A group from the Lakeview Museum of Arts and Sciences in Peoria, Illinois sent in this question. The original answer can be found at The Space Place, along with answers to many other space questions.
|Image above: Dr. Marc talking on the phone.|
Is there life on Mars?
Dr. Marc's reply:
This is an idea that people have thought about for hundreds of years. It is one that I have wondered about for most of my own life.
Earth is the only place that we know of where there is life. Many people have studied Mars. Some have said that they thought they saw signs of life. We now know they were fooled by what they were able to see. That is because we do not have telescopes that are powerful enough. We need a close-up look at the planet!
Robotic spacecraft have given us great views. No humans have ever tried to go to Mars. No human missions to Mars will be tried for years. In fact, the first people on Mars may be your age today. When you are grown, maybe you will watch--or even be one of--the people who make the first trip to Mars!
NASA is working hard to find if there is life on Mars. The United States and other countries have been sending robot spacecraft there. Some have orbited Mars. Some have landed. Each mission teaches us more about this interesting planet. We have learned that Mars is more like Earth than anywhere else in the solar system. So, it is a good place to look for life. But, it is still different from Earth in many ways.
On Earth, a compass points to the North Pole. That is because our whole planet acts like a giant magnet. A planet’s magnetic field does more than turn a compass needle. It turns away dangerous small pieces of space radiation. But Mars does not act this way. Mars does not have a magnetic field. It has a lot less air covering it than Earth. So, it gets more harmful space radiation. Some research tells us there probably is water on Mars. There is a lot less than on Earth. And it is so cold there that most of the water is probably not liquid. It is ice! Mars would be a pretty tough place to try to live!
NASA landed two ships on Mars in 1976. One of these landers worked almost 4 years. The other lasted more than 6 years. Think of spending that much time studying another world! One of their jobs was to see if there was anything living in the soil. They looked for tiny things, even bacteria. So far, we have not found any signs of life.
The landers also had cameras. The pictures they took of Mars were sent back to Earth. They showed changing seasons. They showed close ups of the rocks and dirt. The cameras were not really part of the experiments to search for life. But, they did show that there weren't any large creatures moving around! Future landers will dig under the ground to try to find out if there is anything living there.
Where is the best place to look for life? Mars is smaller than Earth. But it is still a very, very big place. So where should scientists aim landers to give them the best chance of finding signs of life? All life on Earth depends upon water. The next spacecraft will look for more signs of water. This will help later landers find good places to search for life.
There may not be life on Mars. It would still be exciting to know if there used to be life there. NASA will be looking for tiny fossils. These might show that there used to be life on Mars but that it just did not last.
Robots will do a lot of the work on Mars. Someday, samples from Mars may be brought back to Earth. They will be studied in the best labs. Humans may go to Mars in the future. There are many problems that have to be worked out first.
You don't have to wait. You can blast off on a Mars adventure of your own right now. Visit The Space Place. Begin working on your mission. You can find out more about what NASA is doing right now to get us to Mars.
bacteria-- living things that have one cell and can be seen only with a microscope.
magnetic field -- the area around a magnet that has the power to attract other metals. The Earth is like a gigantic magnet, and has a magnetic field around it.