An interesting test case
The New Scientist that dropped through my door yesterday includes what looks like an interesting story, about a strange anomaly affecting spacecraft that have flown past the Earth, a standard technique for hopping about the solar system. Each of them has had what the report’s author, Marcus Chown, calls ‘an inexplicable velocity change’. The effect is small - the Galileo probe, for example, gained 3.9 millimetres per second extra - but according to discoverer John Anderson (formerly of JPL) appears to be real.
I remember seeing his paper when it was first released, and I wasn’t smart enough to do any more than be intrigued. Marcus must be wishing that New Scientist had delayed publication by a week or so, though, because earlier this week a new explanation emerged. In a paper covered by the excellent arXiv blog, the effect disappears when the relativistic effects of the spin of the Earth and the satellite are taken into account.
This isn’t Marcus’ fault - magazine deadlines are what they are. But it will be interesting to see how New Scientist covers this development. They get a lot of flack from academics who think they cherry pick only the weird stories, so let’s see if this more prosaic explanation finds a home in next week’s magazine.
on September 20th, 2008 at 10:54 am
I do not think the flyby anomalies can be any sort of Doppler effect, because, although the anomaly is seen in the Doppler data, as mentioned, it is also seen in the ranging data, this is not mentioned, so it is more than just a frequency shift - it is a real anomaly in position and velocity. The otherwise interesting New Scientist article quotes several papers from the arxiv that have not been through peer review, and failed to mention the only peer-reviewed attempted explanation I am aware of (ie, mine: MNRAS, 389(1),L57-60, arxiv:0806.4159). This makes a mockery of the painful, but useful, peer-review process that I had to go through to publish in a prestigious journal (MNRAS). I have emailed Marcus Chown about this, and to his credit he has forwarded it as a letter to the editor of NewSci. Whether it gets published or not is another matter.