Comet Bennett

[5] The orbit was computed by M. P. Candy of the Perth Observatory and it became apparent that the comet could become a bright object by the end of March, during its perihelion at a distance of 0.54 AU, as it moved northwards.

[8] A few years earlier it had been suggested that comets are surrounded by a shell of hydrogen gas, which could be detected by observing in the ultraviolet the Lyman α line at 121.5 nm.

The results confirmed the assumption that the gas production of comets at small solar distances is determined by the evaporation of water from the nucleus.

[14][15] In further investigations, attempts were then made to theoretically underpin the measurement results with greater agreement and to provide refined models for the formation of the hydrogen shells.

[16][11] At the Goddard Space Flight Center in Maryland, images of the comet were taken from March 28 to April 18, 1970, with interference filters at different wavelengths in the violet, blue, green, and yellow regions of the spectrum.

Maps of the comet's coma with lines of the same brightness (isophotes) up to a distance of 150,000 km from the nucleus were created from these and other images taken on April 8 and 9 at the Hamburg Observatory in white light.

[17] Similar surveys were also conducted from March 31 to April 27 at the University of Western Ontario's Hume Cronyn Memorial Observatory in Canada.

In particular, the emission lines of CN and C2 were measured and their intensity profiles evaluated in parallel and perpendicular directions to the comet's tail[18] and presented in the form of isophotes.

This was done using measurement data provided around the same time by the OGO-5, Vela 5, HEOS-1 and Pioneer 8 spacecraft, as well as by the ALSEP experiment installed on the lunar surface by Apollo 12.

The later evaluation of these observations provided evidence for the peculiarity of a "neckline structure" (NLS) in the dust tail of a comet, which was only theoretically derived in 1977.

[29] Observations of the comet's brightness evolution in the infrared were made in late March to mid-April 1970 at the Lunar and Planetary Laboratory in Arizona.

In addition to the continuum of a black body of about 500 K at short wavelengths, an emission line could also be detected at 10 μm, which was traced back to silicate grains in the dust of the comet.

[32] With the radio telescope of the Green Bank Observatory in West Virginia, an attempt was made over six days in mid-March 1970 to detect the emission of formaldehyde at 4.83 GHz.

[33] Likewise, the radio telescope at the United States Naval Research Laboratory in Maryland attempted to detect the emission of water molecules at 22.2 GHz over four days at the end of March 1970.

On April 14, 1970, after completing the maneuver to orient the spacecraft for a second attempt, Odyssey's service module ruptured, forcing the cancellation of the mission's scientific objectives and touchdown on the lunar surface.