"mars.txt" mentioned: rephrase for survey context, or delete?

[katrinleinweber]

Hi! There are a handful of "mars" mentions left. Do you want those to be rephrased if fitting to the new context, or rather deleted?

[tmorrell]

Looks like the only remaining example in the lesson is in section 08. This could be modified to use the
new lesson screenshot images from section 04. The other two mars.txt examples are in supplemental sections, so not critical to change.