Mercury: the MESSENGER surface map COSMOS actually delivers

Measured facts

Classification

Terrestrial planet

Mean radius

2,439 kmPublished mean radius stored as renderer geometry.

Mean diameter

4,879 km

Mean radius in Earth radii

0.383

Appearance

Tiled observational surface

Observation epoch

Historical multi-observation mosaic; not live

What you are looking at

The mosaic is a global simple-cylindrical product with planetocentric latitude and positive-east longitude. COSMOS reprojects each tile onto a spherical patch, so a close approach magnifies the delivered matrix rather than synthesising detail.

Camera approach stops at a declared minimum safe altitude of 240 km. That floor exists so the delivered pixels stay close to the rendered pixel footprint: below it, the image would start implying resolution the product does not contain.

Surface rotation uses the IAU_MERCURY pole, prime-meridian and phase terms from the pinned NAIF pck00011 release, evaluated at the selected TDB epoch. Phase 1 replaces the earlier static orientation.

Distance, scale and light time

Distances here are computed from the shipped JPL Horizons state archive, sampled once per day across its declared coverage (2020-01-01 00:00 TDB through 2040-01-01 00:00 TDB). Because both bodies move on different orbits, the separation changes constantly; the figures below include the dates at which the extremes occur.

Distance from Earth

1.368 AU · 204,712,375 kmAt the recorded snapshot epoch 2026-08-29 00:00 TDB, one-way light time 11.38 minutes.

Distance from the Sun

0.361 AU · 54,021,513 kmComputed in the same epochs and frame (Earth-centred ecliptic J2000.0 / ICRF).

Closest Earth approach in the archive

0.549144 AU on 2028-06-02One-way light time then: 4.57 minutes.

Farthest separation in the archive

1.451501 AU on 2034-12-04One-way light time then: 12.07 minutes.

Mean separation across the archive

1.039180 AUSampled once per day across 2020-01-01 00:00 TDB through 2040-01-01 00:00 TDB (7,306 samples).

Delivery and camera limits

COSMOS stops the camera at 2,679 km from the body centre (240 km above the mean-radius surface) for Mercury. Surface providers are protected because every imagery product has a native ground sampling distance, and magnifying past it would imply resolution the dataset does not contain.

Appearance status

Tiled observational surface

Renderer provider id

mercury-visual-v1

Declared resolution

665 m/pixel delivered NASA Trek color matrix; underlying MESSENGER BDR reference product is 166.31 m/pixel

Closest permitted approach

2,679 km from the body centre (240 km above the mean-radius surface)240 km minimum safe altitude keeps delivered imagery pixels near the rendered pixel footprint. The renderer clamps the camera's centre distance, so the two figures differ by one mean radius.

Rotation model

IAU_MERCURY — pck00011 (2022-12-27), IAU 2015 Mercury modelSource: https://naif.jpl.nasa.gov/pub/naif/generic_kernels/pck/pck00011.tpc

Geometry

mean-radius-sphereMean-radius sphere; no ellipsoid or terrain displacement yet

Provenance

Appearance provenance is carried by the provider at runtime, not added by the page: an active appearance layer is registered.

Category

observational-composite

Provider

NASA/JPL Mercury Trek · USGS Astrogeology

Project / mission

MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER)

Dataset

MDIS Basemap Enhanced Color Global Mosaic

Version

NASA Trek WMTS matrix checked 2026-09-06; browser delivery to z7

Licence

NASA/USGS public scientific data; retain mission and provider attribution

Attribution

NASA/JHUAPL/Carnegie Institution/ASU; USGS Astrogeology; NASA/JPL Mercury Trek

Source checked

2026-09-06

Limitations COSMOS discloses

• No terrain displacement
• Static mosaic does not change with ephemeris date
• Detail stops at the delivered imagery ceiling
• No terrain displacement: the globe is a mean-radius sphere, not a shape model.
• The underlying MESSENGER BDR reference product is 166.31 m per pixel, but COSMOS does not claim that resolution is delivered in the browser; the delivered matrix is the 665 m per pixel Trek colour map.
• Only two level-0 parent tiles are packaged locally; deeper refinement is requested from NASA Trek and falls back to those parents when the service is unavailable.
• Position is interpolated inside 2020-01-01 00:00 TDB through 2040-01-01 00:00 TDB; requesting an epoch outside that window is rejected instead of extrapolated.