She saw the twinkle in his eyes and nearly laughed. Hassan’s mouth jerked around in an anthology of irritated angles. She noticed that his beard was like a sheen of dirt. Not reddish actual Mars dirt, just grunge. Maybe he was too busy to take his one-per-day allowed shower. Worrying sure can take it out of you.

“What makes you think the Mat wanted you go to there, disturb it?”

“I, uh, we followed the alien. Had no choice.”

Hassan’s eyes narrowed. “I shall file a formal report on this clear breach of protocols.”

Rachel got up, stretched, allowed herself a yawn. Two descents in a day… “By the time Earthside processes it, other events will make it irrelevant.”

Hassan eyed her. “Such as?”

“Plenty.”

The next turn surprised her, though.

The alarm came at night. She stumbled out of Zuminski’s cabin in a hastily thrown-on robe. Some people in the corridor raised eyebrows when they saw her with Zuminski, but the excitement and alarm swept all that away. They all flocked into the communal room and watched the big screen at one end. Somebody was explaining, but the sight of the night sky was the point.

Cameras atop the habitat had alerted them. Feeds let them all see it. A smudge of light hovered on the horizon. It was a pale white cloud, linear, fuzzier at one end. It seemed to point downward. The camera was looking north, and the cloud glowed. A pale ivory finger of illumination spiked up from the surface, broadening. It came from the vent, Rachel knew instantly—an impossibly brilliant outpouring.

Zuminski gasped. “Mat is outgassing.”

A spire of light forked up, luminescence dancing in the filmy cloud, probing with colors that shifted from blue-green to a reddish amber.

Fraq’s crew stood nearby, staring up, eyes wide.

To poke such a glistening probe of light into the sky must have cost the Mat enormous energies, she thought. To make it, the vent would first have to expel a gusher of vapor. Then the entirety of the Mat would have to pour its reserve energy into the pale glow, coherently.

That took coordination—venting vapor, then pulsing the Mat glow. Over a large scale.

The pearly lance, jutting up—a signal? celebration? alarm? Her mind whirled giddily. With so much energy expended, there must be some purpose.

It was natural to see this as a pointed message, but there are many behaviors in biology that defy easy logic. She knew what she would like to believe, but… She closed her eyes to fix the image in memory. An ivory plume, towering kilometers into the sky, mingling with the gleaming stars. Bright displays played in the solemn sky.

So much to learn…. She could stay here a lifetime and not know it all.

How does the Mat do this? From the first, Earthside biologists had been unable to figure out the cycle of life between the surface—dead, sterilized by ultraviolet and solar winds—and the anaerobic underground life zone. Extending more than twenty kilometers down, there was a Byzantine spaghetti of life zones.