1 vehicle uses a proven propulsion system consisting of solid rocket boosters and RS-25 engines to lift more than 27 metric tons [t] to trans-lunar injection (TLI). In its cargo configuration, Block 1 can be fitted with a 5 m payload fairing. The second variant, Block 1B, uses a more powerful upper stage to increase payload mass to TLI to 38-42 t, depending on crew or cargo configuration. In the crew configuration, a co-manifested payload of up to 10 t can ride along in the Universal Stage Adapter (USA), which has as much volume for payloads as a 5 m-class payload fairing. The Block 2 evolved variant will lift 43-46 t to TLI, depending on crew or cargo configuration. The Block 1B and Block 2 vehicles can be outfitted with an 8.4 m-diameter payload fairing, available in 19.1 m and 27.4 m lengths, providing unprecedented volume for payloads. Larger-diameter 10 m fairings may also be an option in the future on the Block 2 vehicle. The unrivalled mass, volume and high-energy launches of SLS can provide significant mission flexibility for payloads and/or additional upper stages to open trade space for a new generation of exploration missions. SLS was designed to meet requirements for launching large-volume infrastructure as outlined in numerous studies of missions to cislunar space or Mars. Mission concept studies from the science community also point toward new possibilities enabled by SLS. Probes with more robust science packages can be sent to the gas giants. Dual spacecraft can be manifested for missions to Uranus and Neptune. Additional third or fourth payload stages can be encapsulated in the payload fairings to achieve missions to the Kuiper Belt or beyond. In addition, the large volume can be used to design and deploy wide-aperture mirrors on future space telescopes and to enable nuclear-thermal propulsion missions. At AIAA Ascend, the SLS Program will provide technical information on vehicle capabilities as well as descriptions of ongoing discussions with mission planners for utilizing the vehicle for an array of deep space missions.

Stephen Creech↗
DOE OSTI2021

A Detailed Characterization of HR 8799's Debris Disk with ALMA in Band 7

The exoplanetary system of HR 8799 is one of the rare systems in which multiple planets have been directly imaged. Its architecture is strikingly similar to that of the solar system, with the four imaged giant planets surrounding a warm dust belt analogous to the Asteroid Belt, and themselves being surrounded by a cold dust belt analog to the Kuiper Belt. Previous observations of this cold belt with ALMA in Band 6 (1.3 mm) revealed its inner edge, but analyses of the data differ on its precise location. It was therefore unclear whether or not the outermost planet HR 8799 b was dynamically sculpting it. We present here new ALMA observations of this debris disk in Band 7 (340 GHz, 880 μm). These are the most detailed observations of this disk obtained so far, with a resolution of 1″ (40 au) and sensitivity of 9.8 μJy beam{sup −1}, which allowed us to recover the disk structure with high confidence. In order to constrain the disk morphology, we fit its emission using radiative transfer models combined with a Markov Chain Monte Carlo procedure. We find that this disk cannot be adequately represented by a single power law with sharp edges. It exhibits a smoothly rising inner edge and smoothly falling outer edge, with a peak in between, as expected from a disk that contains a high-eccentricity component, hence confirming previous findings. Whether this excited population and inner edge shape stem from the presence of an additional planet remains, however, an open question.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS2011

Zodiac II: Debris Disk Science from a Balloon

Zodiac II is a proposed balloon-borne science investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. Zodiac II will measure the size, shape, brightness, and color of a statistically significant sample of disks. These measurements will enable us to probe these fundamental questions: what do debris disks tell us about the evolution of planetary systems; how are debris disks produced; how are debris disks shaped by planets; what materials are debris disks made of; how much dust do debris disks make sa they grind down; and how long do debris disks live? In addition, Zodiac II will observe hot, young exoplanets as targets of opportunity. The Zodiac II instrument is a 1.1-m diameter SiC telescope and an imaging coronagraph on a gondola carried by a stratospheric balloon. Its data product is a set of images of each targeted debris disk in four broad visible wavelength bands. Zodiac II will address its science questions by taking high-resolution, multi-wavelength images of the debris disks around tens of nearby stars. Mid-latitude flights are considered: overnight test flights within the United States followed by half-global flights in the Southern Hemisphere. These longer flights are required to fully explore the set of known debris disks accessible only to Zodiac II. On these targets, it will be 100 times more sensitive than the Hubble Space Telescope's Advanced Camera for Surveys (HST/ACS); no existing telescope can match the Zodiac II contrast and resolution performance. A second objective of Zodiac II is to use the near-space environment to raise the Technology Readiness Level (TRL) of SiC mirrors, internal coronagraphs, deformable mirrors, and wavefront sensing and control, all potentially needed for a future space-based telescope for high-contrast exoplanet imaging.

Bryden, Geoffrey↗
NASA NTRS2012

Coronagraphic Imaging of Debris Disks from a High Altitude Balloon Platform

Debris disks around nearby stars are tracers of the planet formation process, and they are a key element of our understanding of the formation and evolution of extrasolar planetary systems. With multi-color images of a significant number of disks, we can probe important questions: can we learn about planetary system evolution; what materials are the disks made of; and can they reveal the presence of planets? Most disks are known to exist only through their infrared flux excesses as measured by the Spitzer Space Telescope, and through images measaured by Herschel. The brightest, most extended disks have been imaged with HST, and a few, such as Fomalhaut, can be observed using ground-based telescopes. But the number of good images is still very small, and there are none of disks with densities as low as the disk associated with the asteroid belt and Edgeworth-Kuiper belt in our own Solar System. Direct imaging of disks is major observational challenge, demanding high angular resolution and extremely high dynamic range close to the parent star. The ultimate experiment requires a space-based platform, but demonstrating much of the needed technology, mitigating the technical risks of a space-based coronagraph, and performing valuable measurements of circumstellar debris disks, can be done from a high-altitude balloon platform. In this paper we present a balloon-borne telescope concept based on the Zodiac II design that could undertake compelling studies of a sample of debris disks.

Unwin, Stephen↗