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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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NASA NTRS1986

How many earth-approaching asteroids are there?

The discovery process of earth-approaching asteroids is formulated as a periodic sampling problem from an urn with replacement. It presumes as unchanging number of such objects over recent historical times, a fixed limiting magnitude/angular speed combination for detection probability, and allows for the possibility of the lack of detection or the lack of sufficient observations to refine an orbit at the first noticed apparition. While simple, the model is sufficiently powerful to show that an estimate of the number of earth-approaching minor planets is impossible. This conclusion is insensitive to uncertainties in perturbing influences, celestial mechanics, or a model for the distribution of the orbital element sets of these minor planets.

Taff, L. G.↗

NASA NTRS1985

The large-scale structure of the asteroid belt

The distributions of 2888 numbered minor planets over orbital inclination, eccentricity, and semimajor axis are examined, and 19 zones believed to adequately isolate the selection biases in survey programs of the physical properties of minor planets are defined. Six numbered asteroids have exceptional orbits and fall into no zone. Attention is called to rather sharp upper limits, which become increasingly stringent at larger heliocentric distances, on orbital inclinations and eccentricity.

Zellner, B.↗

NASA NTRS1977

Orbit of 1976 AA

The orbit of Asteroid 1976 AA is described, with attention given to calculations of its period and its distance from earth, both of which could be accurately and quickly determined by measuring the minor planet's position over wide ranges of hour angle on one to three nights. The geometry of the asteroid's orbit is compared to that of earth's orbit, and the periodicity of the minor planet's approaches to earth is projected. The motion of 1976 AA over an interval of seven centuries into both past and future is also studied; the possibility of its libration with respect to earth or to Venus is examined. Some data on closest approaches of the asteroid to Mars and Venus, as well as to earth, are given.

Marsden, B. G.↗

NASA NTRS1987

Asteroid families, dynamics and astrometry

The proper elements and family assignments for the 1227 Palomar-Leiden Survey asteroids of high quality were tabulated. In addition to the large table, there are also auxiliary tables of Mars crossers and commensurate objects, histograms of the proper element distributions, and a discussion. Probably the most important part of the discussion describes the Mars crossing boundary, how the closest distances of approach to Mars and Jupiter are calculated, and why the observed population of Mars crossers should bombard that planet episodically rather than uniformly. Analytical work was done to derive velocity distributions of family forming events from proper element distributions subject to assumptions which may be appropriate for cratering events. Software was developed for a microcomputer to permit plotting of the proper elements. Three orthogonal views are generated and stereo pairs can be printed when desired. This program was created for the study of asteroid families. The astrometry task is directed toward measuring and reducing positions on faint comets and the minor planets with less common orbits. The observational material is CCD frames taken with the Palomar 1.5 m telescope. Positions of 10 comets and 16 different asteroids were published on the Minor Planet Circulars.

Williams, J. G.↗

NASA NTRS1977

The asteroid albedo scale. I - Laboratory polarimetry of meteorites

Laboratory reflection polarimetry is presented for crushed rocks, lunar soils, and 24 meteoritic samples. The polarization-phase curves found for the meteorites closely resemble telescopic results for minor planets, but only if the samples are crushed finely enough to coat the larger particles with dust. The results generally confirm the identifications previously made from reflection spectroscopy for the meteoritic analogues of various types of asteroids; the more metal-rich ordinary chondrites, for example, match telescopic observations of the S-type minor planets well enough, as do the basaltic achondrites for Vesta. No meteorite measured, however, has a geometric albedo less than 0.05 as required for many of the C asteroids. A calibration of the polarimetric slope-albedo law, now determined strictly for meteoritic samples, confirms the asteroid albedo and diameter scale derived by the independent method of thermal radiometry.

Zellner, B.↗

NASA NTRS1986

Astrometric observations of comets and asteroids and subsequent orbital investigations

During the past year some 500 observations were made on 66 nights and published on the MPCs (Minor Planet Circulars/Minor Planets and Comets). In addition, a handful of measurements of earlier plates were completed and published. 121 of the observations published referred to comets. Of special importance were observations of comets (P/Giacobini-Zinner and P/Halley) in connection with the NASA ICE and ESA Giotto missions, but a special effort was made to get good coverage of almost all of the observable comets. Observations were also made of (2060) Chiron and of the earth-approaching objects (1627) Ivar, (1866) Sisyphys, (1943) Anteros, (3362) 1984 QA, 1985 JA, PA, TB and WA, and 1986 DA and EB. 46 minor planets were given permanent numbers entirely as a result of the observations.

Mccrosky, R. E.↗

NASA NTRS1991

Cometary spectroscopy and imaging

The objective is to investigate the spectroscopic and morphological characteristics of comets and selected minor planets over a wide range of heliocentric distances as they may suggest or constrain models of cometary processes, their formation environments and evolution. Direct images of all observable comets and 300-800 nm spectra of the brighter ones are obtained on a monthly basis with a charge coupled device spectrograph-camera. The direct images may be used for astrometry, photometry, and studies of coma and tail morphology. In some cases, anisotropic dust emission can provide information on the nucleus spin vector. Spectra may provide data on strengths of the principle emission for comparison of gas/dust ratios of a large sample of comets. Long integrations of minor planets in comet-like and nearby orbits are made to search for faint comae.

Larson, Stephen M.↗

NASA NTRS1979

Optical polarimetry of asteroids and laboratory samples

Interpretations of astronomical polarization data for more than 100 minor planets are summarized with reference to laboratory data for lunar, meteoritic, and terrestrial samples. All observed asteroids, including objects only a few kilometers in diameter, have microscopically intricate surfaces. Detailed comparisons between laboratory measurements of basaltic achondrites and telescopic results for Vesta show that its surface is particulate with a broad range of particle sizes, including a component of fine (1-5 micron) dust. The surface soils have not, however, undergone marked optical alterations as is the case for the lunar fines. For albedos greater than about 0.06, the albedo and hence the diameter can be determined with some reliability from the slope of the ascending branch of the polarization-phase curve. Many minor planets have surfaces that are remarkably uniform in albedo and texture on a hemispheric scale. A notable exception is 4 Vesta, which shows about ten percent albedo variegation between hemispheres.

Dollfus, A.↗

DOE OSTI2025

Monitoring of asteroids in cometary orbits and activated asteroids through archival images and new observations

Transitional objects are minor bodies that share some characteristics with asteroids and others with comets. These objects include asteroids in cometary orbits (ACOs), which behave dynamically like comets, but lack observed activity, while activated asteroids (AAs) follow typical asteroidal orbits, but have shown dust ejections. The monitoring of a set of these objects carried out in 2015 and 2016 is continued using archival images from various observatories and new data from the IMPACTON telescope in Brazil. Two techniques were applied to detect activity: (i) surface brightness profiles were compared with those of field stars to identify widening, and (ii) the magnitudes reported in the Minor Planet Center, combined with our observations, were reduced and analyzed to identify abrupt brightness increases as a function of heliocentric distance. We analyzed the surface brightness profiles of 133 ACOs and 7 AAs. To study the reduced magnitude, we obtained data from the 705 ACOs that were known at the time of the analysis. Together with the data from our previous work, our analysis covered 23% of the total known ACOs; 8 deviated slightly in the surface brightness profile, 6 brightened in the reduced magnitude, and one object is in common in both samples. A very low percentage of objects might show activity (4% of the sample with brightness profiles and <1% in the reduced magnitudes). These results would rule out a slow transition from active to inert. Regarding AAs, 4 showed activity, and 3 of them matched previously reported periods, while the data we analyzed for P/2015 X 6 were obtained 19 days before the first existing activity report. The activity episodes of these objects are very restricted in time and do not always occur in the same region of the orbit.

asteroids: general↗

NASA NTRS1978

Thermal evolutions of the terrestrial planets

Theoretical models are formulated for the thermal evolution of the moon, Mercury, Mars, Venus, and hypothetical minor planets, with consideration of conduction, solid-state convection, and differentiation. A variety of geological, geochemical and geophysical data is used to constrain both the present-day temperatures and the thermal histories of the planetary interiors. The data imply that the planets were heated during or shortly after formation and that all the terrestrial planets started differentiating early in their history. The size of the planet is the primary factor in determining its present-day thermal state. A planetary body with radius less than 1000 km is unlikely to reach melting, given heat source concentrations similar to terrestrial values and in the absence of intensive early heating.

Toksoz, M. N.↗

NASA NTRS1998

Dynamics of the Trans-Neptune Region: Apsidal Waves in the Kuiper Belt

The role of apsidal density waves propagating in a primordial trans-Neptune disk (i.e., Kuiper belt) is investigated. It is shown that Neptune launches apsidal waves at its secular resonance near 40 AU that propagate radially outward, deeper into the particle disk. The wavelength of apsidal waves is considerably longer than waves that might be launched at Lindblad resonances, because the pattern speed, g(sub s), resulting from the apsis precession of Neptune is much slower than its mean motion, Omega(sub s). If the early Kuiper belt had a sufficient surface density, sigma, the disk's wave response to Neptune's secular perturbation would have spread the disturbing torque radially over a collective scale lambda(sub *) approx. = r(2(mu)(sub d)Omega/ absolute value of r dg/dr)(sup 1/2), where mu(sub d)equivalent pi(sigma)r(exp 2)/(1 solar mass) and Omega(r) and g(r) are respectively the mean motion and precession frequency of the disk particles. This results in considerably smaller eccentricities at resonance than had the disk particles been treated as noninteracting test particles. Consequently, particles are less apt to be excited into planet-crossing orbits, implying that the erosion timescales reported by earlier test-particle simulations of the Kuiper belt may be underestimated. It is also shown that the torque the disk exerts upon the planet (due to its gravitational attraction for the disk's spiral wave pattern) damps the planet's eccentricity and further inhibits the planet's ability to erode the disk. Key words: celestial mechanics, stellar dynamics - comets: general minor planets, asteroids

Ward, William R.↗

NASA NTRS1985

Small Solar System Bodies

The feasibility of using ranging data to a spacecraft lander on a synchronously rotating satellite to determine the satellite's orbit, the planet's orbit, the lander coordinates, and the principal term of forced physical librations was studied. Classifications of asteroids into their proper elements and families are also presented. Measurements and reduction of positions on comets and the minor planets with less common orbits was the focus for the astrometry program.

Williams, J. G.↗

NASA NTRS1973

Physical study of planets and satellites

Review of recent progress made in various aspects of planetary research, followed by some comments on ongoing unpublished research at various centers. The results of planetary atmosphere research are cited for Mercury, Venus, Mars, the Jupiter system, Saturn and Titan (the largest satellite of Saturn), and Uranus and Neptune. Findings regarding planetary surfaces are presented for Mercury, Venus, and Mars. Current unpublished research concerning Venus, the minor planets, Jupiter, and Saturn is reviewed, and work currently being performed at the IAU Planetary Photographic Data Center at Meudon, by the Planetary Research Center at the Lowell Observatory, and within the framework of the International Planetary Patrol Program is evaluated.

Pettengill, G. H.↗

NASA NTRS2017

Highly accurate positions of asteroids using astrometry

Astrometry is the precise measurement of positions in the sky of stars and other celestial bodies. In this paper, measurements of asteroids and outer planet natural satellites are discussed. We used the Astro Mechanics, Ritchey-Chrétien reflecting, 0.6m telescope at Table Mountain Observatory (TMO) located in Wrightwood, CA. Equipped with a 4k CCD camera (the ProLine4096x4096 imaging array with 9μm pixels), using 180 second exposures, we imaged the asteroids and outer satellites. We calculated two to three different positions of the asteroids, with different star fields, to best obtain positions. We obtained many different accurate positions of asteroids and the observing conditions, which were noted, inputted, then reduced with other data. We submit our data to the Minor Planet Center, and by the Solar System Dynamics (SSD) group at JPL. The data are also used for predicting occulting events. Through the execution of several Linux reduction programs and scripts, we reduce the data for the most accurate orbital positions.

Carr, Alexander G.↗

DOE OSTI2024

The Active Asteroids Citizen Science Program: Overview and First Results

Abstract We present the Citizen Science program Active Asteroids and describe discoveries stemming from our ongoing project. Our NASA Partner program is hosted on the Zooniverse online platform and launched on 2021 August 31, with the goal of engaging the community in the search for active asteroids—asteroids with comet-like tails or comae. We also set out to identify other unusual active solar system objects, such as active Centaurs, active quasi-Hilda asteroids (QHAs), and Jupiter-family comets (JFCs). Active objects are rare in large part because they are difficult to identify, so we ask volunteers to assist us in searching for active bodies in our collection of millions of images of known minor planets. We produced these cutout images with our project pipeline that makes use of publicly available Dark Energy Camera data. Since the project launch, roughly 8300 volunteers have scrutinized some 430,000 images to great effect, which we describe in this work. In total, we have identified previously unknown activity on 15 asteroids, plus one Centaur, that were thought to be asteroidal (i.e., inactive). Of the asteroids, we classify four as active QHAs, seven as JFCs, and four as active asteroids, consisting of one main-belt comet (MBC) and three MBC candidates. We also include our findings concerning known active objects that our program facilitated, an unanticipated avenue of scientific discovery. These include discovering activity occurring during an orbital epoch for which objects were not known to be active, and the reclassification of objects based on our dynamical analyses.

Astronomy & Astrophysics↗

DOE OSTI2026

An Automated Probabilistic Asteroid Prediscovery Pipeline

We present an automated and probabilistic method to make prediscovery detections of near-Earth asteroids (NEAs) in archival survey images, with the goal of reducing orbital uncertainty immediately after discovery. We refit the Minor Planet Center's astrometry and propagate the full six-parameter covariance to survey epochs to define search regions. We build low-threshold source catalogs for viable images and evaluate every detected source in a search region as a candidate prediscovery. We eliminate false positives by refitting a new orbit to each candidate and probabilistically linking detections across images using a likelihood ratio. Applied to the Zwicky Transient Facility's (ZTF) imaging, we identify approximately 3000 recently discovered NEAs with prediscovery potential, including a doubling of the observational arc for about 500. We use archival ZTF imaging to make prediscovery detections of the potentially hazardous asteroid 2021 DG1, extending its arc by 2.5 yr and reducing future apparition sky plane uncertainty from many degrees to arcseconds. We also recover 2025 FU24 nearly 7 yr before its first known observation, when its sky plane uncertainty covers hundreds of square degrees across thousands of ZTF images. The method is survey agnostic and scalable, enabling rapid orbit refinement for new discoveries from Rubin, NEO Surveyor, and NEOMIR.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2026

Vera C. Rubin Observatory Prompt Products

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2026

Vera C. Rubin Observatory Prompt Products: alert packets data

Data products produced by prompt and daily processing of images obtained in the Legacy Survey of Space and Time. These include realtime alerts sent to community alert brokers, newly-discovered Solar System Objects reported to the Minor Planet Center, processed visit and difference images, and source catalogs. Prompt Products are not a static single data release but continually grow throughout the ten-year LSST survey. This dataset is a subset of the full data release consisting of a dataset named alert packets. This dataset contains measurements for 5-sigma sources detected in difference images that were issued to the community brokers.

79 ASTRONOMY AND ASTROPHYSICS↗