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ESA Document - Emits - ESA

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s<br />

Figure 4-28: Mars albedo (L), ars thermal inertia(R)<br />

HMM<br />

Assessment Study<br />

Report: CDF-20(A)<br />

February 2004<br />

page 281 of 422<br />

As a preliminary approach, no particular constraints are taken regarding the landing site and the<br />

landed time, except to avoid the dust-storm period (Ls 200 to 300). A conservative approach is<br />

therefore considered based on worst-case scenarios. The following figures indicate the seasonal<br />

variation of the thermal environment and the related constraints regarding the thermal design.<br />

Hot cases are conditioned to peak intensity (at noon time) and duration of the day. The first<br />

occurs at the perihelion (Ls = 250) and the second at the solstice (Ls = 270 for the southern<br />

latitudes, Ls = 90 for the northern latitudes).<br />

In the contrast, the worst cold cases are found either with long duration night at the solstice (Ls =<br />

90 for the southern latitudes, Ls = 270 for the northern latitudes) or when Mars is at its aphelion<br />

(Ls = 70).<br />

martian day duration [hr]<br />

24<br />

21<br />

18<br />

15<br />

12<br />

9<br />

6<br />

3<br />

0<br />

0 45 90 135 180 225 270 315 360<br />

heliocentric longitude Ls [deg.]<br />

0N 15N 30N 45N 60N 75N 90N<br />

solar flux [W/m2]<br />

750<br />

700<br />

650<br />

600<br />

550<br />

500<br />

450<br />

400<br />

0 45 90 135 180 225 270 315 360<br />

heliocentric longitude Ls [deg.]<br />

Figure 4-29: Martian day duration versus latitude and Ls (L), Solar flux versus Ls (R)

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