Three papers published in the June 26 Nature allege that the fourth planet from the Sun was probably hit by an asteroid or comet some 4 billion years ago. Apparently, this seems the best explanation for the fact that Mars has a dubious irregular surface: the southern hemisphere pockmarked, featuring rugged highlands, while the northern hemisphere is much smoother and covered by low-rise plains.

It was already known that the northern hemisphere is 4 kilometers lower, and in 1984 Steven Squyres, a planetary scientist at Cornell University, and astrogeologist Don E. Wilhelms theorized that a single impact blasted away half the crust off the Red Planet.

New studies by the scientists apparently back this theory, as the Borealis basin, a crater on the northern hemisphere, is 5,300 miles across and 6,600 miles long. The impact basin is oval-shaped, consistent with a space object which would have hit the planet at an angle.

Calculations reveal that the impact and subsequent damage is roughly due to a 1,000-mile-wide object traveling at more than 13,000 miles per hour. The object probably hit Mars at an angle between 30 and 60 degrees, unleashing energy equivalent up to 150 trillion megatons of TNT.

Meanwhile, NASA’s Phoenix Mars Lander prepares for the new series of tests which will involve the Lander’s wet chemistry laboratory. The Martian soil will be delivered to the laboratory just as before, by using the robotic arm and the tests target the terrain’s compounds and characteristics, such as salts and acidity.