“So, what have you got for me, Mindy?” Venkat asked.

Mindy brought up the online Mars map and focused on the location of the Hab. “Acidalia Planitia is fairly smooth, especially once Mark gets out of the fractured region around the Hab. He’ll leave the last of the gullies behind by the third day of travel, assuming a seventy kilometer average daily transit. And once he gets onto Arabia Terra the continental crust is fairly smooth except for craters and ejecta. If he stays clear of craters, he should make good time. And Schiaparelli Crater has a mostly smooth floor of compacted dust. So the two major problems are getting up onto Arabia Terra and getting down into Schiaparelli.”

“Got it. What’s the solution?”

“There are only two feasible ways for the tandem rover to get up Arabia Terra,” Mindy said. “Arabia is divided from the surrounding Martian terrain by a large escarpment. I think it’s too steep for the weight the rovers will be carrying. It’s broken in only two places.” She pointed to a dry river network almost directly southeast from the Hab. “Mawrth Vallis is my choice. The river bed is uneven, broken in a couple of places, and almost certain to be full of rocks carried down its path by ancient water flows. But the overall grade is one the rover can probably manage, and it meets the level of Arabia Terra here, near Trouvelot Crater. From Trouvelot there are large gaps between major craters to allow easy driving.

“The other way isn’t as good. Mark would have to drive due south from the Hab for about fifteen sols. The escarpment is shallowest in that direction, allowing for a gradual rise in elevation. From there Mark would have to turn east-southeast, and a lot of overlapping craters will be directly in his path. Getting him through that route will be difficult. The only advantage to that route is that it’s a slightly easier ascent to altitude than Mawrth Vallis. But it’s the more difficult route, and it’s several sols longer.”

“Got it,” Venkat said. “I'll tell Mark to pack all his cameras. We’ve wanted data from Mawrth Vallis for decades. We just kept finding even more interesting places to go instead.” He reached down to Mindy’s keyboard and switched the focus of the digital map to Schaparelli. “What about getting him down off the plateau again?”

“That’s not so easy,” Mindy said. “Most of Schiaparelli’s crater walls are sheer drops. And the ground surrounding Schiaparelli to the south and east is rugged and broken- almost impossible for the tandem rover to navigate. There’s only two possibilities.”

She pointed to two spots on the map. “There’s a point just west of Edom Crater where what looks like a smaller crater broke the rim and helped form a sort of ramp down from the highlands into the crater, here on the northwest side. That’s the point closest to Mark’s line of travel, but the ramp down is really rough and questionable. In the southwest corner, not far from the Ares IV MAV, there’s a point where Meridiani Planum is almost the same altitude as the basin inside Schiaparelli’s rim, and there are passes between the rim mountains. A rover might be able to get through them, but the passes aren’t large. It’s out of his direct path, and he might end up losing days to an obstacle we haven’t spotted that he can’t get around.”

“Can we get better photographs of these sites?”

“Not much. I can try.”

“Okay, do that. But in the meantime, let’s assume this northwestern entrance is the way to go. Work up a detailed travel plan for Mark and write it up for transmission through Pathfinder. And look at some alternative routes if we run into a problem.”

“Will do,” Mindy said.

“I suspect Mark’s been too busy to think about his route himself,” Venkat continued, almost to himself. “We didn’t include any detailed maps of Arabia Terra in the Ares III data files. He’ll only have an old planetary map and a detailed map of Acidalia and Chryse Planitias. Getting this will let him focus on more urgent things.”

“Look, all I’m saying,” Dragonfly said, waving her forehooves in the multiversal calm-down motion, “is that Granny Weatherwax is the perfect Slytherin. I never said she was evil.”

“Granny is Griffindor!” Spitfire insisted, slamming the worktable as she said it.

“I thought Granny was Hufflepuff,” Cherry Berry said.

Heads turned. “Hufflepuff?” Mark asked.

“Yeah. Think tough love.”

“But wouldn’t Nanny Ogg be a better Hufflepuff?”

“Think about it,” Cherry urged. “Granny and Nanny are close friends, right? Wouldn’t they be housemates?”

“Or maybe Granny developed Nanny as a friend because she wanted the support and power,” Dragonfly pressed. “Because she’s Slytherin.”

“Look, can we at least agree that Magrat Garlick is a Ravenclaw?” Starlight Glimmer asked.

Fireball snorted. “Well, duh,” he said.

“Too obvious,” Spitfire said.

“Come to think of it,” Cherry Berry added, “what house would Ridcully be? He doesn’t seem to be afraid of anything, so I guess Griffindor.”

“He seems too stupid to be afraid,” Dragonfly said. “Which means definitely Griffindor.”

“Griffindor is not lawful stupid house!” Spitfire shouted. “Ridcully smart in his own way.”

“You know, all of this is nice,” Mark said to the world at large, “but at some point we’re going to have to do something about the three trolls guarding the back door to the opera house.”

None of the other players, nor Starlight the GM, paid the least bit of attention. “I think Hogwarts would need a fifth house for Rincewind,” the unicorn said. “With a cheetah mascot. Or something else that runs really, really fast.”

“Rincewind probably went to Durmstrang,” Fireball theorized. “A perfect place for a wizard to learn about surviving really bad things.”

The debate continued. The game session, not so much.

Author's Notes:

One of the critiques of the original book is that Acidalia/Chryse turns out to have a lot more obstacles than Andy Weir made out, that Arabia Terra is a lot smoother, and that Mawrth Vallis is a nasty obstacle course full of rocks and uneven terrain wide enough at points that the canyon walls are over the horizon, etc. etc. etc.

All set up at Ama-Con (Amarillo Civic Center); we open to the public tomorrow. Had plenty of time today, but not the energy to write more than this.

By the way, I'm no longer going to be building buffers. When I can write ahead, I'm going to be writing the Sol 551 launch. That will be an ENORMOUS chapter, as you might expect, compared to most of the others.