Archive for January 10, 2011

NASA Announces Discovery of First Rocky Planet Outside Solar System

January 10, 2011 Leave a comment

The Kepler Spacecraft. Photo: NASA

It seems every couple weeks there is another story regarding exoplanets.

Oh well, they always seem exciting to me.

In a statement released today, NASA said

NASA’s Kepler mission confirmed the discovery of its first rocky planet, named Kepler-10b. Measuring 1.4 times the size of Earth, it is the smallest planet ever discovered outside our solar system.

The discovery of this so-called exoplanet is based on more than eight months of data collected by the spacecraft from May 2009 to early January 2010.

The Kepler mission is designed specifically to search for exoplanets roughly the size of Earth. It does this through a technique called the Transit Method.

Essentially, Kepler will watch a star for several hours. If a planet orbits that star, it may pass in front of the star and briefly reduce the apparent brightness. By measuring how much dimmer the star gets, and how often it happens, it is possible to determine the size and orbit period of the planet.

While this is a pretty cool discovery, don’t get your hope up about habitable planets yet.

Kepler is the first NASA mission capable of finding Earth-size planets in or near the habitable zone, the region in a planetary system where liquid water can exist on the planet’s surface. However, since it orbits once every 0.84 days, Kepler-10b is more than 20 times closer to its star than Mercury is to our sun and not in the habitable zone.

“Transparent Aluminium!?!”

January 10, 2011 Leave a comment

As Scotty demonstrates in this scene from Star Trek IV (the most entertaining one, imo) a material which is strong like a metal but clear like glass would cause quite a stir.

A paper published today in Nature Materials entitled “A Damage-Tolerant Glass” reports on a “bulk glassy palladium alloy” which displays both strength and toughness.

In materials science, strength and toughness mean two different things.

Strength is a term given to materials which are scratch-resistant and difficult to bend out of shape. However, these types of materials tend to be quite brittle, and therefore break or shatter easily. Glass is an example of a strong material.

Toughness is a term given to materials which are difficult to break. However, these materials can be scratched and are also fairly easy to mold them into a particular shape. Metals are good examples of tough materials.

Finding a material which displays both strength and toughness therefore is a quite an achievement.

The alloy described in this study is called an amorphous metal which is made up of atoms which are highly disordered; as opposed to normal metals which have atoms arranged in a crystalline structure.

Examples of "Glassy Metals". From Wikipedia


When atoms are arranged in a crystalline pattern, they are able to slip past each other easily, and this is why metals tend to be malleable and ductile.

An amorphous metal (or “glassy metal”) has a disordered structure and therefore does not bend to change shape as easily as normal metals. Amorphous metals are created by rapidly cooling a molten metal, freezing the atoms in place before they can arrange themselves in a neat crystal pattern.

The team in this study hit on a nice recipe for an alloy (chemical formula Pd79Ag3.5P6Si9.5Ge2) that would give both strength and toughness.

From Scientific American:

The successful recipe was mostly palladium, with a small fraction of silver and a smattering of other elements. “We don’t yet know why this particular composition works — it will take a deeper investigation to find out what chemical properties have been altered that affect the material’s toughness,” [study author Marios D. Demetriou] says.

The team tested the glassy metal’s toughness by monitoring how quickly and deeply a crack could move through it. “We found that it is as tough as the toughest steel,” he says.

Since this material would be very expensive to produce, it would most likely be used in medical implants, not buildings.

Not quite transparent aluminium, but materials scientists are working on some pretty cool stuff.