Engineering topics

Tedesco, Edward F.

Publications and source records attributed to Tedesco, Edward F..

24 records · Page 2

NASA NTRS1987

Spectral geometric albedos of the Galilean satellites from 0.24 to 0.34 micrometers - Observations with the International Ultraviolet Explorer

An 8-year IUE satellite spectrophotometric observation campaign's results for the Galilean satellites of Jupiter indicate low albedos for all four, consistent with the distribution of sulfurous materials escaping from the surface of Io to the surfaces of the three other bodies by means of magnetospheric processes. A previously reported UV spectral asymmetry between Europa's leading and trailing hemispheres is confirmed. The greater trailing than leading side opposition surge observed in Europa implies that the trailing side is the less compact of the two. Ganymede exhibits UV spectral asymmetry also, but only at wavelengths greater than 0.28 microns.

Nelson, Robert M.↗

NASA NTRS1987

Water frost on Charon

New spectra of the Pluto-Charon system taken just before and during a total eclipse of the satellite are presented. The spectrum of Charon extracted from the data reveals the signature of water ice. There is no evidence for any methane or ammonia frost on the surface of Charon. The significance of these findings for the evolution of the Pluto-Charon system are discussed.

Buie, Marc W.↗

NASA NTRS1987

IRAS constraints on the sizes of Pluto and Charon

Thermal emission models indicate that Charon contributes a significant amount of the infrared radiation detected by IRAS during the observation of mutual eclipse events. The IRAS observations also show that the most probable diameters for Pluto and Charon are 2200 and 1300 (+ or - 150) km. These results are consistent with there being some atmosphere on Pluto.

Tedesco, Edward F.↗

NASA NTRS1987

Discovery of M class objects among the near-earth asteroid population

Broadband colorimetry, visual photometry, near-infrared photometry, and 10 and 20 micron radiometry of the near-earth asteroids (NEAs) 1986 DA and 1986 EB are used to show that these objects belong to the M class of asteroids. The similarity among the distributions of taxonomic classes among the 38 NEAs to the abundances found in the inner astoroid belt between the 3:1 and 5:2 resonances suggests that NEAs have their origins among asteroids in the vicinity of these resonances. The implied mineralogy of 1986 DA and 1986 EB is mostly nickel-iron metal; if this is indeed the case, then current models for meteorite production based on strength-related collisional processes on asteroidal surfaces predict that these two objects alone should produce about one percent of all meteorite falls. Iron meteorites derived from these near-earth asteroids should have low cosmic-ray exposure ages.

Tedesco, Edward F.↗

NASA NTRS1986

Modeling Pluto-Charon mutual eclipse events. I - First-order models

The present 'first order' analytical and numerical models of light curves due to mutual events between close planetary binaries, the effects of shadowing are included. Attention is given to the case of the Pluto-Charon system. The results of the analytical and numerical approaches agree to well within the expected light curve measurement error. The model predicts that the current mutual eclipse event series will end by November 1990.

Dunbar, R. Scott↗

NASA NTRS1986

A refined 'standard' thermal model for asteroids based on observations of 1 Ceres and 2 Pallas

An analysis of ground-based thermal IR observations of 1 Ceres and 2 Pallas in light of their recently determined occultation diameters and small amplitude light curves has yielded a new value for the IR beaming parameter employed in the standard asteroid thermal emission model which is significantly lower than the previous one. When applied to the reduction of thermal IR observations of other asteroids, this new value is expected to yield model diameters closer to actual values. The present formulation incorporates the IAU magnitude convention for asteroids that employs zero-phase magnitudes, including the opposition effect.

Lebofsky, Larry A.↗