Mars came so close to our planet, Earth, up to a distance of 56million kilometers, in August 2003. Scientists estimate that this distance is the closest in 60,000 years. Astronomically, this closeness of mars to us puts the red planet at ‘our backyard’. In 2004, several spacecrafts that were launched had already started exploring Mars. Some explored it from the orbit while others from the Martian surface.
The Mars space craft known as Mars Global Surveyor which arrived Mars in 1997 discovered that it had, at a certain time, a strong magnetic field. This orbiter also mapped the topography of Mars which revealed the distance from the lowest spot to the highest. This distance far exceeds 29 kilometers, compared to about 19 kilometers for the Earth which is the distance from the base of the Mariana Trench in the pacific ocean up to the top of the highest mountain on Earth—Mount Everest.
The lowest spot on the Martian surface is the wide Hellas basin, which was formed by the impact of gigantic asteroids while the highest point is the summit of the magnificent Volcano Olympus Mons which is 21 kilometers high. Cameras mounted on Surveyor recorded the large boulders that seemed to be over 18 meters across including large fields of sand dunes and newly created gullies. Further discoveries revealed that most of the surface rocks on mars were of volcanic origin.
When scientists lost contact with the Mars Global Surveyor in November 2006, other orbiters continued their exploration of the red planet. These orbiters were the Mars Reconnaissance Orbiter, Mars Odyssey and Mars Express. They used more sensitive cameras in their exploration which further revealed the make up of the Martian atmosphere and an abundance of ice on the Martian North pole. This ice discovery was the main focus of yet another explorer known as the Phoenix Mars Lander which landed on the planet in 2008, precisely on the 25th of May. The mission of the Phoenix Mars Lander is to explore the permafrost icy region of the North Pole and find out if it had ever supported microbial life.
The Phoenix Mars Lander provided very useful information about the Martian surface including its icy regions. An arm of this space craft scooped down the surface of the ice and fed both ice and soil samples to the two laboratories on board for analysis. However, the mission was designed to be a short one as just months after the end of the Lander’s mission, the Martian winter was to set in which would wrap the Pheonix in a thick blanket of frosty carbon dioxide ice.
‘Spirit And Opportunity’ At Work
Spirit and Opportunity were two Martian exploration rovers that arrived Mars in January 2004 and their landing sites were informed by data generated from previous Martian explorations. Their mission was to assess the history environmental conditions and phenomena at areas that might be able to support life. While landing on the Mars, they slowed down as they descended through the Martian atmosphere with the aid of heat shields, rockets and parachutes. As they landed they bounced on the surface and freed from a cocoon of airbags as did the earlier Mars Pathfinder in 1997.
Robotic exploration on Mars is made more possible because it has basically the same surface area of dry land as is found on Earth. Spirit landed on a area of Mars close to the giant Gusev crater which is believed to have once contained an ancient lake while Opportunity landed on the Meridiani Planum which is a plateau of ancient rocks in layered platform that contains hematite—an iron rich mineral ore.
Geological Discoveries of ‘Spirit’ and ‘Opportunity’
When Spirit landed on its destination, it was on a barren landscape characterized by shallow but circular depressions that could have been created by meteorites. It further discovered that the surrounding rocks and soil formations were formed and embedded with volcanic rocks. Spirit then drove to a distance of about 2.6 kilometers in order to investigate a group of small hills and plateau where it discovered that there were quite unusual ledges and rock formations that have volcanic origins.
On the 25th of January 2004, Opportunity landed just 25km from its target area. This is after it had travelled over 456million km. Opportunity explored blueberries which were layered rocks that encapsulated small hematite-rich spherules. These blueberries are not truly blue; their gray color is a sharp contrast to the red background of Martian soil and rocks. Further discoveries by Opportunity showed that some rocks were formed ripples similar to that made by sand deposits in a flowing water body. With the discovery of chlorine and bromine in the rocks, scientists believe that salt water could have been present at certain point in time.