Mars is a dry, dead world with no water
The old claim turned out to be wrong and was rejected by evidence.
TaughtMars might have had water long ago, but today it is a dry desert. Any water is speculation.
NowMars Odyssey detected vast subsurface hydrogen in 2002, and NASA's Phoenix lander physically touched and identified water ice in the Martian soil in 2008. There is enough ice at the poles to cover the planet in a global ocean meters deep.
What actually happened
Mariner 4's flyby in 1965 returned images of a cratered, moon-like surface and killed a century of speculation about Martian canals and civilizations. The pendulum swung hard: Mars became the dead planet.
It swung back gradually. Mars Global Surveyor and Mars Odyssey found mineral and hydrogen signatures pointing to buried ice. In 2008 the Phoenix lander, sitting in the northern arctic plains, scraped a trench, exposed a bright material, and watched it sublimate away over several days, exactly as water ice would. Its instruments confirmed it. Later radar from Mars Express and the Mars Reconnaissance Orbiter mapped enormous buried glaciers at mid-latitudes.
What remains genuinely unsettled is liquid water today. Claims about seasonal briny flows and a subglacial lake under the south pole are contested, and some are now better explained by dry processes. Ice, however, is not in doubt.
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Sources
- NASA: Phoenix lander confirms water ice on Marsjpl.nasa.gov
- NASA Science: Water on Marsscience.nasa.gov
Who was taught this
Still standard through 2008, so anyone who finished school between 1950 and 2008 learned the earlier version.