June 13, 2014
Despite Inhospitable Temperatures, Mars Lacks Frigid Wind Chills
Brett Smith for redOrbit.com - Your Universe Online
While the average planet-wide temperature on Mars is a frigid -81 degrees F and the lowest winter temperatures can get down to -184 degrees F, the Red Planet is much more hospitable than those temperatures would suggest due to a lack of wind chill, a new study has found.
The wind chill temperature on Earth is always colder than the thermometer reading, but on Mars the temperature would feel as much as 200 degrees F hotter than the thermometer reading – according to the new report published in the Bulletin of the American Meteorological Society.
Study author Randall Osczevski, an environmental physicist who recently retired from Defence Research and Development Canada in Toronto, said Mars has very negligible wind chill because of its wispy thin atmosphere. On the Martian surface, atmospheric pressure is under one percent what it is on Earth at sea level, equivalent to the pressure in Earth’s atmosphere at an altitude about 2.5 times the cruising heights of jet aircraft.
Even if the Martian winds were to blow at 60 mph, the thin air wouldn't be able to remove much heat from the surface. Combine this with the fact that the Sun shines about as warm as it is does on Earth and the “feels like” temperature is actually much higher than the temperature shown on a thermometer, Osczevski said in his report.
“I hadn’t really thought about this before, but I’m not surprised,” Maurice Bluestein, a biomedical engineer and wind chill expert from Indiana University–Purdue University Indianapolis (IUPUI), said about the study to Science Magazine. The study findings, he added, “will be useful, as people planning to colonize Mars need to know what they’re getting themselves into.”
According to calculations in the new study, the Earth-equivalent high temperature for the typical summertime afternoon on Mars where NASA’s Pathfinder landed in 1997 is nearly 34 degrees F.
“In this aspect, at least, Mars doesn’t seem to be as environmentally harsh as people generally expect,” says Robert Zubrin, an aerospace engineer and founder of the Mars Society.
Osczevski warned how heat loss due to wind would still be an issue on Mars, albeit to a smaller degree. For instance, a Mars explorer exposed to 9.3 mph winds in –40 degrees F would lose only 60 percent as much heat as someone in the Arctic in the same conditions. Just 30 percent of that heat loss would be due to convection enabled by Mars’s thin air and most of the rest would be lost through radiation of heat.
The study author noted this different type of heat loss means engineers will need to create space suits that prevent heat from radiating away. Despite reaching the conclusion of a more hospitable planet, Osczevski said Mars explorers will need to be outfitted with the proper gear to ensure they do not lose too much heat.
“Picking up a rock from the shade will be like picking up a lump of dry ice,” he said.