The Science of Starcraft: What is a Railgun and How does it Work?

Posted September 6, 2010 by Ryan
Categories: Fun Stuff, Science Fiction, Science of Starcraft

I have a new post up at The Science of Starcraft! This time I tackle rail guns: sci-fi staple and the bane of intro physics students everywhere. To learn how these futuristic guns work in the real world and whether their depiction in Starcraft is accurate, go check out my latest post!

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Herschel Finds Water around a Carbon Star

Posted September 6, 2010 by Ryan
Categories: Astronomy, Universe Today

Water is pretty common in the universe, since it is made of hydrogen and oxygen. Hydrogen is left over from the big bang and oxygen is made in most stars. But you don’t typically expect to find water in the atmosphere of stars themselves! That’s what astronomers using the infrared Herschel observatory found though! Deep in the shroud of gas and dust that CW Leonis is expelling as it dies, there is water at temperatures up near 1000 K. To learn more about it, check out my article over at Universe Today!

Seeing Early 20th Century Russia Like a Rover

Posted September 3, 2010 by Ryan
Categories: MER, Pictures

Hello folks! Apologies for the lack of posts lately, I had to go get married and go on a honeymoon! But I’m back now, and adjusting to the real world again. As I sifted through my inbox earlier this week, I came across a link to a fascinating collection of photographs. These are color photos of the Russian Empire taken by Sergei Mikhailovich Prokudin-Gorskii. But wait! How could he have taken color photographs of Russia in 1910 if Kodachrome wasn’t released until 1935?

By taking them like a rover, of course! By photographing the same scene three times, each with a red, green or blue filter, Produkin-Gorskii was able to create realistic color images by using a trio of projectors.This is almost identical to the process used by the MER rovers to acquire color images. The Pancam CCD takes greyscale images through a variety of filters, and these can be used to construct various true- or false-color views of Mars!

The Library of Congress has digitized all of Produkin-Gorskii’s photos of early 20th century Russia, and you can browse them here. Or, you can head over to The Big Picture which recently featured some of the best shots.

Molar Tooth Texture

Posted August 12, 2010 by Ryan
Categories: Carbonates, Current Research, Field Trips, Geology, MSL

Ok, so remember the weird rock I showed in my Galcier Park geology post? No? Here it is again:

This texture is called “molar-tooth” texture, because apparently someone thought it looked like the teeth of elephants. They must have been studying some weird elephants. It’s a very bizarre texture. It cuts across the layers of the rock as if it is related to fractures, but it is often deformed and squished as if it formed in wet sediment. In some places the minerals filling the fractures are broken up and collected as hard clasts, but it other places they clearly formed after the sediment was deformed.

The two leading explanations for this texture are bubbles and waves*. In the bubble model, the fractures form when gas is evolved in the gooey mud, and builds up enough pressure to propagate through the layers. Then once those voids are formed, fine-grained crystals fill them in. Sometimes, the overlying pressure of newer sediment compressed the voids before they are filled, causing them to accordion up into the contorted shapes we see today. In the wave scenario, pressure changes from powerful storm waves cause the sea floor to undulate, forming the fractures which are then filled in with minerals.

This texture has no modern-day analog because macroscopic life forms disrupt the mud before the mineralization can take place.It’s very unlikely that we would find this on Mars, but it is good practice for us martians to try to explain rocks we’ve never seen before!

*I’m sure I am completely oversimplifying, and likely mangling, these explanations.

Can Life Survive in Space?

Posted August 12, 2010 by Ryan
Categories: Astrobiology, Fun Stuff, Humans in Space, Science Fiction, Science of Starcraft

Tags: , , , , , , ,

I’ve got a new post up at The Science of Starcraft! This time I tackle the question of whether unprotected living things could ever survive in the vacuum of space. Go check it out!

The Geology of Glacier National Park: Part 1

Posted August 7, 2010 by Ryan
Categories: Field Trips, Geology, MSL, Pictures

Well, the field trip is over and I am happy to say that I was not eaten by any bears. They seemed much more interested in the huckleberries.

My adviser and two colleagues and a family of bears.

I am also happy to say that I know a little bit more about the geology of Glacier National Park (and about how to interpret sedimentary geology in general) than I did before I left. The park is famous for its large-scale geography of course: towering mountains and deep valleys carved by rivers of ice. Glaciers tend to form broad U-shaped valleys, while rivers and streams cut V-shaped valleys. Take a look at this picture and you can see glaciers have been involved, even though they are mostly gone now (and the few that remain are disappearing fast: there will be no more glaciers in the park by 2030).

Glacier National Park: soon to be known as "U-shaped Valley National Park".

Despite the spectacular views, we actually spent most of our time in the park with our backs to the vistas, staring intently at rocks that most visitors would pass by without a second glance. Most of the rocks in Glacier are Precambrian sedimentary rocks, deposited around 1.5 billion years ago. The world was a very different place back then, with essentially no oxygen in the atmosphere and no multicellular life. Without large life forms crawling around in the mud of the seafloor (a process called “bioturbation”), the physical processes that shape the sediments are nicely preserved, and I learned a lot about how to interpret their record.

For example, take a look at this ripple:

This symmetric ripple indicates back-and-forth flow of water over the soft mud.

A ripple means that the water was flowing and moving sediment, but you can actually learn more than that based on its shape. This ripple is symmetric, meaning that the water was flowing back and forth, rather than only in one direction. That tells us that it didn’t form in a stream, but more likely due to the movement of tides or waves.

Here’s another interesting feature:

You can see that the layers here aren’t parallel – there’s a lens of material with a relatively flat top, but a curved lower portion that cuts into the underlying layers. This is a little channel, carved into the lower sediments while they were still soft and filled with coarser material!

The coarseness of the sediment tells you a lot about the environment where it was dropped. It takes a much faster, more energetic flow to carry rocks than it does to carry sand. Silt and mud will stay suspended in all but the most tranquil of bodies of water, so what happened here?

This location is actually much younger cretaceous rock outside the park, where the ancient Precambrian mountains have been broken down and deposited in a floodplain. (lots of dinosaur bones have been discovered in other outcrops of this cretaceous rock, but alas, we didn’t find any) There has been some crazy deformation in this area, tilting the layers so that they are almost vertical, but you can still see striking evidence of different environments here. This spot actually shows another much larger example of a channel, filled with big green and red rocks. (The channel is the coarse layer behind the geologist in the picture that narrows as you go upward) The size of the rocks in this channel means the water must have been flowing pretty fast to move them. But you can see that other parts of the same outcrop are very different. The tan stuff is extremely soft, and when you crush it between your fingertips, it turns into a powder with grains far too small to see or feel.

This soft stuff could have been emplaced when the river carrying the larger rocks flooded its banks, dumping its sediment as it stagnated in the floodplains. This same process is why places like the Nile river valley are so fertile. It’s not a sure thing that the fine-grained stuff came from a flooding river though. It could also be fine ash from a volcanic eruption (a more likely scenario for Mars!).

There’s a lot more cool geology to show you from the park, but this post is long enough, so I will leave you with a puzzle. Take a look at this bizarre rock texture that we saw all over the park:

What is going on here?

What do you think it is? We were asked the exact same question by our field trip leader to get us to practice explaining completely unknown rock types, something that could very well happen on Mars. Stay tuned for my next post where I’ll attempt to explain what this texture is!

Is Eberswalde Really a Smoking Gun?

Posted August 3, 2010 by Ryan
Categories: Curiosity, MSL, Water on Mars

The other day in Mars journal club, we took a look at a paper about the “fan” in Eberswalde crater. You may recognize this name: it is one of the four finalist landing sites for MSL. The site was chosen because at the western end of the crater, there is a feature that most Mars scientists consider to be a delta, formed when sediment transported by rivers  encountered standing water and settled out.

The paper we looked at considered an alternative to the delta hypothesis. Instead, Jerolmack et al. proposed that the fan could be an alluvial fan, formed by river channels that “avulsed” back and forth to form a gradually sloping fan. “Avulsed” means that the river abruptly changes its course. When you average out over lots of avulsions, you get a broad, shallow cone of material deposited: an alluvial fan.

Jerolmack used a computer model of this style of fan formation and fit it to the slope of the Eberswalde feature’s surface. They found that, if the Eberswalde fan is actually alluvial, it would have formerly extended about 40 km out into the crater, and that it could have formed extremely rapidly: in tens to hundreds of years, and with no need for a standing body of water.

That’s a much different story than the more popular one: that the Eberswalde fan is a delta that formed over many thousands of years in a lake. Which scenario is correct? I don’t know. It may not be possible to know from orbit. That’s part of why Eberswalde is a candidate MSL landing site: if our “smoking gun” evidence of a lake on Mars turns out to be an alluvial fan deposited in 50 years, then that certainly has an influence on the question of the habitability of Mars as a whole! Of course, everyone hopes that it is truly a delta, in which case it would have been favorable for preserving organic biomarkers and would record a lot of information about the martian environment.

There’s only one way to know for sure: land there!

ResearchBlogging.orgJerolmack, D. (2004). A minimum time for the formation of Holden Northeast fan, Mars Geophysical Research Letters, 31 (21) DOI: 10.1029/2004GL021326