What Has NASA Learned About Mars?
NASA has used both spacecr aft and robots to learn more about Mars. In 1965, Mariner 4 was the first NASA spacecraft to get a close look at the planet. In 1976, Viking 1 and Viking 2 were the first NASA spacecraft to land on Mars. They took pictures and explored the planet’s surface. Since then, more spacecraft have flown near or landed on Mars.>
NASA's Spirit and Opportunity rovers landed on Mars in January 2004. They found evidence that water once flowed on Mars. Living things need water to survive. So, any sign of water on Mars would mean that there could be, or could have been, life on the planet.
How Is NASA Exploring Mars Today?
Today, three spacecraft are circling above, or orbiting, Mars. The spacecraft are using scientific tools to measure the volcanoes, canyons, craters, temperature and the kinds of minerals on Mars. They also are taking pictures and searching for water.
Two robots that move, called rovers, are exploring Mars’ surface. Their names are Opportunity and Curiosity. The rovers travel around taking pictures and looking closely at the planet’s soil and rocks. NASA uses pictures and information from the spacecraft and the rovers to learn more about Mars.
How Will NASA Explore Mars in the Future?
NASA plans to send more robots to Mars. NASA wants robots to someday collect Martian soil and rocks and bring them back to Earth to be studied. The MAVEN spacecraft started orbiting Mars in September 2014. MAVEN studies Mars’ atmosphere. NASA plans to send a lander to Mars in 2016. And a new Mars rover is planned for launch in 2020.
NASA also wants to send astronauts to Mars someday. To get ready to send humans to Mars, NASA is studying new kinds of homes where astronauts can live. Scientists are studying how people in space could grow plants for food. By watching what happens to astronauts on the International Space Station, scientists are finding out how living in space affects humans.
5.Ring-a-Round the Saturn
Saturn is a funny-looking planet. True, it's not the only planet with rings. Jupiter, Uranus and Neptune have rings, too. But Saturn's rings are the biggest and brightest.
An astronomer named Galileo was the first person to see Saturn's rings. He spotted them while looking into space through a telescope in 1610. That's almost 400 years ago! Scientists have been trying to learn more about Saturn's rings ever since.
One thing we know for sure. Saturn's rings are made of ice and rock. These pieces vary in size. Some are as small as a grain of sand. Others are as large as a house. But scientists aren't sure when or how Saturn's rings formed. They think the rings might have something to do with Saturn's many moons.
Earth has only one moon. But Saturn has at least 60 moons orbiting it that we know about. Asteroids and meteoroids sometimes crash into these moons and break them into pieces. The rings could be made from these broken pieces of moons. The rings may also be made from material left over from when Saturn first formed.
From far away, Saturn looks like it has seven large rings. Each large ring is named for a letter of the alphabet. The rings were named in the order they were discovered. The first ring discovered was named the A ring, but it is not the ring closest to or farthest from Saturn.
Some of the rings are close together. Others have large gaps between them. The rings do not sit still. They circle around Saturn at very high speeds. A closer look shows that each large ring is made up of many small rings. The small rings are sometimes called ringlets. More rings and ringlets could still be discovered.
Saturn is much larger than Earth. More than 700 Earths could fit inside Saturn. Saturn's rings are thousands of miles wide. If there were cars in space, it would take more than a week to drive across some of Saturn's rings. On the other hand, the rings are quite thin. They are only about 30 to 300 feet thick.
Cassini is the latest NASA spacecraft to explore Saturn. Cassini left Earth in 1997 and arrived at Saturn seven years later, in 2004. The spacecraft has been orbiting the planet since then. Cassini sends new pictures and information back to Earth all the time. Cassini has taken amazing pictures of Saturn's rings.