Who Wants to be an Astronaut?

"First, I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish."

With these words on May 25, 1961 before a joint session of Congress, President John F. Kennedy ushered in the age of space exploration. On July 20, 1969 his vision was realized. Almost 40 years later, the desire to learn more about our solar system has not diminished.

NASA's Apollo program was dedicated to exploring the Moon. The question for NASA scientists was how can we learn about the Moon before we go there?

The answer...Craters of the Moon...Idaho

In August, 1969, Apollo astronauts Eugene Cernan, Joe Engle, Edgar Mitchell, and Alan Shepard traveled to the lava beds of Southern Idaho to study volcanic features at Craters of the Moon National Monument. Later, this knowledge would be used to identify volcanic features on the Moon and help determine which rock specimens should be brought back.

Southern Idaho's Snake River Plain and Craters of the Moon have some of the most varied volcanic features found anywhere In the United States. In this activity you will train your eye, much like they did in 1969. But first, let's meet the astronauts (click on a name to view a short biography in the Glossary).





Now, let's begin your training...

Volcanic Crater vs. Meteor Crater

Most bodies in the solar system show evidence of meteor bombardment. If a planet has an atmosphere, like Earth, the meteors will burn up before impact or the meteor craters will erode over time. On the moon however, where there is very little atmosphere, the erosion of craters is slow and there isn't much resistance to burn meteors up so many of them end up striking the Moon's surface. Meteor craters on the Moon can resemble volcanoes on Earth, but there are differences.

Volcanic features have a positive relief, meaning that they are above the mean "sea" level. They may or may not have a summit crater. The Menan Buttes of Idaho are a great example.

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Meteor impacts have a negative relief meaning they are below mean "sea" level. They may have a central peak and rayed features. Check out Meteor Crater in Arizona.

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One of the keys to determining the difference between raised volcanic features and sunken crater features is illumination. Light from the sun will produce different shadows on each of these features. If a feature has positive relief the shadow will fall on the far side (away from the sun). If the feature has negative relief the shadow will fall on the near side (toward the sun). Sometimes an image will state where the illumination is coming from. Many times it does not. If it does not, you may be able to tell the direction of illumination by the direction of the majority of shadows in an image. Most features on the surface of the Moon are meteor impact craters, have negative relief and the shadows are toward the sun. Any features that show reversed shadowing will most likely be raised features.

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To make it through the first stage of astronaut training you must be able to identify some basic volcanic features. There is no better place to do this than the Snake River Plain and Craters of the Moon. Pack your bags, you are going to Idaho. Click on the following images to study volcanics on Earth. The description next to each image explains what you are viewing.





Snake River Plain (SRP) Images

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SRP Image 1
Three separate basalt lava fields (flows) of the Snake River Plain. They are the three dark areas in the photo. Notice how the large lava fields at the top and the one on the right edge show curved, arcing fronts with fingers of lava occasionally breaking out. The backward L-shaped flow to the left shows the sinuous nature of lava tubes and channels. Generally lava fields can be traced back to their narrowest section to find the source of the lava. The dark shape near the bottom right corner is a reservoir with the Snake River coming out of it. Note the mountainous topography and dendritic (branch-like) stream channels formed by erosion in the upper right of the photo.
SRP Image 2
Vertical aerial photograph of a small basalt flow. Vent is in the lower left-hand corner with the flow moving up and right and spreading out. Note the arcing "lobate" characteristics of the flow front.
SRP Image 3
Black patches are numerous basalt flows. Note the collapse crater in the upper left-hand corner with the flows radiating from it. The open arrow marks a summit crater and the black arrows showing raised-rim craters possibly associated with a lava tube.
SRP Image 4
Vertical aerial photograph of a cinder and tuff cone on the Snake River Plain. The concentric circle appearance is an indication of a raised outer rim with a sunken crater in the center.
SRP Image 5
Vertical aerial photograph of two buttes with positive relief. The light source is from left and below the buttes thereby casting a shadow on the backside of them. Notice the small cone with summit crater on the lower left flank of the upper dome. A crater with negative relief would have the sunlit and shadowed sides reversed. The white lines are roads.
SRP Image 6
Vertical aerial photograph of a rift system on the Snake River Plain. Notice how they are linear (straight) and relatively parallel. Apparently there was no eruption through the rifts since no basalt flow is present. Rifts occur because of a stretching of the crust. If the crust continues to stretch, a graben may form. The black patch in the upper left corner is part of the Craters of the Moon lava field.
SRP Image 7
Vertical aerial photograph of a linear rift with basalt flows issuing from it. Note how the arcing, lobate flow fronts trend away from the rift. Older flows are evident in the upper right corner of the photo. Spatter cones are present on the rift and the white patch in the center of the photo right of the rift is a layer of ash on top of the basalt. The white line from left to right is a road crossing the flow.
SRP Image 8
Vertical aerial photograph of a line of cinder and spatter cones on a rift on the Snake River Plain. The top center black patches are basalt flows left of the rift.
SRP Image 9
Oblique aerial photograph of a major vent and linear rift system. Notice the layers of basalt right of the main vent indicating multiple eruptions. Further right, along the edge of the basalt, several sets of parallel fractures are visible. Other fractures are visible to the left. Parts of the fractures are covered by later flows making the fractures older than the lava flows. The white lines are roads built along the edge of the basalt flows. The white splotches left of the main vent are ash and tephra deposits.
SRP Image 10
Oblique aerial photograph of a slot vent southeast of Big Southern Butte on the Snake River Plain. The vent has negative relief and the light source is from the left so the shadow is on the left. Notice the sinuous channel emanating from the lower side of the vent and curving back up and out the right side of the photograph.
SRP Image 11
Vertical aerial photograph of Bear Crater on the Snake River Plain. The vent and the lava tube/channel have negative relief. The light source is from the right producing shadows on the right side of the crater and the channel and lighting the left side of each. Note the overlap of lobate flows in the bottom half of the photo.
SRP Image 12
Oblique aerial photograph of Inferno Chasm on the Snake River Plain and its 1 km long lava channel. Compare the sinuous nature of the lava channel to the linear rifts running left and right along the bottom of the photo. The crater and channel have negative relief and the light source is from the left casting shadows on the left. Near the bottom left there must be a feature with positive relief as the sunlight is on the left and shadow on the right. This may be the jagged flow front of an older flow.
SRP Image 13
Vertical aerial photograph of the partially collapsed Bear Trap lava tube. Notice that if the lava tube had not collapsed in sections it would remain hidden from view. The white lines are roads. Can you find basalt flow fronts and a possible older collapsed lava channel? Look along the major road running from the upper left corner to the lower right corner. Near the upper left the road crosses a basalt flow. In the center of the photo, just off the road up and right, there may be some other flow fronts and straight down from there, below the road may be an old channel paralleling the main channel.
SRP Image 14
Oblique aerial photograph of a sinuous lava channel system. Note several lava tubes just left of center in the photo. They are surrounded by basalt flows. Note right of center, the pressure ridge running up and down in the photo. It is formed by a buckling of the hardened top of a basalt flow as the front of the flow encounters an obstacle of some kind, such as a bump or small hill in the topography.
SRP Image 15
Vertical aerial photograph of a pit crater and lava tube/channel. This feature is sinuous (curved) rather than linear (straight) indicating flowing liquid rather than a tectonic feature such as a fault or rift. Notice the cut-off branches and parallel channels.


All Snake River Plain images are used with permission from "Volcanism of the Eastern Snake River Plain, Idaho: A Comparative Planetary Geology Guidebook" by Ron Greeley.





Now that you know some of the basic volcanic features, you can identify some of the same features on the Moon. These images will not state what you are viewing. Click on each image, study it, and given what you know about Snake River Plain volcanic features, identify those same features in the lunar images. Check with your teacher to see if you have found them all.

Lunar Images

Lunar Image 1
 Lunar Image 2
Lunar Image 3
 Lunar Image 4
Lunar Image 5
 Lunar Image 6
Lunar Image 7
 Lunar Image 8

Last Modified Mon, Feb 12, 2001