The proton is one of the fundamental components of the atom. For a long time scientists have believed it to be 0.8768 femtometers in size (a femtometer is one quadrillionth of a meter). Now, it looks like they may have been wrong, the size is 0.84184 femtometers. In a way, the discrepancy is very small…as in anything measured in quadrillionths of a meter is already incredibly small…and this discrepancy (an error by another name) is but a tiny fraction of a femtometer. In other ways, this is a big deal: One, because so many have been wrong for so long, and two, because the size of a proton is so fundamental to so many other aspects of nuclear and quantum physics that even so small an error could lead to massive changes in models of atomic dynamics.
But wait. This is the reported result of one paper, based on one type of (novel) experiment. True, the scientists representing a large collegium of institutions and publishing in the journal Nature put the size uncertainty at 0.00067 femtometers, whereas the old uncertainty size was 0.0069. The new one is an order of magnitude better. Nevertheless, whenever something this, well, the word is shocking, comes along the reaction of most scientists is to ask questions: What is the integrity of the experimental setup? Is it possible that mistakes in measurement or calculation were made? Is it possible that while this may seem to contradict or invalidate many theoretical constructs, a small tweak here or there might explain this result? In short, the basic reaction is not “This must be wrong!” It is, “We must question, test, and validate (or invalidate) this result as thoroughly as possible because it is extremely important.” That it is. More
Two Notable Space Successes
Concerning space missions, there’s always something happening in space. Most of it is ‘routine’ in the sense that what happens was expected and a normal part of the mission. Re-supply of the International Space Station generally falls into that category (except a couple of weeks ago when the resupply vehicle missed the station on the first try). There are a lot of missions currently underway; some just getting started, others have been at it for years. They all generate events of one kind or another. In the last week or so, there are two pieces of news from space missions that deserve more attention, not only because they represent successes, but because they were difficult first-of-a-kind achievements: The Rosetta flyby of Lutetia, and the IKAROS solar-sail uses photon propulsion.
The asteroid Lutetia with Saturn (the background dot)…..Credit: ESA, MPS Osiris Team
The Rosetta probe flyby of the asteroid Lutetia
The spacecraft Rosetta, launched in 2004 by the European Space Agency (ESA) was maneuvered into position for a flyby of the asteroid Lutetia. The closest approach point was to be 3162 m (10,374 ft) from the surface of the relatively large asteroid. The flyby was unique on several grounds:
1. It was the first flyby of Lutetia and the largest asteroid yet visited (longest axis 126 kilometers, 78.29 miles).
2. The camera used was of exceptionally high resolution (2000 pixel frame), which yielded many extremely fine photographs.
3. The flyby was available through ‘live feed’ on the Internet as it was being observed at ESA headquarters on Earth.
Almost going without mention is the extraordinary accuracy of the celestial navigation and the obvious reliability of the Rosetta probe. One of the images captured by Rosetta during the flyby just happened to also include another heavenly body – the unmistakable ringed planet Saturn. Such juxtapositions are extremely rare. Of more immediate scientific interest will be the crater pocked surface of Lutetia for analysis of the geology and possible history of the asteroid.
Rosetta is now on its uninterrupted way to a rendezvous with the comet Churyumov-Gerasimenko in 2014. Much of the next four years will be spent in ‘deep hibernation’ to conserve energy during another very long swing around the sun in order to gain matching speed with the comet. More »