Introduction to special section on the Phoenix Mission: Landing Site Characterization Experiments, Mission Overviews, and Expected Science

Abstract

Phoenix, the first Mars Scout mission, capitalizes on the large NASA investments in the Mars Polar Lander and the Mars Surveyor 2001 missions. On 4 August 2007, Phoenix was launched to Mars from Cape Canaveral, Florida, on a Delta 2 launch vehicle. The heritage derived from the canceled 2001 lander with a science payload inherited from MPL and 2001 instruments gives significant advantages. To manage, build, and test the spacecraft and its instruments, a partnership has been forged between the Jet Propulsion Laboratory, the University of Arizona (home institution of principal investigator P. H. Smith), and Lockheed Martin in Denver; instrument and scientific contributions from Canada and Europe have augmented the mission. The science mission focuses on providing the ground truth for the 2002 Odyssey discovery of massive ice deposits hidden under surface soils in the circumpolar regions. The science objectives, the instrument suite, and the measurements needed to meet the objectives are briefly described here with reference made to more complete instrument papers included in this special section. The choice of a landing site in the vicinity of 68°N and 233°E balances scientific value and landing safety. Phoenix will land on 25 May 2008 during a complex entry, descent, and landing sequence using pulsed thrusters as the final braking strategy. After a safe landing, twin fan‐like solar panels are unfurled and provide the energy needed for the mission. Throughout the 90‐sol primary mission, activities are planned on a tactical basis by the science team; their requests are passed to an uplink team of sequencing engineers for translation to spacecraft commands. Commands are transmitted each Martian morning through the Deep Space Network by way of a Mars orbiter to the spacecraft. Data are returned at the end of the Martian day by the same path. Satisfying the mission's goals requires digging and providing samples of interesting layers to three on‐deck instruments. By verifying that massive water ice is found near the surface and determining the history of the icy soil by studying the mineralogical, chemical, and microscopic properties of the soil grains, Phoenix will address questions concerning the effects of climate change in the northern plains. A conclusion that unfrozen water has modified the soil naturally leads to speculation as to the biological potential of the soil, another scientific objective of the mission.

Scalloped terrains in the Peneus and Amphitrites Paterae region of Mars as observed by HiRISE

“…At the same latitudes, landforms possibly as young as one million years old have been interpreted as evidence of recent localized reworking of the martian surface by the action of near-surface ground ice (Malin and Edgett, 2000;Baker, 2001;Mustard et al, 2001). Direct evidence of the presence of ground ice at high latitudes (68.22°N) on Mars has been provided by the Phoenix lander (Arvidson et al, 2008), which found widespread icy soil only a few centimeters below the surface, under a desiccated layer of soil (Smith, 2009). Although this ice was found at high latitude, its presence reinforces the possibility of the existence of similar icerich ground in the mid-latitudes, possibly in lower amounts and/ or at a greater depth.…”

Field Measurements of Terrestrial and Martian Dust Devils

“…NASA's Mars Phoenix spacecraft (Smith et al 2008(Smith et al , 2009 . Equipped with the Surface Stereo Imager (SSI), with adequate resolution to image dust devils, and a high-resolution pressure sensor, Phoenix became the second Mars lander, after Pathfinder, that had the capacity to detect dust devils both visually and by meteorological measurements.…”

Phoenix surface mission operations processes

“…For an overview of the Phoenix mission, see Smith et al [2008]. The suite of scientific instruments Phoenix is bringing to Mars will enable it to better understand the history of Martian water by examining the chemistry and mineralogy of arctic soils and ice.…”