Dec. 7, 2001 -- It might seem like the weather's getting warmer here on Earth, but Mars appears to have an even bigger global warming problem.
High-resolution images snapped by NASA's Mars Global Surveyor show that levels of frozen water and carbon dioxide at the Red Planet's poles have dwindled dramatically — by more than 10 feet — over a single Martian year (equivalent to 687 days or about two Earth years).
Touring Mars in a Parka?
Michael Caplinger of San Diego's Malin Space Science Systems points out that if the warming were to continue at the same rate (that's a big "if"), Mars could become a nearly inhabitable place for people within 5,000 years or so.
"Rather than wearing a spacesuit, you could get away with wearing just an oxygen mask and a thick parka," said Caplinger, who co-authored a study about the observations in this week's issue of Science. "It would be like standing on top of Everest."
The change in climate could also support the presence of more liquid water on Mars.
The evidence came by monitoring icy pits, ridges and mounds at Mars' south pole at the start and end of a Martian year. By comparing images in 1998 and 2001, the team noticed a dramatic widening of pits in the frozen mass and a shrinking of the mounds and ridges. The images were captured and relayed by NASA's robotic orbiter, the Surveyer, which was launched in 1996 and began orbiting Mars in 1997.
"We weren't expecting to see something nearly this large," said Caplinger.
Driving Warm and Wet Cycles
Caplinger and lead author Michael Malin, also of Malin Space Science Systems, suggest that the dwindling layers of frozen carbon dioxide could be sublimating (changing from solid to gas the same way ice cubes shrink over time in a freezer) and contributing carbon dioxide gas to the Martian atmosphere.
More carbon dioxide gas in the air would create a denser atmosphere. And a denser atmosphere insulates the planet and leads to warmer temperatures and higher evaporation points for carbon dioxide and water.
As Caplinger explains, the dramatic change observed at Mars' south pole could help scientists understand why images taken of the Red Planet's surface show signs of former lakes and rivers.
These markings suggest the planet was once much warmer and wetter, with a thicker atmosphere. Scientists are not sure what caused that to change, but this evidence indicates such changes could happen rapidly on Mars.
"We know that the pits we see at the surface today are not very old, and that they will not last very long," said Malin. "These layers of carbon dioxide are very ephemeral on a geological timescale."
CO2 Snow: It's Not Fluffy
Mars might not only change dramatically from year to year, it also appears to host very extreme seasons.
In a separate study published this week in Science, researchers analyzed the surface of Mars using a laser instrument on the Mars Surveyor and found the planet loses up to a third of its ice caps — tons of ice — every summer.
The six-month-long Martian winter, meanwhile, hosts chilling carbon dioxide snowfalls. By combining Surveyor's laser data, the team learned carbon dioxide snowfalls don't produce the same kind of powder that skiers crave.
"It's not fluffy snow," said Maria Zuber of the NASA Goddard Space Flight Center and the Massachusetts Institute of Technology. "It's almost like when snow melts and then gets very icy at the end of the winter. So the density is about that of water ice, but denser."
And, much like the weather here on Earth, Zuber and her colleague Gregory Neumann learned that weather on Mars is unpredictable and influenced by many factors.
For example, the team observed a sudden dust storm over Mars' south pole led to a spike in temperatures at the other side of the planet from about -188 degrees Fahrenheit to (a not much warmer) -135 degrees.
"It shows that most of our models of Martian weather are probably too simple," said Zuber. "Whenever you go in and look at things more closely, you find out they're a lot more complicated than you thought."