Ice mountains
July 15, 2015 at 11:33 PM by Dr. Drang
Like many of you, I’ve been following this week’s news on the New Horizon’s close approach of Pluto and marveling at the photos. Today (or maybe it was last night) we got this early image of mountain ranges near the equator:
Image from NASA.
The big news in NASA’s accompanying article is that the mountains appear to be relatively young, surprising on a body that isn’t subject to tidal deformations. But I was struck by this passage:
The mountains are probably composed of Pluto’s water-ice “bedrock.”
Although methane and nitrogen ice covers much of the surface of Pluto, these materials are not strong enough to build the mountains. Instead, a stiffer material, most likely water-ice, created the peaks. “At Pluto’s temperatures, water-ice behaves more like rock,” said deputy GGI lead Bill McKinnon of Washington University, St. Louis.
Water ice, although not as deeply studied as a structural material as, say, steel or aluminum, has fairly well known strength and stiffness properties. When I was in college and casting about for a topic for my senior design project, I briefly considered designing a structure for polar regions. In my preliminary research, I found several references on the use of ice as a building foundation. And ice roads get built across the northern reaches of Canada and Alaska every year, so there’s a lot of experience, lab testing, and published literature on the structural properties of water ice. But who studies the strength of methane and nitrogen ice enough to know that you can’t build mountains out of them?
Planetary scientists, that’s who. This is another in a long list of examples proving that other people have jobs that are much cooler than yours or mine.
