Cassini orbit not influenced by phantom planet
NASA has released a statement casting doubt on a theory put forward by French astronomers that analyzed anomalies in the trajectory of the Cassini spacecraft in order to determine the general location of the unconfirmed solar system body "Planet Nine."
The existence of an as of yet unobserved ninth planet in our solar system has been a topic of hot debate among astronomers for some time. Konstantin Batygin andMike Brown of Caltech recently stoked the fire by proposing that theunusual orbits of several Kuiper belt objects could havebeen induced by the gravitational influence of a huge planet orbitingbeyond Neptune.
Based on a series ofnumerical simulations, the duo argued that to account for the excitedorbits of the Kuiper belt objects, the offending planet would need to have a mass around 10 times that of our home world. The team alsosuggested that Planet Nine would follow a highlyeccentric inclined orbit, which would take the mysterious body 60billion miles (97 billion km) awayfrom our Sun, with an anticipated orbital period of between10,000 – 20,000 years.
Though recentobservations have provided compelling evidence for a ninth planet,confirmation of such a body could only be achieved via a directtelescopic sighting. The problem is, while Batygin and Brown haveprovided useful theories regarding the characteristics of the phantomplanet's orbit, we still have no idea where to start looking.
A team of Frenchastronomers had hoped to narrow down the position of Planet Nine byobserving the trajectory of NASA's Cassini spacecraft. In a paperpublished in journal Astronomy & Astrophysics, the group argued that the presence of Planet Nine would createperturbations in the movement of Saturn around the Sun.
By observing radiotracking data transmitted by the Cassini spacecraft, the astronomershad hoped to identify the signature of Planet Nine's gravitationalpull, and thus infer its general position in space.
Unfortunately, a recentNASA statement has effectively debunked the theory by stating thatthe spacecraft had experienced no unexplained course deviations sincemaking orbit around Saturn in 2004.
"An undiscoveredplanet outside the orbit of Neptune, 10 times the mass of Earth,would affect the orbit of Saturn, not Cassini," states WilliamFolkner, a planetary scientist NASA's Jet Propulsion Laboratory."This could produce a signature in the measurements of Cassiniwhile in orbit about Saturn if the planet was close enough to thesun. But we do not see any unexplained signature above the level ofthe measurement noise in Cassini data taken from 2004 to 2016."
Were it possible forCassini to continue its observational campaign of the Saturniansystem up to the year 2020, then the spacecraft may have been able tocollect enough tracking data to establish a probable location for theplanet.
However, Cassini'sdwindling fuel supply places any such ambition far out of reach, asthe probe is currently scheduled to end its mission by plunging intothe surface of Saturn in late 2017. With Cassini out of the picture,the location of the theoretical planet will have to be pinpointed byanother, possibly as of yet unconceived, mission.