Author Topic: NASA - Juno - Updates  (Read 123067 times)

Offline Norm38

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Re: NASA - Juno - Updates
« Reply #20 on: 06/26/2012 04:19 AM »
Can anyone tell me what specific power the Juno arrays achieve, in W/kg? Thanks!

Did some research.  Credit NASA:
Quote
"The entire solar arrays combined are almost 750 pounds," Gehling said. "They’re a little more massive than typical solar arrays because of all these various requirements of stiffness and pointing and carrying the magnetometer."

The reason the wings have to be so stiff and strong is because Juno will be a spinning spacecraft -- another retro-aspect of this mission. "The wings dominate how true it spins on its axis," Gehling said. "Our goal is to make it spin about the direction of our high gain antenna boresight."

Assign some mass to the stiffness requirements and call it 700lb, or 300kg for the arrays. 

Power output is 484W initial degrading to 420W at mission end due to radiation degredation.  Power requirements are 405W, split as 250W electrical, the balance dedicated to thermal heating.

So in W/kg the arrays are 1.61 to 1.4.

Which is really low.  But sunlight is 25 times fainter at Jupiter than here, so the arrays have to be much larger.  For comparison, they would produce 12kW here, and achieve 40W/kg.  They weigh the same, but have only a fraction of the output.

Also for comparison, the Galileo RTG was 300W electrical at 60kg, or 5W/kg, and had thermal heating to spare.

I'd been wondering how well the arrays would hold up to the radiation they'll endure, given the shielding that has been given to the main electronics vault.  The mission is listed as 33 orbits, then decomissioning.  I wonder if that's due to an expected knee in the power curve.  Is there any chance they could or would need to extend the mission?

Say years from now a comet is inbound and Juno just happens to be in the right spot.  How long could they keep it in orbit I wonder?
 

Offline Jim

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Re: NASA - Juno - Updates
« Reply #21 on: 06/26/2012 11:20 AM »

Say years from now a comet is inbound and Juno just happens to be in the right spot.  How long could they keep it in orbit I wonder?
 

It doesn't really have any imaging capability.  Junocam is more for outreach

Offline sdsds

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Re: NASA - Juno - Updates
« Reply #22 on: 08/11/2012 06:58 AM »
The NASA mission status page says, "The Juno spacecraft is presently on the far side of the sun as seen from Earth, and is in solar conjunction between Aug. 8 and Aug. 13. During conjunction Juno appears to be very close to the sun and briefly disappears behind it."

So it must be essentially half way from launch to its planned Earth flyby?
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Offline ugordan

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Re: NASA - Juno - Updates
« Reply #23 on: 08/11/2012 11:56 AM »
So it must be essentially half way from launch to its planned Earth flyby?

You can't really use a solar conjunction to infer that. In just so happens that in this particular case, it is very roughly right - 12 months after launch and 14 months before the flyby.

Offline simonbp

Re: NASA - Juno - Updates
« Reply #24 on: 08/11/2012 02:38 PM »
And to clear to reason is because the current trajectory has a larger semimajor axis than Earth. So, via Kepler's laws, Earth has a faster angular speed around the sun, and so will have moved more than one full orbit (12 months) by the time Juno returns for the gravity assist. Plus, Juno will do a burn at aphelion (farthest point from the Sun on current trajectory, at the end of this month) which will lower its semimajor axis, changing the Earth intercept point further.

Offline robertross

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Re: NASA - Juno - Updates
« Reply #25 on: 08/30/2012 06:17 PM »
Couldn't find a press release, but:

Most recent spacecraft significant events

Juno’s deep space maneuvers (or DSMs), are slated to take place on Aug. 30 and Sept. 4. During these maneuvers the spacecraft will fire its main engine for 30 minutes. The maneuvers refine the spacecraft’s trajectory and set up the Earth flyby gravity assist maneuver in Oct. of next year. Nominal start time (spacecraft event time) for the burns is 22:30 UTC (3:30pm US Pacific time) on both dates; Earth received time for the signals from the spacecraft is 27 minutes later.

http://www.nasa.gov/mission_pages/juno/main/index.html
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Offline robertross

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Re: NASA - Juno - Updates
« Reply #26 on: 08/31/2012 01:09 AM »
NASA's Jupiter-Bound Juno Changes its Orbit

08.30.12

PASADENA, Calif. – Earlier today, navigators and mission controllers for NASA's Juno mission to Jupiter watched their computer screens as their spacecraft successfully performed its first deep-space maneuver. This first firing of Juno's main engine is one of two planned to refine the spacecraft's trajectory, setting the stage for a gravity assist from a flyby of Earth on Oct 9, 2013. Juno will arrive at Jupiter on July 4, 2016.

The deep-space maneuver began at 6:57 p.m. EDT (3:57 p.m. PDT) today, when the Leros-1b main engine was fired for 29 minutes 39 seconds. Based on telemetry, the Juno project team believes the burn was accurate, changing the spacecraft's velocity by about 770 mph (344 meters a second) while consuming about 829 pounds (376 kilograms) of fuel.

"This first and successful main engine burn is the payoff for a lot of hard work and planning by the operations team," said Juno Project Manager Rick Nybakken of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We started detailed preparations for this maneuver earlier this year, and over the last five months we've been characterizing and configuring the spacecraft, primarily in the propulsion and thermal systems. Over the last two weeks, we have carried out planned events almost every day, including heating tanks, configuring subsystems, uplinking new sequences, turning off the instruments and increasing the spacecraft's spin rate. There is a lot that goes into a main engine burn."

The burn occurred when Juno was more than 300 million miles (483 million kilometers) away from Earth. A second deep space maneuver, of comparable duration and velocity change, is planned for Sept. 4. Together, they will place Juno on course for its Earth flyby, which will occur as the spacecraft is completing one elliptical orbit around the sun. The Earth flyby will boost Juno's velocity by 16,330 mph (about 7.3 kilometers per second), placing the spacecraft on its final flight path for Jupiter. The closest approach to Earth, on Oct. 9, 2013, will occur when Juno is at an altitude of about 310 miles (500 kilometers).

"We still have the Earth flyby and another 1.4 billion miles and four years to go to get to Jupiter," said Scott Bolton, Juno's principal investigator from the Southwest Research Institute in San Antonio. "The team will be busy during that whole time, collecting science on the way out to Jupiter and getting ready for our prime mission at Jupiter, which is focused on learning the history of how our solar system was formed. We need to go to Jupiter to learn our history because Jupiter is the largest of the planets, and it formed by grabbing most of the material left over from the sun's formation. Earth and the other planets are really made from the leftovers of the leftovers, so if we want to learn about the history of the elements that made Earth and life, we need to first understand what happened when Jupiter formed."

Juno was launched on Aug. 5, 2011. Once in orbit, the spacecraft will circle Jupiter 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

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Offline catdlr

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Re: NASA - Juno - Updates
« Reply #27 on: 09/05/2012 07:50 PM »
This is coming from a news agency (AP).  Still waiting on NASA to report it officially.

Jupiter-bound craft's 2nd maneuver delayed 10 days

http://news.yahoo.com/jupiter-bound-crafts-2nd-maneuver-delayed-10-days-235143798.html
« Last Edit: 09/05/2012 07:51 PM by catdlr »
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Offline racshot65

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Re: NASA - Juno - Updates
« Reply #28 on: 09/05/2012 09:46 PM »
This is coming from a news agency (AP).  Still waiting on NASA to report it officially.

Jupiter-bound craft's 2nd maneuver delayed 10 days

http://news.yahoo.com/jupiter-bound-crafts-2nd-maneuver-delayed-10-days-235143798.html

Confirmed on the mission status page

http://www.nasa.gov/mission_pages/juno/main/index.html

Offline sdsds

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Re: NASA - Juno - Updates
« Reply #29 on: 09/18/2012 04:00 AM »
Quote
September 17, 2012

PASADENA, Calif. - NASA's Juno spacecraft successfully executed a second Deep Space Maneuver, called DSM-2 last Friday, Sept. 14. [...] Based on telemetry, the Juno project team believes the burn was accurate

http://www.jpl.nasa.gov/news/news.php?release=2012-291
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Offline Artyom.

Re: NASA - Juno - Updates
« Reply #30 on: 08/13/2013 07:52 AM »
NASA's Juno is Halfway to Jupiter

Quote
NASA's Juno spacecraft is halfway to Jupiter. The Jovian-system-bound spacecraft reached the milestone today (8/12/13) at 5:25 a.m. PDT (8:25 a.m. EDT/12:25 UTC).

"Juno's odometer just clicked over to 9.464 astronomical units," said Juno Principal Investigator Scott Bolton, of the Southwest Research Institute in San Antonio.  "The team is looking forward, preparing for the day we enter orbit around the most massive planet in our solar system."

http://www.nasa.gov/mission_pages/juno/news/juno20130812.html

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Offline Blackstar

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Re: NASA - Juno - Updates
« Reply #31 on: 10/08/2013 01:10 PM »
Apparently Juno is supposed to do an Earth flyby tomorrow. But they are not doing updates, so you won't read about it unless the science team makes an announcement.

Offline ugordan

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Re: NASA - Juno - Updates
« Reply #32 on: 10/08/2013 01:26 PM »

Offline jacqmans

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Re: NASA - Juno - Updates
« Reply #33 on: 10/08/2013 06:53 PM »
Space Weather News for Oct. 8, 2013
http://spaceweather.com

JUNO TO BUZZ EARTH: En route to Jupiter, NASA's Juno spacecraft will make a very close flyby of Earth on October 9th, only 347 miles above our planet's surface. Juno's
radio will be turned on, and radio amateurs on Earth will be able to communicate with the spacecraft via Morse Code.  Ground tracks and further instructions may be
found on today's edition of http://spaceweather.com


Offline Star One

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Re: NASA - Juno - Updates
« Reply #34 on: 10/09/2013 09:35 AM »
« Last Edit: 10/09/2013 09:37 AM by Star One »

Offline wakka

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Re: NASA - Juno - Updates
« Reply #35 on: 10/09/2013 11:45 AM »
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

Offline bolun

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Re: NASA - Juno - Updates
« Reply #36 on: 10/09/2013 01:33 PM »
ESA and NASA stumped by cosmic mystery

9 October 2013

A mystery that has stumped scientists for decades might be one step closer to solution after ESA tracking stations carefully record signals from NASA’s Juno spacecraft as it swings by Earth today. 

NASA’s deep-space probe will zip past to within 561 km at 19:21 GMT as it picks up a gravitational speed boost to help it reach Jupiter in 2016.

During the high-speed event, radio signals from the 3225 kg Juno will be carefully recorded by ESA tracking stations in Argentina and Australia.

Engineers hope that the new measurements will unravel the decades-old ‘flyby anomaly’ – an unexplained variation in spacecraft speeds detected during some swingbys.

http://www.esa.int/Our_Activities/Operations/ESA_and_NASA_stumped_by_cosmic_mystery

Image credit: NASA/JPL
« Last Edit: 10/09/2013 01:36 PM by bolun »

Offline bolun

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Re: NASA - Juno - Updates
« Reply #37 on: 10/09/2013 04:06 PM »
https://twitter.com/esaoperations

Engineers at ESA's #Estrack control room at #ESOC now recording Doppler signals from @NASAJuno #junoflyby

Distance to Earth: 128,700 km. @NASAJuno approaching at 46,476 km/hr - which is really fast! #junoflyby #flybyanomaly

NASA confirms: Now receiving signals from Juno via ESA's #Estrack Malargue station #aos #junoflyby #flybyanomaly

Offline bolun

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Re: NASA - Juno - Updates
« Reply #38 on: 10/09/2013 04:12 PM »
https://twitter.com/Juno_101

First JunoCam image of the day! Taken at 11:07 UTC when #Juno was 206,000 Kilometers from the Moon (via MSSS) - pic.twitter.com/86amdfgF6X

Offline bolun

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Re: NASA - Juno - Updates
« Reply #39 on: 10/09/2013 04:16 PM »
https://twitter.com/esaoperations

34m DSS-55 antenna at NASA's Madrid complex abt to end contact w/ @NASAJuno, as planned. ESA's 35m Malargue station in contact #junoflyby

Tags: Jupiter Juno JunoCam JUMPER