While the proposal for Phoenix was being written, the Mars Odyssey Orbiter used its gamma-ray spectrometer and found the distinctive signature of hydrogen on some areas of the Martian surface, and the only plausible source of hydrogen on Mars would be water in the form of ice, frozen below the surface.
The mission was therefore funded on the expectation that Phoenix would find water ice on the arctic plains of Mars.
In August 2003 NASA selected the University of Arizona "Phoenix" mission for launch in 2007.
It was hoped this would be the first in a new line of smaller, low-cost, Scout missions in the agency's exploration of Mars program.
The selection was the result of an intense two-year competition with proposals from other institutions.
The $325 million NASA award is more than six times larger than any other single research grant in University of Arizona history.

Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory, as Principal Investigator, along with 24 Co-Investigators, were selected to lead the mission.
The mission was named after the Phoenix, a mythological bird that is repeatedly reborn from its own ashes.
The Phoenix spacecraft contains several previously built components.
The lander used for the 2007–08 mission is the modified Mars Surveyor 2001 Lander (canceled in 2000), along with several of the instruments from both that and the previous unsuccessful Mars Polar Lander mission.
Lockheed Martin, who built the lander, had kept the nearly complete lander in an environmentally controlled clean room from 2001 until the mission was funded by the NASA Scout Program.

Phoenix was a partnership of universities, NASA centers, and the aerospace industry.
The science instruments and operations were a University of Arizona responsibility.
NASA's Jet Propulsion Laboratory in Pasadena, California, managed the project and provided mission design and control.
Lockheed Martin Space Systems built and tested the spacecraft.
The Canadian Space Agency provided a meteorological station, including an innovative laser-based atmospheric sensor.
The co-investigator institutions included Malin Space Science Systems (California), Max Planck Institute for Solar System Research (Germany), NASA Ames Research Center (California), NASA Johnson Space Center (Texas), MacDonald, Dettwiler and Associates (Canada), Optech Incorporated (Canada), SETI Institute, Texas A&M University, Tufts University, University of Colorado, University of Copenhagen (Denmark), University of Michigan, University of Neuchâtel (Switzerland), University of Texas at Dallas, University of Washington, Washington University in St. Louis, and York University (Canada).
Scientists from Imperial College London and the University of Bristol provided hardware for the mission and were part of the team operating the microscope station.

On June 2, 2005, following a critical review of the project's planning progress and preliminary design, NASA approved the mission to proceed as planned.
The purpose of the review was to confirm NASA's confidence in the mission.
While the proposal for Phoenix was being written, the Mars Odyssey Orbiter used its gamma-ray spectrometer and found the distinctive signature of hydrogen on some areas of the Martian surface, and the only plausible source of hydrogen on Mars would be water in the form of ice, frozen below the surface. The mission was therefore funded on the expectation that Phoenix would find water ice on the arctic plains of Mars. In August 2003 NASA selected the University of Arizona "Phoenix" mission for launch in 2007. It was hoped this would be the first in a new line of smaller, low-cost, Scout missions in the agency's exploration of Mars program. The selection was the result of an intense two-year competition with proposals from other institutions. The $325 million NASA award is more than six times larger than any other single research grant in University of Arizona history.
Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory, as Principal Investigator, along with 24 Co-Investigators, were selected to lead the mission. The mission was named after the Phoenix, a mythological bird that is repeatedly reborn from its own ashes. The Phoenix spacecraft contains several previously built components. The lander used for the 2007–08 mission is the modified Mars Surveyor 2001 Lander (canceled in 2000), along with several of the instruments from both that and the previous unsuccessful Mars Polar Lander mission. Lockheed Martin, who built the lander, had kept the nearly complete lander in an environmentally controlled clean room from 2001 until the mission was funded by the NASA Scout Program.
Phoenix was a partnership of universities, NASA centers, and the aerospace industry. The science instruments and operations were a University of Arizona responsibility. NASA's Jet Propulsion Laboratory in Pasadena, California, managed the project and provided mission design and control. Lockheed Martin Space Systems built and tested the spacecraft. The Canadian Space Agency provided a meteorological station, including an innovative laser-based atmospheric sensor. The co-investigator institutions included Malin Space Science Systems (California), Max Planck Institute for Solar System Research (Germany), NASA Ames Research Center (California), NASA Johnson Space Center (Texas), MacDonald, Dettwiler and Associates (Canada), Optech Incorporated (Canada), SETI Institute, Texas A&M University, Tufts University, University of Colorado, University of Copenhagen (Denmark), University of Michigan, University of Neuchâtel (Switzerland), University of Texas at Dallas, University of Washington, Washington University in St. Louis, and York University (Canada). Scientists from Imperial College London and the University of Bristol provided hardware for the mission and were part of the team operating the microscope station.
On June 2, 2005, following a critical review of the project's planning progress and preliminary design, NASA approved the mission to proceed as planned. The purpose of the review was to confirm NASA's confidence in the mission.
Phoenix (spacecraft)