13 March 2008
Ask not where Earth got its water…
For decades, planetary scientists have been arguing about how the Earth acquired its oceans. Maybe the water came from volcanic outgassing, or was delivered by icy comets, or came from a bombardment of asteroids over geologic time. Models of the Earth’s formation show that our planet didn’t form with enough water to account for its present oceans – that means the water came from somewhere else. But maybe our …
Why is Mars Lopsided?
Take a look at this topographic map of Mars. The first thing that most people notice is that the northern hemisphere is mostly lower elevation (blue), and the southern hemisphere is mostly higher elevation (red). Nobody knows why. This “dichotomy” is one of the biggest questions in Mars science, and there were several talks yesterday afternoon trying to explain it. There are two main types of theory to explain the …
12 March 2008
A Little Career Advice from Mike Griffin
If you haven’t heard, the NASA Mars Exploration Program budget is in a bit of a tight spot. The budget for the next 12 years was already going to be tricky, with the cost overruns of MSL, the delay of the 2011 Scout mission, and plans for the uber expensive 6-missions-in-1 Mars Sample Return. Now, because NASA is moving money to Outer Planets to fly a new flagship mission, the …
Martian Greenhouse: Volcanic CO2 Doesn't Cut It
With all the evidence for water on the surface of Mars in the distant past, we always return to the same question: how was it possible for water to be stable back then? These days any liquid water on the surface would boil due to the low pressure or freeze due to the low temperature (or maybe do both at the same time!). To explain liquid water on the past, …
Impacts, Occam's Razor, and Layers
The final Mars talk that I saw yesterday came at the end of a session rich with discussion of geochemistry, aqueous alteration, hydrothermal systems, and reference to the ubiquitous layers seen by both Mars rovers as being emplaced, or at least altered, by water. So I was interested to hear that the final presenter, Don Burt, has an alternative hypothesis. Burt suggested that since layers are so ubiquitious, and that …
Spiders on Mars?!
Yes, it’s true –there are multi-legged, creepy-crawly looking things on Mars. The HiRISE camera has taken pictures of a slew of these things. But don’t worry, arachnophobs – they won’t bite or lay eggs under your skin at night. They’ll just spit. The “spiders” are actually systems of channels near the south pole of Mars, as Dr. Candy Hansen explained during one of this morning’s LPSC sessions. These channels …
Networking the Moon
This afternoon I was listening to Mars talks about geochemistry, but I reached saturation. I had to go hear about somewhere else in the solar system. So, I wandered in a stupor over to the session on lunar exploration. It turns out I had good timing: I got there just in time to hear none other than Alan Stern, associate administrator of NASA’s science mission directorate, give a talk about …
11 March 2008
Layers and Swiss Cheese
No, this isn’t a post about sandwiches. There just happen to be layers and swiss cheese (terrain) in the ice caps on Mars. The morning session that I attended today was all about the north and south polar ice caps, and what people are seeing there, especially with new high-resolution data. The poles of Mars are really interesting because every winter the atmosphere condenses out to form layers of carbon …
9 March 2008
Lunar and Planetary Science Conference XXXIX
We are heading down to Texas today for the 39th Lunar and Planetary Science Conference (LPSC)! This conference is one of the biggest annual gatherings of planetary scientists, and there are sure to be lots of interesting results. We will do our best to cover the highlights while we’re there and post about them here. If you’re interested, you can browse the abstracts at this link. Stay tuned for loads …
7 March 2008
How old is the Grand Canyon? The speleologist knows…
I learned a new word in Science this week: Speleology: the study or exploration of caves. Think “spelunking.” The word was in an article by UNM geologists Polyak et al. on a new age estimate of the Grand Canyon. For many years now, geologists have estimated the formation time of the Canyon at around 6 million years. The new study puts the age at close to 20 million. This may …
