Phoenix Mars Lander

Phoenix

Agency

NASA / University of Arizona

Launched

2007-08-04

Landed

2008-05-25

Operated

152 sols (last contact 2008-11-02)

Technical Details

Agency	NASA / University of Arizona
Country	🇺🇸 USA
Landing Site	Green Valley, Vastitas Borealis (68.22°N, 125.7°W)
Power System	Solar panels (degraded and eventually buried by polar winter frost)
Mass	350 kg

Key Findings

1.Confirmed the presence of water ice just below the Martian surface at high latitudes — directly observed ice with the robotic arm
2.Discovered perchlorates in Martian soil — likely explaining the Viking biology experiment results and the absence of organics in Viking GC-MS data
3.Measured soil pH of 7.7 ± 0.5 (neutral-to-alkaline), similar to terrestrial soils in which some life thrives
4.Observed snowfall falling from water-ice clouds — the first confirmed precipitation on Mars
5.Operated 152 sols, nearly 70% beyond its 90-sol design life, before polar winter darkness ended the mission

Mission Outcome

Phoenix directly confirmed subsurface water ice at high Martian latitudes and fundamentally altered understanding of Martian soil chemistry through the discovery of perchlorates. Its TEGA and MECA instruments revealed a soil environment more complex — and potentially more habitable — than previously believed. The mission ended when polar winter darkness depleted its solar-powered batteries in November 2008.

Sources

[1] NASA Mars Exploration Program — retrieved 2026-06-01
[2] NASA NSSDCA — retrieved 2026-06-01

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