Can dark matter explain the flyby anomalies?

[SF]

The flyby anomalies, you may remember, are a set of fascinating data indicating that spacecraft flying past Earth undergo a strange, step-like change in their acceleration.

The Galileo, Near, Cassini and Rosetta spacecraft all seem to have been hit by this weird phenomenon and while that’s not a large number of data points, it is an impressive proportion of the few spacecraft that have flown past Earth on their way to other parts of the solar system.

Nobody knows what causes this effect but there are a growing number of fascinating ideas. For example, I’ve blogged about a Casimir force-like change in inertia. And today, Stephen Adler at the Institute for Advanced Study in Princeton considers the possibility that these spacecraft are banging into lumps of dark matter as they swing past the planet.

In an impressive analysis, Adler doesn’t rule out an interaction with dark matter but he does impose some severe limits on how this process might occur. The problem is that we’ve witnessed both increases and decreases in the acceleration of these spacecraft so any dark matter model would have to allow for this.

http://arxivblog.com/?p=428

 

[ZapperZ]

Did you completely missed the recently reported analysis by Slava Turyshev of JPL?

http://www.skyandtelescope.com/news/17846774.html

Zz.

 

[Garth]

Zz, Turyshev's paper was about the Pioneer Anomaly, not the Flyby Anomalies, which are distinctly different, but which might be related

Garth

 

[ZapperZ]

Zz, Turyshev's paper was about the Pioneer Anomaly, not the Flyby Anomalies, which are distinctly different, but which might be related

Garth

Yes, I know, but I've attended several seminars on this whereby this issue has been brought up together to illustrate the "parameter space" in which any kind of definitive statement about exotic mechanisms responsible for such anomalies need to be tempered down until we know a LOT more.

zZ.

 

[D H]

Some exotic explanations have been proposed as the explanation of the flyby anomaly, including the Unruh effect (McCulloch, M.E., "Can the flyby anomalies be explained by a modification of inertia?", submitted 18 Dec 2007 to arxiv.org)

Here, these flybys are modeled using a theory that assumes that inertia is caused by a form of Unruh radiation, modified by a Hubble-scale Casimir effect. ... However, these results were extremely sensitive to the Hubble constant used. As an experimental test of these ideas, it is proposed that metamaterials could be used to bend Unruh radiation around objects, possibly reducing their inertial mass.​

... and dark matter (Adler, S.L., "Can the flyby anomaly be attributed to earth-bound dark matter?", submitted 19 May 2008 to arxiv.org).

We make preliminary estimates to assess whether the recently reported flyby anomaly can be attributed to dark matter interactions. ... We discuss a number of strong constraints on the hypothesis of a dark matter explanation for the flyby anomaly. These require dark matter to be non-self-annihilating, with the dark matter scattering cross section on nucleons much larger, and the dark matter mass much lighter, than usually assumed.​

The answer is probably a lot more mundane: It is probably just sloppy math (Mbelek, J.P., "Special relativity may account for the spacecraft flyby anomalies", submitted 11 Sep 2008 to arxiv.org).

In the following, we show that SR transverse Doppler shift together with the addition of velocities are sufficient to explain the flyby anomalies. Thus, GR does not need to be questioned and the flyby anomaly is merely due to an incomplete analysis using conventional physics.​

Oops.

The final paper is very short.

 

[Zman]

I have read a number of comments on the web asking if the moon's gravity was taken into account with this anomaly. I am sure it was but can no reference to the fact.

Was the moon's influence taken into account?

 

[Garth]

The effect is seen with flybys of other planets where there is no significant moon to take into account.

However see Special relativity may account for the spacecraft flyby anomalies for a possible conventional explanation.

Garth