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.