Mars Phoenix Lander

The Phoenix Mars Lander is the first project in NASA's openly competed program of Mars Scout missions. Phoenix will land in icy soils near the north polar permanent ice cap of Mars and explore the history of the water in the ice while monitoring polar climate. It will serve as NASA's first exploration of potential modern habitat on Mars and renew a search for carbon-bearing compounds, last attempted with NASA's Viking missions in the 1970s.

The Phoenix landing on May 25th will be on arctic ground where a mission currently in orbit, Mars Odyssey, has detected high concentrations of ice just beneath the top layer of soil.

A stereo color camera and a weather station will study the surrounding environment while the other instruments check samples of soil and ice for evidence about whether the site was ever hospitable to life. Microscopes will reveal features as small as one one-thousandth the width of a human hair.

Like its namesake mythological bird, Phoenix rises from remnants of its predecessors. It will use many components of a spacecraft originally built for a 2001 Mars lander mission, which was kept in careful storage after that mission was cancelled. The science payload for Phoenix includes instruments built for the 2001 lander and improved versions of others flown on the lost polar lander in 1999.

Science Objectives
Findings from Mars Odyssey indicate the top half meter (20 inches) of Mars' surface layer is mostly ice throughout large regions of the planet pole-ward of 65 degrees north latitude. Phoenix will seek clues about the history of that ice. Is this the frozen residue of an ancient ocean? Did it diffuse into the ground from water vapor in the atmosphere? Did a retreating ice sheet leave it behind? Information such as the amount of layering, the textures of the ice and soil, and the chemical composition at different depths could distinguish among those other possibilities.

Indicators about the history of the near-surface ice, together with Phoenix instruments' observations of seasonal changes over a span of several months, will improve understanding about climate cycles on Mars. One tantalizing question is whether cycles, either short-term or long-term, might produce conditions when even small amounts of near-surface water might stay melted.

The goal of learning about ice history and climate cycles dovetails with the Phoenix mission's most exciting task--to evaluate whether an environment hospitable to microbial life may exist at the ice-soil boundary. Even if water remains liquid only for short periods between long intervals, life can persist if other factors are right, as studies of arctic environments on Earth testify. Phoenix will examine some of those other factors, such as whether organic compounds are present and whether strong oxidants in the soil make conditions too harsh for life.