On August 6, the Curiosity rover landed on Mars. The mobile science lab started its journey on November 26. The project is costing $2.5 billion - it's the most expensive Mars mission to date.
Gale Crater is located near Mars' equator. This is NASA's most precise landing of a probe on Mars to date. The landing area was calculated down to the last 20 kilometers.
The landing capsule had to decelerate from 13,000 kilometers per hour (km/h) to a full stop within seven minutes. Mars' atmosphere is 100 times thinner than that of Earth's - the atmosphere will have helped reduced the capsule's speed massively. Then, a parachute and reverse rockets were deployed to slowed the craft before landing.
The parachute had to withstand powerful forces. Tested in a massive wind tunnel at NASA's AMES Research Center in California, the parachute - itself weighing only 45 kilograms - could carry a truck weighing 30 tons on Earth.
After 560 million kilometers of travel, the journey for the Mars rover came to a peaceful end. Using its own rockets, the landing craft - itself located in the capsule - decelerated from 110 km/h to zero. It then hovered eight meters above ground and set the rover down using cables.
Curiosity - as the rover is known - is set to look for organic compounds, as well as nitrogen, carbon, oxygen, hydrogen, sulfur and phosphorus. Scientists want to analyze isotopes and minerals on Mars to learn how the planet's atmosphere has developed over the past four billion years.
At three meters long, Curiosity is about five times the size of both its predecessors, "Spirit" and "Opportunity." It weighs 900 kilograms (2,000 pounds) and can carry much more analytical gear than earlier rovers. Curiosity is scheduled to work for one Mars year - or 686 Earth days - moving at speeds of 30 to 90 meters per hour.
This image is from a previous rover mission. It is hoped Curiosity will provide much more precise images. It is intended to reveal whether the atmosphere on Mars was once able to host life - or still is, even if only at a microbial level. The rover is equipped with an electron microscope that achieves a resolution of 12 micrometers.
Since 1960, there have been over 40 missions to Mars - almost all American and Soviet/Russian. There has been just one European mission. But only 20 missions have been successful. Some probes even failed to reach Earth's own orbit.
Mars has two polar ice caps composed of frozen CO2 or "dry ice," and frozen water. There are also indications of liquid water in images taken by NASA's Phoenix lander. It hosts volcanoes and massive rift systems - 4,000 kilometers long and seven kilometers wide - and gets its red color from iron oxide dust that has scattered itself across the planet and atmosphere.
Mars (right) is relatively close to Earth. It orbits the sun at a distance of 228 million kilometers; the Earth orbits at 150 million kilometers. Mars' atmosphere is mainly composed of carbon dioxide and nitrogen. Venus (center left) resembles the Earth in size and has an atmosphere, while Mercury (left), the planet closest to the sun, has no atmosphere.
Mars has long inspired the imagination - its red color lending it the name of the Roman god of war. Like Earth, it is considered a candidate for hosting life. In 1898, H.G. Wells addressed the topic in his novel "War of the Worlds." In 1938, Orson Welles' all-too-realistic radio drama based on the novel was misunderstood as a real news broadcast, causing many to panic in the United States.
On August 6, the Curiosity rover landed on Mars. The mobile science lab had been traveling since November 26. The project is costing $2.5 billion - the most expensive Mars mission to date.
