Tag: crater

News from Space: Mars Gets New Crater!

martian_craterThe Mars Reconnaissance Orbiter (MRO) captured this image of a 50-meter wide crater on the Red Planet back on March 28th, 2012. But the impressive thing is that this same crater was not there when the MRO took pictures of the area the day before. In other words, this crater was spotted less than a day after the impact that formed it. This is a record=setting events, since it usually takes a few years before the presence of new craters have been confirmed.

In this case, though, the constant sweep of the Mars weather camera (called the Mars Color Imager, or MARCI) picked up the black smudge that is a telltale sign of a fresh impact. Because the imager is low-resolution, it sees a large area of the surface, and does so all the time. It’s also the largest crater in the solar system ever seen with before and after shots. At 50 meters or so across, it’s half the length of a football field, so the impacting object was probably up to a few meters across.

mars_crater_marcimars_crater_marci2Something that small would burn up in Earth’s atmosphere, but given that Mars has a much thinner atmosphere (about 1 percent as thick of Earth’s) rocks of this size make it to the surface with ease. Once they make it to the ground, they hit hard enough to carve out a hole and blast out ejecta debris – which was how the crater was found. But the atmosphere is thick enough to cause a lot of pressure in front of the incoming meteoroid, which can break it up into smaller pieces.

As you can see from the images above – the top which was taken on March 27th and the bottom on the following day – there was one big crater, one smaller one, and quite a few even smaller ones around the main one. These may have been from pieces of the meteoroid that broke up as it came in. Not only that, but landslides were observed in the area that occurred around the same time, so they may have been caused by the seismic ground wave from the impact as well.

mars_avalanche4Events like this are not only novel, they are also very useful for scientists, since they help them to understand how impacts have shaped the Martian landscape. They also help determine the number of small impacts suffered by Mars (and by extrapolation, Earth), and in some cases reveal what’s underneath the surface of the planet (including ice). This latest impact is many ways a gift, since most craters are very old and the atmosphere have eroded them to the point that there results are no longer fresh.

Kudos to the MRO team for their fine work in spotting this new Martian surface feature. And in the meantime, be sure to enjoy this video that explains this record find, courtesy of the NASA Jet Propulsion Laboratory.


Sources: slate.com, space.IO9.com, mars.nasa.gov

News From Space: Ancient Meteorite Crater Found

meteorIn southern Alberta, scientists have found a vast, ancient crater that they claim dates back some 50 to 70 million years. Discovered entirely by accident in near the hamlet of Bow City, some 20 km south-west of Brooks, and 100 km south-east of Calgary. According to assessments of the impact zone, researchers estimate that the space rock would have been the size of an apartment block, and would have left a crater 8 kilometers wide and roughly 2 and half km deep.

All told, this explosive force of this impact would have been 200 times stronger than the most powerful thermonuclear bomb ever built. That’s basically a force of 1000 megatons, a detonation so powerful that anything within 200 km of the impact would have received 1st-degree burns. To put that in perspective, this means that the city of Calgary would have been decimated by the blast, and in Edmonton, some 400 km away, every window would shattered.

alta-meteorite-crater-20140507But even more awe inspiring was the long-term effects of the damage, which would have thrown enough dust and debris into the atmosphere to mess with the Earth’s climate for the next few years. As Schmitt put it:

Something of that size, throwing that much debris in the air, potentially would have global consequences; there could have been ramifications for decades.

But after eons of erosion, very little of the crater is left. In fact, the discovery happened entirely by accident when a geologist – who was doing some routine mapping of the underground layers a few meters beneath the surface – apparently noticed a circular disturbance that was covered. Schmitt and his lab were called in to inspecting the feature and used seismic data to create a complete image of it. They quickly realized that it was most likely an impact crater, complete with a central peak where the meteorite would have struck.

Alberta_craterThe size of the object can only be estimated, but assuming the meteor was composed mostly of iron, it would have had to have been between 300 and 500 meters in diameter to create a crater of this size. If the meteorite was rock, it would have had to have been a kilometre across. Schmitt said the crater is a rare opportunity to study the floor of an impact crater. His team is now looking for certain types of minerals that form only under certain conditions so as to confirm the crater is from a meteor impact.

But he doesn’t have much doubt. As he put in a recent interview with CBC news:

We’re able to get at the lower parts of (a crater) and see how rocks have been moved around… We’re pretty confident it can only be a meteorite impact. It’s pretty clear.

Once they’ve had a chance to uncover and examine the area in greater detail, a clear picture of the meteorite’s size, composition, and what lasting marks its impact left beyond the crater. This information will only contribute to our understanding of our Solar System, but of the history of our planet as well.

Sources: cbc.ca, calgarysun.com