Mars
Measured by RAD on Curiosity. A 500-day surface stay plus the round trip is roughly 1 Sv — near the career limit NASA sets for an astronaut.
Surface conditions on Mars
Every figure below is tagged with where it came from. Measured means an instrument read it on or at the body; modeled means it was computed and never directly observed.
What it would take to settle Mars
No world off Earth is habitable — the honest habitable fraction of every surface here is zero. What can be answered is how far each one sits from Earth along the seven axes a habitat has to buy its way out of. Mars scores 26.6 out of 100, on 100% coverage of the axes. The single worst axis here is pressure (6.4 mbar); the one that most sets Mars apart from the other thirteen is radiation.
Below the Armstrong limit (0.062 bar) body fluids boil at body temperature — the difference between needing a mask and needing a pressure vessel. Above 1 bar the problem inverts into containment, and Venus at 92 bar has never let a lander live two hours.
Shielding is mass, and mass is the single most expensive thing to move. Above roughly 1 mSv/day a surface habitat has to be buried.
Delta-v sets what a launch costs; cruise time sets how much consumable, shielding and crew patience each kilogram of payload drags with it.
Both directions cost power continuously. A cold world burns reactor output to stay warm; a hot one has no cold sink to dump heat into at all.
Who has been to Mars
Ten successful soft landings by three agencies. Every one of them arrived with no way home.
Unprotected survival: About two minutes. At 6 mbar your saliva boils before you suffocate.
Polar caps, buried glaciers at mid-latitudes, and ice within a metre of the surface across a third of the planet (Mars Odyssey neutron spectrometer, SHARAD radar).
The named places on Mars
The IAU has approved 2,049 names on Mars, each drawn from a theme the naming committee chose for this world. Every name in the scene above is one of them, placed at its catalogued coordinates.
Sources
- Viking Orbiter VIS — Viking colour mosaic, 232 m/px (NASA Trek / USGS Astrogeology)
- IAU / USGS Gazetteer of Planetary Nomenclature
- Hassler et al. 2014, Science — MSL RAD surface radiation
- USGS — Viking MDIM 2.1 colour mosaic
Imagery is public-domain NASA/USGS mission data, streamed live from NASA Trek as a plate-carrée tile pyramid and draped on our own sphere — no third-party globe library and no cached copy of anyone else's map.