MadSci Network: Astronomy
Query:

Re: glass tubes on mars?

Date: Tue Aug 31 10:51:25 2004
Posted By: Jennifer Anderson, Geological Sciences
Area of science: Astronomy
ID: 1092225715.As
Message:

You have hit on two extremely important questions that everyone studying Mars is trying to figure out! First, what are we looking at when we get these wonderful, high-resolution images back from Mars? And second, is there evidence for liquid water on Mars today (not in the past, but potential sources of usable liquid water right now)? These are both very complicated questions that need a lot of study, and there are many people working on their answers. Let me try to address each of these questions.

What are we looking at in these high-resolution images from Mars?

It is difficult to study another planet without actually being able to wander around on its surface. We are used to asking questions about our own planet and then being able to walk over (dive down, climb up, dig down, fly up) to a feature that will help us understand the answer to that question. For example, if we wanted to study sand dunes on Earth, we would start by figuring out where the sand dunes are and then walking right up to them to investigate and get our hands dirty while we figure out how sand dunes work on Earth.

On Mars, we don’t have that luxury. While there are many rovers and landers on Mars (for example the Mars Exploration Rovers right now – link below), these machines are limited in mobility. They are able to study a small region of Mars in almost unbelievable detail, but they cannot travel across the planet to study all of it. And there are only a few rovers and landers, not like on Earth where we have people spread all over the globe. So, to study Mars globally, we use orbiting spacecraft (like Mars Global Surveyor) that take images and send them back to Earth for us to look at. In this way, we can gather images from all across the planet.

But here is where one of our main difficulties arises. When we get these fantastic and amazing images back from Mars, we have to always remember that we are looking at Mars and not the Earth. As humans, we are used to how things work on Earth and so we tend to look at other planets with "Earth Goggles" on. We want to try and interpret other planets by how they look compared to Earth, and while it may be useful at some times, we can run into huge problems when we try to do this. The first thing we need to do is take off our "Earth Goggles" and remember that we are looking at the planet Mars, which is very different from Earth.

The surface of Mars behaves differently than the surface of Earth because of these differences between the planets. Earth has a huge atmosphere, with lots of liquid and gaseous water. Mars is a desert planet – it is dry, has a thin atmosphere with lots of huge dust storms and, because of the temperatures and pressures at the surface of the planet, water cannot exist as a liquid at its surface. It is important to remember these differences when we look at the "glass tubes on Mars" that are in the MOC (Mars Orbiting Camera) image that you referenced (MOC narrow-angle image M04-00291). We also need to remember that this is Mars and not Earth when we try to interpret the images, and when we read articles by people who are trying to interpret these images.

The features on Mars that look like "glass tubes" in the MOC images do have an official interpretation. These "glass tubes" are not tubes at all. In fact, they are depressions in the surrounding surface caused by either ancient river valleys that have since dried up or surface faulting. Scientists might refer to these depressions as valleys or troughs. The bright linear features that cross these valleys are sand dunes made up of material that is transported by strong winds on Mars to these valleys. This interpretation is agreed upon not only by the people who built and operate the MOC camera (Malin Space Science Systems), but also NASA, as well as the overwhelming majority of professional planetary scientists who are interpreting these images. (I showed these images to a number of planetary geologists and asked them how they would interpret these features. Every single scientist said they were sand dunes inside of valleys, without hesitation. This is mainly because we are used to looking at such images on Mars and seeing the different forms that sand dunes can take. We have been trained to take off our "Earth Goggles when we see an image from another planet. I encourage you to check out Malin Space Science Systems main page (link below). They have a huge searchable image collection (link below) of not only sand dunes on Mars, but all sorts of other features as well, like impact craters and ancient river valleys.)

Is there evidence for liquid water on Mars today?

This question is what is driving almost all of NASA’s planned Mars missions right now! Policy is being shaped around whether there are sources of liquid water on Mars, for two main reasons. First, life on Earth needs liquid water (careful, we have our "Earth Goggles" on again) and so, perhaps if we found liquid water on Mars, we would be able to find life, or even signs of ancient life. Second, if we want to send humans to Mars someday, we need water to live and it is too difficult to bring all that water with us. So, we would need a reliable source of liquid water near the surface of Mars today that we could use for human missions. In fact, if you want more information about how the search for water plays a role in NASA’s planned Mars missions, check out NASA’s official Mars Exploration Program (link below).

As it stands right now, there is a lot of evidence that there was liquid water on the surface of Mars a long long time ago (billions of years ago, when Mars was warmer). There are ancient valley networks that look like dried up riverbeds (link below). There are images that show huge outflows of water (link below) that carved the surface and left scars for us to see billions of years later. More recently, the Mars Global Surveyor’s MOC camera imaged what are called "Martian gullies" and appear to be relatively recent outflows of water down the sides of impact craters and canyon walls. Again, Malin Space Science Systems has a great collection of these images (link to their "Gullies" page below). Even more recently, the Mars Exploration Rover called "Opportunity" has found evidence in Martian rocks of certain minerals that can only be formed in the presence of water (link to Mars Exploration Rover main page below). So, there is lots of evidence that suggests that there was water on the surface of Mars at some point in its history. If there is liquid water on Mars today, it most likely is below the surface and so many scientists are trying to determine how deep the water might be. If it is near enough to the surface, future astronauts could mine it and use it. But if it is very deep within the Martian surface, it might be impossible for us to get to. The question is still very open...

Finally, I just wanted to caution you about where to find information about Mars on the internet. The internet is a big place and there is lots of information on it, but we all need to be careful about where we are getting our information from. We want to make sure that information is reliable and accurate. If you have questions about what you are looking at in any of the MOC images (the really high-resolution close-up images of Mars), go straight to the source: Malin Space Science Systems (link below). This is the company that built the MOC camera and operates it. They have thousands of images that are easily searchable and often the images have descriptions that help you understand what you are looking at. These descriptions represent the highest level of science being done throughout the world today and will help you remove your "Earth Goggles" and appreciate the beauty and wonder and mystery that we are seeing on Mars – an amazing planet indeed!

Malin Space Science Systems Homepage: http://www.msss.com/

MOC image gallery – searchable by topic, such as "sand dunes" http://ww w.msss.com/mars_images/moc/index.html

NASA’s Mars Exploration Program: http://mars.jpl.nasa.gov/over view/

A fantastic article about ancient valleys and channels on Mars with lots of great images!: http://w ww.msss.com/http/ps/channels/channels.html

A Large Outflow Channel on Mars: http://www.msss.com/mars_images/moc/7_19_99_fifthMar s/11_hrad/

Martian Gullies can be found at: http://www.msss.com/mars_images/moc/themes/GULLIES.html

Mars Exploration Rovers main page: http://marsrovers.jpl.nas a.gov/home/


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