There are two interesting developments to discuss, so let's get right to them:
1. Today, several chunks of a decommissioned satellite will strike the surface of the Earth (hundreds of kilograms at hundreds of km/h)
For the past week, earthlings have been warned that a defunct satellite will enter the Earth's atmosphere on Friday, Sept 23, 2011. Unlike small satellites, this one, the size of a bus, will not entirely burn up upon re-entry. Although the simulation is hard to predict with high precision, it is certain that a significant portion of the satellite will survive the re-entry, and will find a terminal velocity in the region of 300 km/hr. Like the weather, aerodynamic problems involving extreme heat transfer are difficult to solve with much accuracy long in advance. The location of where on Earth these satellite chunks will land is still somewhat up in the air.
NASA explained last week that this should not worry us, as there is a 75% chance that the said pieces will hit water (gee, thanks for the geography lesson). As of this morning, we now know that the satellite pieces will strike the Earth in its Southern Hemisphere.
This sort of thing happens roughly once per year...
Basically, a LEO (Low Earth Orbit) satellite, once decommissioned, usually stops generating the tiny impulses required to maintain orbit. Even though a satellite that is 250 km from the surface of the Earth is in a quasi-vacuum, the odd molecule of gas lies in its path, and is displaced every so often. This results in a tiny decrease in velocity, which leads to a tiny drop in altitude, where the abundance of such molecules is a tiny bit higher. Over time, all LEO satellites eventually hit our atmosphere.
The majority of satellites are so small that they burn up entirely upon re-entry. But, on a roughly annual basis, a satellite is large enough such that some will remain in tact; it becomes a projectile (or several) falling from the sky. The kind of effect this would have ranges from a large splash in an ocean to a hole in the road. Should it strike a home, it would crash through to the basement. Should it strike a person, it would be, well, a terrible start to the weekend.
Even though only 25% of the Earth has land, man occupies a surprisingly small percentage of this land. While there is perhaps, a 1 in 500 chance that the satellite will collide with a man-made structure, there is a 1 in 4000 chance that it will actually strike a person today. Those odds are not that small. In fact, if you live in South America, and you step outside in a thunderstorm today, you have a far better chance of being struck by a satellite than by lightning.
2. CERN scientists claim that a neutrino has been clocked at a velocity greater than that of light.
This, if confirmed, would be, perhaps, the most compelling advance in modern science since 1905, when Einstein observed that faster than light travel is not possible. It would challenge relativistic physics, and pretty well all advances in modern science over the past century.
But... I suspect that the conclusion is a false one.
Neutrinos are subatomic particles, like electrons, which are released during the nuclear fusion reactions that take place in the Sun. In an experiment, a neutrino travelled from Geneva to a lab in Italy (730 km distance). At light travel (299,792 km/s), such a trip would take just 0.002435022 seconds. The neutrino completed the trip in 0.002434962 seconds, a wopping 60 nanoseconds faster. This difference in time is like Usain Bolt's nose hairs, which crosses the finish line just ahead of his nose. Nevertheless, faster is faster, and any speed faster than that of light has never, ever been recorded in history.
The scientists claim that their equipment is precise to 10 nanoseconds. I am inclined to believe that the equipment had on off-day, and was slightly less precise than usual when this reading was taken. While the Large Hadron Collider is breaking new ground in physics, this latest development must be repeated before we begin rewriting our entire library of science books.
In summary, I believe that the speed of light is in fact a hard limit that, in man's experience, has yet to be surpassed by anything. I am taking this potentially groundbreaking finding with a grain of neutrino.
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