One plasma screen showed their ground track, a few hundred kilometers from Labrador, heading east by southeast. NASA press flacks loved ground path indicators, but the things were next to useless for serious navigation. In-stead, Teresa watched the horizon’s tapered scimitar move aside to show more stars.

And hello, Mama Bear, she thought. Good to see your tail pointing where I expected.

“There’s ol’ Polaris,” Mark Randall drawled to her right. “Calculating P and Q fix now.” Teresa’s copilot compared two sets of figures. “Star tracker fix matches global positioning system to five digits, in all nine degrees of freedom. Satisfied, Terry?”

“Sarcasm suits you, Mark.” She scanned the figures for herself. “Just don’t get into the habit of calling me Terry. Ask Simon Bailie, sometime, why he came home from that peeper-run wearing a sling.”

Mark smiled thoughtfully. “He claims it was ’cause he got fresh with you on the Carter Station elevator.”

“Wishful thinking,” she laughed. “Simon’s got delusions of adequacy.”

For good measure, Teresa compared satellite and star tracker data against the ship’s inertial guidance system. Three independent means of verifying location, momentum, and orientation. Of course they all agreed. Her compulsive checking had become notorious, a sort of trademark among her peers. But even as a little girl she had felt this need — one more reason to become a pilot, then astronaut — to learn more ways to know exactly where she was.

“Boys can tell where north is,” other children used to tell her with the assurance of passed-down wisdom. “What girls understand is people!”

To most sexist traditions, Teresa had been impervious. But that one seemed to promise explanations — for instance, for her persistent creepy feeling that all maps were somehow wrong. Then, in training, they surprised her with the news that her orientation sense was far above average. “Hyperkinesthetic acuity,” the doctors diagnosed, which translated into measurable grace in everything she did.