Craters on Mars

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Talk about a beat up surface. There are hundreds of thousands of craters on Mars, including 43,000 that are 5 kilometers in diameter or larger. Hundreds of them have been named after scientists or famous astronomers. Craters smaller than 60 km across are named after towns on Earth. The largest known crater on Mars is the Hellas Basin. It is 2,100 km across and as deep as 9 km in places. It is surrounded by an ejecta filed that stretches 4,000 km from the center of the basin.

The majority of the craters on Mars were probably created during the Late Heavy Bombardment period of our Solar System, which occurred approximately 4.1 to 3.8 billion years ago. During this period a large number of impact craters are believed to have formed on all of the terrestrial bodies in the Solar System and may have destroyed some smaller bodies that are unknown today. The evidence for this event comes primarily from the dating of lunar samples, which indicates that most impact melt rocks were created during that interval of time. Scientist can not agree as to the cause of this bombardment, but a theory called the Nice model is popular. Under this theory, the orbits of the gas giants migrated, which caused the orbit of objects in the main asteroid belt and the Kuiper belt to become more eccentric, reaching into the orbits of the terrestrial planets. Others argue that the Moon samples are not multiple events, but the ejecta from one large impact.

The Hellas Basin is also known as the Hellas Planitia and the Hellas Impact Basin. It is located in the southern hemisphere of Mars, centered at 42.7°S 70°E. It is the second largest impact crater and the largest visible impact crater known in the Solar System. Hellas has been the second largest crater behind the South Pole-Aiken Basin on the Moon for many years, but new data may drop it into third place. Data from NASA’s Mars Reconnaissance Orbiter and Mars Global Surveyor seems to indicate that most of the planet’s northern hemisphere is actually one large impact crater. This disputed basin is being called the North Polar Basin-Borealis Basin and could potentially be 10,500 km in diameter. That accounts for roughly 40% of Mars. Scientists are still debating the interpretation of the data, so be sure to look for updates from NASA or here on Universe Today.

A person could write an entire ebook just listing the named craters on Mars. Hopefully, you have an idea of how cratered the planet’s surface is. It is almost impossible to describe in one article.

We have written many articles about craters on Mars. Here’s a recent story with links to crazy mars craters, and here’s an article about debris filled craters on Mars.

If you’d like more info on Mars, check out Hubblesite’s News Releases about Mars, and here’s a link to the NASA Mars Exploration home page.

We have recorded several podcasts just about Mars. Including Episode 52: Mars and Episode 92: Missions to Mars, Part 1.

Sources:
http://search.nasa.gov/search/search.jsp?nasaInclude=hellas+basin
http://search.nasa.gov/search/search.jsp?nasaInclude=craters+on+mars
http://www.nasa.gov/mission_pages/MRO/news/mro-20080625.html