LMD1D v1 and v2 Comparison with Phoenix Flight Data. TEC-MTT/2012/3788/In/SL. Prepared by Stéphane Lapensée ESA-ESTEC, TEC-MTT Keplerlaan 1, 2201 AZ Noordwijk The Netherlands E-mail: [email protected] Tel.: +31 (0)71.565.8733. Phoenix Landing Site Characteristic.
LMD1D v1 and v2 Comparison with Phoenix Flight Data
Prepared by Stéphane Lapensée
ESA-ESTEC, TEC-MTTKeplerlaan 1, 2201 AZ NoordwijkThe NetherlandsE-mail: [email protected]: +31 (0)71.565.8733
Phoenix Landing Coordinates: 68.218830N 234.250778E,
Landing Mars Solar Longitude (Ls)= 76.6. Mars Spring, May 25th 2008
Albedo = 0.21, Thermal Inertia 250
Ref: Martian High latitude permafrost depth and surface-cover thermal inertia distribution: Josh Bandfield and al., 2008
Ref: RELATIONSHIPS BETWEEN REMOTE SENSING DATA AND SURFACE PROPERTIES OF MARS
LANDING SITES. M. P. Golombek and al, 2009
The following slide show the measured OD at the landing site during the mission.
There is an approximation made based on the figure since access to numerical values is not possible.
Greatest uncertainty is at the beginning of the mission, ie Sol 9 varies from 0.5 to 0.7
Access to the numerical measurement values performed at every mission Sol would reduce the uncertainty.
Ref: PHOENIX AND MRO COORDINATED ATMOSPHERIC SCIENCE. L. K. Tamppari et al., 2009
The Phoenix Lander is approximately 1m off the ground.
The temperature measurements are at 0.25m, 0.5m and 1m from the deck.
Measurements at 0.25 and 0.5m experienced perturbation from the lander deck
For comparison, the measurement performed at 1m is used.
Hence total height is 2m from the ground
There is mismatch of 1m in the comparison between LMD1D v1 and flight data, since LMD1D v1 outputs data at 1m and Phoenix flight data are at 2m
First comparison of LMD1D v2 to flight data was made using a height of 1m in order to have a direct comparison with LMD1D v1.
Following comparison of LMD1D v2 was made at 2m for one to one comparison with flight data.
The Flight measurement is estimated to be 2m from the ground. The LMD 1D flux tool input was set to 2m
It was found initially that very low Thermal inertia and high Albedo was necessary to correlate with flight data.
It was recommended to consider water ice at a depth of 5cm with an inertia of 2000.
As observed during the Phoenix Mission, clouds and ground fog appeared mid way in the mission, Sol 60 – Sol 80. Their presence affects the surface Albedo since they remained throughout the day as the mission progressed in time. Hence, it may be necessary to increase the Albedo in order to account for cloud presence.
Note: Sol 119, problem correlating in early morning. Could be caused by instrument heat dissipation since they were doing night and early morning observations
For the comparison between the LMD1D v2 and flight data, the OD values were adjusted but remained within the measurements range taking over several days.
The pressure values were measured with the flight pressure sensor
The version 2 of LMD1D temperature profile fit better to the actual flight measurement.
We can observed from the flight measurement that the lander deck does affect the measurements due to heat generated by the payloads as well as surface finish of the lander deck
The Albedo values used are within the TES measurement error except for Sol 147, which can be explained with the formation of ground fog and clouds. Sol 83 and 119 used a higher Albedo value in order to correlate, which is probably due to Cloud formation.
Thermal inertia values used are comparable to other references as long as sub-surface ice at 5cm is considered in the input parameters.