By
07.21.15
Scientists have found an unusual material called “impact glass” on Mars. The discovery is important. Impact glass could provide information about how well Mars can support life and show if there ever was life on Mars.
Signs of impact glass were discovered by Kevin Cannon and John Mustard. Cannon is a student at Brown University and Mustard is a professor there. They located the impact glass with help from a NASA Mars spacecraft.
Impact glass can be formed when an asteroid or comet crashes into a planet. The crash causes the release of a lot of energy that can melt rocks and soil. If the melted rock cools quickly enough, it becomes solid, and forms impact glass. This impact glass is different than the see-through glass we find in daily life. It is dark brown, almost black, and only partly see-through. It may look like freshly cooled lava from a volcano, says Cannon. However, lava and impact glass are formed differently.
Planet Slams Are Not New
Asteroids and comets routinely slam into planets. Therefore, scientists have long suspected that impact glass exists on other planets. The new study supports this idea.
Until now, it has been hard to find impact glass on Mars. Scientists identify different types of rocks on the surface of the planet by looking at the sunlight that reflects off the planet. Different rocks leave unique marks in the reflection, sort of like fingerprints. The fingerprint is a rock's spectral signal. Impact glass has a weak spectral signal.
Rocks are dark and have a strong signal because they absorb so much heat from the sun. If rocks and impact glass are in the same place, the rocks' signal blocks the signal coming from the glass.
Copying The Martian Glass
Cannon solved this problem by making his own artificial Martian impact glass. First, he mixed together powders that were like what rocks on Mars are made of. Then he melted them in an oven. After that, Cannon and Mustard measured the spectral signal of this imitation impact glass. It helped them to know precisely what to look for on Mars.
Their search turned up a bunch of glass in deep holes called craters on the planet's surface. “It wasn’t completely surprising,” Cannon said. “We thought that it should be there.”
One scientist said the study was the first time impact glass was found on Mars.
Looking For Tiny Life Signs
Impact glass has also been found on Earth. Studies show that the glass can hold signs of what lived on a planet before the glass was formed. It can also show bits of what lived on a planet after the glass was formed.
Last year, a team of scientists led by Peter Schultz of Brown University said they found plant leaves inside impact glass that was found in a crater in Argentina. Schultz says impact glass on Mars might also hold bits of tiny life. “There is no proof that there ever was life on Mars,” said Kieren Howard, a professor at the City University of New York. However, if there was once life on Mars, bits of life trapped inside impact glass could let scientists figure out what the planet used to be like, he said.
Impact glass is not only good for showing life-forms from where the planet was hit. The glass can hold tiny life-forms that moved in later.
The tiny life-forms called are called chemolithoautotrophs, which are thought to be some of the earliest life on Earth. They can tunnel into the glass and live.
Some of these microbes, or tiny life forms, create acid. The acid allows them to dissolve the glass. As the glass dissolves, the microbes dig in deeper, forming tiny tunnels.
Bringing The Glass To Earth
If these tiny tunnels were found in the Martian glass, could that be evidence that Mars was home to alien life? Could life even still be on the planet? Cannon said there is no reason to think there is life on Mars today. Besides, scientist Haley Sapers says that scientists would need to bring the glass to Earth to try to find any tunnels. Doing this would surely kill anything still alive in the glass.
Still, the glass may contain gases from the time the comet or asteroid hit the planet. This could show what the atmosphere on Mars used to be like.
Questions:
1. What is found on Mars?
2. Why is the discovery important?
3. What is "impact glass"?
4. How is the "impact glass" formed?
5. How did Cannon find the "impact glass" on Mars?
6. How does impact glass shows what lived on the planet?
7. What are chemolithoautotrophs?
8. Do you think there is life on Mars? Support your answer.
