Frank Giovane

Coronagraphic technique to infer the nature of the Skylab particulate environment

Photographs taken with the High Altitude Observatorys White Light Coronagraph (Skylab experiment SO52) are shown to contain information on the sizes and velocities of contaminant particulates around Skylab. Sizes as small as 5 microm (radius) are derived for particles as far away as 200 m from the spacecraft. The random error in the size derivation is about 30%, and no particle larger than 120 microm was observed. Transverse velocities are determined to within 0.08 m sec(-1) and radial velocities to within 9 m sec(-1). The S052 data bank contains about 3500 contaminated frames from which the nature of the Skylab environment can be inferred.

Stellar Refraction: A Tool to Monitor the Height of the Tropopause from Space

Abstract Calculations of stellar refraction for a setting or rising star as viewed from a spacecraft show that the tropopause is a discernable feature in a plot of refraction vs time. The height of the tropopause is easily obtained from such a plot. Since the refraction suffered by the starlight appears to be measurable with some precision from orbital altitudes, we suggest this technique as a method for remotely monitoring the height of the tropopause. Although limited to nighttime measurements, the method is independent of supporting data or model fitting and easily lends itself to on-line data reduction.

Photographic coronagraph, Skylab particulate experiment T025

A photographic coronagraph, built to monitor Skylabs extravehicular contamination, is described. This versatile instrument was used to observe the earths vertical aerosol distribution and Comet Kohoutek (1973f) near perihelion. Although originally designed for deployment from the solar airlock, the instrument was modified for EVA operation when the airlock was rendered unusable. The results of the observations made in four EVAs were almost completely ruined by the failure of a Skylab operational camera used with the coronagraph. Nevertheless, an aerosol layer at 48 km was discovered in the southern hemisphere from the few useful photographs.

Photomultiplier for optically probing Comet Halley

A low mass eight-color channel photopolarimeter was developed for the Giotto spacecraft. Utilizing the spin of the spacecraft, a multichannel plate photomultiplier, and a unique optical design, the instrument required no moving parts to measure color and linear polarization. The photopolarimeter collected data as the spacecraft passed through the coma of Comet Halley on 13 and 14 Mar. 1986. This instruments design, calibration, and reduction are discussed and some final results are presented.

In-situ photopolarimetric measurements of dust and gas in the coma of Halley's comet

Abstract The Halley Optical Probe Experiment (HOPE) on board the Giotto spacecraft has provided the first in-situ measurements, both of the dust and of some gaseous species, from inside the coma of the comet. The instrument has already been described /1/, together with first results /2/. The purpose of this note is to show how optical measurements can lead to in-situ information, how those were obtained during the 13–14 march 1986 Halley fly-by, and what is the status of the data analysis.

Coronagraph: The Ultimate Device To Monitor Orbiting Particulates In The Space Transport System (STS) Environment

To extract the maximum information content of orbiting particulates from a remote-sensing particulate monitor there are three instrument design requirements: (1) the monitor must be an imaging coronagraph; (2) it must be capable of range-finding; and (3) it must yield absolute photometric measurements. When all three requirements are met, the number, size, and velocity distributions of the vehicle-induced particulates can be deduced. Examples of each of these requirements, as realized during the Shuttle-3 and Skylab-3 missions, are discussed. A design is presented for a coronagraph suitable as a particulate monitor for Shuttle missions.