Author Topic: NASA - Juno - Updates  (Read 312471 times)

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Offline Danderman

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Re: NASA - Juno - Updates
« Reply #61 on: 10/09/2013 08:34 pm »
As a spinning spacecraft, I guess that Juno cannot be called a "Mariner-class" spacecraft.

Offline Nickolai

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Re: NASA - Juno - Updates
« Reply #62 on: 10/09/2013 09:03 pm »
Does anyone know where I might find a basic diagram of Juno's trajectory, or if such a thing exists? I'd like to see the various fly-by's in its trajectory.

Offline Avariel

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Re: NASA - Juno - Updates
« Reply #63 on: 10/09/2013 09:56 pm »
I said HI to Juno during the flypast.

I wonder when we will hear if it worked?

http://www.jpl.nasa.gov/hijuno/

Online LouScheffer

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Re: NASA - Juno - Updates
« Reply #64 on: 10/10/2013 01:13 am »
Juno is in safe mode, but according to the Planetary Society blog below, JPL says it is in a stable state with command and control as usual in a safe mode.  So it does not seem like a serious problem....

http://www.planetary.org/blogs/emily-lakdawalla/2013/10091550-juno-safe-mode.html

Offline TomH

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Re: NASA - Juno - Updates
« Reply #65 on: 10/10/2013 01:23 am »
Edit: I see that bolun already posted this a couple of pages back. My link below seems to be a longer article re. the gravitational anomaly, however.

BBC reports that the accelerometers were turned on during the gravity assist for a specific experiment into an anomaly that has been occurring  on gravity assists when spacecraft are just beyond the upper reaches of the atmosphere. On several occasions, spacecraft have accelerated slightly more than mathematical models predicted and the anomalies have no explanation. Some physicists have even posited that there may be a previously unknown variable in gravitational mechanics causing the anomaly. At an altitude around 1000 miles, the anomaly doesn't seem to exist. At the outer edge of the atmosphere, drag negates the ability to read it. At an altitude of 500-600 miles, spacecraft have accelerated several millimeters per second more than models have predicted. That may not seem like much, but modern instrumentation and computer calculations are so accurate that this is a significant anomaly.

http://www.bbc.com/future/story/20131009-spacecraft-tests-sling-theory/1
« Last Edit: 10/10/2013 01:29 am by TomH »

Offline Sesquipedalian

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Re: NASA - Juno - Updates
« Reply #66 on: 10/10/2013 02:31 am »
I hope the safe mode didn't interfere with the accelerometer experiment...

Offline Danderman

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Re: NASA - Juno - Updates
« Reply #67 on: 10/10/2013 04:23 am »
Edit: I see that bolun already posted this a couple of pages back. My link below seems to be a longer article re. the gravitational anomaly, however.


The last such anomaly that was ultimately resolved was regarding the Pioneer/Voyager probes which demonstrated a different velocity than expected in the outer solar system - that turned out to be related to their paint job.

This may be a similar issue, perhaps Earthshine at close proximity imparts some velocity that has not been accounted for.

Offline Star One

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Re: NASA - Juno - Updates
« Reply #68 on: 10/10/2013 06:46 am »

Juno is in safe mode, but according to the Planetary Society blog below, JPL says it is in a stable state with command and control as usual in a safe mode.  So it does not seem like a serious problem....

http://www.planetary.org/blogs/emily-lakdawalla/2013/10091550-juno-safe-mode.html

Hopefully we hear some positive news on this matter sooner rather than later.

Offline Celebrimbor

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Re: NASA - Juno - Updates
« Reply #69 on: 10/10/2013 07:53 am »
Article for the event:
http://www.nasaspaceflight.com/2013/10/juno-slingshot-spacecraft-zips-earth-jupiter/

If anyone was wondering about the trade between heavier launch vehicles and longer duration missions:

Quote
“A direct mission to Jupiter would have required about 50 percent more fuel than we loaded,” said Tim Gasparrini, Juno program manager for Lockheed Martin Space Systems. “Had we not chosen to do the flyby, the mission would have required a bigger launch vehicle, a larger spacecraft and would have been more expensive.”

So there we have it "from the horses mouth" ;)

Offline wakka

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Re: NASA - Juno - Updates
« Reply #70 on: 10/10/2013 01:01 pm »
hello, this is my first message to France you ask what is the difference in speed between the beginning and the end of the flyby?
thank you

http://www.spaceflight101.com/juno-mission-updates-2013.html

7.3 km/s heliocentric velocity change.

Thank you !!  :)

Offline bolun

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Re: NASA - Juno - Updates
« Reply #71 on: 10/10/2013 08:14 pm »

Offline plutogno

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Offline sdsds

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Re: NASA - Juno - Updates
« Reply #73 on: 10/12/2013 08:43 am »
Juno out of safe mode, reports AWST
http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:04ce340e-4b63-4d23-9695-d49ab661f385&plckPostId=Blog%3a04ce340e-4b63-4d23-9695-d49ab661f385Post%3a21a50f23-8f2f-442c-b555-44c3b1c022a9

Hurray!

This detail from Mark Carreau's report seemed new (to me at least):
Soon after Wednesday's closest approach, a signal was received by the European Space Agency's 15-meter ground station antenna just north of Perth, Australia, indicating the spacecraft initiated [...] "safe mode."

If we knew how soon after perigee, would that tell us the spacecraft altitude and thus whether or not it was in the Van Allen Belts at the time of the fault?
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Offline ugordan

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Re: NASA - Juno - Updates
« Reply #74 on: 10/12/2013 10:23 am »
I'm speculating here,  but it's unlikely the safe mode was caused by Van Allen belt passage. If it did, then this spacecraft is not going to have much fun at Jupiter at all, regardless of avoiding the majority of its radiation belts.

More likely it's some reading/event that the spacecraft didn't like. Things like software sequence errors, star trackers being blinded by a huge object the spacecraft is just passing by, etc.

Off the top of my head, Dawn entered safe mode during its Mars flyby. Rosetta safed its narrow angle camera during asteroid Steins flyby due to instrument readings it didn't like.

When I first heard of Juno entering safe mode, I almost chuckled because I half-expected something like that to happen. It's more often of a sign of conservative spacecraft operation than design deficiencies.

Offline plutogno

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Re: NASA - Juno - Updates
« Reply #75 on: 10/12/2013 12:33 pm »
a few more info http://www.spaceflight101.com/juno-mission-updates-2013.html
safe mode appears to be caused by power consumption limits being exceeded in eclipse

Offline Avariel

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Re: NASA - Juno - Updates
« Reply #76 on: 10/12/2013 04:07 pm »
Still waiting to hear if Juno picked up our HI in CW.

Offline Artyom.

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Re: NASA - Juno - Updates
« Reply #77 on: 10/17/2013 02:21 pm »
Juno is in Safe Mode again, but still okay

Quote
I just got off the phone with Rick Nybakken, Juno Project Manager, with an update on Juno. I had originally called two days ago to get some information for a wrap-up story on the Earth flyby. I didn't know when I called that while Juno had been brought out of safe mode after entering it during the Earth flyby, the spacecraft went back into safe mode on Sunday. As of now it is still in safe mode. Nybakken told me they expect to be back to normal by the end of next week. In this phase of the mission, there's no need to hurry and every reason to take things slowly.

http://www.planetary.org/blogs/emily-lakdawalla/2013/10161651-juno-in-safe-mode-again-but-okay.html

Online Targeteer

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Re: NASA - Juno - Updates
« Reply #78 on: 10/19/2013 01:20 am »
http://www.nasa.gov/mission_pages/juno/main/index.html#.UmHdNSSikwM

As of Oct. 17, Juno was approximately 4.4 million miles (7.1 million kilometers) from Earth. The one-way radio signal travel time between Earth and Juno is currently about 24 seconds. Juno is currently traveling at a velocity of about 23.6 miles (38 kilometers) per second relative to the sun. Velocity relative to Earth is about 6.5 miles (10.4 kilometers) per second. Juno has now traveled 1.01 billion miles (1.63 billion kilometers, or 10.9 AU) since launch.

Juno’s Earth flyby gravity assist was completed on Oct. 9th. Navigation has confirmed that Juno's current trajectory is "near-perfect" vs. planned. Several Juno science instruments made planned observations during the approach to Earth, including the Advanced Stellar Compass, JunoCam and Waves. These observations provided a useful opportunity to test the instruments during a close planetary encounter and ensure that they work as designed. The main goal of the flyby – to give the spacecraft the boost it needed in order to reach Jupiter – was accomplished successfully, and the spacecraft is healthy and operating as expected.

Soon after its closest approach to Earth, the spacecraft initiated the first of two "safe modes" that have occurred since the flyby.  Safe mode is a state that the spacecraft may enter if its on-board computer perceives conditions on the spacecraft are not as expected.  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 likely cause of the safe mode was an incorrect setting for a fault protection trigger for the spacecraft's battery. During the eclipse the solar cells, as expected, were not generating electricity and the spacecraft was drawing on the battery supply. When the voltage dropped below this fault protection trigger, the spacecraft initiated the safe mode sequence. The spacecraft acted as expected during the transition into and while in safe mode. The spacecraft exited the safe mode on Oct. 11.

The spacecraft entered the safe mode configuration again on Sunday evening (10/13/13).  When the spacecraft's onboard computer transitioned from the Earth flyby sequence to the cruise sequence, a component called the stellar reference unit remained in the Earth flyby configuration.  When the spacecraft's computer saw the draw on electricity was slightly greater than expected, it did as it was programmed to do and initiated a safe mode event. The mission team is in two-way communications with the spacecraft and it is operating as expected, and designed for, in safe mode. They expect to exit safe mode sometime next week.
Best quote heard during an inspection, "I was unaware that I was the only one who was aware."

Online Targeteer

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Re: NASA - Juno - Updates
« Reply #79 on: 10/23/2013 04:46 pm »
https://solarsystem.nasa.gov/news/display.cfm?News_ID=45251

UPDATED Oct. 23: Juno exited safe mode on Friday, Oct. 18.

As of Oct. 17, Juno was approximately 4.4 million miles (7.1 million kilometers) from Earth. The one-way radio signal travel time between Earth and Juno is currently about 24 seconds. Juno is currently traveling at a velocity of about 23.6 miles (38 kilometers) per second relative to the sun. Velocity relative to Earth is about 6.5 miles (10.4 kilometers) per second. Juno has now traveled 1.01 billion miles (1.63 billion kilometers, or 10.9 AU) since launch.

Juno's Earth flyby gravity assist was completed on Oct. 9. Several Juno science instruments made planned observations during the approach to Earth, including the Advanced Stellar Compass, JunoCam and Waves. These observations provided a useful opportunity to test the instruments during a close planetary encounter and ensure that they work as designed. The main goal of the flyby -- to give the spacecraft the boost it needed in order to reach Jupiter - was accomplished successfully, and the spacecraft is in good health and responding to ground controllers.

Soon after its closest approach to Earth, the spacecraft initiated the first of two "safe modes" that have occurred since the flyby. Safe mode is a state that the spacecraft may enter if its onboard computer perceives conditions on the spacecraft are not as expected. 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 likely cause of the safe mode was an incorrect setting for a fault protection trigger for the spacecraft's battery. During the eclipse, the solar cells, as expected, were not generating electricity, and the spacecraft was drawing on the battery supply. When the voltage dropped below this fault protection trigger, the spacecraft initiated the safe mode sequence. The spacecraft acted as expected during the transition into and while in safe mode. The spacecraft exited the safe mode on Oct. 12.

The spacecraft entered the safe mode configuration again on Sunday evening (10/13/13). When the spacecraft's onboard computer transitioned from the Earth flyby sequence to the cruise sequence, a component called the stellar reference unit remained in the Earth flyby configuration. When the spacecraft's computer saw the draw on electricity was slightly greater than expected, it did as it was programmed to do and initiated a safe mode event.

Navigation has confirmed that Juno's current trajectory is "near-perfect" vs. planned. The mission team is in two-way communications with the spacecraft and it is operating as expected, and designed for, in safe mode. They expect to exit safe mode sometime next week.

Juno will arrive at Jupiter on July 4, 2016, at 7:29 p.m. PDT (10:29 p.m. EDT).

Juno was launched on Aug. 5, 2011. Once in orbit around Jupiter, the spacecraft will circle the planet 33 times, from pole to pole, and use its collection of eight science instruments to probe beneath the gas giant's obscuring cloud cover. Juno's science team will learn about Jupiter's origins, structure, atmosphere and magnetosphere, and look for a potential solid planetary core.

Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.

More information about Juno is online at http://www.nasa.gov/juno and http://missionjuno.swri.edu
Best quote heard during an inspection, "I was unaware that I was the only one who was aware."

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