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Headshot of Emily Lakdawalla

Juno update: 53.5-day orbits for the foreseeable future, more Marble Movie

Posted By Emily Lakdawalla

03-11-2016 9:44 CDT

Topics: amateur image processing, mission status

Juno suffered two setbacks in October. First, a problem with check valves in the main thruster system prevented a planned rocket burn during its October 19 close pass by Jupiter. The science team raced to use the burnless perijove pass to do some science, but then the spacecraft went into safe mode on October 19, before perijove, and before the science sequences could kick in. Juno exited safe mode on October 24 and performed a half-hour burn with its maneuvering thrusters -- not its main thrusters, which were still not being used, pending the outcome of the investigation into the check valve problem. An article at Spaceflight Now goes into much more detail about the investigation into both engine problem and safing event.

At the DPS/EPSC meeting last week, principal investigator Scott Bolton spoke about keeping Juno in its long, 53.5-day orbit for a long time, not ruling out the possibility of performing the entire mission in such an orbit. Juno only gets exposed to dangerous radiation when very close to Jupiter, so the spacecraft wouldn't be exposed to any additional radiation by doing this, though it would seriously prolong the mission. If the mission has not ended by September 2019, Jupiter will have traveled far enough around the Sun that Juno will pass into Jupiter's shadow for several hours on every orbit, a condition that it was not designed for and which could harm its power system; the mission would need to develop a solution to that problem.

At present, the future orbital path of Juno is still uncertain. For the time being, it will stay in its 53.5-day orbit. According to JunoCam team member Glenn Orton, the next planned perijoves in that orbit would be:

PerijoveDate/time (UTC, SCET)longitude of equator
crossing (System III)
PJ2 2016 Oct 19 18:12:01 348.83 deg W
PJ3 2016 Dec 11 17:05:08 7.03 deg W
PJ4 2017 Feb 2 12:59:12 277.00 deg W
PJ5 2017 Mar 27 08:53:20 187.00 deg W
PJ6 2017 May 19 06:01:51 142.00 deg W
PJ7 2017 Jul 11 01:55:56 52.00 deg W
PJ8 2017 Sep 1 21:50:01 322.00 deg W
PJ9 2017 Oct 24 17:44:04 232.00 deg W
PJ10 2017 Dec 16 17:58:48 299.50 deg W
PJ11 2018 Feb 7 13:53:23 209.50 deg W
PJ12 2018 Apr 1 09:47:24 119.50 deg W
PJ13 2018 May 24 05:41:25 29.50 deg W
PJ14 2018 Jul 16 05:18:44 74.50 deg W
PJ15 2018 Sep 7 01:13:46 344.50 deg W
PJ16 2018 Oct 29 21:07:49 254.50 deg W
PJ17 2018 Dec 21 17:01:52 164.50 deg W
PJ18 2019 Feb 12 17:36:13 243.25 deg W
PJ19 2019 Apr 6 13:30:13 153.25 deg W
PJ20 2019 May 29 09:24:18 63.25 deg W
PJ21 2019 Jul 21 05:18:43 333.25 deg W
PJ22 2019 Sep 11 20:14:43 61.87 deg W

At any perijove, of course, they could decide to go ahead and shift Juno to a shorter orbit with a main engine burn -- we'll just have to wait and see.

In the meantime, JunoCam imaging scientist Candy Hansen told me that the camera has not been turned on since the sticky-valve problem reared its head, and will not be turned on until perijove 3, on December 11. I've now updated my Marble Movie index page with all the JunoCam images received on Earth to date. Below is the near-final version of the JunoCam Marble Movie, covering July 10 through October 14, 2016, between perijoves 0 and 2; all that is missing is the extra-close frames of perijove 1.

This movie is assembled from processed JunoCam images. It covers the whole, initially scheduled Marble Movie Phase from after perijove 0 (July 4, 2016) to before perijove 2 (October 19). There are two 7-hour gaps when JunoCam didn't take images before perijove 1 (August 27), and a weeklong gap during solar conjunction (September 23-29). The perijove 1 flyby itself is also not included; it requires special processing, which is ongoing.

NASA / JPL / SwRI / MSSS / Gerald Eichstaedt

See other posts from November 2016


Read more blog entries about: amateur image processing, mission status


Red: 11/03/2016 10:39 CDT

It is a shame about the valve problems, although compared to Galileo's dual problem of a stuck main antenna and a broken tape recorder Juno's still doing fine. Hopefully any radiation-induced safing events are kept to a minimum and they can find a way to reduce the spacecraft period; perhaps like JAXA's probe at Venus they could use minor thrusters to perform a smaller burn to similar effect; that would seem like one alternative especially if the valve issue is tied to the main engine.

LocalFluff: 11/03/2016 12:05 CDT

I just hope they will be able to use the instruments during the next "perijove" close flyby. An 8 week orbit seems great, as long as the flybys are useful.

Messy: 11/03/2016 04:48 CDT

It's better than what happened to Scapperelli, but still....

LocalFluff: 11/04/2016 07:09 CDT

That "Marble Movie" is great! It is so classical astronomy because of Galileo. That a spacecraft is actually out there filming this, is amazing. The longer orbital period doesn't seem to be a major problem. I'm more worried about the safe mode kicking in during the close flybys. I hope that will go away. Even one successful perijove science operation would give the brunt of the science. The rest is a bonus. In the best case, can Juno map Jupiter as well in this orbit as it would've with the intended orbit? Albeit it takes longer. Was this 53½ day orbit designed with this scenario in mind, to reach the science goals anyway?

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