Eternal Ice Age: Unusual ridges near Pluto’s Sputnik Planitia formed by ancient glaciers
Two types of ridges are positioned next to Sputnik Planitia, the basin that constitutes the western half of Pluto’s heart-shaped feature known as Tombaugh Regio. Flat regions such as basins and valley floors contain “washboard” ridges while steeper areas, such as crater walls, have “fluted” ridges. Both types of ridges connect to an apparent tectonic system at Sputnik Planitia’s edge.
Using images captured by NASA’s New Horizons mission when it flew by Pluto in July 2015, White and his team mapped the ridges’ shapes, dimensions, and distributions in an effort to uncover their origin.
Based on the ages of crater surfaces, the researchers determined the strange ridges formed approximately four billion years ago, after the giant impact believed to have created Sputnik Planitia. Computer models of the behavior of volatiles on Pluto indicated these low-elevation areas likely held nitrogen ice glaciers, which subsequently migrated into Sputnik Planitia over time.
Water ice stayed afloat at the tops of pits that contained nitrogen ice from these glaciers. Over tens of millions of years, the nitrogen ice sublimated into gas while the water ice remained behind in the form of the ridges.
“These terrains constitute an entirely new category of glacial landform that is unique to Pluto, and represent geological evidence that nitrogen ice glaciation was more widespread across Pluto in its early history prior to the formation of the Sputnik basin,” White said
Using the spacing of the ridges, the researchers created very precise maps of the glaciation coverage four billion years ago.
Findings of the study have been published in the journal Nature Astronomy.
Video courtesy of NASA Video
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.