Wiktionary
n. (context astronomy geology English) A long, narrow, steep-sided depression on a planet (other than Earth), a moon, or another body in the solar system.
Wikipedia
In planetary geology, a chasma (plural: chasmata) is a deep, elongated, steep-sided depression. As of January 2013, the IAU has named 118 such features in the Solar System, on Venus (63), Mars (24), Saturn's satellites Mimas (6), Tethys (2), Dione (8) and Rhea (5), and Uranus's satellites Ariel (7), Titania (2) and Oberon (1). An example is Eos Chasma on Mars.
Usage examples of "chasma".
They turn north and then south again, following a fairly even thirty-degree slope, and at last the floor of the chasma appears to the west, a light-tan plain mottled with black and ocher patches, the iceblink of the western wall flashing at the horizon more than twenty kilometers away.
By midmorn-ing they have reached the Chinese rover, squat as a black bug in the shadow of the slip face of one of the swarm of barchan dunes blown along the eastern side of the Chasma Boreale.
The Chinese are moving along the largest of these dry valleys, Chasma Boreale, which ends at crater Zw, nicknamed the Plughole.
Penn Brown is searching for a way onto the ice, but the cliffs that loom above them, although terraced, rise up from the floor of the chasma in setbacks fifty meters high.
Zw and the end of Chasma Boreale are only three hundred and fifty kilometers away.
Americans will drive down the ice-choked ramparts of Chasma Boreale and take samples from their boreholes.
They could come right up the Chasma Boreale and be on us before we know it.
It is the first of the terraced benches at the edge of the great wind-carved valley of Chasma Boreale.
Vastitas Borealis, skirting the scarp of the big Lomonsov crater and navigating the rolling dune sea to the mouth of Chasma Boreale.
Ann and Nadia and Simon took rover Three and drove back down Chasma Borealis and around to the west, where one of the glaciers curling away from the cap thinned to a perfect rampway.
Out on the flat sediment of the chasma floor there stood aical Greek temple, six Dorian columns of white marble, capped by a round flat roof.
He ran into a north-south transponder road, and followed it up a short rise to the southern rim of Melas Chasma, and got out of the rover to have a proper look.
He could just make out the gaps in distant cliffs that marked the entrances to other canyons: Ius Chasma to the west, Candor to the north, Coprates to the east.
It had been spotted at the water station in Chasma Borealis last year, during an ice fall and subsequent power outage.
On Mangalavid they saw programs about a fusion prototype in Chasma Borealis.