Mysteries of Science!
Has anyone written an SF story on either of these topics, proposing even an outrageous possible explanation? My reading is not up to date in the field.
When Europe’s comet chaser Rosetta swings by Earth tomorrow for a critical gravity assist, tracking data will be collected to precisely measure the satellite’s change in orbital energy. The results could help unravel a cosmic mystery that has stumped scientists for two decades.
Since 1990, scientists and mission controllers at ESA and NASA have noticed that their spacecraft sometimes experience a strange variation in the amount of orbital energy they exchange with Earth during planetary swingbys. The unexplained variation is noticed as a tiny difference in speed gained or lost during the swingby when comparing that predicted by fundamental physics and that actually measured after the event.
Tiny unexplained speed variations
The unexplained speed variations are extremely small: NASA’s Galileo satellite experienced an increase of just 3.9 mm/s above the expected value when it swung past Earth in December 1990. The largest unexpected variation – a boost of 13.0 mm/s – was observed with NASA’s NEAR spacecraft at its Earth swingby in January 1998. On the other hand, variations seen at the swingbys of NASA’s Cassini in 1999 and Messenger in 2005 were so small that they lay within the bounds of uncertainty.
ESA’s Rosetta has made two Earth swingbys, in 2005 and 2007. It too, experienced the strange anomaly. Frustratingly, Rosetta sped up by an unexplained 1.8 mm/s during the first passage, but experienced no slowing or speeding in 2007. No one knows what will happen on 13 November 2009 for Rosetta’s third and last Earth swingby: scientists are stumped.
“It’s a mystery as to what is happening with these gravity events. Some studies have looked for answers in new interpretations of current physics. If this proves correct, it would be absolutely ground-breaking news,” says Trevor Morley, lead flight dynamics specialist working on Rosetta at ESOC, ESA’s European Space Operations Centre, Darmstadt, Germany.
ESA researchers study Rosetta
Together with ESA colleague and orbital mechanics specialist Frank Budnik, Morley co-authored a scientific report in 2006 that studied the Rosetta anomaly during the 2005 swingby and listed possible causes.
These range from tidal effects peculiar to the near-Earth environment, atmospheric drag, or the pressure of radiation emitted or reflected by the Earth, to much more extreme possibilities, such as dark matter, dark energy or previously unseen variations in General Relativity, one of the most fundamental and well-tested theories of modern physics.
One American research team, led by ex-NASA scientist John Anderson, is even looking at the possibility that Earth’s rotation may be distorting space-time – the fundamental fabric of our Universe – more than expected, thus affecting nearby spacecraft. But there is as yet no explanation how this could happen.
Before even considering such exotic explanations, all the usual causes of spacecraft speed errors have been thoroughly eliminated by numerous investigations conducted over the years at both ESA and NASA. Software bugs, calculation errors, tracking uncertainties and other, much more mundane, causes have all been systematically eliminated or accounted for, leaving the speed anomaly maddeningly unexplained.
NASA’s Pionneer 10 & 11 similarly affected
Scientists at a number of universities and research centres in Europe, the US and Japan have worked on the anomaly problem over the past years. The Earth swingby anomaly has been compared to another unexplained anomaly – one experienced by NASA’s Pioneer 10 and 11 spacecraft. As they travel on trajectories that will take them eventually into interstellar space, both have experienced an unexpected acceleration directed toward the Sun, which has yet to be explained.
And this from Of Particular Significance. Prof Strassler of Rutgers University writes:
The non-zero Higgs field has a size of about 250 GeV, and that gives us the W and Z particles with masses of about 100 GeV. But it turns out that quantum mechanics would lead us to expect that this size of a Higgs field is unstable, something like (warning: imperfect analogy ahead) a vase balanced precariously on the edge of a table. With the physics we know about so far, the tendency of quantum mechanics to jostle — those quantum fluctuations I’ve mentioned elsewhere — would seem to imply that there are two natural values for the Higgs field — in analogy to the two natural places for the vase, firmly placed on the table or smashed on the floor. Naively, the Higgs field should either be zero, or it should be as big as the Planck Energy, 10,000,000,000,000,000 times larger than it is observed to be. Why is it at a value that is non-zero and tiny, a value that seems, at least naively, so unnatural?
This is the hierarchy problem.
Many theoretical physicists have devoted significant fractions of their careers to trying to solve this problem. Some have argued that new particles and new forces are needed (and their theories go by names such as supersymmetry, technicolor , little Higgs, etc.) Some have argued that our understanding of gravity is mistaken and that there are new unknown dimensions (“extra dimensions”) of space that will become apparent to our experiments at the Large Hadron collider in the near future. Others have argued that there is nothing to explain, because of a selection effect: the universe is far larger and far more diverse than the part that we can see, and we live in an apparently unnatural part of the universe mainly because the rest of it is uninhabitable — much the way that although rocky planets are rare in the universe, we live on one because it’s the only place we could have evolved and survived. There may be other solutions to this problem that have not yet been invented.
Many of these solutions — certainly all the ones with new particles and forces or with new dimensions — predict that new phenomena should be visible at the Large Hadron Collider. Even as I write this, the Large Hadron Collider is slowly but surely excluding many of these possibilities. So far it has not seen any unexpected new phenomena. But these are still early days.
By the way, you will often read the hierarchy problem stated as a problem with the Higgs particle mass. This is incorrect. The problem is with how big the non-zero Higgs field is. (For experts — quantum mechanics corrects not the Higgs particle mass but the Higgs mass-squared parameter, changing the Higgs field potential energy and thus the field’s value, making it zero or immense. That’s a disaster because the W and Z masses are known. The Higgs mass is unknown, and therefore it could be very large — if the W and Z masses were very large too. So it is the W and Z masses — and the size of the non-zero Higgs field — that are the problem, both logically and scientifically.)