MUMBAI (TIP): The red planet has been bombarded by more than 200 small asteroids or bits of comets annually forming craters which are atleast 3.9 metres across, according to Nasa. This has been revealed from images from Nasa’s $720- million Mars Reconnaissance Orbiter (MRO) which was launched on August 12, 2005. The mission’s original life span was for two years, but it has stretched to six. According to Nasa, researchers have identified 248 new impact sites on parts of the Martian surface in the past decade, using images from MRO to determine when the craters appeared. The 200-per-year planetwide estimate is a calculation based on the number found in a systematic survey of a portion of the planet. MRO’s High Resolution Imaging Science Experiment camera took pictures of the fresh craters at sites where before-and-after images by other cameras bracketed when the impacts occurred. This combination provided a new way to make direct measurements of the impact rate on Mars. This will lead to better age estimates of recent features on Mars, some of which may have been the result of climate change, according to Nasa.