Search NASA⌕ Search

Engineering topics

Lynch, D. K.

Publications and source records attributed to Lynch, D. K..

22 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

The sudden appearance of the tail of Comet Halley

An outburst event on Comet Halley, which was photographed in November 1985 when the comet was very near the ecliptic plane at 1.82 AU from the sun, is discussed. An irregular mass of material was observed, reaching about 1 arcmin south of the comet, approximately 70 degrees from the expected angle of the tail. Brightness changes during the event, up to a factor of 20, were shown in 2.3-10.3-micron IR measurements. The behavior of the outburst is consistent with the rapid expulsion of volatile ice particles. It is shown that the tail formed rather suddenly, though somewhat episodically. It is suggested that the outburst was not caused by a meteorite impact. It is concluded that the probable cause of the outburst was thermal heating of the nuclear crust with modest heat storage.

Lynch, D. K.↗
NASA NTRS1986

Multiple aperture airborne infrared measurements of Comet Halley

Observations at 10 microns with a 3.5' diameter beam made from the NASA Lear Jet Observatory during April 7.6 to 11.6, 1986 UT are presented. Data show evidence for a dramatic outburst (factor of 3 in 10 micron flux) with a turn-on time of 1 day and turn-off time of 1 to 2 days. Total mass ejected in the outburst is estimated. When combined with 8 and 10 microns data taken by Campins et al the dependence of the dust density on distance from the nucleus can be evaluated. It is shown that the flux within an aperture of diameter D is directly proportional to D well beyond 60" (2 million m at the comet). At 64 million m diameter (210"), the measurements are only 30% below the level expected for a strict F varies as d dependence. This, combined with the time scales of the event, places constraints on processes of grain destruction. The energy of the outburst is derived and compared to solar heating.

Russell, R. W.↗
NASA NTRS1986

Test of IR arrays on the Kuiper Airborne Observatory

NASA's Kuiper Airborne Observatory, which is a C-141 transport aircraft equipped with a 90-cm, all-reflective altazimuth telescope, has been engaged in the Kuiper Infrared Technology Experiment. Attention is presently given to the Experiment's flight series for state-of-the-art two-dimensional, 500-element arrays that use either blocked impurity band or bulk silicon devices. The switched FET readout scheme used on the three arrays flown thus far yields exceptionally low crosstalk. System sensitivities are found to be sufficient for the detection of both pointlike and extended sources; several of each type have been used in staring and scanning experiments.

Russell, R. W.↗