Phoenix at the northern plains

Phoenix · 2008 CE · Mars

Phoenix at the northern plains — Phoenix · 2008 CE · Mars — Recorded expedition route · schematic map

Dig into the arctic ground of Mars and find out whether there is ice in it.

Historical context

In 2002 the Mars Odyssey orbiter found plentiful water ice just beneath the surface across much of high-latitude Mars. Phoenix, built on a lander left over from a mission cancelled after the loss of Mars Polar Lander in 1999, and led from the University of Arizona by Peter Smith, was sent to dig for it in the arctic plains. It landed on 25 May 2008, uncovered the ice within weeks, found perchlorate salts in the soil and watched snow fall from clouds before the autumn took away its power in November.

The voyage, step by step

  1. Down on rockets

    25 May 2008

    On 25 May 2008 the lander hit the top of the Martian atmosphere at about 5.7 kilometres a second, opened its parachute some 12.6 kilometres up, dropped free about a kilometre above the ground and came down on thrusters rather than airbags, pulsing its twelve descent engines. It touched down at 23:38 Universal Time, as the event happened on Mars, in the afternoon of the local day; the radio signal confirming it reached Earth at 23:53.

  2. Ground cracked in polygons

    2008 CE

    The first pictures, the first ever taken on the surface of Mars’ polar regions, NASA said, showed a flat plain of pebbles cut by shallow troughs into polygons. Michael Mellon’s team had measured such small polygons from orbit at three to six metres across.

  3. Dodo-Goldilocks

    19 June 2008

    The robotic arm joined two trenches, Dodo and Goldilocks, and scraped down to a hard, bright layer. Several dice-size clumps left at the bottom on sol 20 had vanished within four days, by sol 24. On 19 June 2008 the team announced that they must have been ice.

  4. Salt in the beaker

    5 August 2008

    The wet chemistry laboratory stirred spoonfuls of soil into water brought from Earth and found perchlorate salts, about half a percent of the soil’s mass, in a moderately alkaline solution. On 5 August 2008, with the result still unconfirmed, the team discussed it in public.

  5. Snow from a Martian cloud

    29 September 2008

    The Canadian lidar, a laser sounder pointed straight up, watched ice-crystal clouds form at night in late summer and caught snow falling from clouds about four kilometres above the lander. NASA announced it on 29 September 2008.

  6. The polar sun goes down

    2 November 2008

    As summer turned to autumn the nights lengthened, the sky grew dustier and colder, and the power fell away. Phoenix entered safe mode on 28 October, and the last signal came on 2 November 2008. On 10 November NASA announced that the lander had ceased communications.

Outcome

Water ice uncovered and confirmed, perchlorate salts measured and snow seen falling, over 152 Martian days.

Phoenix

Polar lander that touched down in Vastitas Borealis in May 2008, farther north than any earlier Mars lander, and dug down to water ice.

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