Thermal and Electrical Conductivity Probe (TECP) for Phoenix

Abstract

[1] The Thermal and Electrical Conductivity Probe (TECP) is a component of the Microscopy, Electrochemistry and Conductivity Analyzer (MECA) payload on the Phoenix Lander. TECP will measure the temperature, thermal conductivity, and volumetric heat capacity of the regolith. It will also detect and quantify the population of mobile H 2 O molecules in the regolith, if any, throughout the polar summer, by measuring the electrical conductivity of the regolith as well as the dielectric permittivity. In the vapor phase, TECP is capable of measuring the atmospheric H 2 O vapor abundance as well as augmenting the wind velocity measurements from the meteorology instrumentation. TECP is mounted near the end of the 2.3 m Robotic Arm and can be placed either in the regolith material or held aloft in the atmosphere. This paper describes the development and calibration of the TECP. In addition, substantial characterization of the instrument has been conducted to identify behavioral characteristics that might affect landed surface operations. The greatest potential issue identified in characterization tests is the extraordinary sensitivity of the TECP to placement. Small gaps alter the contact between the TECP and regolith, complicating data interpretation. Testing with the Phoenix Robotic Arm identified mitigation techniques that will be implemented during flight. A flight model of the instrument was also field tested in the Antarctic Dry Valleys during the

The Modern Near-Surface Martian Climate: A Review of In-situ Meteorological Data from Viking to Curiosity

“…Values of temperature and RH covered in the pre-flight calibration (Zent et al 2009) overlap only partially with the environmental conditions found at the Phoenix landing site ). The calibration function was revised in 2016 to correct for inaccuracies at the lowest temperatures observed at the Phoenix landing site (Zent et al 2016), but the new processed RH values are not available in the PDS yet.…”

“…Of all spacecraft landed on Mars, only the PHX and MSL carried sensors to measure the near-surface relative humidity (Table 1) (Zent et al 2009;Gómez-Elvira et al 2012). For Among the full set of REMS RH measurements, only those taken during the first four seconds after the RHS has been turned on after at least ∼5 min of inactivity are considered here.…”

“…The optical extinction coefficient derived from the LIDAR signal can then be related to the ice-water content (IWC) profile to resolve the internal structure of water-ice clouds (Whiteway et al 2009;Daerden et al 2010;Dickinson et al 2010;Moores et al 2011). In addition, Phoenix's Thermal and Electrical Conductivity Probe (TECP) was used to measure subsurface and near-surface temperature, conductivity, permittivity and humidity (Hecht et al 2008;Zent et al 2009). The TECP consisted of a single electronics box, fitted with four needles, which could be inserted into the Martian soil, and was mounted on the Phoenix Robotic Arm.…”

Calibration of non-ideal thermal conductivity sensors

“…Later on, in the frame of the Huyghens-Cassini mission, the thermal conductivity of Titan's atmosphere was determined by a probe working on the basis of the hot needle method (Hathi et al, 2007). However, the only space instrument that has measured thermal conductivity in the solid material of an extraterrestrial body other than the Moon was the TECP-instrument aboard the NASA Phoenix spacecraft, which landed on the Martian polar plains in 2008 (Zent et al, 2009(Zent et al, , 2010. The method used to evaluate the thermal conductivity measurements obtained from the TECP-instrument is described in Cobos et al.…”

Constraints on water vapor vertical distribution at the Phoenix landing site during summer from MGS TES day and night observations

“…The Phoenix lander ran a suite of surface and weather experiments in the martian northern polar region (at the location with coordinates latitude 68°N, longitude 234°E) from L s = 76.5°to 148°in MY29 (Smith et al, 2009b). In particular, the Phoenix lander Thermal and Electrical Conductivity Probe (TECP) (Zent et al, 2009;Zent, 2014) measured diurnal variations in the water vapor partial pressure (from $0.1-0.2 Pa at noon to $0.01-0.05 Pa at 2 am, corresponding to mixing ratio changes from $100 to $10 ppmm) within 2 m of the ground, which was interpreted as a manifestation of water vapor adsorption by the soil at night (Smith et al, 2009b). The Light Detection and Ranging (LIDAR) measurements (Whiteway et al, 2009) observed sporadic water ice clouds above 10 km altitude around L s = 90°.…”