Astrogeology Science Center

Mercury global mosaic using flyby MESSENGER data
Mercury global mosaic using flyby MESSENGER data
Mercury global mosaic closeup
Mercury global mosaic closeup
Mercury global mosaic showing image borders
Mercury global mosaic showing image borders

This mosaic represents the best geodetic map of Mercury's surface to date. MESSENGER's three flybys alone provide 90.90% of the data in the global mosaic (see Table above). Although MESSENGER went in to safe mode during the third flyby, the approach imaging was acquired and contributes ~6.82% additional coverage from earlier versions. Only the poles remain to be imaged, some of which are in permanent shadow.

The mosaic is comprised entirely of flyby data (Mariner 10 also had three Mercury flybys). The images were collected with large variations in resolution (see table below) and with varying lighting conditions while the spacecraft was traveling at speeds greater than 2 km/sec. It has been photometrically corrected using a Hapke-Henyey-Greenstein photometric model. Pixel density values are in I/F reflectance units. The darker vertical regions to left and right of center are coverage provided by images near or at the terminator (low Sun). These areas required special processing to retain illuminated features that are otherwise eliminated at incidence angles greater than 90° when the photometric model is applied.

The "smeared" data at the outer overlapping edges of the observations are limb images. These images are at high emission angles resulting in distortion within a derived map projection. The limb data are trimmed at lower emission angles in order to visually limit this effect. The mosaic is provided at 500 meters/pixel (~85.17 pixels/degree) resolution, planetocentric latitudes with a center latitude of 0.0., and -180 to +180 positive east longitudes with a center longitude of 0.0.

Coverage Percentages for MESSENGER and Mariner 10

Data SetSurface Area (km2)Coverage (%)
Mercury 74,822,795 100.0
M1+M2 64,323,084 85.97
M1+M2+M3 68,014,600 90.90
M3 New Coverage 3,691,516 4.93
Mariner 10 32,179,875 43.01
M1+M2+M3+M10 73,118,095 97.72
M10 contribution to mosaic 5,103,495 6.82

Control Network

There are 13 total observation sequences from all three MESSENGER flybys included in the control network. The figure above outlines of the locations of selected MDIS image observations used in the mosaic. The MDIS/NAC image observations Table (above) shows the breakdown of these observations in terms of number, resolution and inclusion in the mosaic.

The existing Mariner 10 base map provided a ground "truth" for the MESSENGER control network. Select MESSENGER images were tied to the Mariner 10 base at seven different ground truth locations. Using ISIS3 software, 5,301 control points (18,834 measurements) were selected in 886 MDIS narrow-angle camera (NAC) images. Highly specialized bundle block adjustment software was used to minimize image boundary mismatches.

The maximum RMS error for the global control is 3.48 pixels. The average RMS error is 0.2 pixels. Pixel density values are in I/F reflectance units. Absolute errors of the MESSENGER bundle adjustment are relative to the base map as reported to be ~25 km [Robinson 1999]. Hun Kal, a small crater defining the longitude system of Mercury, is within ~2.257 km of its predicted position of 20°W longitude.

MDIS-NAC Image Observations

Observation Total
Images
Images in
Global Mosaic
Average
Resolution
(m/pxl)
Minimum
Resolution
(m/pxl)
Maximum
Resolution
(m/pxl)
M1_APP_NAC_MOSAIC_1 38 38 511 470 553
M1_DEP_NAC_MOSAIC_1 87 87 532 473 590
M1_DEP_NAC_MOSAIC_2 66 0 625 573 677
M1_DEP_NAC_MOSAIC_2 66 0 625 573 677
M1_DEP_NAC_MOSAIC_3 43 0 806 764 847
M1_DEP_NAC_MOSAIC_4 36 36 862 822 903
M1_NAC_MOSAIC_1 68 68 144 116 171
M1_NAC_MOSAIC_2 96 96 281 236 325
M2_APP_NAC_MOSAIC_1 27 27 461 426 496
M2_DEP_NAC_MOSAIC_1 35 0 132 99 166
M2_DEP_NAC_MOSAIC_2 175 175 254 162 347
M2_DEP_NAC_MOSAIC_3 86 86 578 522 633
M2_DEP_NAC_MOSAIC_4 67 0 671 621 720
M3_APP_NAC_MOSAIC_1 62 58 1983 396 3570
Total 886 671  

References

  • K. J. Becker, M. S. Robinson, T. L. Becker, L. A. Weller, S. Turner, L. Nguyen, C. Selby, B. W. Denevi, S. L. Murchie, R. L. McNutt, S. C. Solomon, Near Global Mosaic of Mercury, Eos, Vol. 90, Number 52, 29 December 2009, Fall Meet. Suppl., Abstract P21A-1189.
  • Robinson, Mark S., et al., (1999) Revised control network for Mercury, Journal of Geophysical Research, 104(E12) Pages 30,847-30,852.
  • Becker, Kris J, et al., (2008) A New Global Mosaic of Mercury, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract U21A-0015.
  • Anderson, Jeffery A, et al., (2004) Modernization of the Integrated Software for Imagers and Spectrometers, Lunar and Planetary Science XXXV, Abstract 2039.

See Also