The Mars rover Sirius 8 (all Ares mission rovers were now called Sirius, with the already existing rovers renamed retroactively) rolled up to a well-worn hollow on the northeastern slope of the hill now officially named Amicitia Mons by the International Astronomical Union. Any tracks which might have been left by previous visitors had blown away over a complete Martian year, but the deeper ruts and hollows left behind by frequent travel had proven more resilient against the feeble Martian weather.

If a Martian, or a space probe, had been on site to witness the first new arrival in over seven hundred sols, it would have had a prolonged wait before anything else happened. Certain technologies had made enormous leaps in recent days, but others hadn't yet been affected, and rover airlocks still took several minutes to cycle and allow passengers to exit. But eventually they did: Dr. Alberto Rodriguez, the mission commander and top Project Ares field geologist; Piu Chen, a taikonaut transferred from Ares V when the decision was made to send Ares IV back to Acidalia Planitia; and Hunter Webb, the mission botanist.

If duties and the space inside a single rover had permitted, all six of the Ares IV crew would have gone to Amicitia Mons that sol. But there had been the new Ares IV Hab to unpack and assemble, the old Ares III Hab to inspect, reinflate, and re-equip with new equipment sent in special supplemental resupply flights, experiments to set up, and so forth. The others would get to visit on other sols; Ares IV had supplies for a sixty-sol excursion, thanks to the Sparkle Drive installed on Hermes, extra presupply launches powered by the new repulsor launch systems, and the unused extra supplies sent on Sleipnir 2 and Sleipnir 3. Barring more freak storms, each crew member would get their chance to visit.

But Hunter Webb had to be on the first visit for obvious reasons- to see if the cave farm which had fed the Ares III / Amicitas 3 castaways was still alive, and if so to determine its condition. Piu Chen has come as a special thank-you to the Chinese government for their help during the Ares III crisis, and also to nullify protests that NASA held too strong a monopoly on the new science of magic. And Dr. Rodriguez had to be there as commander, as the man who had trained the geology specialists of the first three Ares flights...

... and as the mission's magic specialist, having been trained by Mark Watney himself prior to launch.

The three astronauts approached the cave's airlock with caution, each carrying a large case full of tools and equipment. They'd all been instructed- again, by Mark Watney personally- on the operation of the airlock. But before they tried anything with the airlock, they were going to make certain it still functioned. They spent an hour inspecting the site, noting the thin rime of frost covering the end of the atmospheric relief valve sticking out of the mountain nearby, the three out of four status lights that still functioned, the inches-thick drifts of dust built up in the hollow the airlock sat in. They climbed up above the airlock, finding the solar collection crystals exactly as described, with only a thin layer of dust in the deepest crevices of the floral-cut quartz. They climbed back down and used compressed air to clear the doors of dust, then applied silicone lubricant as a further precaution.

Only after they had checked the door controls and the nearby fuel plant for live current and inspected the doors for any sign of corrosion or seal breach did they key in the code to open the outer airlock door. It opened reluctantly at first, but once it began moving its motion smoothed out, shortly opening wide for the astronauts to enter. Once inside, they ordered the door to close, which it did as if there had never been any hesitation in the first place. They keyed in the order to pressurize the airlock, and immediately air began to flow into the little chamber. Their suits registered the rapid rise in atmospheric pressure. as the dust they tracked into the airlock swirled in place, finding no exit.

Then, when the control panel light lit up green for equalized pressure, they opened the inner door...

... and stepped into a glittering wonderland.

The walls flickered in waves of color, rainbows sweeping from the far end of the cave up to the entrance. Thin solid strips of blue ran along the walls, dividing the light show into segments. Sunlight, significantly brighter than the natural light outside, shone down from dozens of quartz shafts in the ceiling.

And the floor of the cave was a solid mass of various shades of green. Alfalfa stood waist-high as far as the astronauts could see, blocking the view of the potato plants beyond. Young cherry trees had grown up to the ceiling along the right-hand side of the cave, their limbs stretching towards the sun-crystals above.

"Check air composition," Dr. Rodriguez said, looking around him. "I've found the Sirius 5 atmospheric system. It seems to still be operational."

"I think that's kind of obvious, Doc," Webb muttered. He pulled a piece of equipment out of his tool kit- a portable atmospheric analyzer, a tool that hadn't been available for Ares III. "Oxygen twenty-nine percent, carbon dioxide three hundred ten parts per million. Trace amounts of methane. Nothing toxic. Air pressure one point oh five atmospheres, ambient temperature twelve degrees Centigrade. I'd say it's safe to unsuit. Gonna be a bit chilly, though."

"Compared to what's outside, I believe it will be positively tropical," said Piu, who unlatched her helmet assembly first. The others followed suit, taking deep breaths of the cool air inside the cave. "It smells like old leaves," she added.

"Of course it does," Webb said. "Nobody's been here to rake up or tend the crops for two years." He wriggled out of his spacesuit, stepped away from it, and reached down to the roots of the nearest alfalfa plants, scraping a bit of soil from around the plants' bases, sniffing it, rubbing it between his fingertips. "Soil's pretty poor," he said quietly. "I'll need to take samples back to the Hab for analysis, but I'm guessing the potassium and phosphates are low. The alfalfa's a bit off its color. I don't know if it's the soil, the plants senescing, or what." He looked over to the trees and said, "The cherry trees seem to be doing all right, though."

Dr. Rodriguez didn't look away from his inspection of what had been Ares III's Rover 1 computer and atmospheric console. "But not dying, I trust?"

"I don't think so," Webb said. "Just not thriving as well as it could. The fertilizer we brought down with us should help with that. And, of course, we'll need to cut back the alfalfa to encourage fresh growth. We might even get flowers before we leave."

Piu had turned her attention to the improvised atmospheric transfer system- the line that intermittently pumped concentrated Martian air into the cave, the valve that let excess pressure out again. "The relief valve is significantly corroded on this side," she said. "The humidity of the air being released must accelerate the process. I would recommend moving up the installation of the new atmospheric regulation system."

"Just as well," Dr. Rodriguez said. "The keyboard on the computer keeps giving me errors. I suppose it's a wonder it's still running at all. It's as if a computer was left running outdoors for years at a time."

Webb had begun working his way around the left side of the cave, in the narrow gap between the wild alfalfa and the cavern wall. "Hey!" he shouted. "I've found the abandoned mana batteries!" He reached down and, with a little grunt, picked one up. "Not even any rust on the frames! How's that work?"

"I'm told that magic artifacts automatically protect themselves against decay," Dr. Rodriguez said. "I presume they're working?"

"Well, the readout on this one is pegging the meter," Webb said. "Either it's stuck that way, or it's fully charged."

"Well, we'll find out soon enough." Dr. Rodriguez stepped away from the console and walked back to where his own tool kit sat by the airlock door. "As much as I'm looking forward to exploring this cave in full, we have a responsibility to fulfill. Let's get all those batteries together and connected."

That took a little time, but before long they had eight mana batteries connected and ready to go. Dr. Rodriguez connected the leads from the batteries to a small box, which lit up the moment the leads were tight on the posts. "Likely we'll only have a few minutes of operational time," he said. "But that should be enough for this."

Dr. Rodriguez turned on the switch, and what looked like a large window opened up in the air between the little box and the cave wall. Colors swirled in the window for a moment before words appeared in two languages: Connection established.

A moment later the projection became a group of faces gathered around a console in a control room. There were some faces the astronauts recognized: the dark skin and semi-ironic smile of Dr. Venkat Kapoor, the newly promoted chief director of NASA; Captain Melissa Lewis, retired now from both the U. S. Navy and the astronaut corps, now acting as capcom; and Mark Watney, who history would remember forever as the first Martian. But there were other faces the astronauts didn't recognize among the people.

Or, rather, among the humans. There were five non-humans also in view, and anyone who'd watched the news or read the NASA reports recognized those faces, including the large pink face with blonde hair curling around huge, anxious violet-grey eyes.

But it was the first time any of the three of them had seen the pony aliens in realtime.

"Mission Control," Dr. Rodriguez said, "this is Ares IV, communications check."

"We read you, Ares IV," Lewis said. "And we see you, too."

"What's the good word on the cave, Doc?" Mark Watney interrupted. "We've got a pony ready to explode over here waiting to find out."

"The word is good, Dr. Watney," Dr. Rodriguez said politely. "Initial findings suggest the cave continues to be viable and can be sustained for future missions. The plants are alive and, though not thriving, healthy enough. " Taking a deep breath, he added, "Salvation Base is go."

Mission Control erupted into cheers, none louder than the pink pony with the blonde mane, who spun and danced and whooped with joy.

There would be quite a bit of work over the next fifty sols: bringing in the forty new mana batteries built on Earth under Equestrian guidance, planting new crops in deeper parts of the cave, replacing water lost to the improvised atmospheric control system, replacing that system with a specially designed atmospheric regulator, and- at the very end of the mission- installing The Mirror. Designed on Earth (and deliberately using much different methods than the molecule-scrambling life support crystals), The Mirror formed one end of a portal which would allow new astronauts to travel between the planets in a single step. At the end of the work, the cave would become Salvation Base, the first permanent base on Mars, and the stepping-off point for all post-Ares Mars exploration and conquest.

Of course, travel in the other direction via The Mirror would require weeks if not months of recharge time for the batteries, so Ares IV would return to Earth on Hermes... launching in the same newly-designed MSS (Mars Shuttle System) which replaced both MAV and MDV. By using a variant of the pony life support crystals to transmit fuel and oxidizer to the ship- the triply-redundant crystals kept well away from each other and from the reaction chamber- the new design did away with the weight of both, allowing the same ship to be used for descent and ascent while, at the same time, allowing larger payloads in both directions.

Massive changes had happened in two years... and yet the MSS was already obsolescent thanks not just to the Mirror but also to other advances coming from magic. Hermes itself was obsolete, and after Ares VI it would be decommissioned, turned into the core of a new space station somewhere in Earth, Mars, or lunar orbit. And as Sparkle Drive technology experiments continued, before long humanity would be able to take the next step to the outer solar system, and then to the stars, using the pony universe, with its limitless mana supply, as a free-fuel shortcut between points in Earth's universe.

And the advances in technology hardly went in one direction- as witness the presence of three ponies, a changeling and a dragon in Houston. Just as the frontiers were opening for humanity, so also were they opening for the races of Equus. They had their own universe to explore, and at the same time the mysteries of a homeworld that, by Earth standards, remained mostly empty and unexplored.

So much had changed. So much would continue to change.

... and yet, a voice none of the three Ares IV astronauts could hear proclaimed, Today, I am still here.

Author's Notes:

Happy April Fool's Day.

Except, this chapter isn't a joke. This is the "what happened?" you all requested.

I was prompted to write this when I went looking on derpiboru for images for the header for a new group I'm working on, and encountered what I devoutly hope is their idea of an April Fool's joke (or, at least, a one-day protest against the new European Union copyright laws). I saw that, gave it a moment's thought, and decided: Today's the day.

Of course, the fact that I spent most of today working on my income taxes, and that tomorrow I have to file my property tax rendition with the local appraisal district, also had something to do with it. (Plug Patreon, plug Ko-Fi, plug direct PayPal donations...)

Repeat: this chapter isn't a joke, and it's not going to be gone April 2. But it is- I hope- the very, very, VERY last writing I'll do on this project.

Now back to working on Haycartes' Pluperfect Method, if you hadn't heard about my current (almost) daily writing attempt...

OH- and sorry I couldn't fit Sojourner in here. It just didn't work. I feel guilty even giving the cave its voice without Dragonfly around to maybe be imagining it. But it's still running on its new batteries and wiring, taking pictures of rocks and being useful, which is as close as a rover can get to being happy.