Mädler (Martian crater)
Mädler is a large impact crater on Mars, centered at 10.68° south latitude, 2.70° east longitude (357.30° west longitude) in the planet's southern hemisphere, with a diameter of about 125 km.1 It is named for the German astronomer Johann Heinrich Mädler, who directed the observatory at Dorpat in Tartu, Estonia, and who with his collaborator Wilhelm Beer produced the first accurate maps of Mars in the early 1830s.2
| Key fact | Detail |
|---|---|
| Feature type | Crater, Mars; Gazetteer Feature ID 40921 |
| Diameter | 125.00 km (control-network value); 124.16 km for the mapped polygon1 |
| Center | Latitude −10.68°, longitude 2.70° E (357.30° W)1 |
| Extent | From 9.59° S to 11.67° S and 1.70° E to 3.80° E1 |
| Floor character | Described in a NASA landing-site study as a smooth-floored, ancient crater of roughly 100 km diameter3 |
| Namesake | Johann Heinrich Mädler, German astronomer and director of the Dorpat observatory, co-maker of the first accurate Mars maps (early 1830s)2 |
Location and dimensions
The Gazetteer of Planetary Nomenclature, maintained by the U.S. Geological Survey, lists Mädler as a crater on Mars with Feature ID 4092. Its bounding coordinates place it between 9.59° and 11.67° south latitude and between 1.70° and 3.80° east longitude, near the Martian equator but slightly south of it.1 The gazetteer records two diameter values: 125.00 km for the control-network definition and 124.16 km for the digitized polygon boundary, a difference that reflects how the rim is traced rather than any change in the feature itself.1
Floor and interior
A NASA proposal for the Mars 2001 mission described Mädler as a smooth-floored, ancient crater approximately 100 km in diameter, centered at 11° S, 357° W, and proposed it as a landing site. The study argued that investigating the nature and composition of the materials forming the crater floor would provide opportunities to test many hypotheses about hydrogeological processes on Mars.3 The smooth floor is the property that made the site attractive for this purpose, since a level, ancient surface records the history of any water or sediment that once occupied the basin.
The interior contains younger impact features of its own. The High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter imaged a well-preserved 12-kilometer-diameter crater inside Mädler Crater (image ESP_020916_1695), a fresh feature superposed on the older basin.4
Naming
Planetary crater names on Mars honor scientists and others who contributed to the study of the planet, and Mädler follows this convention. Johann Heinrich Mädler (1794–1874) was a German-born astronomer who served as director of the observatory at Dorpat (Tartu, Estonia).2 A smaller lunar crater also named Mädler, 27.58 km across, is a separate feature in the same nomenclature system.5
References
- Mädler, Gazetteer of Planetary Nomenclature, USGS Astrogeology Science Center
- De Tartu, Estonia, a Vitoria-Gasteiz para observar el eclipse de 1860, Cadena SER
- Mars 2001 Landing Site: Using Craters to Explore the Martian Subsurface, NASA NTRS
- Well-Preserved 12-Kilometer Diameter Crater inside Madler Crater (ESP_020916_1695), HiRISE, University of Arizona
- Mädler (lunar crater), Gazetteer of Planetary Nomenclature, USGS
Initially written Oct 21, 2026 · Edited: Oct 25, 2026
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