Archive for the ‘MOC’ category

Microsoft goes to Mars

July 12, 2010

Today, NASA and Microsoft announced a very cool new addition to Microsoft’s Worldwide Telescope (WWT) program: Mars images! Yep, now you can use WWT to cruise around Mars and to view the planet with a handful of datasets, including 13,000 mind-blowingly high-resolution HiRISE images, and even more almost-as-high-resolution MOC images. There is also the standard MOLA colorized topography and a low-resolution approximately true color map.

It’s great to see all of this data being made available to the public! Of course, HiRISE images have been available though the HiRISE website all along, but they are so much more useful when they are map-projected and shown with all the other datasets. I do wish there was an option to show both MOC and HiRISE images on the same map. And hey, while I’m wishing, it would be nice if there were CTX images too, but the camera team for CTX is more stingy with their data than the HiRISE team.

The Mars viewer comes with some nifty pre-loaded tours of Mars, but at least on my computer, the images loaded almost too slowly to match up with the words and there were some buggy moments when multiple image layers interfered to form moire patterns.

In general, I find the interface for the program isn’t as intuitive as it could be. Maybe I’m just too used to using Google Earth’s Mars viewer, but I found the thumbnails along the top and the bottom to be much less user-friendly than the wireframe image outlines that you get in Google Earth. The menus that pop up when selecting guided tours were very flickery and difficult to read on my computer also.

Still, maybe the interface works well for others, and I’m certainly happy to see another easy-to-use way to view all of this data being made public. Just the fact that WWT has so many map-projected HiRISE and MOC images mosaicked together makes it a powerful tool, both for interested amateurs and actual Mars researchers.

You can download the program at this link. Check it out!

Advertisements

Be a Martian!

November 17, 2009

Fact #1: As a Mars scientist, I am incredibly spoiled. There are so many missions to Mars right now sending back so much data, that even if they all went silent tomorrow, it would be decades before we managed to look at all the data and figure out what it’s telling us.

Fact #2: There are lots of people out there (I’m looking at you, loyal readers!) who would love to be able to actively participate in exploring Mars. I mean, have you seen the stuff that the folks at UnmannedSpaceflight have managed to put together? They do more with the data from Mars than a lot of scientists!

So, given those two facts, you can see why I think the new “Be a Martian” collaboration between NASA and Microsoft is a great idea. Check out this excerpt from the press release:

Drawing on observations from NASA’s Mars missions, the “Be a Martian” Web site will enable the public to participate as citizen scientists to improve Martian maps, take part in research tasks, and assist Mars science teams studying data about the Red Planet.

“We’re at a point in history where everyone can be an explorer,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “With so much data coming back from Mars missions that are accessible by all, exploring Mars has become a shared human endeavor. People worldwide can expand the specialized efforts of a few hundred Mars mission team members and make authentic contributions of their own.”

How cool is that? It’s a really brilliant idea, and I hope it goes well. A similar project was pioneered by galactic astronomers who had way too many pictures of galaxies to deal with, so they opened up the database to the public in the form of GalaxyZoo. It was a tremendous success, with thousands of people helping to classify millions of galaxies.

I just created my account and played around a bit, and it looks like a very user-friendly introduction to Mars science. You can contribute in two main ways: aligning images to contribute to a global map, and also counting craters. Both of these tasks can sort of be done by computers, but humans will always be better.

There’s more to the Be a Martian site than just work though, there are also lots of goodies like videos and Mars wallpapers, and great information about Mars. There is even a “movie theater” where you can watch the first few episodes of a series of videos called “The Martians”, that focus on people from all over the country who are involved with Mars, ranging from members of the rover teams to enthusiastic amateurs to actors putting on a play about Mars! There are more episodes on the way, and I encourage you to keep watching… you might see someone you recognize. ;)

Bottom line, it looks like a great site, and a great way to get involved in Mars exploration and learn about everyone’s favorite Red Planet and the people who are fascinated by it. What are you waiting for? Head on over and sign up! I’ll see you on Mars!

 

The MOC “Book”: Volcanic Landforms

March 2, 2009

More about the MOC paper! This is part six of a series of posts looking at the huge 2001 paper summarizing the results from the Mars Orbital Camera (MOC): the first high-resolution camera in orbit around Mars. Check out the previous posts if you want to get caught up: 1,2,3,4,5

Today’s topic is volcanism, something I’ve written a lot about before on the blog. Mars is essentially a volcanic planet, so this is an important part in understanding the surface that we see today. The paper first looks at lava flows on the large shield volcanoes of Tharsis, and notes that near the summit, flows are difficult to distinguish, but they become more distinct farther down:

The upper flanks of Olympus Mons are a confusing mess of interfingered lava flows and leveed lava channels that are difficult to tell apart.

The upper flanks of Olympus Mons are a confusing mess of interfingered lava flows and leveed lava channels that are difficult to tell apart.

Farther down on Olympus Mons, flows are more distinct. This is partly due to the fact that there are fewer of them, but they are also thicker because the lava has flowed farther and therefore was cooler and more viscous.

Farther down on Olympus Mons, flows are more distinct. This is partly due to the fact that there are fewer of them, but they are also thicker because the lava has flowed farther and therefore was cooler and more viscous.

The authors also note that collapse features are generally rare on the large volcanoes. Ceraunius Tholus is an exception: its caldera is pock-marked with many circular collapse pits.

Collapse pits in the caldera of Ceraunius Tholus. These pits are distinct from impact craters because they have no rim, are of a more uniform size, and vary in concentration across the caldera.

Collapse pits in the caldera of Ceraunius Tholus. These pits are distinct from impact craters because they have no rim, are of a more uniform size, and vary in concentration across the caldera.

There is ample evidence for volcanism other than the giant volcanoes. Vast expanses of Mars are a “platy” terrain formed by the rafting of large plates of basalt on the surface of lava lakes and seas. These have been mistakenly interpreted as evidence of sea ice on Mars because it looks very similar to ice on terrestrial oceans. This makes sense, because the process is essentially the same: you have a large body of liquid exposed to an atmosphere cold enough to freeze the surface, resulting in floating plates. One of my favorite examples from the paper was in Amazonis, where the platy lava surface is being exhumed from beneath wind-eroded yardangs. Nearby, the lava surrounds the ejecta from a crater, so that you immediately get a multiple step timeline: first the crater formed and emplaced its ejecta, then the flood of lava surrounded but didn’t quite bury the ejecta. The lava froze to form a hard, flat surface, which was then covered with a soft sedimentary rock (perhaps ash from the same eruption that formed the flood of lava). Now the soft rock is eroding away to expose the much harder plates and ejecta underneath.

This is a CTX view of a platy lava flow being exhumed from beneath yardangs in Amazonis. It is clear that the yardang material is much softer than the underlying rock, which is emerging unscathed even as the yardangs are being eroded by the wind.

This is a CTX view of a platy lava flow being exhumed from beneath yardangs in Amazonis. It is clear that the yardang material is much softer than the underlying rock, which is emerging unscathed even as the yardangs are being eroded by the wind.

MOC also confirmed that there are much smaller volcanoes, such as this one:

A small shield volcano inside the caldera of Arsia Mons. You can just barely make out a texture of lava flows radiating from the central pit.

A small shield volcano inside the caldera of Arsia Mons. You can just barely make out a texture of lava flows radiating from the central pit.

That sums of the volcanism section! Obviously there are plenty more MOC pictures of volcanoes and volcanic features on Mars, but those were the highlights of the section for me. We also spent a while discussing the very interesting Olympica Fossae, but that’s complicated enough that it will need its own post.  Stay tuned: tomorrow’s topic is valleys of all shapes and sizes!

The MOC Book: Polar Processes

February 28, 2009

I’m falling behind on my blogging of the MOC “book”! We read a lot this week, so I will just stick to the highlights. In other words: mostly pictures, less text. This paper is really all about the pictures anyway! (if you’re just tuning in to the MOC series, check out posts 1,2,3 and 4)

The Martian poles are extremely fascinating but extremely bizarre places. The polar caps are made of water and CO2 ice, and as that ice freezes and thaws, it forms some strange landscapes.

a) South polar "swiss cheese" terrain, formed by sublimating CO2 ice. b) North polar pitted terrain. It is not clear why the north and south pole look so different.

a) South polar "swiss cheese" terrain, formed by sublimating CO2 ice. b) North polar pitted terrain. It is not clear why the north and south pole look so different.

The north and south polar caps are very different-looking, and there is no good explanation for why. This image shows layers from the south and north polar cap. The southern layers are very rough and rugged-looking, while the north polar layers are much smoother.

a) Rough, rugged layers in the south polar cap; b) Very smooth layers in the north polar cap. These layers may reflect changes in the Martian climate driven by changes in the planet's tilt and orbital eccentricity.

a) Rough, rugged layers in the south polar cap; b) Very smooth layers in the north polar cap. These layers may reflect changes in the Martian climate driven by changes in the planet's tilt and orbital eccentricity.

The layers in the north polar cap are amazingly coherent. They can be traced for hundreds of kilometers in some places:

Layers in the north polar cap can be traced for hundreds of kilometers. Prior to MOC, it was thought that the polar cap layers were tens of meters thick, and could be explained solely by changed in the planet's tilt. The fact that these layers are so narrow indicates that there are higher-frequency changes contributing to layer formation.

Layers in the north polar cap can be traced for hundreds of kilometers. Prior to MOC, it was thought that the polar cap layers were tens of meters thick, and could be explained solely by changed in the planet's tilt. The fact that these layers are so narrow indicates that there are higher-frequency changes contributing to layer formation.

Not all of the polar layers are perfectly flat, though. There are some examples of layers that have been deformed, or which intersect with each other, implying that they were subject to tectonics and erosion between periods of deposition.

a) An "angular unconformity", implying that enough time elapsed for some of the layers to become tilted and eroded before the next set were depositied. b) Deformation implies that these layers have a complex history as well.

a) An "angular unconformity", implying that enough time elapsed for some of the layers to become tilted and eroded before the next set were depositied. b) Deformation implies that these layers have a complex history as well.

The paper had a lot of observations, but not many conclusions about the Martian poles. The poles are still not well understood, though missions like Phoenix and MRO are helping to shed some light on the mysterious processes that shape the polar regions.

The MOC “book”: Dunes, Ripples and Streaks

February 16, 2009

This is the fourth in a series of posts about the huge paper by Malin and Edgett summarizing the results from the Mars Orbital Camera’s (MOC’s) primary mission. If you’re just tuning in, get caught up by reading the first three posts, and if you want to read along, download a pdf of the paper here.

This week we’re looking at two sections: “Aeolian Processes and Landforms” and “Polar Processes and Landforms”. Also known as wind and ice features. These represent the most active features on the martian surface and they are also some of the weirdest looking! I’ll post about the aeolian features today and polar processes tomorrow since both have tons of images to go with them.

The authors make a distinction between dunes, which are always dark-toned and are likely made of sand-sized volcanic minerals, and ripples which are smaller, and are often light toned. This picture shows exactly what each term refers to:

Examples of dark-toned dunes overriding light-toned ripples.

Examples of dark-toned dunes overriding light-toned ripples. The arrows point to the most obvious places where the dunes are on top of the ripples.

The dark-toned dunes come in a variety of shapes, depending upon the amount of sand available and the wind direction. Figure 39 of the paper shows several of the types of dunes:

a) Thick sand sheet; b) These dunes are likely inactive - they have been eroded into more rounded shapes than you would expect to see on an active dune.; c) Barchan dunes near the north pole. d) Stubby barchan dunes. The wind is blowing from bottom to top in this figure ;e) Barchan dunes that extend far downwind (toward bottom right) become linear "seif" dunes ; f) Dunes near the north pole showing a "rectilinear" pattern.

a) Thick sand sheet; b) These dunes are likely inactive - they have been eroded into more rounded shapes than you would expect to see on an active dune.; c) Barchan dunes near the north pole. d) Stubby barchan dunes. The wind is blowing from bottom to top in this figure ;e) Barchan dunes that extend far downwind (toward bottom right) become linear "seif" dunes ; f) Dunes near the north pole showing a "rectilinear" pattern.

By comparing MOC observations with older Viking images, Malin and Edgett tried to detect evidence for dune movement. But even over 10-14 martian years, no dunes were seen to move. Not all dunes on Mars are inactive though: MOC did see streaks appear on the downwind sides of some dunes indicating that sand was moving.

An example of dunes with avalance streaks on their slip faces.

An example of dunes with avalance streaks on their slip faces.

As for ripples, they are almost everywhere on Mars. Interestingly, they are often much larger than ripples seen on earth, and they are always perpendicular to the wind direction.  When they are in troughs, they are always perpendicular to the trough trend, and they even “refract” around obstacles, following the surface winds.

The ripples are very similar in size to some of the ridged units mentioned earlier in the paper, but whether they are actually related is not clear.

Giant granule ripples. Notice that the ripples are oriented perpendicular to the trought that they are in, indicating that the wind that formed the ripples was blowing along the trough.

Giant granule ripples. Notice that the ripples are oriented perpendicular to the trough that they are in, indicating that the wind that formed the ripples was blowing along the trough.

Some of the most dramatic changes on the martian surface occur when dust is lifted or deposited, leaving either a dark or light wind streak. Wind streaks typically form behind some sort of topographic obstacle that disrupts the wind and causes turbulence which lifts dust, or alternately causes a space with less wind, causing dust to collect there.Some wind streaks are also composed of frost.

Large wind streaks composed of frost.

Large wind streaks composed of frost.

Hundreds of small wind streaks tracing the wind flow over topography. The surface is covered in frost and the narrow end of the streaks point downwind.

Hundreds of small wind streaks tracing the wind flow over topography. The surface is covered in frost and the narrow end of the streaks point downwind.

Dust devils are also very common on Mars, and they leave intricate patterns in their wakes as they vacuum dust from the martian surface. This figure shows a bunch of examples, including some dust devils caught in motion:

A collection of photos of dust devil streaks. c is a rare example of light-tones streaks, and h&i are examples of dust devils caught in action.

A collection of photos of dust devil streaks. c is a rare example of light-tones streaks, and h&i are examples of dust devils caught in action.

Of course, with the wind blowing sand and dust around on the surface, it makes sense that wind erosion is the most active erosional process on Mars today (unless you count the sublimation of the polar caps). Here is an example of terrain that has been eroded by the wind into a ridged and grooved pattern (also known as “yardangs”).

Most of the visible surface here is eroded by the wind into yardangs.

Most of the visible surface here is eroded by the wind into yardangs.

That concludes the aeolian section of the paper. Tomorrow I’ll be posting about polar processes, with lots more cool pictures!

ResearchBlogging.orgMichael C. Malin, Kenneth S. Edgett (2001). Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission Journal of Geophysical Research, 106 (E10), 23429-23570 DOI: 10.1029/2000JE001455

The MOC “Book”: Subsurface Patterns and Properties

February 15, 2009

The MOC paper saga continues. If you’re just tuning in, I’ve been writing a series of posts detailing a slow and detailed reading of the classic 2001 paper summarizing the results from the Mars Orbital Camera (MOC), the first high-resolution camera in orbit around Mars. Check out the previous posts here and here. Also, a reader pointed out to me that the full PDF of the paper is freely available at the author’s website! So if you’re interested, I encourage you to download it and read along with us.

On friday we talked about section 3.6 of the paper: subsurface patterns and properties. The real take-away message of this section is that Mars is layered. Everywhere that bedrock is exposed, it has layers. From the paper:

“On Earth, the observation of layers would not be a surprise, but the prevailing consensus … prior to the MGS mission held that much of the Martian crust, particularly in the ancient, heavily cratered highlands, should be something like that of the lunar highlands: an upper kilometer or two of interbedded crater ejecta, lava flows, and perhaps sediments and soils underlain by tens of kilometers of megabrecciated primordial crust…”

A great example of layering on Mars is the walls of Valles Marineris. The kilometers-high walls of this giant canyon show layers as much as 10 km below the surface! The authors point out that they had suspected that Mars was layered but they were really surprised by how deep the layers go!

moc_fig24

a) Layers in Valles Marineris; b) the box shows the extent of a, the arrows point to outcrops of light-toned layered material; c) & d) show other light-toned outcrops, and e) provides their context.

One especially interesting part of the Valles Marineris section was the observation that there aren’t very many boulders at the bottom of the cliffs. This implies that the rocks the walls are made of is breakable enough that large blocks can’t survive the violent tumble down the canyon walls. Thick volcanic rocks could easily survive such a fall, so the authors deduced that many of the layered outcrops are made of sedimentary rather than igneous rocks! That’s a pretty important conclusion based on an observation I wouldn’t even have thought of!

The paper points to other examples of sedimentary rocks elsewhere on the planet. In some cases, locations that were thought to be layered based on low-resolution images turned out to indeed be layered, but at a much finer scale. The large apparent layers were actually accumulations of dark sand, but where there was no sand, MOC revealed many small layers.

A spectacular example of layered sedimentary rocks in Arabia Terra on Mars.

A spectacular example of layered sedimentary rocks in Arabia Terra on Mars.

Based on the discovery of layers all over the planet, at depths up to ten kilometers, Malin and Edgett proposed a new model for the crust of Mars, depicted in this cartoon:

The new model for the martian surface as a "cratered" volume in which surfaces are constantly buried and re-exhumed while also undergoing impacts.

The new model for the martian surface as a "cratered volume" in which surfaces are constantly buried and re-exhumed while also undergoing impacts.

This model shows the surface of Mars as a very complicated place, constantly being buried and then uncovered, with craters interspersed throughout the sequence of layers. It’s a big contrast from the view of Mars as being essentially the same as the moon, with a  cratered surface and kilometers of crumbled up debris underneath. To support their new model, Malin and Edgett give some great examples:

Reull Vallis cuts right through the rim of a large impact crater. If the river had been flowing over a flat plain and encountered the crater, it should have been diverted. However, if the crater was buried, the river's course could pass right over it. Then as the landscape was eroded, the river could carve through the crater walls as they began to emerge. This is often seen on earth (e.g. the Susquehanna river cutting through the Appalachians) where mountains are lifted up and pre-existing rivers carve through them.

Reull Vallis cuts right through the rim of a large impact crater. If the river had been flowing over a flat plain and encountered the crater's rim sticking up, it should have been diverted. However, if the crater was buried, the river would not "see" it, and could pass right over it. Then, as the landscape was eroded, the river could carve through the crater walls as they began to emerge. This is often seen on earth (e.g. the Susquehanna river cutting through the Appalachians) where mountains are lifted up but pre-existing rivers maintain their original course by carving through them.

moc_fig33

Buried craters, ranging from completely filled (a), to partially exhumed (b,c) to almost completely uncovered, with only a small remnant of the fill remaining (d).

The authors point out that the constant burial and exposure of surfaces on Mars makes it very difficult to reliably tell the age of the surface by crater counting. A heavily cratered surface is certainly old, but it may have only been uncovered relatively recently. And how do you deal with a surface that accumulated some craters, was buried for a billion years, and then exposed, and hit by more impacts? Obviously, the new “cratered volume” idea of the martian surface in this paper poses some difficulties…

a) Context image showing a valley; b) a view of the valley wall. Notice that there are two craters that appear to be partially underneath the valley's layered wall. It is not obvious whether these are ancient craters that are being uncovered as teh valley erodes away the overyling layers, or whether they formed on teh valley floor and have been partially covered by debris falling off of the wall. These are shown in more detail in e. c and d show views of the upland and valley floor. It is impossible to tell whether the craters on the valley floor are old or young.

a) Context image showing a valley; b) a view of the valley wall. Notice that there are two craters that appear to be partially underneath the valley's layered wall. It is not obvious whether these are ancient craters that are being uncovered as teh valley erodes away the overyling layers, or whether they formed on teh valley floor and have been partially covered by debris falling off of the wall. These are shown in more detail in e. c and d show views of the upland and valley floor. It is impossible to tell whether the craters on the valley floor are old or young.

ResearchBlogging.orgMichael C. Malin, Kenneth S. Edgett (2001). Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission Journal of Geophysical Research, 106 (E10), 23429-23570 DOI: 10.1029/2000JE001455

Weird Outcrops in Schiaparelli Crater

February 6, 2009

Today while we were discussing the section of the MOC paper that I posted about yesterday, we decided to look more closely at one of the figures. In the paper, the authors suggest that the light-colored rocks are on top of the dunes, implying that the dunes are fossilized, were buried and are now being uncovered. We found a HiRISE image of the area and found out that the truth is even stranger. It doesn’t look to me like the light-toned rock is on top of the sand ripples, and in some places, the ridges in the sand gradually merge and become ridges in the rock! And the bedrock itself is really strange looking itself: it reminds me of feathers and scales, though in reality its surface is covered with shallow “scoops” or a “scalloped” texture. My best guess is that this is a fine-grained, soft rock that has been eroded into this texture by the wind. How the light-toned rock and the sand ripples are related, I can’t tell for sure…

hirise_schiaparelli_weird