n. One Mars day ago.
NASA, normally dedicated to uncovering cosmic mysteries, has discovered a new word: yestersol. A sol is a Martian day. Reporting on last week's Mars rover activities, a space agency website reports: "Opportunity first completed the alpha particle X-ray spectrometer work from yestersol . . ."
—“Column 8,” Sydney Morning Herald, March 24, 2004
MER-A ratted Adirondack yestersol while solar groovy, even though it was high tau in Gusev."

Rendered in plain English, the sentence would read:

"Spirit, the first Mars exploration rover, used its rock abrasion tool to grind into a rock nicknamed for an Eastern mountain range one Mars day ago while receiving adequate power from its solar panels, even though there was a large amount of dust suspended in the martian atmosphere above its landing site, named after a 19th century Russian astronomer.
—Andrew Bridges, “Mars mission spawns its own unworldly lingo,” The Associated Press, February 22, 2004
2003 (earliest)
Participating in the science team is fun but has unusual drawbacks. The scientific teams must live on Mars time. A day on Mars is 47 minutes longer than a day on Earth, Crumpler said.

"We'll basically be waking up in the Mars morning, which will be 47 minutes later each day, and uploading our commands from 'yestersol,'" he said. "Sol is what a Mars day is called. We've had to make a bunch of new terms to deal with Mars time. Of course, we haven't come up with a name for tomorrow on Mars. We're open to suggestions."
—Sue Vorenberg, “Mars Central,” Albuquerque Tribune (New Mexico), December 19, 2003
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