NASA’s Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at ∼1.5 m and ∼0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft.

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Thermal indicators in milk, which had been subjected to one of the six industrial processes of thermization, pasteurization, direct and indirect UHT-sterilization, pre-sterilization and in-bottle sterilization, were studied. The following three indices of heat damage were analyzed by high performance liquid chromatography (HPLC), hydroxymethylfurfural (HMF), lactulose and acid-soluble ␤-lactoglobulin(␤-LG). Average amounts found were 1710 mg/L of ␤-LG and 2.49 mol/L of HMF in pasteurized milk. In UHT milk, the amounts for direct and indirect processes were 389 and 322 mg/L of ␤-LG, 12.0 and 250 mg/L of lactulose and 5.6 and 8.7 mol/L of HMF. In sterilized milk the amounts were 1120 mg/L of lactulose and 22 mol/L of HMF, without any detectable presence of undenatured whey proteins. On the basis of the time/temperature profiles, a sterilization factor, expressed as seconds, was defined for each thermal treatment. By applying discriminant analysis each industrial process could be classified independently at the 95% confidence level (pasteurization, UHT-treatment and in-bottle sterilization), but direct-UHT treated milk could not be discriminated from indirect-UHT milk, nor thermized milk from raw bulk milk. The simultaneous application of several heat-induced parameters improves the classification of industrial processed milks, and is therefore a useful tool for optimization of the processing conditions.

5-(Hydroxymethyl)-2-furfuraldehyde (HMF) is formed upon heat treatment of milk and milkresembling systems by the Maillard reaction, via its Amadori product, and also by isomerization and subsequent degradation of sugars. Traditionally, the HMF content has been used as an indicator of both degradation routes. A new analytical approach has been developed for determining the HMF formed only by the acidic degradation of Amadori products, called bound HMF, and that could be related to the extent of the Maillard reaction due to heat treatment or long-term storage of foods. Optimal conditions for the acidic digestion procedure were determined. Reversed-phase HPLC is applied for accurate measurement of bound HMF.

New analytical techniques were used to study the kinetic behavior of 5-(hydroxmethyl) furfural (HMF) and blockage of available lysine in milk and model systems. Both determination of HMF by the chromatographic method and estimation of available lysine by the ortho-phthaldialdehyde (OPA) method at sterilization temperatures proved valid. Activation energies for the lysine loss reaction were 91.14, 112.41 and 66.67 kJ·mol−1 in the model systems and the milk respectively in fluorimetric determination with OPA. Activation energy for HMF determination ranged from 118.5 to 93.04 kJ·mol−1

Hydroxymethyfurfural (HMF) content and loss of available lysine were measured as indices of heat damage in various Spanish commercial milks (pasteurized, UHT sterilized and in‐bottle sterilized milks) with similar processing dates. HMF level was determined by the traditional colorimetric procedure and by the reversed‐phase HPLC method. Available lysine was measured by an alternative method with o‐phthaldialdehyde as fluorescent marker. A significative relationship has been found between the HMF content and loss of available lysine and both are suitable for use as heat‐induced indices. When loss of lysine (y) was expressed as percentage and HMF (x) as μm, the function of the correlation line was, y=0.47x−0.089 (r=0.958, P<,0.005).

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