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Campins, Humberto

Publications and source records attributed to Campins, Humberto.

18 records
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NASA NTRS2016

Asteroid Redirect Mission (ARM) Formulation Assessment and Support Team (FAST) Final Report

The Asteroid Redirect Mission (ARM) Formulation Assessment and Support Team (FAST) was a two-month effort, chartered by NASA, to provide timely inputs for mission requirement formulation in support of the Asteroid Redirect Robotic Mission (ARRM) Requirements Closure Technical Interchange Meeting held December 15-16, 2015, to assist in developing an initial list of potential mission investigations, and to provide input on potential hosted payloads and partnerships. The FAST explored several aspects of potential science benefits and knowledge gain from the ARM. Expertise from the science, engineering, and technology communities was represented in exploring lines of inquiry related to key characteristics of the ARRM reference target asteroid (2008 EV5) for engineering design purposes. Specific areas of interest included target origin, spatial distribution and size of boulders, surface geotechnical properties, boulder physical properties, and considerations for boulder handling, crew safety, and containment. In order to increase knowledge gain potential from the mission, opportunities for partnerships and accompanying payloads were also investigated. Potential investigations could be conducted to reduce mission risks and increase knowledge return in the areas of science, planetary defense, asteroid resources and in-situ resource utilization, and capability and technology demonstrations. This report represents the FASTâ€"TM"s final product for the ARM.

Mazanek, Daniel D.↗
NASA NTRS1996

Chiron and the Centaurs: Escapees from the Kuiper Belt

The outer Solar System has long appeared to be a largely empty place, inhabited only by the four giant planets, Pluto and a transient population of comets. In 1977 however, a faint and enigmatic object - 2060 Chiron - was discovered moving on a moderately inclined, strongly chaotic 51-year orbit which takes it from just inside Saturn's orbit out almost as far as that of Uranus. It was not initially clear from where Chiron originated. these objects become temporarily trapped on Centaur-like orbits Following Chiron's discovery, almost 15 years elapsed before other similar objects were discovered; five more have now been identified. Based on the detection statistics implied by these discoveries, it has become clear that these objects belong to a significant population of several hundred (or possibly several thousand) large icy bodies moving on relatively short-lived orbits between the giant planets. This new class of objects, known collectively as the Centaurs, are intermediate in diameter between typical comets (1-20 km) and small icy planets such as Pluto (approx. 2,300 km) and Triton (approx. 2,700 km). Although the Centaurs are interesting in their own right, they have taken on added significance following the recognition that they most probably originated in the ancient reservoir of comets and larger objects located beyond the orbit of Neptune known as the Kuiper belt.

Stern, Alan↗
NASA NTRS1993

Multifrequency comparison of Cepheids and nonvariable supergiants

New IUE data and infrared J, H, K, L, and M observations have been obtained for nonvariable yellow supergiants and the prototype classical Cepheid Delta Cephei. These data have been combined with data in the literature to make a comparison between nonvariable yellow supergiants and Delta Cephei from the UV through the near-IR. The supergiant sequence shows a smooth progression of energy distributions with spectral type over this extended wavelength range. The Delta Cephei energy distributions on the descending branch of the light curve (free-fall portion of the pulsation curve) are well matched by supergiant energy distributions with the same (B-V)(0) for most phases. At the hottest phases, however, there is some extra flux at 3000 A as compared with the nonvariables. The Delta Cephei observation on the ascending branch of the light curve ('piston' phase of the pulsation cycle) has slightly more UV light than would be predicted from either the supergiant observations or the free-fall Delta Cephei phases.

Evans, Nancy R.↗
NASA NTRS1993

Detection of the 2165 inverse centimeter (4.619 micron) XCN band in the spectrum of L1551 IRS 5

We report the detection of a broad absorption band at 2165/cm in the spectrum of L1551 IRS 5. New laboratory results over the 2200-2100/cm wavenumber interval, performed with realistic interstellar ice analogs, suggest that this feature is due to a CN-containing compound. We will refer to this compound as XCN. We also confirm the presence of frozen CO through absorption bands at 2140/cm and 2135/cm. The relative abundance of solid state CO to frozen H2O is about 0.13 while the abundance of XCN seems comparable to that of frozen CO.

Tegler, Stephen C.↗
NASA NTRS1993

Detection of the 2165 Inverse Centimeter (4.619 Micron) XCN Band in the Spectrum of L1551 IRS 5

We report the detection of a broad absorption band at 2165 cm (4.619 microns) in the spectrum of L1551 IRS 5. New laboratory results over the 2200-2100 /cm wavenumber interval (4.55-4.76 microns), performed with realistic interstellar ice analogs, suggest that this feature is due to a CN-containing compound. We will refer to this compound as XCN. We also confirm the presence of frozen CO (both in nonpolar and polar matrices) through absorption bands at 2140 /cm (4.67 microns) and 2135 /cm (4.68 microns). The relative abundance of solid-state CO to frozen H2O is approx. 0.13 while the abundance of XCN seems comparable to that of frozen CO.

Tegler, Stephen C.↗
NASA NTRS1992

High resolution images of P/Tempel 1 and P/Tempel 2 constructed from IRAS survey data

Infrared images of P/Tempel 1 and P/Tempel 2 were constructed from IRAS survey data using a computer algorithm based on the Maximum Correlation Method for Image Construction (Aumann et al, 1990). The resulting images are of sufficiently high quality and resolution to delineate coma and tail morphology, and permit accurate photometry of the total dust complex. Comparisons of the infrared colors and photometric profiles of Tempel 1 and Tempel 2 at similar heliocentric distances show that the grains produced by the two comets are quite similar in radiometric and dynamic properties. Tempel 1 is found to produce about 30 percent more dust in its coma and tail than Tempel 2. The comae of Tempel 1 and Tempel 2 are expanding with mean velocities of 5.8 plus or minus 0.07 and 6.1 plus or minus 0.17 m/sec respectively, indicative of the ejection of large grains. The IRAS cataloged infrared fluxes (Walker, 1986) are found to be underestimated by as much as a factor of three for the comets. Therefore, it is essential to create images of the comets to obtain meaningful IRAS photometry.

Walker, Russell G.↗
NASA NTRS1991

The dust coma of Comet Austin (1989c1)

Thermal-infrared (10 and 20 micron) images of Comet Austin were obtained on UT 30.6 Apr., 1.8, 2.8, and 3.6 May 1990. The NASA-Marshall Space Flight Center 20 pixel bolometer array at the NASA 3 meter Infrared Telescope Facility in Hawaii was used. The 10.8 micron (FWHM = 5.3 microns) maps were obtained with maximum dimensions of 113 arcsec (57,500 km) in RA and 45 arcsec (23,000 km) in declination, with a pixel size of 4.2 x 4.2 arcsec. A smaller, 45 x 18 arcsec, map was obtained in the 19.2 micron (FWHM = 5.2 microns) bandpass. At the time of these observations Comet Austin's heliocentric and geocentric distances were 0.7 and 0.5 AU respectively. The peak flux density (within the brightest pixel) was 23 + or - 2 Janskys for the first three dates and only marginally lower the last day; i.e., within the observational uncertainties no evidence was found for day-to-day variability like that observed in Comet Halley. A dynamical analysis of the morphology of the extended dust emission is used to constrain the size distribution and production rate of the dust particles. The results of this analysis are compared with similar studies carried out on comets P/Giacobini-Zinner, P/Brorsen-Metcalf, P/Halley, P/Tempel 2, and Wilson (1987).

Campins, Humberto↗
NASA NTRS1991

Short-period comets

The spacecraft flybys of Comet Halley in 1986 confirmed Whipple's icy conglomerate hypothesis for cometary nuclei and showed that comets are far richer in volatiles than any other class of solar system bodies. Water is the most abundant volatile, comprising roughly 80 percent of the gas flowing out from the nucleus. Carbon monoxide is next with a content of 15 percent relative to water, though with approximately half of that coming from an extended source in the cometary coma, i.e., hydrocarbon dust grains. The detection of large numbers of hydrocarbon CHON grains was one of the more significant discoveries of the Halley flybys, as was the ground-based observation that CN occurs in jets, again indicating an extended source. Evidence was also found for more complex hydrocarbons. Estimates of the total dust-to-gas ratio for Halley range as high as 2:1, indicating that a substantial fraction of the volatile material may be tied up in solid hydrocarbons rather than ices. The role of clathrates in trapping more volatile ices is not yet understood. If Halley can be taken to be representative of all short-period comets, then the short-period comets may provide a significant source of volatiles in near-earth space. This resource is more difficult to reach dynamically than the near-earth asteriods, but the high volatile content may justify the additional effort necessary. In addition, there is considerable evidence that at least some fraction of the near-earth asteriods are extinct cometary nuclei which have evolved into asteroid orbits, and which may contain significant volatiles buried beneath an insulating lag-deposit crust of nonvolatiles. Knowledge of comets will be greatly enhanced in the near future by the Comet Rendezvous Flyby mission now under development by NASA, and by the proposed Rosetta mission.

Weissman, Paul R.↗
NASA NTRS1990

Ground-based thermal IR images of Comet Tempel 2

The 10.8-micron images of Comet Tempel 2 obtained on the four days from September 21 to 24, 1988, indicate that the dust coma contributed about half of the nuclear pixel brightness. The nuclear condensation brightness exhibited a temporal variability slightly larger than observational uncertainty. The structure of the observed extended dust emission is interpretable as (1) a large grain tail primarily generated by cm-scaled particles, (2) the result of an outburst near 2.5-3.0 AU perihelion, and (3) a sunward emission of dust in a fanlike pattern.

Campins, Humberto↗
NASA NTRS1989

The nucleus of Comet P/Tempel 2

Simultaneous optical photometry and IR radiometry of Comet P/Tempel 2 are presented. Periodic variations of brightness are present and in phase at all wavelengths. Because the optical and thermal rotational light curves are in phase, it is concluded that the variations are caused by the changing apparent cross section of an elongated nucleus rotating with a period near 8.9 h. The variation of flux with aperture makes it possible to separate the contributions of the nucleus and the coma. The contribution by the coma is about 25 percent at maximum light in the optical and undetectable at the level of 10 percent at all times in the thermal IR.

A'Hearn, Michael F.↗
NASA NTRS1989

A spectral difference between silicates in Comet Halley and interstellar silicates

The authors obtained an intermediate resolution (1 percent) spectrum of the 8 to 13 micron region in Comet Halley which shows a prominent silicate emission feature with structure not observed before in other comets or in interstellar silicates. They confirm the presence of a strong 11.3 micron peak reported by Bregman et al. (1987) and find evidence for additional structure in the band. The 11.3 micron peak represents the main difference between the Halley Spectrum and that of Comet Kohoutek. The Kohoutek Spectrum is similar to that of the circumstellar shell around mu Ceph. Based on a comparison with the spectra of Interplanetary Dust Particles (Sandford and Walker 1985), most of which are believed to be of cometary origin, the authors attribute the 11.3 micron peak to small crystalline olivine particles, although other minerals cannot be ruled out. Their interpretation is supported by the airborne observation of four emission peaks near 24, 28, 35 and 45 microns which can also be matched with iron-magnesium silicates including crystalline olivine. Other types of silicates (such as hydrated or amorphous) are necessary to explain the width and the 9.7 micron peak of the emission observed in Comet Halley.

Campins, Humberto↗
NASA NTRS1989

The 10 micron spectral structure in comets

The 10 micron spectra of comets Halley (1982i), Wilson (1986l), Kohoutek (1973f) and Bradfield (1987s) are presented and compared. The silicate emission profiles of Halley and Bradfield are seen to be remarkably similar in that both contain a sharp break in the spectrum at 11.3 microns. Comet Bradfield does not show the same double peak structure seen in olivine and reported in Comet Halley be Campins and Ryan (1988) and Bregman, et al. (1987). The authors interpret the 11.3 micron signature as being due to olivine-type dust grains with at least some degree of crystallinity. Olivine alone is not enough to reproduce the shape of the 10 micron structure. However, in view of the authors' past success in fitting interstellar dust features with the emissivity profile obtained from amorphous grains produced by laser-vaporizing olivine, this is a very appealing identification. They note that there are significant variations in olivine spectra due to compositional differences, grain size distribution and related grain temperature variations to make the olivine identification tentative. They further tentatively identify the 9.8 micron feature in Halley as being due to either amorphorous olivine or a phyllosilicate (layer lattice). Neither the spectra of Halley, Kohoutek, nor Bradfield exhibited the 12.2 micron feature seen in Comet Wilson, which may prove diagnostic of the composition or thermal history differences between these comets. IR spectra of various mineral samples are discussed in terms of their match to cometary spectra.

Lynch, David K.↗
NASA NTRS1989

Surface discharges on natural dielectrics in the solar system

In a variety of environments, notably those defined by the magnetospheres of the giant planets, natural dielectrics are exposed to large fluxes of charged particles. Laboratory simulations of these potentially discharge-inducing charging phenomena have been conducted to ascertain whether discharges can occur on natural dielectrics. Charging beam intensities ranged from 10 to the 10th to 10 to the 12th particles/sq cm per sec, with exposure times of 1-10 min; the lowest intensity is comparable to that expected on the surface of Io. Discharges were recorded during all exposures.

Campins, Humberto↗
NASA NTRS1989

Infrared imaging of the coma of Comet Wilson

The brightness of the nuclear condensation noted in March 13-15, 1987 thermal IR images of Comet Wilson did not vary, in contrast to Comet Halley's behavior; a dynamical analysis of the dust coma/tail structure establishes that the particle size distribution in this comet, while different from that of Comet Giacobini-Zinner, is nevertheless more similar to that in Comet Halley. The nonisotropic character of the dust ejection is taken to be evidence for prograde rotation of the nucleus, and it is speculated that Comet Wilson is too young to have developed a dust mantle; this would account for the lack of short time scale variability.

Campins, Humberto↗
NASA NTRS1989

The identification of crystalline olivine in cometary silicates

An intermediate-resolution spectrum of the 8-13 micron region in comet Halley is obtained which shows a prominent silicate emission feature with structure not observed before in other comets or in interstellar silicates. The presence of a strong 11.3 micron peak reported by Bregman and coworkers is confirmed, and evidence is found for additional structure in the band. By comparison with spectra of interplanetary dust particles and laboratory silicates, it is concluded that small crystalline olivine particles are a major component of the silicates in this comet; other silicates (e.g., amorphous or hydrated) must also be present. The identification of crystalline olivine in this part of the spectrum is supported by the observation of four peaks in 20-50 micron airborne spectra of this comet which have also been attributed to olivine.

Campins, Humberto↗
NASA NTRS1988

An investigation of the nucleus and coma of Comet P/Arend-Rigaux

Narrow-band photometry of Comet P/Arend-Rigaux in the visible and near-ultraviolet are presented for six nights during the 1884/1985 apparition, including three nights of simultaneous observations in the thermal infrared made with the NASA IRTF. The results indicate a period of rotation of 13.47 hr, dimensions for the nucleus of 13 x 8 x 8 km (under the assumption of prolate spheroid shape), and a steady decrease in the comet's gas production from a month before perihelion to more that two months after perihelion. Results for the nucleus and the coma suggest that the nucleus is totally covered with a nonvolatile mantle.

Millis, Robert L.↗
NASA NTRS1987

The bare nucleus of comet Neujmin 1

Simultaneous visible and infrared observations of comet P/Neujmin 1 1984c are presented which show that the comet has a large (mean radius 10 km), dark (geometric albedo 2-3 percent) nucleus with a surface which is mostly inert material but which still shows a low level of gaseous activity. This is the first physical evidence that cometary nuclei can leave behind an inert body after the coma activity ceases. No asteroid or asteroid class has been found to match the reflectance and albedo of this comet except possibly some D asteroids.

Campins, Humberto↗