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Headshot of Emily Lakdawalla

Juno is in safe mode, but okay and on course following Earth flyby

Posted by Emily Lakdawalla

09-10-2013 17:56 CDT

Topics: mission status, Juno

Following its Earth flyby earlier today, Juno is in safe mode. This is the protective state a spacecraft goes into when it detects a problem. But everything is okay.

For more details, I just spoke with Rick Nybakken, Juno Project Manager at the Jet Propulsion Laboratory. For a bit of background: as Juno flew past Earth, it spent some time in Earth's shadow, that is, "in eclipse." Nybakken told me that Juno entered eclipse in a nominal state, and came out of eclipse in safe mode. He said they have established communications with the vehicle, and that they have full commandability, and that they are in a safe, stable state. They don't know what caused the safe mode yet; they have to analyze the telemetry further.

The gravity-assist flyby was a totally passive event in terms of propulsion for the spacecraft, so the safe mode has no effect whatsoever on Juno's planned trajectory; it's on its way to Jupiter. Nybakken told me they hit the target within 2 kilometers.

I asked him if he knows if the planned Earth imaging took place. He said they don't know yet, as they're still analyzing the telemetry they're getting from the spacecraft; he said he hoped they'd know tonight or early tomorrow morning.

I will update you all as I learn more. Safe modes during gravity assists are not unheard of -- because it's a passive event, they don't disable fault protection as they would for, say, an orbit insertion burn. And a gravity assist flyby is a highly unusual event for a spacecraft. It'd be nice if it hadn't happened, but not a great concern that it did, and Nybakken sounded calm.


NASA / JPL-Caltech

Launched from Earth in 2011, the Juno spacecraft will arrive at Jupiter in 2016 to study the giant planet from an elliptical, polar orbit. Juno will repeatedly dive between the planet and its intense belts of charged particle radiation, coming only 5,000 kilometers from the cloud tops at closest approach.

See other posts from October 2013


Or read more blog entries about: mission status, Juno


Paul Cox: 10/10/2013 02:48 CDT

I created a video showing two time-lapse movies of the spacecraft Juno as it made its fly-by of Earth in a "gravity assist" manoeuvre tonight. I controlled a robotic telescope based in the Canary Islands from the comfort of my home in Somerset to capture over 100 images of the speeding spacecraft. There are two versions: Juno Spacecraft Earth Fly-By Video (WMV 1920x1080 39MB): YT HD (MP4 1280x720 12MB):

George Ellis: 10/10/2013 03:35 CDT

Paul, very nicely done! Why is it that the spacecraft, or better: the long-exposure streak of the spacecraft seems to be wobbling from one image to another? Cheers, George

Stephen Uitti: 10/10/2013 10:49 CDT

When Galileo passed by Earth, they did an experiment to see if they could detect life. This was certainly a reasonable thing to do. But a fake paper was written up claiming that they were looking for Elvis. Very amuzing. This doesn't sound like a terribly worrisome safing.

Pete Jackson: 10/10/2013 02:51 CDT

George, yes I notice that the spacecraft seems to be 'attracted' to stars that it passes near in the movie. Must be some kind of optical illusion since I have noticed the same thing with satellites passing near stars in the night sky. Great video, Paul!

Ricardo Silva: 10/11/2013 08:14 CDT

Anyone interested about Juno's safe mode management, back in 2011 the team published a short explanatory video about fault protection:

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