Mars Exploration Program 2007 Phoenix landing site selection and characteristics

Abstract

[1] To ensure a successful touchdown and subsequent surface operations, the Mars Exploration Program 2007 Phoenix Lander must land within 65°to 72°north latitude, at an elevation less than À3.5 km. The landing site must have relatively low wind velocities and rock and slope distributions similar to or more benign than those found at the Viking Lander 2 site. Also, the site must have a soil cover of at least several centimeters over ice or icy soil to meet science objectives of evaluating the environmental and habitability implications of past and current near-polar environments. The most challenging aspects of site selection were the extensive rock fields associated with crater rims and ejecta deposits and the centers of polygons associated with patterned ground. An extensive acquisition campaign of Odyssey Thermal Emission Imaging Spectrometer predawn thermal IR images, together with $0.31 m/pixel Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment images was implemented to find regions with acceptable rock populations and to support Monte Carlo landing simulations. The chosen site is located at 68.16°north latitude, 233.35°east longitude (areocentric), within a $50 km wide (N-S) by $300 km long (E-W) valley of relatively rock-free plains. Surfaces within the eastern portion of the valley are differentially eroded ejecta deposits from the relatively recent $10-km-wide Heimdall crater and have fewer rocks than plains on the western portion of the valley. All surfaces exhibit polygonal ground, which is associated with fracture of icy soils, and are predicted to have only several centimeters of poorly sorted basaltic sand and dust over icy soil deposits.

Selection of the InSight Landing Site

“…Engineering constraints on the landing sites were fairly mature at the beginning of the project, because they were largely inherited from the PHX landing site selection (Arvidson et al 2008;Spencer et al 2009;Adams 2008;Bonfiglio et al 2011) and changed only modestly during project development. Elevation, latitude and ellipse size requirements more severely limited acceptable areas on Mars for consideration than any other successful selection activity.…”

“…The process for selecting the InSight landing site was broadly similar to that used for selection of the Mars Pathfinder (MPF) , the Mars Exploration Rover (MER) (Golombek et al 2003a), PHX (Arvidson et al 2008) and MSL (Golombek et al 2012a) landing sites, which involved close coordination between the engineering and science teams to identify potential landing sites and to assess their safety. Engineering constraints on the landing sites were fairly mature at the beginning of the project, because they were largely inherited from the PHX landing site selection (Arvidson et al 2008;Spencer et al 2009;Adams 2008;Bonfiglio et al 2011) and changed only modestly during project development.…”

Small-scale trench in the north polar region of Mars: Evolution of surface frost and ground ice concentration

“…The wind speed u at elevation 5 meters above the surface is either 5 m s −1 , or 20 m s −1 . The latter is the highest wind speed considered as acceptable for the Phoenix landing site (Arvidson et al, 2007).…”

“…The authors state, that their result are applicable to mixtures where the material properties vary at scales larger than a thermal skin depth. Analysis of high resolution HiRISE stereo images (down to 2 m length scale) indicates that in the area selected for the Phoenix landing site rocks abundances are low and slopes are typically < 3 o even at fine scales (Arvidson et al, 2007). Thus, in our work dealing with the trough up to meter scale we assume, that the surface is horizontal and initially flat.…”

NASA Mars 2007 Phoenix Lander Robotic Arm and Icy Soil Acquisition Device

“…The ISAD consists of a scoop with two blades for acquiring dry and icy soil (DIS) samples, and a rasp for rapid acquisition of hard icy soils. Very strong icy soil is expected to be encountered $1 to 10 cm beneath a cover of loose to duricrust-like soil for the chosen landing site [Smith et al, 2008;Arvidson et al, 2008;Mellon et al, 2008]. In this paper we focus on the RA and ISAD since the RAC and TECP are described in detail in companion papers (A. P. Zent et al, The Thermal Electrical Conductivity Probe (TECP) for Phoenix, submitted to Journal of Geophysical Research, 2008; H. U. Keller et al, The Phoenix Robotic Arm Camera, submitted to Journal of Geophysical Research, 2008).…”