Human spaceflight to Mars is yet to happen, with the development of NASA's Orion capsule still underway. But already NASA is making breakthrough discoveries in their Martian exploration, with the help of its crew of robotic comrades currently roving the planet.
Here are the five robots that are helping NASA and the Earth know more about the neighboring Red Planet.
1. Curiosity Rover
The Curiosity Rover or Mars Science Laboratory is designed to determine the planet's habitability by assessing whether Mars ever had an environment capable of supporting small life forms or microbes. The rover, which is considered one of NASA's most ambitious interplanetary missions, landed on Mars' Gale Crater in 2012. Its mission was supposed to end after two years, but NASA decided to extend Curiosity's exploration of Mars indefinitely.
Curiosity was able to find evidence that Mars once held liquid water. In 2014, the rover also found the organic chemical methane in Mars' atmosphere, which could be linked to microbial life. The discovery will be the basis for a manned mission to Mars.
2. MAVEN
NASA's Mars Atmosphere and Volatile Evolution (MAVEN) is designed to study the Martian atmosphere, ionosphere and interactions with the sun and solar wind. The spacecraft, which launched in 2013 and arrived on Mars in September 2014, is also tasked to find out how the Red Planet had lost its water and atmosphere.
3. Odyssey
The Odyssey spacecraft launched in 2001 and is the longest Mars mission to date. The mission is designed to map the amount and distribution of many chemical elements and minerals that make up the surface of Mars. Using its high-power cameras, Odyssey closely observes the weather conditions on Mars to determine risks to future crewed missions.
4. Mars Reconnaissance Orbiter
The Mars Reconnaissance Orbiter (MRO) is on a mission to search for evidence of liquid water that may have existed long ago on the planet. The spacecraft is equipped with six instruments that search for underground deposits of ice and water on Mars, as well as monitor the daily weather on the planet.
5. Opportunity
The Opportunity rover was launched in 2003 as part of the Mars Exploration Rover (MER) program and landed on Mars' Meridiani Planum in 2004. Its twin rover, Spirit, which arrived three weeks ahead, got stuck in the sand and ceased communications in 2010. Opportunity remains active, continuing with its task of finding and classifying a wide range of rocks and soils that could hold clues to the existence of liquid water on Mars.
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