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Let's go to Mars

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water

9 milestones, in chronological order.

  1. c. 3.8 billion years agoFormation

    Rivers run, and an ocean nobody can prove

    Thousands of branching valleys and a delta in Jezero crater show water flowed for a long time. Whether it ever pooled into a northern ocean is still argued.

  2. 18 February 1993The Rover Decades

    Mars's tilt turns out to be chaotic

    Two 1993 calculations showed the Martian axis wanders chaotically — one integration ran it from 11 to 49 degrees over 80 million years. The present 25.19 degrees is a low value, not a constant.

  3. 12 September 1997The Rover Decades

    Mars Global Surveyor maps the planet Mars Observer lost

    Mars Observer died three days short of orbit in 1993. Its instruments were rebuilt as Global Surveyor, which found fossil crustal magnetism and geologically fresh gullies.

  4. 28 May 2002The Rover Decades

    Odyssey counts neutrons and finds buried ice

    Neutron counts fell away over both poles. Odyssey read that as ice within a metre of the surface — by one estimate enough to fill Lake Michigan twice, and a target for landers.

  5. January 2004The Rover Decades

    Spirit and Opportunity find the chemistry of water

    Built for 90 sols apiece, Spirit lasted six years and Opportunity fourteen. Within eight weeks Opportunity had jarosite and hematite spherules: rock soaked in acidic water.

  6. 25 May 2008The Rover Decades

    Phoenix digs five centimetres and touches ice

    Phoenix landed on rockets at 68 degrees north and scraped down to white material. It vanished in four sols — ice, not salt — and in September the lidar watched snow fall.

  7. 12 March 2013Follow the Water

    Gale Crater held a lake you could have drunk from

    Curiosity's first drill hole, 6.4 cm into a mudstone called John Klein, produced clay, sulfur and nitrogen — and an ancient lake of fresh, neutral water.

  8. 28 September 2015 – November 2017Follow the Water

    The streaks that turned back into sand

    NASA announced briny water seeping down warm slopes. Two years later the same streaks were shown to stop exactly where dry sand stops, and the claim collapsed.

  9. 12 January 2018Follow the Water

    Ice cliffs expose clean water in the mid-latitudes

    Eight eroding scarps at 55 to 58 degrees latitude cut open water ice more than 100 metres thick, its top just 1 to 2 metres down — and visibly banded.

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