Planet 9 not affecting Cassini at Saturn

NASA said late in the day on Friday (April 8, 2016) that the hypothetical object known as Planet 9 – which so far has not been discovered – is not affecting the Cassini spacecraft in orbit around Saturn. Contrary to recent reports in the media, Cassini is not experiencing:

… unexplained deviations in its orbit around Saturn.

That’s a lot of “nots” but some people apparently need to hear them. According to recent reports online:

… a mysterious anomaly in Cassini’s orbit could potentially be explained by the gravitational tug of a theorized massive new planet in our solar system, lurking far beyond the orbit of Neptune.

But NASA says it’s just not true:

While the proposed planet’s existence may eventually be confirmed by other means, mission navigators have observed no unexplained deviations in the spacecraft’s orbit since its arrival there in 2004.

At this point, Planet 9 is still hypothetical, although astronomers at CalTech said in January that there’s solid evidence for this unseen planet, lurking in the outer solar system.

William Folkner is a planetary scientist at NASA’s Jet Propulsion Laboratory. He’s a true expert in developing planetary orbit information used for NASA’s high-precision spacecraft navigation. He said in NASA’s statement:

An undiscovered planet outside the orbit of Neptune, 10 times the mass of Earth, would affect the orbit of Saturn, not Cassini.

This could produce a signature in the measurements of Cassini while in orbit about Saturn if the planet was close enough to the sun. But we do not see any unexplained signature above the level of the measurement noise in Cassini data taken from 2004 to 2016.

Earl Maize, Cassini project manager at JPL, added:

Although we’d love it if Cassini could help detect a new planet in the solar system, we do not see any perturbations in our orbit that we cannot explain with our current models.

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Botton line: Hypothetical Planet 9 is not affecting the Cassini spacecraft, which has been orbiting Saturn since 2004.