12 March 2008
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 radiate outward from a central point (hence the spideriness), and they’re covered with a layer of translucent carbon dioxide ice. When sunlight starts to heat the bottom of that ice layer, the carbon dioxide sublimates into a gas, mixes with some surface dust, and gets spewed up from the channel through a crack in the ice. So you could say that the spiders spit from their legs.
In this series of pictures, HiRISE captured the same spider at different times of the year:
The dark splotches are the spider “spittle”. You’ll notice that those dark trails change directions – that’s because when the gas and dust shoots up, the wind carries the plume, and the dust gets laid down onto the surface in whichever direction the wind was blowing. If the wind changes direction, the dust gets deposited in a different way.
Fascinating! This is great science and an amazing discovery, but I have a bone to pick with the presenters: Dr. Hansen said that the term “spiders” was too colloquial, and asked the scientific community to start calling them “araneiforms.” I like the term “spiders” – it’s easy to say, easy to spell, and easy to visualize. “Araneiforms” is none of those things. I always thought that most scientists used excessive jargon because they didn’t know how else to communicate (I gave them the benefit of the doubt). But here’s an example of scientists inventing jargon for the express purpose of sounding more scientific – and in the process making their discovery less accessible to a lay audience.
To prove my point: would you have been as interested in reading this post if I had called it “Araneiforms on Mars?!” (don’t answer if you’re a scientist).