From a couple sites about Polar regions. Long parallel ridges in the snow formed by wind action.
No clue as to etymology. Not a spellingbee word. From article in TIME.
"It surface ripples with undulati;ng pressure ridges and solid wind hewn waves called sasturgi......"

Definition: zastruga, var. sastruga. sastruga (__________). Also zastruga; chiefly as pl. sastrugi (__). [a. G. sastruga, f. dial. Russ. zastrúga small ridge, furrow, f. zastrugát to plane, smooth, f. strug plane.] One of a series of irregular ridges formed on a snow surface by wind erosion and deposition, aligned parallel to the direction of the prevailing wind. 1840 E. J. Sabine tr. von Wrangell’s Narr. Exped. Polar Sea vii. 146 We were guided by the wave-like stripes of snow (sastrugi) which are formed, either on the plains on land or on the level ice of the sea, by any wind of long continuance. Ibid. 147 It often happens that the true permanent sastruga has been obliterated by another produced by temporary winds. 1878 E. L. Moss Shores of Polar Sea vi. 42 The sloping shore hills are barred with ‘sastrugi’–wind-made ridges of snow–but the abrupt scooped-out rifts between them are smothered over with fleecy powder in gentle undulations.