Tag: impact crater

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

News from Space: Biggest Lunar Explosion Ever Seen!

moon-asteroid-impact-1600Back in September of 2013, something truly amazing happened on the surface of the Moon. Granted, small objects impact with Earth’s only satellite all the time, hence its cratered surface. But this time around, Earth-based instruments observed an impact that was caused by an object the size of a small car, ten times bigger than any previously-recorded impacts.

The burst occurred on Sept. 11, 2013, at about 20:07 GMT in a area on the moon known as Mare Nubium, producing a flash that would have been visible from Earth. It was caused by a meteor that is believed to measure between 0.6- and 1.4-meters wide, weighed some 400 kg (880 pounds) and generated a crater with a diameter of about 40 meters.

Mars_impact_craterJudging from the explosion and the crater it left behind, scientists estimate that the rock hit Mare Nubium at a speed of 61,000 kph (38,000 mph), generating an explosion equivalent to roughly 15 tons of TNT. This beats the previous record, which occurred in March 2013 when a 40 kg meteoroid 0.3 or 0.4 meters wide struck the moon at about 90,000 km/hr (56,000 mph) and caused an explosion equivalent to 5 tons of TNT.

These findings appeared in the February issue of Monthly Notices of the Royal Astronomical Society (MNRAS), in a paper entitled “A large lunar impact blast on 2013 September 11”. According to the paper’s authors – Jose M. Madiedo, from the University of Huelva and Jose L. Ortiz, from the Institute of Astrophysics of Andalusia – the impact was the longest and brightest impact ever observed, as the “afterglow” remained visible for 8 seconds.

moonIn a subsequent press release, Madiedo and Ortiz said that:

Our telescopes will continue observing the Moon as our meteor cameras monitor the Earth’s atmosphere. In this way we expect to identify clusters of rocks that could give rise to common impact events on both planetary bodies. We also want to find out where the impacting bodies come from.

Knowing how often such collisions happen on the moon could be important for future lunar explorers, one reason why NASA has set up a specific program – Lunar Impacts, working out of the Marshall Space Flight Center – to study them. This campaign started in 2005 and has already proved that lunar impacts happen about 10 times more frequently than scientists previously expected.

Russian_meteorBecause the moon is our next-door neighbor, and a place where human beings may someday live in large numbers, knowing the frequency and severity of meteoric impacts is certainly important. These latest findings also suggests that the Earth might get hit more often than we previously thought by objects of a similar size. And given the damage associated with such impacts, knowing all we can is certainly prudent.

In the meantime, check out this outreach video provided by J.M. Madiedo (co-author of the MNRAS paper) that discusses this record-breaking lunar impact:


Source: universetoday.com, wired.com, nasa.gov

News from Space: First Detailed Map of Ganymede

ganymedeLast week, researchers released the first-ever geological map of Ganymede, Jupiter’s largest moon and the largest planetary satellite in the Solar System. Led by Geoffrey Collins of Wheaton College, these scientists produced the first global geologic map that combines the best images obtained by NASA’s Voyager 1 and 2 spacecraft (1979) and the Galileo orbiter (1995 to 2003).

The information of these probes was pieced together as a mosaic image of the planet, giving us our first complete image of the geological features of the world. This image has now been published by the U. S. Geological Survey as a global planar map. The 2D version of the planet surface illustrates the varied geologic character of Ganymede and is the first global, geologic map of the icy, outer-planet moon.

ganymede_mapAnd its about time too! As Robert Pappalardo of NASA’s Jet Propulsion Laboratory in Pasadena, California put it:

This map illustrates the incredible variety of geological features on Ganymede and helps to make order from the apparent chaos of its complex surface. This map is helping planetary scientists to decipher the evolution of this icy world and will aid in upcoming spacecraft observations.

Since its discovery in January 1610 by Galileo Galilee, Ganymede has been the focus of repeated observation; first by Earth-based telescopes, and later by the flybys and orbiting spacecraft. These studies depict a complex, icy world whose surface is characterized by the striking contrast between the dark, very old, highly cratered regions, and the lighter, somewhat younger regions marked with an extensive array of grooves and ridges.

Ganymede-JupiterMoon-GeologicMap-SIM3237-20140211The map isn’t just aesthetically pleasing; it also informs our understanding of Ganymede’s geological history. Researchers have identified three geological periods – one involving heavy impact cratering, followed by tectonic upheaval, and then a decline in geological activity. The more detailed images let them study the ridges and groves, and have revealed that the formation of cryovolcanos is rare on Ganymede.

Baerbel Lucchitta, scientist emeritus at the U.S. Geological Survey in Flagstaff, Ariz., who has been involved with geologic mapping of Ganymede since 1980, had this to say:

The highly detailed, colorful map confirmed a number of outstanding scientific hypotheses regarding Ganymede’s geologic history, and also disproved others. For example, the more detailed Galileo images showed that cryovolcanism, or the creation of volcanoes that erupt water and ice, is very rare on Ganymede.

ganymede_ridges_craters_600According to the Jet Propulsion Laboratory, Ganymede is an especially valuable body to study because it is an ice moon with a richly varied geology and a surface area that is more than half as large as all the land area on Earth. The Ganymede map will also enable researchers to compare the geologic characters of other icy satellite moons, since most features found on other icy satellites have a similar feature somewhere on Ganymede.

Laszlo Kestay, the director of the United States Geological Survey (USGS) Astrogeology Science Center, explained the implications of this in a statement:

After Mars, the interiors of icy satellites of Jupiter are considered the best candidates for habitable environments for life in our solar system. This geologic map will be the basis for many decisions by NASA and partners regarding future U.S. missions under consideration to explore these worlds.

The project was funded by NASA through its Outer Planets Research and Planetary Geology and Geophysics Programs, and the images can all be downloaded by going to the Jet Propulsion Laboratory’s website at the California Institute of Technology (Caltech). And be sure to check out the animated version of the Ganymede planetary map below:


Sources: IO9.com, (2), jpl.nasa.gov, space.com