Thanks Neil

I've had a great time reading First Man by James Hansen and wanted to thank Neil Armstrong for making the book possible. It was great to learn more about the man and get his view of the historic events.

Whenever I read a book or watch a movie about the Apollo program I always come away a little sad. I was just a kid then but remember the Space Age as a time a great adventure and endless possibilities. I'm grateful I got to live through it, but I miss it with all my heart.

Identification II

I'm back from my week at the American Geoplysical Union conference in San Francisco. On Monday, I again met with students. In the past we had identified pretty simple features like impact craters, wind streaks and small rivers. It was time to move beyond the simple and look at something that wasn't "obvious". The subject of this post can be found at latitude = 7, longitude = -77.


Here, I'm curious about the long linear feature cutting through the image from north to south. What is it? Or, more importantly, how do you figure out what it is? First thing, as usual, I got an elevation cross section along part of the linear feature. It shows that the area to the left of the linear feature is lower and the area to the right is higher. By moving the mouse around the feature and watching the elevation displayed at the bottom of the screen I can see the difference in elevation is over 600 meters.
One of the things that makes planetary geology a little easier is that determining features can be matter of multiple choice. In this case, what might cause the difference in elevation between the left side and the right? Offhand, I can think of four possibilities:
Material on the left has been eroded away.
Material on the right has been added.
The area on the left has undergone some kind of collapse.
The area on the right has undergone some kind of uplift.

Also, notice that on the left side of the feature there are fewer craters than on the right. The number of craters is typically proportional to a geologic feature's age. New features can cover the old features they form on top of resulting in an area with no craters. Over time, impact craters accumulate. The oldest areas are dominated by craters. For an example of this, check out the southern highlands of Mars.

Uplift and collapse are more rare geological processes so first let's consider the more likely ones first. How might material have been added on the right to create the linear feature? There are several ways. Wind can deposit dust. Retreating glaciers can leave material behind. Lava can turn into rock to build up an area.
I don't see how wind blown dust could create the sharp difference in elevation that we see here. I'd expect it to be more gradual. Sadly, I don't know much about glacier deposits so I can't rule them out. Lava could easily create the feature on the right, but that is the older side. If linear feature was created by some process it is more likely it was created by the most recent process.
Since the crater record suggests that the left side is the newer side it makes sense to figure out how that side became the lower side. There are several ways the old surface on the left side could have been removed to expose what we see now. Wind can blow away part of a region. Advancing glaciers can scour a region. Meteorites can create impact craters. Flowing liquids, such as water, can erode whatever it flows over. Again, I wouldn't expect wind (or as the scientists call it "aeolian") erosion to form such a stark difference in height. It doesn't make sense for either deposition or erosion. Again, glaciers must be skipped since I don't know much about them.
That leaves either cratering or a river or some other water based removal of the old surface. These are easy to tell apart. Craters are round (or rarely, oval) while rivers are long. Simply by panning north a couple times you can see the feature isn't round. Panning north and zooming in reveals this significant feature:


Teardrop shaped features form in rivers with the pointy end pointing downstream. By drawing some elevation cross sections you can verify that downstream is downhill. With two pieces of evidence suggesting which direction the mouth of the river lies. Let's turn south and search for the headwaters. Going south, you eventually find:


At the start of the feature, it looks like a regular river with two banks not very far apart. As it flowed north it got very, very wide. We've mostly been looking at the right bank. You could also explore the left bank. Further evidence for this being a river/water feature can be found by identifying a couple tributaries.

This feature isn't reminiscent of typical rivers on Earth. On Earth, rain water feeds streams that combine to create rivers. They constantly flow with a seasonally determined amount of water. If rivers on Mars look different, perhaps the source of water is different.

Collaborators Needed

Next week, there won't be my usual update about what happened with the students. Instead of meeting with them I'll be at the AGU conference. Normal weekly updates will resume the week of Dec 11th.

At the AGU conference, I'll be presenting a poster (ED31C-1225) on Wednesday morning. Most of my poster describes the project that, if you've been reading the blog, sounds very familar. The poster also goes into the kinds of collaborations I'm looking for. Since I haven't covered that on the blog before, I'll do it now.

The most important ideas are suggestions for student or amateur projects. Specifically, what might they do? Projects can last from a person-hour to several person-months. Requiring a less extensive background in planetary geology from the user is good, but not necessary.

All the projects currently planned for the students have them basically identifying features (wind streaks, rivers, chaos and rampart craters). What other features might they survey the Martian globe for. Perhaps more importantly, what can they do beyond simply identifying a feature? Are there properties of a feature they could measure and compute some interesting result?

PEP downloads THEMIS images with a single menu selection. It is a great and ever changing data set. However, there aren't any projects relying THEMIS images yet. Are there some small, interesting features students could study?

PEP intergates several sensor data sets such as thermal inertia, albedo, gravity variation and a mineral map. The user can simply load in other data sets and they are integrated into both the map and 3D views. But, none of these data sets are used. What might students do with these data sets?

PEP ships with Mars data but it isn't limited to Mars. Since it reads in PDS formatted files it deals with most NASA data sets. I've used it extensively with Magellan Venus data and Clementine Moon data. So, what projects make sense for these worlds?

Are there old research projects students might enjoy repeating? I can go back through old issues of the JGR looking for ideas but would much prefer some informed suggestions!

Could a dozen or a hundered volunteers be put to good use? Both bird watchers and amateur astronomers make valuable contributions to the scientific community. Is it possible to build a similar non-professional community to collaborate with planetary scientists? Now that students and amatures can look at the same data as scientists, is there something useful for them to do?

Finally, what features should be added to PEP to help people do more useful work? Is it support for specific data sets? Are there some mathematical models that should be added? Are there existing mathematical models that should be intergrated into PEP?

Comments on any of the above issues are most welcome. Feel free to add a comment to this post or email me at Steve@SiliconSpaceships.com. Thanks.

Welcome

I'd like to welcome those who just found this blog from Meredeth Higbie's email or the new LPI SCORE website. To date, I've been the only person posting on it. My posts deal with a project in planetary exploration at a local high school. Students are using a program I wrote (the Planetary Exploration Program or PEP) to analyze global Martian wind patterns by mapping wind streaks, figuring out the ancient river systems or Mars, etc.

I've been working with the students for a couple weeks and most have installed PEP on their home computers. They have until the end of February to complete their projects and put together a presentation for a Science Fair. To catch up on whats been going on you can read the old blog entries. They will make more sense if you start with the oldest one first.

Blogs are set up so only a specified list of people can post to it. Right now, that list contains only me. I'm happy to add more people to the list (making this a "team blog") so many can post. If you'd like to just post occasionally, feel free to email me your post (Steve@SiliconSpaceships.com) and I can put it on the blog. I'd be happy to post introductions, questions, project descriptions, announcements or anything else you think is valuable.

If you'd like a PEP demo, a free copy of PEP or talk face to face about these issues I'll be at the AGU meeting next week.

This blog is set up so anyone can post comments to any article. To add your views on how this blog should be administered, please add a comment to this post.

Thanks for visiting!

Meeting Two Wrap-up

Following the advice of an experienced teacher, today was a hands-on session. I prepared over half a dozen areas on Mars to look at. The idea was students would gain some experience in using PEP and try to identify some features on Mars.

The four students from the first meeting successfully installed PEP on their home computers. Today two more students joined the project.

Soon, I'll post some details on the specific features we looked at. First, I just wanted to say it went better than I expected. Students didn't have any problem using the simple features of the software. Given a geodetic coordinate (a latitude and a longitude) they can easily pan and zoom to the location. They didn't have any problems creating and understanding elevation cross sections. They can identify easy features such as volcanoes, craters, rivers and wind streaks. The idea of superposition (new features forming on top of old ones) made sense to them as we looked at intersecting features.

For the two new students, this was their first look at the software and they also missed my overview of planetary geology lecture. They didn't seem any worse for it. So, maybe the first lecture isn't needed and instead students can begin with a hands-on exercise.

Coordinates For Planetary Exploration

When you're exploring another world you need to record where you find interesting things. This is vital if you want to be able to find them again or share you discoveries with other explorers. Fortunately, scientists have already established a nice system of coordinates for spheres that is used on Earth and other planets.

But first, since I'm so fond of coordinate systems, I'd to discuss somes we use every day. All over the world we give buildings addresses. The system requires that streets be given names while buildings are given numbers. This works pretty well, but since the names are mostly randomly assigned if you're in a new area it can be very hard to find a particular street. Since building numbers are not random but assigned in order, once you've found the street it is always easy to find the building. On much of the island of Manhattan most street names are not randomly assigned. Instead the streets are laid out in a grid with numbered avenues running one way and numbered streets running the other. If you're in New York trying to find the building at 5th Avenue and West 34 Street you shouldn't get lost.
This isn't the only system we use to keep of locations. We use zip codes even though they only make sense to the Post Office. We use phone numbers but program our cell phones so we don't have to actually remember the number. In school, we learned the Carteasian Coordiante System that used an X and Y axis.

The universally used coordinate system for planets is the "Geodetic Coordinate System". It uses latitude and longitude to specify locations on the surface of a planet. Latitude is a measure of how many degrees something is from the equator. The north pole is at 90 degrees north latitude and the south pole is at 90 degrees south latitude. Latitude divides a globe into a northern hemisphere (the area to the north of the equator) and a southern hemisphere.
Longitude is a measure of how far east or west a point is from an origin. Like latitude, it is measured in degrees. Where latitude could use the equator as a natural origin, there is no natural origin for longitude. So, some convenient or random line is selected to serve as the "prime meridian", the line of 0 longitude. Usually, longitude is said to increase as one moves to the east. On Earth, the agreed upon prime meridian runs through the astronomical observatory in Greenwich England. All measurements of east and west are referenced to this line. Sometimes longitude is measured from 0 degrees all the way around the planet to 360 degrees. Other times, you'll see it measured from 0 to +180 degrees and from 0 to -180 degrees. On rare occasion, you might even find a resource that has longitude increasing to the west.

The PEP map displays the geodetic coordinates of mouse at the bottom of the frame. Any time you need to know the latitude and longitude of something, just move the mouse over it. The PEP 3D display also displays the geodetic coordinates of your virtual spaceship. Note that this isn't the location of what you might be looking at out in front of you. It is where you are looking from.

Post Monday Meeting

Today's meeting with the students went well. Four of the six students were able to attend. Over about half an hour I reviewed a couple important topics: geodetic coordinates, planetary formation and large scale structure. We also discussed the question I had emailed over the weekend. Clearly, this is a bunch of material for such a short time. Time will tell if it is too much but the idea was to start by saying interesting things about planets. I also handed out DVDs so students can install my Planetary Exploration Program on their home computer.
Although my email with questions didn't get any responses, the students mostly knew the answers. They could itemize the basic types of rocks, geological features and processes and some idea of latitude and longitude. It was a good sign.

Following this, I'll post some more on geodetic coordinates and planetary structure. This will be useful to the students that couldn't attend today's meeting.
Next week we'll probably do a hands-on session. I installed my Planetary Exploration Program on three more machines so there will be a computer. By next Monday students likely will have the software running at home so it will be a good time to give them a more in-depth introduction.

Pre-Monday Meeting

After school on Monday I'll be meeting with the students. This will be the real beginning of the project. We'll meet once a week (holidays permitting) until the end of the year. By then, students should be working on their own projects. Here's a email I sent to the students this morning. Note that in this post I included the answers to the questions I posed to them.

As you've probably heard we'll be meeting after school on Monday. This first meeting, and the next couple, will review various topics in planetary exploration. Each meeting will probably last about half an hour. If anyone wants to stay a little while longer, I can go over the software a little and install it on a couple more computers.

Before we meet, I'd be grateful if you could take 5 minutes and answer the following questions. I'm sending them because the current thinking in education is you don't try to teach people something unless you first understand what they know and what they don't. So, just answer these questions off the top of your head without looking anything up. If you don't know any of the answers, please respond with an email saying "I don't know" so I release you read the email. Feel free to take wild guesses.

Do you understand geodetic coordinates (latitude/longitude)?
Yes.

What is the prime meridian and how is it selected? What is the intersection of the prime meridian and the equator called?
The prime meridian is the line at 0 degrees longitude. It doesn't define which direction positive longitude is measured in or if negative numbers are used to describe longitude. These social conventions vary.
To the best of my knowledge, the intersection of the prime meridian and the equator has no name. I think this is very interesting. The familiar Cartesian coordinate system is all about "the origin", the point where the X and Y axis intersect. We usually scale data just to get the origin on the graph. But in a geodetic coordinate system, the origin goes unmentioned.

Can you name the three most basic kinds or types of rock?
Igneous, sedimentary and metamorphic

Can you name several kinds of geological features?
Mountains, volcanoes, rivers, craters

Can you list the four most important geological processes?
Volcanic, tectonic, impact cratering, erosion.

I'll post after the meeting to report on how it went.

Project: Global Water Patterns

In previous posts I described a project to map the global wind patterns using wind streaks. At a more abstract level, that project involved mapping a directional field on a global scale. (I say directional field because we're not measuring the magnitudes of elements in a vector field, just their direction.) Naturally, there is more than one directional field on Mars that can be identified.

You don't have to search Mars too hard to find evidence of past water. You can even find many features that look like rivers. Where do these rivers empty out? On Earth, rivers tend to combine and eventually empty out in an ocean. Does this happen on Mars? Did it have oceans?

Can anything be learned by following the rivers up-stream? On Earth where rivers tend be fed by rainfall the just keep branching into small and smaller streams. Does this happen on Mars? Besides rain, where else might surface water come from?

Here's a map view of a region of Mars showing only elevation data. The lowest terrain is in red, the highest in blue. Some of these red features could be rivers. By studying them more closely you discover how likely it is they were formed by a flowing liquid.


Remember that water flows down hill. But what is downhill today might not have been downhill a billion or more years ago when the river formed. Planets change, a low region can be uplifed or a high region can sink down. Water isn't the only thing that can flow. Lava can pour out of the ground and flow down downhill. Some planets support other liquids like methane. Dust in the air behaves similarly to debris in water and can cause similar features. As is always the case, identifying features can be a little tricky.