Modeling of volatile contamination transport for surface operations of the Mars Science Laboratory

Brian Blakkolb; Ira Katz; Ioannis Mikellides

doi:10.1117/12.796092

2 September 2008 Modeling of volatile contamination transport for surface operations of the Mars Science Laboratory

Brian Blakkolb, Ira Katz, Ioannis Mikellides

Proceedings Volume 7069, Optical System Contamination: Effects, Measurements, and Control 2008; 70690G (2008) https://doi.org/10.1117/12.796092
Event: Optical Engineering + Applications, 2008, San Diego, California, United States

Abstract

Gas-phase contamination modeling for space systems typically looks at the free molecular flow regime, Knudsen number » 1, wherein transport is characterized by collisionless motion of contaminant molecules and deposition proportional to grey- or black-body view factors. Such an approach, however, was not applicable to the contamination transport environment [to be] encountered by the NASA Mars Science Laboratory (MSL) during surface operations on the Red Planet. For MSL, we required an understanding of contaminant transport under the Mars-ambient conditions of an approximately 8 Torr CO2 atmosphere in order to provide traceability between hardware outgassing limits and the allowable vapor-phase contaminant concentrations in the vicinity of atmospheric sampling sensors and deposition to prospective solid sample sites on the Martian surface. In setting outgassing requirements for the MSL surface system, an engineering upper-bound estimate--rather than a precise result based on an all-inclusive simulation of the dynamic flow field--of the local contamination density was needed. Here we describe a 3-D, low-speed computational fluid dynamics approach, including molecular diffusion, to determine mixing ratios of contaminants at the atmospheric sample inlets and solid sample inlet deposition rates. Turbulence enhances the effective diffusion, leading to the dilution of the volatile contaminants, which reduces contamination concentration at a distance far from the source in comparison to inviscid or laminar flow fields: Therefore, the approach employed here results in a conservative upper bound compared to one in which turbulence is explicitly addressed. Because contaminant transport in this environment (Peclet number in the range of 50-1000) is advection dominated, spatial contamination concentration is a strongly-peaked function of the wind direction. Results of sample calculations for expected Mar wind speeds (u = 1-20 m/s) and several wind directions are presented.

Citation Download Citation

Brian Blakkolb, Ira Katz, and Ioannis Mikellides "Modeling of volatile contamination transport for surface operations of the Mars Science Laboratory", Proc. SPIE 7069, Optical System Contamination: Effects, Measurements, and Control 2008, 70690G (2 September 2008); https://doi.org/10.1117/12.796092

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available