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saved mass.
Four telepresence robots were standing beside the fissure. They had six spindly arms, four stubby legs,
and a big central control box, all in sleek polycarbon, and she no longer found them odd. These had done
the first study, lowering themselves on cables to check for life. Long experience had shown that letting
'bots do a lot of the roving saved time and accidents.
Sometimes Julia wondered if Mars could have been explored at all without plenty of 'bots. Sitting warm
and snug in the habs, she and Viktor and rotations of crews from Earth had tried out dozens of candidate
vents.
In two decades they had found that most fissures, especially toward the poles, were duds. No life within
the top kilometers, though in some there were fossils testifying to ancient mats' attempted forays.
Natural selection-a polite term for Mars drying out and turning cold-had pruned away these ventures.
The planet's axial tilt had wandered, bringing warmer eras to the polar zones, then wandering away
again. Life had adapted in some vents, but mostly it had died. Or withdrawn inward.
Not this vent, though.
Somebody back at Gusev made the 'bots all turn and awkwardly bow as the humans approached. Julia
laughed with the others, and, as if right on cue, Praknor came on the comm. No preliminaries.
"You deliberately stood me up."
"Sorry, it was a scheduling mix-up," Julia said.
"I cannot believe-"
"Hey, got work to do here. Talk later." Julia cut off the long-range comm frequency and switched to
local, 2.3 gigahertz. And felt an impish joy that turned up her lips. When she told Viktor, he smiled, too,
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with an expression she had come to cherish. Long relationships had their rewards.
First, as always, they set up the base camp. The team was quick and precise, hustling in the forward-
leaning trot that was the most energy-efficient way to move on Mars. Every expedition now, there was
new tech to make jobs easier, like the ball tents. She watched them deploy, nearly without human effort.
Under pressure any object wants to shape into a sphere. The ball tents took advantage of this. The ball
was made of a flexible, thermally insulating material that could take wear and tear, especially the
constant rub of dust. Light wires or ropes anchored the ball to the ground as an air tank inside inflated it,
with the people already inside. A small chem cracking plant squatted beside each ball, running steadily
to split the atmosphere's CO2 for oxygen. Adding hydrogen from water let the cracker build up stocks of
methane gas and oxygen, which could then burn to drive the rover. To get powerful methane fuel
demanded only the CO2 plus water from buried ice, which was everywhere. With energy, all the
chemistry became easy.
The robots had already arranged the electrical power supply, comm and computation center, and other
backups, all now standard for a descent. Telepresence had come a long way. Bossed from the Gusev tele-
team, robots helped the humans put two tanks apiece on their lines, double-clamping them meters above
the personal yokes. She did not like the idea of that much mass ready to fall on her and checked the
clamps three times. Even robots make mistakes; maybe especially robots.
She got into the yoke, all sized and adjusted for her. Like putting on a jacket now, easy. Her shoulders
ached a bit, maybe from her swimming. She had gone back to the pool a few times, whenever she started
brooding about Andy Lang. Exercise erased cares.
"Is ready?" Viktor called. Everyone answered, "Aye!" and they began. The watch crew back at Gusev
sent them a salute, a few bright bars of John Philip Sousa.
Backing down the slope, playing out their cables, Julia looked up into a bowl of sharp stars-always
there, even at high noon. The 'bots got the oxy tanks past the Y-frame that routed the lines. There was a
neat get-around, far easier than the awkward old days.
Rappelling, bouncing in the light grav, having fun. Down the first hundred meters in good time, just
playing out the monofilament cables in a straight drop. She and Viktor were lowest and went down fast,
clicking on their suit lamps as the light from above faded. After weeks of indoor work it actually felt
good to be doing something-clean, direct, muscles and mind.
A large folded diaphragm lay at the bottom, where the fissure took an abrupt turn sideways. "Pressure
seal," Julia said, and Viktor nodded.
"Four-leaf design," Viktor observed, playing a strong beam of light over the interleaved folds. "Not see
that one for a time."
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Julia took several pictures. "Pretty thick. Got little grapplers at the edges, see? Sturdy."
In the girlhood Australian ecology, water was the rare resource. Underground Mars, its pressure was
precious. Life evolved to seal off passages, allowing a buildup of local vapor density. Then it could
hoard the water and gases it needed, building up reserves from the slow trickle from below.
The mat kept itself secured from the atmosphere with folded sticky layers, preventing moisture loss. The
vaults below were thick with vapor, but by ordinary gas dynamics that could not be sustained for long.
The valve must cut off the losses to the surface, to manage this eerie environment. A pressure lock.
But how did the valve know to close? How to respond to pressures and moisture densities? She was
convinced that the glows and vapors somehow carried messages, organizing this whole shadowy realm.
Biological organisms always had good sensors for toxics they made, their own wastes. The mat exhaled
methane and probably had sensors that opened its valves at the right time-or so said a paper with her
name on it, and she was halfway convinced. Still, progress in deciphering the mat's meanings had been
painfully slow, these two decades.
This mat valve was classic, grown at a narrow turn in the vent. As nearly as Julia and other biologists
had been able to determine, these were like Earthly stomates, the plant cells that guard openings in
leaves. Plants open or close the holes by pumping fluid into or out of the stomate cells, changing their
shape.
Still, analogies were tricky, because the mat was not a plant or an animal-both Earthly categories-but
rather another form of evolved life entirely. Not just another phylum, but another kingdom altogether.
Some thought it should be classed with the Earthly biofilms, but the mat was hugely more advanced.
Daphne knelt beside a pool covered with slime, next to the valve. The top was a crusty brown, and it
dented when she poked it with a finger. Underneath it was most likely a pool of water.
"Standard defense against desiccation," Daphne said. Julia had written a paper on that, but she said
nothing as Daphne teased apart the mat and scooped up some of the underlying liquid in a sample vial
and tucked it into her pack. Let them work, she thought. Anyway, independent confirmation is always
good. Julia's paper had concluded that the pools of liquid in mats supported mobile algal colonies, like
Volvox and other pond life on Earth. But maybe this one would prove to be different, a local adaptation.
Mars was a big place.
Julia swept her handbeam around. The mat hung here like drapes from the rough walls. Viktor was
taking high-res pictures. "The upper lip of the mat flows down," Julia pointed out. "It covers this pool, [ Pobierz całość w formacie PDF ]