摘要:

This Mercury issue contains 11 papers submitted as an interim report from the team that has analyzed photographs from two encounters between Mercury and Mariner 10. Several specific areas of work, such as cartographic control, tectonic processes, and gravitational effects on craters, are detailed. A final paper offers working hypotheses about major processes that may have affected the history of Mercury.These reports are starting points for future work. Indeed, several of our reviewers were stimulated to offer alternative interpretations not developed in detail here. Although the formal Mercury project is scheduled to end in June, the first International Colloquium on Mercury in Pasadena, California, June 25–27, will encourage further debate on techniques of analysis and problems of Mercury physics. We hope that this issue of theJournal of Geophysical Researchand the colloquium, like the Mars colloquium following Mariner 9, will establish foundations and define tests for future research on Mariner 10 and other Mercury dat

ISSN:0148-0227    

DOI:10.1029/JB080i017p02341

年代:1975

数据来源: WILEY

摘要:

The 11 papers in this issue, comprising the Mariner 10 imaging team final report, are brought together, and the salient results of the Mariner 10 imaging experiment at Mercury are summarized. Those aspects of the data set acquired which were worked by the team are identified, and other areas where further work is needed are designated.

ISSN:0148-0227    

DOI:10.1029/JB080i017p02342

年代:1975

数据来源: WILEY

摘要:

The second Mercury encounter has resulted in the acquisition of about 360 pictures of the south polar regions which provide a reliable cartographic and geologic tie between the two sides of the planet photographed on the first encounter. Stereoscopic coverage of large areas of the southern hemisphere was obtained by combining Mercury 1 and 2 pictures taken at different viewing angles. The south polar regions consist of heavily cratered terrain and intercrater plains interspersed with patches of smooth plains. No large areas of smooth plains similar to those surrounding Caloris occur in the south polar regions. No new types of terrain have been recognized, but lobate scarps are common. The second largest basin seen by Mariner 10 (∼600‐km diameter) has been confirmed on the new photography. At high solar elevations the surface displays an abundance of rays and rayed crat

ISSN:0148-0227    

DOI:10.1029/JB080i017p02345

年代:1975

数据来源: WILEY

摘要:

The Mariner 10 television science subsystem was an improved version of the Mariner 9 system, using 1500‐mm‐focal‐length optics. An elaborate picture‐taking sequence resulted in transmission of over 4000 frames back to earth during two flyby encounters with Mercury. These sequences utilized a real‐time data rate of 117.6 kbit/s, resulting in coverage of about 75% of the lighted portion of Mercury's surface at a resolution of better than 2 km. The complete set of useful images, which amounted to about 3000 frames, was processed with three different types of digital image‐processing e

ISSN:0148-0227    

DOI:10.1029/JB080i017p02357

年代:1975

数据来源: WILEY

摘要:

This paper describes the digital processing performed by the Image Processing Laboratory (IPL) of the Jet Propulsion Laboratory (JPL) on the images of Mercury returned to earth from Mariner 10. Each image contains considerably more information than can be displayed in a single picture. Several specialized processing techniques and procedures were utilized to display the particular information desired for specific scientific analyses: radiometric decalibration for photometric investigations, high‐pass filtering to characterize morphology, modulation transfer function (MTF) restoration to provide the highest possible resolution, scene‐dependent filtering of the terminator images to provide maximum feature discriminability in the regions of low illumination, and rectification to cartographic projections to provide known geometric relationships between features. A principal task was the construction of full disk mosaics as an aid to the understanding of surface structure on a global scale; the detailed steps involved in the production of pictures for these mosaics are descri

ISSN:0148-0227    

DOI:10.1029/JB080i017p02394

年代:1975

数据来源: WILEY

摘要:

The rotation period of Mercury has been determined to be 58.661 ± 0.017 (1 sigma) days by using high resolution photography from the Mariner 10 mission. This value matches the period required for 3/2 synchronism with the orbital period (58.6462 days) within the 1‐sigma errors assigned and is consistent with the latest values derived from radar and earth‐based telescopic observat

ISSN:0148-0227    

DOI:10.1029/JB080i017p02415

年代:1975

数据来源: WILEY

摘要:

A control net of Mercury has been established photogrammetrically by using the Mariner 10 pictures; coordinates of 1328 points are given. The Mariner 10 coordinate system uses a system of longitudes in which the twentieth meridian passes through the center of the small crater Hun Kal and the spin axis is assumed normal to the orbital plane. A reference mosaic of Mercury has been published, and a series of 1:5,000,000 maps is now being produced.

ISSN:0148-0227    

DOI:10.1029/JB080i017p02417

年代:1975

数据来源: WILEY

摘要:

The elimination of the residual image problem which plagued previous Mariner imaging systems allowed photometry of moderately high quality to be carried out on Mercury by Mariner 10. Relative radiance measurements are accurate to about ±1% within a frame; absolute measurements have an uncertainty of about ±5%. The conclusions from the photometric analysis are as follows. To a surface resolution of 20 km, Mercury is covered with a dark fine‐grained soil similar to the lunar regolith. No regions having anomalous polarization or color were discovered, which might have implied large amounts of metallic Fe or exposed bare rock. Photoclinometry suggests that the center of the Caloris Basin may be 9 ± 3 km below the outside rim. The heavily cratered plains have albedos of about 0.17, somewhat brighter than the lunar highlands. The albedos of the darker smooth plains and the interiors of bright fresh craters are systematically higher than their lunar counterparts. Bright craters are invariably bluer than most of the surface. One consistent interpretation of the color and albedo relationships is that the dark smooth plains resemble the low‐Ti, low‐Fe lunar maria and that the crust is generally low in Ti, metallic Fe,

ISSN:0148-0227    

DOI:10.1029/JB080i017p02431

年代:1975

数据来源: WILEY

摘要:

Although the general morphologies of fresh mercurian and lunar craters are remarkably similar, comparisons of ejecta deposits, interior structures, and changes in morphology with size reveal important differences between the two populations of craters. The differences are attributable to the different gravity fields in which the craters were formed and have significant implications for the interpretation of cratering processes and their effects on all planetary bodies.

ISSN:0148-0227    

DOI:10.1029/JB080i017p02444

年代:1975

数据来源: WILEY

摘要:

A geologic terrain map of Mercury has been constructed by use of the photogeologic methods employed for the moon and Mars. The oldest and most widespread unit, intercrater plains, forms nearly level to rolling surfaces on which are superposed numerous secondary impact craters. This unit may represent a very old surface that predates the last heavy bombardment of the inner planets. The effects of this bombardment are recorded in a second widespread unit, heavily cratered terrain, consisting of closely spaced craters and basins from 30 km to several hundred kilometers in diameter. Units formed by excavation of the 1300‐km‐diameter Caloris basin are widespread on one hemisphere of the planet. The development of the Caloris basin was followed relatively quickly by emplacement of widespread plains materials, most of which are probably volcanic. Younger craters, including some with rays, followed emplacement of the plains; they are much less abundant than the preplains craters. The geologic history of Mercury is remarkably similar to that of the m

ISSN:0148-0227    

DOI:10.1029/JB080i017p02461

年代:1975

数据来源: WILEY