Fine Structure

Flexible Metallic Glass Headed Our Way

Glass molecules arranged in ways that are more like metals than traditional glass have some pretty metal-like properties according to a new paper. Flexibility of such arrangements is much higher than what you'd expect from glass... being not very flexible at all.

I don't quite understand the details of how this type of glass is formed, but it sounds pretty interesting:

"Nanoindentation essentially uses a tiny needle with a very precise shape to push on the surface of a sample in a very controlled way. Even though the force is very small, the tiny tip of the needle concentrates the stress in a very small region until a single shear band is generated in order to relieve some of that stress."

It's not very clear how we'll see metallic glass appear in our daily lives (if it does, ever). The specific mentions of it in this article seem to suggest the researchers are still dealing with the new material on a very, very small scale (the picture in the article is from some sort of SEM-like device) but flexible and transparent glass would be a very futuristic development.

Published March 4, 2014 •[ ]

More Commercial Spaceflight Planned for 2016

Sierra Nevada Corporation, a sort of do-it-all contractor for technology and space, is planning to take the new Dream Chaser orbital spacecraft into space atop an Atlas V rocket in 2016. The spacecraft is being built with the hope that it can take over duties to ferry astronauts and supplies to and from the International Space Station, though it has some stiff competition in Orbital Science's Cygnus and SpaceX's Dragon modules which have recently began docking at the ISS. The Russian Progress module and European ATV already service the ISS.

SNC also produces the rocket motor for Scaled Composite's SpaceShipTwo which appears to be working nicely as they test the larger craft closer and closer to space.

Published February 10, 2014 •[ ]

Tiny Carnot Engine With Supercharger

Dust off your thermodynamics textbooks for this one; the smallest version of a carnot heat engine works on just a single atom trapped in a tiny confined space known as a Paul trap.

The electron cloud of the atom expands and contracts as it is "heated" and "cooled" by lasers on either side of the trap. However, it's the notable additions drive this engine towards the efficiency limit for carnot engines. First, adding energy to the atom is timed precisely with the resonance of the atom and then the atom is "squeezed" as it cools, causing it to pulse as it moves back towards the cold side.

While these engines probably won't be used as engines by themselves, research into heat transfer with high efficiency in nanoscale devices will be incredibly useful as we keep making smaller and smaller devices.

Published February 6, 2014 •[ ]

Rosetta Wakes From 31 Month Nap

Rosetta is the ESA's comet-chasing mission aiming to intercept the Churyumov-Gerasimenko comet outside of Jupiter, go into "orbit" around the comet and deploy a lander to the comet surface. Yes, that sounds far-fetched but it's happening right now.

There's a good overview of the whole mission here but the short version so far is that Rosetta has been in hibernation mode for the last 31 months as it traveled out towards the comet after a number of gravitation assists and flybys since its original launch in 2004 (!!!). Closer to the end of this year it will intercept the target comet and match its orbit, then send a lander to the surface via grappling hook to perform the first real science on a comet.

Today is notable on the journey towards the comet because Rosetta has been hibernating and conserving energy without communicating with Earth for the last 31 months and today was "alarm clock day", or the day it was supposed to wake up and contact Earth again. As you can see from the tweet below, wake up was a success.

Published January 20, 2014 •[ ]

Building the NIF in Photos

I had no idea the National Ignition Facility has been under construction for so long - it's really only been live for the last few years - but In Focus has a nice review of construction and experiment photos since the 1990s.

Published January 10, 2014 •[ ]

Beautiful Images of System HR4796

Exoplanet searches must be the new hot thing right now, Kepler detected hundreds of exoplanets before having issues with reaction wheels and now the newest member, Gemini Planet Imager, is taking awesome photos of some neighbor systems.

GPI is located in the Chilean Andes, very much unlike the space-based Kepler, and is already able to capture such amazing images as this dust ring surrounding the nearby star HR4796A. HR4796 is a binary star system in Centaurus and this is an image of the main "A" star, about twice as large as our sun but significantly younger at only 8 million years.

It should be noted that GPI is very new so we should be seeing more like this in the coming years. And if GPI proves to be fruitful in its southern location, there are plans to build a second 'north' version atop Hawaii's Mauna Kea.

Published January 8, 2014 •[ ]

Asteroid Hunting Getting Better

In only the second incident ever, humans spotted an asteroid hours before it hit Earth. The life of the asteroid has already come and gone as it was only car-sized and burnt up while entering the atmosphere.

While we didn't exactly spot it with a lot of time to spare, it was admittedly a very tiny object (on a planet scale) and spotting it at all is impressive considering the brightness of other celestial objects it was contending with.

Do we have any concrete plans on what we would do if this was a larger asteroid with adequate warning? Not really, but the fact that we're starting to detect these before they hit gives us at least a semblance of chance against one that might do more damage.

Published January 2, 2014 •[ ]

Gravity With Spandex

From Kottke, here's a neat visualization of how mass warps spacetime to produce gravitation. The instructor stretches a bolt of spandex around a circular edge and one can "see" the curve of spacetime when masses are placed on the surface.

The one thing I don't particularly like about curved sheet spacetime visualizations is that one has to extrapolate the visualization in every direction, not just the single plane that is presented. It's convenient for orbital mechanics though since most of the stuff in our solar system exists on the same orbital plane.

Published December 6, 2013 •[ ]

The Melty Part of a Meltdown

One doesn't often see the results of a nuclear reactor meltdown, mostly because of the danger and inaccessibility of reactor cores. Truthfully though, there are parts of the fuel and containment that reach their melting point and form a lava-like substance known as corium) during runaway reactions that can't be adequately cooled. Corium is a fascinating substance that isn't very well studied, as it would be fairly dangerous to get near some for the next few thousand years.

Perhaps the most famous (the only one with a name?) bit of corium is the elephant's foot of Chernobyl, a meter-sized chunk of nuclear material, concrete and steel that melted its way through the floor of the containment vessel and onto the level below. Nautilus has a great series of pictures of the foot and other corium flows which illustrate well the uncontrollable mess you've got on your hands when a reactor melts down.

Published December 4, 2013 •[ ]

Kepler Could Be Operational Again with K2

The Kepler planet-hunting mission had already detected hundreds of exoplanets by the time its mission was cut short by broken reaction wheels in August. The four wheels that kepler launched with kept the telescope pointed steadily at the same part of the sky for long periods of time but two of the wheels had stopped working during the summer and engineers were unable to get them active again from afar. Without at least three sources of stability the craft is unable to keep itself pointed at the same spot in the sky.

Now NASA has outlined a plan that could potentially bring Kepler back for shorter periods of star gazing again. The plan involves using the photon pressure from the sun to keep Kepler aligned in one direction by using its symmetric solar panels. The other two reaction wheels would be able to stabilize Kepler along its other two axes.

There's a pretty good diagram of the plan at the NASA news announcement so check that out for more details. Engineers are still working on details of the plan and it's scheduled to be put in a proposal by the end of the year. Expect more Kepler data in 2014 if it passes.

Published November 27, 2013 •[ ]

MAVEN Launches Towards Mars

MAVEN launched successfully this morning to start its mission to study the Martian atmosphere. Launching aboard the Atlas V 401, the most -used and lighter version of the V, the spacecraft will take 10 months to reach Mars before inserting itself into a highly elliptical orbit.

The mission summary is often a bland "to study the martian atmosphere" but the longer version is actually quite interesting. Despite Mars' similarity in size and proximity to Earth, it's obviously quite different. One of the reasons why Mars is so incredibly arid is the lack of an atmosphere like ours and without it many of the qualities that keep Earth habitable are lost.

While the greenhouse effect is usually noted as part of some doomsday scenario on Earth, the danger is actually a significant change in the greenhouse effect, not the effect itself. In fact, the greenhouse insulation provided by our atmosphere is how we can stay comfortable in comparison to the cold void of space. Our atmosphere's ability to hold moisture is also a key part of what makes Earth habitable. The thin Martian atmosphere is unable to do both of these things and it's much of the reason for Mars' current condition.

The question is, of course, how did Mars get this way? We know that Mars has a negligible magnetic field which would otherwise help keep the solar wind from slowly blowing away the atmosphere. But how strong is the solar wind and what are the effects on the outer regions of Mars' atmosphere? Can we use this data to tell if and when Mars was a place with more atmospheric moisture? These are just some of the questions that MAVEN hopes to answer when it arrives in September of 2014.

Published November 18, 2013 •[ ]

Dangerous Moon Dust

Why haven't we gone back to the moon? Most people would cite the high price as the top reason we haven't stepped foot on the moon in 40 years but I suspect the dust problem has something to do with it as well.

As described in this New Yorker article, moon dust escaped all attempts at sealing it into a low-pressure container on each Apollo landing mission. The dust is actually pieces of rock, just like dust on Earth, pulverized by meteorites into razor sharp particles. Without wind or water to smooth the edges out the dust stays sharp indefinitely.

It was notoriously difficult for astronauts to clear from their equipment when returning from EVAs and it's unknown what effect the dust has on the lungs when exposed for long periods of time, though I would not be surprised if it's akin to asbestos exposure.

If shooting humans at the moon is going to be commonplace in the future, finding a way to deal with the dust is definitely one of those subtle hard problems that we'll eventually, inevitably face.

Published November 12, 2013 •[ ]

Polywater: a Peer Review Success

The scientific "discovery" of polywater is fascinating both in itself and the time in which it took place - the cold war was raging, military applications of an "unfreezable" water were unknown. While the wikipedia article is fascinating, a new article from Slate is based on a first hand account from one of the scientists involved who actually coined the term polywater. It's a more interesting account than a string of facts and it really highlights the way confirmation bias can infect peer reviewers.

All in all, the peer review process did eventually conclude that polywater was not really a new kind of water. We have a much more sensitive array of tools at our disposal today, I wonder how we would deal with a similar caliber claim in our current time.

Published November 10, 2013 •[ ]

D-Wave: Quantum Computation or Not

The D-Wave quantum computer has been in use by a few companies for a few months now. While most people have just started warming up to the kinds of problems you can feed into the computer to take advantage of its quantum-ness, there are still questions about what exactly is going on.

Keep in mind the computer does show promising results; certain algorithms run significantly faster on a D-Wave device than on traditional computers. Whether this improvement is based on actual quantum computing or some other classical computing improvement is yet to be seen.

I am naïvely likening the difference in performance to that of GPUs versus CPUs. Both are classical computation devices but certain tasks run significantly faster on GPUs. Is the D-Wave device seeing improvements in the same way or is it actual quantum computing? Only time will tell.

Published November 6, 2013 •[ ]

Dark Matter Search at LUX

LUX, the Large Underground Xenon experiment, has released results from the first three months of run time in its private underground mine at the Sanford Underground Research Facility.

In terms of results there's not much to report. If LUX is really as sensitive as it claims to be then light WIMPs are almost ruled out of existence though the accuracy of this kind of xenon detector is still fairly theoretical. And the team has only recently published data related to their experiments; not a lot of scientists have really dug into the data.

More fascinating is the experimental setup itself. Though the liquid xenon inside takes up a significant volume, only the liquid deepest inside the detector is used to look for interactions. The rest is used to screen out any stray radiation that isn't WIMP-like, and that's on top of the mile of dirt and rock already insulating the detector from the radiation we see on the surface of the Earth.

Published October 30, 2013 •[ ]

Time From Entanglement

From the Physics arXiv Blog (an excellent resource covering preprints with very accessible language), a paper describing experiments to test the idea that time itself is an emergent property of entanglement.

It's pretty fascinating to read ideas that are starting to think about what time really is. The 'problem of time' in the article refers to the observation that physical processes seem to be entirely reversible - no rules are broken if you take the physics of an ordinary event (Feynman gives the example of an egg falling and breaking) and run them backwards. Furthermore, there doesn't seem to be any discovered mechanism for why time moves in one direction and not the other.

The idea that quantum entanglement might be responsible for time is fascinating, though the experiment given and the reasoning aren't real clear to me. I don't quite understand how the experimenters simulate being outside the universe to test the theory.

Published October 23, 2013 •[ ]