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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Spectral Models of Kuiper Belt Objects and Centaurs

We present models of the spectral reflectances of groups of outer Solar System objects defined primarily by their colors in the spectral region 0.4 -1.2 microns, and which have geometric albedo 0.04 at wavelength 0.55 microns. Our models of the groups with the strongest reflectance gradients (reddest colors) use combinations of organic tholins. We test the hypothesis that metal-reddened igneous rock-forming minerals contribute to the red colors of Centaurs and KBOs by using the space-weathered lunar soil as one of the components of our models. We find that our models can admit the presence of moderate amounts of space-weathered (metal-reddened) minerals, but that they do not require this material to achieve the red colors of the reddest outer Solar System bodies. Our models with organic tholins are consistent with the results of other investigators.

Cruikshank, Dale↗
NASA NTRS2019

A Kuiper Belt Source for Solar Flare Track-Rich Interplanetary Dust Particles

The presence of solar flare particle tracks in mineral grains within interplanetary dust particles (IDPs) has long been accepted as proof of their extraterrestrial origin [e.g. 1]. The 10-20 micrometers diameter IDPs released by dust producing objects in the solar system (mainly comets and asteroids) spiral in towards the Sun under the influence of Poynting-Robertson (PR) drag forces [2] and accumulate solar flare energetic particle tracks during their journey. The number of IDPs with well-constrained track density measurements is small, owing to the difficulty in the measurements and the lack of appropriatelysized crystals in which to image them. In order to use track densities as a chronometer of space exposure, the track production rate must be known. All previous work relied on track production rates determined by chemical etching techniques [e.g. 3], but tracks in IDPs are measured using TEM imaging. Here we report measurements of track densities in IDPs from both the anhydrous and hydrated IDP groups. Using the track production calibration determined from TEM observations of anorthite and olivine in lunar rock 64455 [4] we estimate space exposure times for these IDPs to constrain their parent body sources.

Keller, L. P.↗
NASA NTRS1994

The Kuiper Belt

Comets have long been recognized as a very different type of solar system body.

comets↗
NASA NTRS1989

Constraints on impact rates in the Pluto-Charon system and the population of the Kuiper comet belt

Impact rates in the Pluto-Charon system are dominated by comets from the proposed Kuiper Belt, 30 to 50 AU from the sun. Such collisions excite the eccentricity of Charon's orbit, which then decays due to tidal dissipation. Charon's eccentricity approaches a quasi-steady state, which can be used to constrain the total number and mass of comets in the Kuiper Belt. Unfortunately, the current upper limit on Charon's orbital eccentricity must be reduced by more than a factor of ten before useful constraints can be set.

Weissman, Paul R.↗
NASA NTRS1993

(abstract) The Impactor Flux in the Pluto-Charon System

The impactor flux on Pluto and Charon consists of long-period comets from the Oort cloud passing through the region, and intermediate-period comets evolving inward to (or outward from) short-period orbits. The source of the intermediate-period comets is likely an extended disk of remnant planetesimals beyond the orbit of Neptune, commonly referred to as the Kuiper belt, though the Oort cloud may be an additional source of some short-period comets. The Pluto-Charon system actually circulates within the Kuiper belt, and with an aphelion of 49.3 AU, moves through a region where remnant planetesimal orbits would likely be stable over the age of the solar system. The recent discovery of two objects at Kuiper belt distances, 1992 QB 1 and 1993 FW, and the fact that the orbit determined for 1992 QB 1 is likely of low eccentricity and low inclination, have provided strong observational evidence for the Kuiper belt. Weisman et al (1989) showed that, for the expected number of objects in the Kuiper belt necessary to provide the short-period comet flux, cometary cratering on Pluto and Charon is dominated by Kuiper belt comets. We will provide updated estimates of the numbers, based on an improved understanding of Oort cloud and Kuiper belt dynamics since 1989, and on improved estimates for the radii and masses for Pluto and Charon. Because Pluto and Charon actually penetrate the stable region of the Kuiper belt beyond 40 AU, expected cratering rates for the pair are substantially higher than for Triton, which is located at the inner edge of the Kuiper belt. However, the Pluto-Charon system is tidally evolved and this may have led to resurfacing events at various times in its history. Thus, detailed predictions of the integrated crater density or comparisons with Triton are not very meaningful without a knowledge of that history. Differences in the suspected compositions of Pluto and Charon may also lead to different surface rheologies and thus, different retention times for cratered surfaces.

Pluto↗
NASA NTRS1997

The Solar System Beyond Neptune

The aim of this research is to study the objects in the Kuiper Belt, in order to understand the nature of its origin and the evolutionary processes which have affected the Kuiper Belt. Particular science objectives include: 1) the determination of the sky-plane surface density of Kuiper Belt Objects (KBOs); 2) the determination of the slope of the cumulative luminosity function (CLF); 3) the determination of the KBO size distribution; 4) the isolation of bright KBOs from which physical measurements can be secured using existing 10-meter diameter class telescopes; 5) physical measurements of bright KBOs designed to assess their composition. Major results obtained under the grant include: 1) The determination of the surface density of KBOs (objects per square degree of sky) as a function of apparent red magnitude in the range 21 less than MR less than 24.8. 2) The discovery of a new dynamical class in the Kuiper Belt, exemplified by 1996 TL66. 3) Physical observations of two bright KBOs were secured using the Keck 10-meter telescope and an infrared imager/spectrometer; 4) In support of public interest in the Kuiper Belt, we wrote a popular article for Scientific American magazine and we developed a "Kuiper Belt Home Page" on the world-wide web.

Jewitt, David↗
NASA NTRSDate not supplied

Hydrated Interplanetary Dust Particles: Implications for Oxygen Reservoirs in the Outer Solar System

A re-evaluation of solar energetic particle (SEP) track densities in interplanetary dust particles (IDPs) show that many are derived from outer solar system parent bodies such as Kuiper belt objects (KBOs) or beyond. Kuiper belt objects are widely believed to represent the frozen remnants from the birth of the solar system. The population of track-rich IDPs include members from both the anhydrous chondritic-porous and hydrated chondritic-smooth classes and earlier work suggested that the hydrated IDPs may represent anhydrous IDP material that was aqueously altered. We are performing systematic studies of the mineralogy, chemistry and isotopic compositions of track-rich IDPs to gain a fuller understanding of the origin and evolution of KBOs. Here, we focus on the identification of hydrated Kuiper belt dust particles that allows for the direct evaluation of their O isotopic compositions and the implications for the oxygen isotopic composition of outer solar system ices.

L. P. Keller↗
NASA NTRS1996

Kuiper Express: A Sciencecraft

The Kuiper Express is a mission to achieve the first reconnaissance of one of the primitive objects in the Kuiper Belt. The Kuiper Express is a sciencecraft mission. It will be launched using a Delta vehicle and will use solar electric propulsion to shape its trajectory in the inner Solar System, while executing two Earth gravity-assist flybys.

Kuiper↗
NASA NTRS2003

Origin of Outer Solar System

We feel that at the present moment the available theoretical models of the Kuiper belt are still in advance of the data, and thus our main task has been to conduct observational work guided by theoretical motivations. Our efforts over the past year can be divided into four categories: A) Wide-field Searches for Kuiper Belt Objects; B) Pencil-beam Searches for Kuiper Belt Objects; C) Wide-field Searches for Moons of the Outer Planets; D) Pencil-beam Searches for Faint Uranian and Neptunian Moons; E) Recovery Observations. As of April 2002, we have conducted several searches for Kuiper belt objects using large-format mosaic CCD camera on 4-meter class telescopes. In May 1999, we used the Kitt Peak 4-meter with the NOAO Mosaic camera we attempted a search for KBOs at a range of ecliptic latitudes. In addition to our wide-field searches, we have conducted three 'pencil-beam' searches in the past year. In a pencil-beam search we take repeated integrations of the same field throughout a night. After preprocessing the resulting images we shift and recombine them along a range of rates and directions consistent with the motion of KBOs. Stationary objects then smear out, while objects moving at near the shift rate appear as point sources. In addition to our searches for Kuiper belt objects, we are completing the inventory of the outer solar system by search for faint satellites of the outer planets. In August 2001 we conducted pencil beam searches for faint Uranian and Neptunian satellites at CFHT and CTIO. These searches resulted in the discover of two Neptunian and four Uranian satellite candidates. The discovery of Kuiper belt objects and outer planet satellites is of little use if the discoveries are not followed by systematic, repeated astrometric observations that permit reliable estimates of their orbits.

Holman, Matthew J.↗
NASA NTRS2002

The Solar System Beyond Neptune

This proposal supported deep and wide-field optical imaging of the trans-Neptunian Solar System capitalizing on our broad access to state-of-the-art facilities on Mauna Kea. Key quantities determined include the size distribution of Kuiper Belt objects (a differential power law with an index -4), and the inclination and radial distance distributions. We identified an outer edge to the classical Kuiper Belt that has since been confirmed by independent workers. We also obtained an assessment of the population densities in the mean-motion resonances with Neptune and discovered the Scattered Kuiper Belt Object dynamical class. Scientific issues on which these measurements have direct bearing include the collisional environment of the Kuiper Belt, the origin of the short-period comets, and the origin by capture into resonance of Pluto and other Kuiper Belt objects.

Jewitt, David↗