This will be quite a short post as I’m currently experiencing heavy outbreaks of paper corrections and lab work planning (this is how life goes as a third year PhD student) but an awesome new discovery has been made and I wanted to write about it. There are currently several spacecraft orbiting Mars, one of these missions is Mars Reconnaissance Orbiter, which is run by NASA/JPL. It’s equipped with an incredibly powerful camera known as HiRISE (high resolution imaging science experiment – scientists go nuts for acronyms). HiRISE imaged a region within the Terra Sabaea area of Mars in July 2010 and again in May 2012; scientists noticed that between these observations a dark patch had appeared. HiRISE acquired a high resolution image of the area on November 19th last year and the spectacular result was released yesterday.
Terra Sabaea is an impact scarred highland area just to the west of Syrtis Major near the equator. This new crater is around 30 metres across with fresh dark debris scattered up to 15 km in ejecta rays. The rays appear much darker than their surroundings as the fresh igneous rocks of Mars are dark coloured. Usually this dark rock mass is obscured under the red dust that coats most of the planet. Over time the iron minerals in this fresh material will slowly oxidise to an earthy red colour and the material as a whole will be blown and dispersed by the Martian winds. In my first post I discussed rampart craters, which are craters surrounded by lobes of fluidised ejecta formed when an impactor encounters underground ice. Here the crater is far too small to encounter any major ice bodies that might exist underground near the equator so the powdery ejecta spreads out in rays.
While we are lucky to see such a recent and spectacular crater this is not the first fresh impact observed on Mars. In a paper published in the journal Science in 2006 Malin, Edgett and others studied images taken by the Mars Global Surveyor spacecraft, a predecessor to Mars Reconnaissance Orbiter. In three study areas they identified twenty new impact craters that formed between 1999 and 2006 and were between 2 to 150 metres in diameter. They were likely formed by meteoroids 2-3 m in diameter (a meteoroid is a small rocky body in space, basically a small version of an asteroid. A meteor is the streak of light produced when such a body enters an atmosphere and a meteorite is any solid material that survives the impact). This new 30 metre crater is therefore not unexpected and is consistent with the rate of small impacts that occur on the planet.
When considering these individual areas of Mars it can be useful to get a global context. One of the best ways to do this is with Google Earth. In the program click the toolbar button featuring the picture of Saturn and you will get a dropdown menu where Mars is an option. Click it and you get a Mars globe to play with. The coordinates of this new crater are 3° 40′ 37.2″, 53° 25′ 40.7994″. Paste them into the search box and it will take you straight to the area. The resolution is pretty low but in the sidebar you can overlay HiRISE images, including a link to the one featuring this fantastic new crater. Enjoy!