Colliding satellites

The first collision of two major man-made objects has occurred in Earth orbit, with an Iridium satellite colliding with a Russian satellite. While the size of the objects in the collision might not be much compared to some of the major collisions that occur on the ground, the high speeds necessary for orbits makes these collisions much more energetic. Let's just hope that the problem doesn't get too much worse, where a chain reaction of collisions creating lots of space debris that in turn collide with other satellites occur.

Bit rot from cosmic rays

Mars Rover
Mars Rover

It's common computer folklore that cosmic rays cause errors in computer chips. This is not actually true, or at least it is so rare that a cosmic ray actually manages to reach the ground and knock out a bit in a computer chip, that it might not as well happen compared to the far more common occurrence of an alpha particle emitted by ordinary materials causing errors in computer chips.

So it's rather a surprise that the Mars Rover Opportunity suffered a problem because it may have been hit by a cosmic ray. What is even more impressive is that the hardware in the rover could detect such problems. It's a testament to how robust its systems were designed to be.

Fusion supporting fission

Practical power generation with controlled fusion is one of those things that has always been "just thirty years away", in contrast to uncontrolled fusion that goes boom from over fifty years ago. But it turns out that controlled fusion does not even have to reach its breakeven point, where more power is generated by fusion than is consumed, to be useful as researchers at the University of Texas at Austin have devised a way to use fusion to reduce nuclear waste.

While atoms such as uranium or plutonium can break apart all by themselves, they're much more likely to split apart when hit by a neutron. Fission in nuclear bombs or nuclear reactors takes advantage of neutrons emitted from splitting atoms, where a dense enough blob of fissionable elements will cause a chain reaction and generate a lot of energy. In fact, one of the issues in nuclear reactors is to keep the neutron emissions low enough lest a meltdown occurs. But nuclear fuel in nuclear reactors eventually reach the point that they are no longer useful for generating energy, as not enough neutrons are emitted to split the still plentiful fissionable atoms. Even worse, the fissionable atoms make nuclear waste radioactive.

What the researchers from the University of Texas at Austin did was to devise a way to use fusion to promote fission. Using a room-sized tokamak, neutrons are emitted from the fusion reaction in the tokamak. These neutrons bombard nuclear waste and promote fission in the material. Not only does this generate energy from the nuclear waste, it also turns much of the fissionable atoms into non-fissionable ones, which greatly reduces the amount of radioactive nuclear waste. The researchers have yet to build an actual system for reducing nuclear waste, though, so it still remains to be seen whether there will be an unforeseen caveat that renders their method impractical.

This method of reducing nuclear waste and generating energy is an interesting reversal of the relationship between fusion and fission in thermonuclear warheads, which use fission to cause a fusion reaction. On the other hand, they aren't so different after all as both end up using neutrons from fusion to enhance fission, since most thermonuclear weapons use the fission-triggered fusion only to force more fission to occur.