This elongated depression is about 78 km in length, opens from just under 10 km wide at one end to 25 km wide at the other, and reaches a depth of 2 km. It was probably caused by the impact of a train of projectiles. The data were acquired during orbit 8433 using the High Resolution Stereo Camera on Mars Express.
Credit: ESA/DLR/FU Berlin (G. Neukum)
PARIS: The European Space Agency’s (ESA) Mars Express has returned images of an elongated impact crater that could help scientists understand how they are formed and provide information about the potential presence of water that melted due to the impact.
Located in the heavily cratered southern highlands of Mars near the 450 km-diameter Huygens basin, the 'elongated crater' stands out. Researchers think it could have been carved out by a train of projectiles striking the planet at a shallow angle.
This unnamed elongated crater is about 78 km in length, opens from just under 10 km wide at one end to 25 km at the other, and reaches a depth of 2 km. Impact craters are generally round because the projectiles that create them push into the ground before the shockwave of the impact can explode outwards. So why is this one elongated?
Were there two projectiles?
The clue comes from the surrounding blanket of material, thrown out in the initial impact. This ‘ejecta blanket’ is shaped like a butterfly’s wings, with two distinct lobes. This hints that two projectiles, possibly halves of a once-intact body, slammed into the surface here.
In the crater itself, there are three deeper areas that could be evidence for more than two projectiles. In addition, a second elongated crater lies to the north-northwest. It can be seen in the wider contextual image and is in line with the one seen here, reinforcing the notion that these structures were the result of a train of projectiles.
The new image of the crater covers an area of 133 x 53 km at 21 degrees S / 55 degrees E. The scene was captured in August 2010 and the smallest objects distinguishable by the camera are about 15 m across.
Clues about possible past Martian life
In the early 1980s, scientists proposed that elongated impact craters were formed by incoming chains of orbital debris following trajectories that decayed with time. As the debris spiraled downwards, it eventually struck the planet at shallow angles, gouging out the elongated craters.
This particular ejecta blanket contains many smaller craters, indicating that the original formed a relatively long time ago and then itself become a target.
In addition, there are several small channels on the blanket, suggesting that the strike took place into a surface rich in volatiles, perhaps even water, that were melted by the heat of impact and flowed away. Water is essential for life as we know it, and evidence of water on Mars could help astrobiologists understand if the planet was once habitable for living organisms.
