The Greatest Meteorite on Earth EarthCache

The Greatest Meteorite on Earth

The Hoba Meteorite

The Hoba meteorite is a meteorite that lies on the farm of the same name, not far from Grootfontein, in the Otjozondjupa Region of Namibia. It has been uncovered but, because of its large mass, has never been moved from where it fell. The main mass is estimated at more than 60 tonnes, in 1920 its mass was estimated at 66 tonnes. Erosion, scientific sampling and vandalism reduced its bulk over the years. The remaining mass is estimated at just over 64 tonnes.
The meteorite is composed of about 84% iron and 15% nickel, with traces of cobalt. It is classified as an ataxite iron meteorite belonging to the nickel-rich chemical class IVB. A crust of iron hydroxides is locally present on the surface of the meteorite due to weathering oxidation.

Impact

The Hoba meteorite impact is thought to have occurred more recently than 80.000 years ago. It is inferred that the Earth's atmosphere slowed the object in such a way that it impacted the surface at terminal velocity, thereby remaining intact and causing little excavation (expulsion of earth). The meteor appears to have slowed to about 320 m/s from an entry speed to the atmosphere typically in access of 10 km/s. The meteorite is unusual in that it is flat on both major surfaces.

No Crater?

It is surprising that this meteorite is not surrounded by a crater. Objects of this size should punch through the atmosphere at a very high rate of speed and hit Earth with enough force to blast a significant crater. No crater is present around the site of the meteorite. That suggests that it fell to Earth at a lower rate of speed than expected. Some scientists believe that the flat shape of the object may be responsible for its low velocity at impact. 

Discovery

The Hoba meteorite left no preserved crater and its discovery was a chance event. In 1920, the farmer and owner of the land, Jacobus Hermanus Brits, was plowing one of his fields, when is plow suddenly screeched to a halt. Curious about what he had run into, he dug in the soil to find a large piece of metal. The large metal mass quickly attracted the attention of scientists and others, who identified it as a meteorite and removed the soil around it. The farmer had discovered a 66-ton iron meteorite - the largest single meteorite ever found and the largest piece of iron ever found near Earth's surface.
The Namibian government has declared the meteorite and the site where it rests as a national monument. The site now has a small tourist center.

Your task to log the cache:

Answer the following questions via message (not mail!) in English or German via my geocaching profile:

1.) Look at and feel the surface of the meteorite. How does it feel? Is the material warm or cold? Why do you think the surface of the meteorite is designed the way it is?
2.) Look at the top edge on the east side of the meteorite - what traces can you see here? Are they old or new?
3.) In some places the meteorite is sanded and you can see the inner structure. Why doesn't the surface rust here?
4.) Get on the meteorite. Approximately in the middle is the inscription "31-8-83 HH" on the surface. Below there is an arrow - in which direction does it point?
5.) Optional: Post a photo with your log, showing you and/or your GPS near the meteorite!


After you've sent me the message with your answers, feel free to log! Only if there's something wrong, I'll contact you via message!

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