Tag: Flyby anomaly

Jovian Joviality: Juno is a Healthy Spaceship, On-Track for 2016 Jupiter Rendezvous

Artist's impression of the Juno flyby (NASA)
Artist’s impression of the Juno flyby (NASA)

Last week’s Juno flyby of Earth was an exciting event. NASA’s Jupiter-bound mission buzzed our planet on Wednesday (Oct. 9) only 350 miles from the surface, providing amateur astronomers with an opportunity to snapshot Juno as she flew past, stealing a little momentum from Earth and sling-shotting toward the largest planet in the Solar System. Alas, the flyby event wasn’t without incident.

The spacecraft dropped into “safe mode” shortly after its terrestrial encounter. Safe mode is a fail safe on spacecraft that protects onboard instruments from an unexpected condition. This can come in the form of a power spike or some other instrumental error. It is not known at this time what triggered this particular event, but the upshot is that Juno is back in its nominal state.

From a Southwest Research Institute news release:

“Onboard Juno, the safe mode turned off instruments and a few non-critical spacecraft components, and pointed the spacecraft toward the Sun to ensure the solar arrays received power. The spacecraft acted as expected during the transition into and while in safe mode.”

Juno’s planned trajectory was not impacted during the flyby and it is expected to make orbital insertion around Jupiter in July 2016.

The mission was launched from Cape Canaveral, Fla., in 2011 and, through a wonderful bit of orbital mechanics, was commanded to do one 2-year orbit around the Sun. Then, last week, it ended up where it started to use our planet as a speed booster, flinging it further out into the Solar System toward Jupiter’s orbit. This acceleration “freebie” was needed as the launch vehicle, an Atlas V rocket, didn’t have the oomph to propel the spacecraft deeper into space.

Once Juno arrives at Jupiter, it will give the gas giant a thorough full-body examination, investigating what lies beneath its clouds, how it generates its powerful magnetic field and how it evolved. The repercussions of Juno’s one-year primary mission will hopefully expose not only how Jupiter is formed, but how Earth evolved into its current state.

As Juno sped past on Wednesday, I allowed myself an early celebration of some fine flying by NASA scientists with a Gin & Tonic (or a Juno & Tonic) in my special JPL-bought Juno glasses.

Good luck Juno, will look forward to seeing you at Jupiter in a little under three years time!

MORE: Read my Discovery News post about the possibility of Juno exhibiting the mysterious “flyby anomaly.”

Flyby Anomalies Solved?

When the Galileo probe used the Earth for a gravitational slingshot, an anomaly in its velocity was observed (NASA)
When the Galileo probe used the Earth for a gravitational slingshot, an anomaly in its velocity was observed (NASA)

This is a captivating mystery. In 1990 and 1992 when the Jupiter probe Galileo used the Earth for gravitational assists (or “slingshots”), ground-based observers noticed a small (unexpected) boost in velocity as the spacecraft approached Earth. A boost in a few millimetres per second had also been observed in the slingshot of NASA’s NEAR probe two years previously. The same was seen in the flybys of Cassini (in 1999), MESSENGER and Rosetta (in 2005). Many explanations have been put forward – including my favourite that it could be dark matter in Earth orbit kicking our robotic explorers around – but flyby anomalies may have a more mundane explanation.

In keeping with Occam’s Razor (i.e. the simplest explanation is usually the right one), a short paper has been published suggesting that flyby anomalies can be accounted for by using conventional physics…
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