This little chunk of crystalline metal is a tiny slice of a meteorite — a rock that fell from the sky. When one says that, the next natural question is, “how do you know it’s a meteorite?” (We will get to that.) But what is really staggering is not just that we know, but how much we know about it and its history. And what a long history it is.
This specimen is a 68 gram sample cut from a fragment of the Muonionalusta meteorite. According to our best current understanding, the parent body that Muonionalusta came from was one of the earliest bodies to take shape during the formation of our solar system. It began as a protoplanet (or planetisimal) that accreted within the protoplanetary disk that would eventually become our solar system. It accreted over the course of roughly the first million years after the beginning or our solar system. (That is to say, during the first million years after the very first solids condensed from the protoplanetary disk.) The parent body had an iron-nickel “planetary” core, 50–110 km in radius, that was eventually exposed by collisions that stripped away most of its insulating mantle. It cooled very slowly over the next 1-2 million years. It is estimated (with startling precision) by Pb-Pb dating that the body crossed below a temperature of ~300 °C at 4565.3 ± 0.1 million years ago, just 2-3 million years after the solar system began to form. For the next four billion years, it led a largely unremarkable existence as an asteroid (minor planet) until it broke apart (possibly due to a major collision) about 400 million years ago. Then, one fine day roughly one million years ago, a large fragment entered the earth’s atmosphere, breaking into hundreds (perhaps, thousands) of smaller fragments that rained down in a shower of fire upon what is now northern Sweden and Finland. Four ice ages transported the surviving meteorite fragments across the Swedish tundra, until their first discovery (and naming after the nearby Muonio river) in 1906.
But, how do we know all of that?
Continue reading A Fragment of Muonionalusta
In our annoucement article about the EggBot Electro-Kistka — the hot wax dispenser for the EggBot — we noted that it can be challenging to reposition an egg after taking it out to dye the egg between wax layers.
As an alternative suggestion, reader Dan commented:
Could you leave the egg in the EggBot and paint on the first layer(s) of dye with a brush? Then dip the egg for the last layer to get the ends covered.
Well, let’s try and see how it turns out!
Once upon a time, cameras did not come with LED illumination or even xenon strobes, but rather with a socket that could fire a one-time-use flashbulb.
An advance from this was the “flip flash” cartridge which held 8 or 10 flash bulbs, ganged up so that you could take one photo after another, without pausing to swap bulbs. Each time that you took a picture (exposing actual film!), the next flashbulb in the cartridge would fire.
But you might ask a tricky question here: How does it know which bulb to fire next?
One of the common reactions that people have when they first see our Three Fives kit is to joke “Now all I need is a giant breadboard!” Well, Michael Pechner actually designed and made one, and put the files up on Thingiverse. He built the design in Fusion 360 with a little help from Michael Gregg and printed it out in
PLA ABS on his 3D printer.
Thus far, the design is “plastic only,” without the metal inserts that one would find in a real electronic breadboard — but that’s okay, since the aluminum legs on the Three Fives kit are also decorative rather than functional. But, there are holes in the tops and slots in the bottom in case someone would like to add them.
Inspired by the global hackerspace movement and (software) hack days, Kids Hack Day is a 1-day event held in various locations around the world, where children and adults come together to “hack” and make new uses of every day items.
This incredibly charming video from the Kids Hack Day kickoff event in Moscow on May 25 shows you what it’s all about. (And, we are tickled to see our own WaterColorBot and EggBot making little appearances as well.)
I loved this little piece by Bryan Kennedy titled “It’s just wood.” A concise philosophical statement about the freedoms that come along with knowing how to make things.
The same approach applies in so many different contexts. Sometimes, it’s just aluminum, just software, or just silicon. It also reminds me of what a physics professor of mine used to say when explaining how simple something was: “It’s just math.”
Ever wonder how they make foam rubber into an “egg crate” shape? You can tell that it isn’t molded that way, because there is not a smooth skin on the surfaces. And it clearly isn’t milled to that shape, since it comes in matched top and bottom pieces that are cut from the same initial block of foam. So how is it done? Amazingly enough, it’s done with a bandsaw.
Egg crate, acoustic, and other shapes of “convoluted foam” are cut with a special machine called a convolutor, which uses powerful rollers to feed flat sheets of foam rubber into a high-tension bandsaw. The rollers are covered with bumps that stretch and distort the foam such that the saw cuts to a variable depth, with extremely little waste.
You can watch the process in this video from Italian Cutting Systems (noting that the bandsaws are hidden behind protective covers):