haqqmisra.net » early mars

Cold Oceans on Early Mars

Jacob — Wed, 26 Oct 2011 19:38:02 +0000

Billions of years ago, the planet Mars appears to have been covered by a liquid water ocean. Geologic evidence of riverbeds, deltas, canyons, and other features in the Martian landscape all suggest that a flowing liquid once meandered on the surface of the red planet. Even so, the fainter young sun at the time, combined with Mars’ orbital distance from the sun, suggests that even a wet early Mars was probably quite chilly.

In a recent paper published in Nature Geoscience, on which I am a co-author, we examine the idea that early Mars featured a cold glacial ocean on its northern hemisphere. This study combines some theoretical climate calculations (which was my contribution) along with a mineralogical analysis to reach this conclusion. In particular, the formation of minerals known as phyllosilicates would have been prevented in a cold ocean, which may explain the scarcity of phyllosilicates observed in the northern martian hemisphere today.

And if oceans did exist on Mars billions of years ago, then perhaps the processes of life also could have arisen in the early history of the red planet. Mars today appears barren and lifeless, but signs of past or present life could very well be lurking beneath the soil. Future Mars missions, and possibly human exploration, will eventually help to uncover this mystery.

Sulfur Can’t Keep Mars Warm

Jacob — Mon, 28 Jun 2010 15:30:13 +0000

Satellites and rovers sent to Mars keep giving us compelling geologic evidence that liquid water flowed on the surface of the red planet in the distant past. Three billion years ago, when oceans may have existed on parts of Mars, the sun was about 30% fainter. Mars today is well below the freezing point of water, so any lakes or oceans would be frozen over. In the distant past, then, this problem is even more pronounced: how was Mars able to stay warm enough to sustain liquid water?

Many attempted resolutions have been proposed to this problem, but none has provided a complete solution for a warm, wet early Mars. In a recent paper published in Earth and Planetary Science Letters, on which I am a co-author, we argue that greenhouse warming by sulfur dioxide could not have kept early Mars warm enough. Sulfur dioxide has been suggested in the literature because it is an effective greenhouse gas, similar to carbon dioxide or methane. However, we show that atmospheric photochemistry with sulfur dioxide leads to the production of sulfate aerosols in the upper atmosphere that absorb incoming sunlight and cool the surface. Thus, sulfur dioxide may have caused net cooling on early Mars, rather than warming.

We’re still trying other mechanisms to explain a warm, wet early Mars. Most likely, it was some combination of processes, including several greenhouse gases and warming by clouds. A negative result for sulfur dioxide is not as exciting as a solution to the early Mars problem, but it’s still a small step forward.

AbGradCon Ho!

Jacob — Mon, 13 Apr 2009 18:36:16 +0000

My abstract on “Warming Early Mars with NO2″ has been accepted for a talk at this summer’s Astrobiology Graduate Conference! I’ll discuss a possible mechanism by which early Mars (3 billion years ago) could have sustained above-freezing temperatures as well as liquid water with a carbon dioxide/water vapor/nitrogen dioxide greenhouse effect. We are currently putting the finishing touches on our manuscript before submitting it to Earth & Planetary Science Letters in a week or so.

The organizers of AbGradCon09 have done a great job of putting together an excellent conference, including a field trip to Mt. St. Helens. Additionally, the conference will be broadcast live on Second Life, so if you can’t travel to Seattle you can still participate!