Like a dried-out tomato. "So the surface is wrinkled."

"Yes. There are rupes and dorsa: ridges and lobate scarps, cliffs a couple of miles tall and extending for hundreds of miles. Great climbing country. And in some places there are gas vents, chimneys of residual thermal activity." He turned to her, corona light misty in his face plate. "So Mercury isn't really so much like the Moon at all... Look. You can see Thoth."

She looked up, following his pointing arm. There, just above the far horizon, was a small blue star.

She had her face plate magnify the image. The star exploded into a compact sculpture of electric blue threads, surrounded by firefly lights: the Thoth construction site.

Thoth was a habitat to be placed in orbit close to Sol. Irina Larionova was the consulting engineer contracted by Superet to oversee the construction of the habitat.

At Thoth, a Solar-interior probe would be constructed. The probe would be one Interface of a wormhole, loaded with sensors. The Interface would be dropped into the Sun. The other Interface would remain in orbit, at the center of the habitat.

Thoth's purpose was to find out what was wrong with the Sun.

Irina Larionova wasn't much interested in the purpose of Thoth, or any of Superet's semi-mystical philosophizing. It was the work that was important, for her: and the engineering problems posed by Thoth were fascinating.

The electric-blue bars she could see now were struts of exotic matter, which would eventually frame the wormhole termini. The sparks of light moving around the struts were GUTships and short-haul flitters. She stared at the image, wishing she could get back to some real work.

Irina Larionova had had no intention of visiting Mercury herself. Mercury was a detail, for Thoth. Why would anyone come to Mercury, unless they had to? Mercury was a piece of junk, a desolate ball of iron and rock too close to the Sun to be interesting, or remotely habitable. The two Thoth exploratory teams had come here only to exploit: to see if it was possible to dig raw materials out of Mercury's shallow -- and close-at-hand -- gravity well, for use in the construction of the habitat. The teams had landed at the South Pole, where traces of water-ice had been detected, and at the Caloris Basin, the huge equatorial crater where -- it was hoped -- that ancient impact might have brought iron-rich compounds to the surface.

The flitters from Thoth actually comprised the largest expedition ever to land on Mercury.

But, within days of landing, both investigative teams had reported anomalies.

Larionova tapped at her suit's sleeve-controls. After a couple of minutes an image of Dolores Wu appeared in one corner of Larionova's face plate. Hi, Irina, she said, her voice buzzing like an insect in Larionova's helmet's enclosed space.

Dolores Wu was the leader of the Thoth exploratory team in Caloris. Wu was Mars-born, with small features and hair grayed despite AntiSenescence treatments. She looked weary.