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Full Version: 2014 MU69 "Ultima Thule" flyby
Unmanned Spaceflight.com > Outer Solar System > Pluto / KBO > New Horizons
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elakdawalla
It's only 10 days now until the "Core" phase of the 2014 MU69 flyby begins! I thought it was time for a new thread. Carry on discussing distant observations of other KBO worlds in the KBO encounters thread, and use this one for MU69 until after the departure phase is officially over on 8 January.

I'll be posting a "What to Expect" article next week.
Steve5304
How longafter flyby will we get the first image or hint of success?
Explorer1
Nice overview at the bottom of this post: http://www.planetary.org/blogs/jason-davis...ut-100days.html
QUOTE
Then, there won't be much to do but wait and hope that things go according to plan. Around 10:00 a.m. EST on Jan. 1, the team expects to get a health and safety report from New Horizons letting them know it survived the encounter. The first up-close images of Ultima Thule are expected to arrive on Earth between 6:00 and 8:00 p.m. EST Jan. 1 (22:00 on Jan. 1 and 00:00 on Jan. 2 UTC), a NASA spokesperson said.
nprev
One thing I'm curious about is the anticipated total data acquisition as well as the time that will be required to downlink it at this greater distance. Obviously there won't be nearly as much data as there was from Pluto just because UT is pretty tiny and the near encounter hi-res phase will thus be exceedingly brief, but as with the Pluto encounter I wonder if they're gonna have an expected recorder space used message as part of the survival confirmation message.
Alan Stern
QUOTE (nprev @ Dec 16 2018, 03:10 AM) *
On thing I'm curious about is the anticipated total data acquisition as well as the time that will be required to downlink it at this greater distance. Obviously there won't be nearly as much data as there was from Pluto just because UT is pretty tiny and the near encounter hi-res phase will thus be exceedingly brief, but as with the Pluto encounter I wonder if they're gonna have an expected recorder space used message as part of the survival confirmation message.


Actually the total data volume taken and stored on the recorders is very close to the same as at Pluto; downloading it all will take 20 months. Through Aug-Sep, 2020.
nprev
Really! Delighted to be wrong, then. Thank you, Alan! smile.gif

So there will be an 'expected volume acquired' ping post-flyby as well, then? That was a big moment at Pluto.
Explorer1
And we have our first mystery: No light curve!
http://pluto.jhuapl.edu/News-Center/News-A...p?page=20181220
fredk
What about a very slow rotation rate? I didn't see anything about what interval the light curve was taken over. Presumably the lightcurve would look flat if the rotation period was significantly longer than the interval the lightcurve was measured over.

I don't know whether there may be expectations that these objects rotate faster than some rate - if so, that could explain the surprize.
Alan Stern
QUOTE (fredk @ Dec 24 2018, 07:09 PM) *
What about a very slow rotation rate? I didn't see anything about what interval the light curve was taken over. Presumably the lightcurve would look flat if the rotation period was significantly longer than the interval the lightcurve was measured over.

I don't know whether there may be expectations that these objects rotate faster than some rate - if so, that could explain the surprise.



We have photometry from HST stretching over years and on NH we have been making measurements routinely since September; since later November the SNRs have been quite good. We're looking for periods ranging from ridiculously long (weeks) to ridiculously short (2 hours). Nothing firm yet.
NMRguy
Very curious for better resolution on the shape of the object, if itís a dumbbell, a binary or something more conventional. The occultation data was certainly curious. Best to the amazing NH team in the coming weeks.
scalbers
I wonder how much difference there is in the Ultima Thule viewing angles presently from New Horizons and the from Earth perspective informing the occultation data? Consideration of this may help constrain a 3-D shape model (and light curve interpretation). The answer to this is a modest about 11 degree difference, since Emily's article mentions an 11 degree phase angle from NH and we can assume a near zero phase angle from Earth.

http://www.planetary.org/blogs/emily-lakda...tima-thule.html
Explorer1
Nice interview on Planetary Radio, some very good details: http://www.planetary.org/multimedia/planet...w-horizons.html
WTW
Very good Engineering Colloquia presentation by Marc Buie at Space Telescope Science Institute on the challenges re. discovery and tracking of MU69, and of the encounter itself:

https://webcast.stsci.edu/webcast/detail.xh...47&parent=1
nprev
Emily has posted a new article providing links to flyby coverage.

ADMIN NOTE: There will likely be no NASA TV or other NASA media coverage of the event due to the partial government shutdown in the United States at this time. All members are reminded to please read and heed rule 1.2. We have to acknowledge this fact, but we will not discuss or debate it.

The Forum is politics-free, and it will stay that way.

Thanks!
Explorer1
Based on the Administrator's recent tweet, and this observation by Keith Cowing, I think there might be something on NASA TV after all. The last few shutdowns had no major space events happening, so my guess is that some arrangement must have been made behind the scenes. We'll see if there is actually a briefing tomorrow...
nprev
That would certainly be a most welcome development if it happens; thanks!

In the meantime...UMSF itself is of course a project of The Planetary Society, and we are a part of their education and public outreach efforts. Accordingly, I would encourage all to share any information sources concerning the flyby you can not just here but on your other social media platforms.

Above all else save the success of the flyby itself, it is vitally important that as many people as possible are made aware of this historic event and are afforded the opportunity to witness it. The NH team also should know that they are far from forgotten, and we are all working to spread the word of their work to the world.

It's on. And we, as in each of us, will be a part of making it happen.

GO NEW HORIZONS!!!!
MahFL
Not sure if everyone knows but NASA Eyes does have a MU69 flyby preview and a current live view.

https://eyes.nasa.gov/
JRehling
Before this flyby takes place, I feel a surge of wonderful curiosity about what we will see. The oldest books about the solar system I read as a kid speculated what the surface of the Moon would look like, and similarly had art depicting imagined landscapes of Mars, Mercury, Venus, Titan, and more. I remember the first Viking photos of Phobos and the supposition (not inaccurate) that asteroids would be similar. Pluto most recently brought us unconstrained surprise.

And now we're seeing yet another new kind of world, and this may not happen many more times (constrain that as you will: this century, in any given person's lifetime, or ever). And we just do not know what we'll see. Will it look like a main belt asteroid, but of nitrogen? Strangely eroded? Shaped by electrostatic forces? A globular cluster of pellets slowly orbiting a center? We do not know!

There'll be some wonderful moments ahead, and it may be that nothing is as fun as the anticipation. Anticipate away!
nprev
Undoubtedly. It is a remarkable privilege to be the first of all the humans that ever have lived to see an entirely new type of world for the very first time up close...to say nothing of the fact that KBOs/TNOs were only theoretical concepts until perhaps 40 years ago with the discovery of Chiron. smile.gif

We already have one mystery: Why no light curve? Unless NH is flying nearly parallel to UT's rotation axis and/or it just doesn't have any significant albedo variations at all that's a real head-scratcher; other KBOs definitely have them.
MahFL
2.9m miles now... wheel.gif
nprev
BREAKING: Alan Stern now reporting that NASA social media and NASA TV will indeed cover flyby activities. smile.gif
dudley
Perhaps Ultima Thule's lack of a normal light curve means that it's rotating extremely slowly, so slowly that its aspect hasn't changed appreciably since we've had it under observation. Perhaps it's not rotating at all.

Then again, assuming the object is binary in form, perhaps the object's outer-facing hemispheres are lighter in color than those facing each other. This might provide a steady light as it rotates. The light level could be enhanced when less surface area is presented to our view, and detracted from when both lobes are in fuel view.

Judging by the shape model derived from stellar occultation, the two lobes appear to be very close to one another, and to partially overlap, from our point of view.
fredk
Check this post from Stern where he addresses slow rotation.

For sure a cancellation between shape and albedo markings could be to blame, but it does seem unlikely.

Another point is that S/N isn't infinite, so all they can say is that the lightcurve is consistent with flat to some % level, and we don't know what that level is (of course it's decreasing as we approach).
nprev
Slow rotation in itself would be a fascinating find. Most of the asteroids in the inner system we've visited seem to have rotation periods in single-digit hours.

If this turns out to be true then gotta wonder if UT might be completely pristine, as in virtually no impacts or outgassing throughout its history. Alternatively, if it is a contact binary then how was the system's angular momentum dissipated so much?
scalbers
NASA TV Briefing on now...
rhr
On where? I can't find a live stream from any of Emily's links.
elakdawalla
Sorry about that. I did my best with the information provided, but it turned out not to be accurate. Here is a partial recording of today's briefing but it's only 19 minutes' worth -- if anyone finds a full recording, please share it here! https://www.youtube.com/watch?v=N5BNOo4LJmM
scalbers
Looks like a full 30min recording here, now posted on the jhuapl site & YouTube channel.

Next briefing Dec 31 2pm EST.
PDP8E
We have seen several artist's interpretations of MU69 ... a contact binary ... an orbiting binary...

Here is a computer program's interpretation of MU69 ... a programmed hallucination ... but based on inputs of Vesta, Phobos, and the Lorri image released a few days ago (which was 10x if I am not mistaken but was used to constrain the program's output). The program crunched the data for 17 minutes and came up with the image below. This is what MU69 might look like from Lorri at about 50K km away... or probably not.

Click to view attachment

for your enjoyment only...
Explorer1
Well, we'll see next week how accurate that is!
tanjent
PDP8E, in the same spirit, I predict that the soon-to-be-revealed observations will bear "some" but "not too much" resemblance to your model image.


MahFL
1.9m miles now. wheel.gif
jasedm
Were this the Saturn system, we'd be within Iapetus' orbit now...

smile.gif
Lucas
Interesting tweet from Alan... perhaps they have resolved Ultima Thule?

https://twitter.com/alanstern/status/1079111629604831233
MahFL
QUOTE (Lucas @ Dec 29 2018, 11:29 PM) *
Interesting tweet from Alan... perhaps they have resolved Ultima Thule?

https://twitter.com/alanstern/status/1079111629604831233


It seems to be something, but they are still too far out to resolve anything, except maybe if it's a binary or not ?
Also according to Emily's posted schedule no pics are due to be downloaded today.
Alan Stern
QUOTE (MahFL @ Dec 30 2018, 12:12 AM) *
It seems to be something, but they are still too far out to resolve anything, except maybe if it's a binary or not ?
Also according to Emily's posted schedule no pics are due to be downloaded today.


Emily's article is about scirct science data. But all data are useful for science, even OpNav images.....
dtolman
QUOTE (Alan Stern @ Dec 29 2018, 07:54 PM) *
Emily's article is about scirct science data. But all data are useful for science, even OpNav images.....


Squinting at where the wand is pointing in your twitter post, I'd say LORRI has resolved Ultima Thule into multiple pixels, right on schedule! I guess all will be revealed soon enough smile.gif
fredk
I don't think he can see where he's pointing.

There appears to be a vaguely ringlike structure about the centre of that image (and darkness at the very centre). My guess: they've subtracted a point-source model (PSF) from the image where MU69 is predicted to be and see a residual around it, which would suggest it's starting to be resolved.
john_s
The raw image page is now up-

http://pluto.jhuapl.edu/soc/UltimaThule-Encounter/

Enjoy!
nprev
Thanks, John. I assume that the fact that UT is near the center of the frame is a very good indication of nav accuracy...? smile.gif
nprev
Spaceflight Now is going to live-blog the encounter in real time from JHAPL.
JohnVV
artist's concept
do to software constraints a render of UltimaThule as a SPHERE

Click to view attachment
( this is basically my default KBO generator using Blender )

we will see in a few days , then something much closer to the real thing


PS.

dose anyone know of a naif spice kernel for New Horizon for the fly-by.
The last kernel ( nh_pred_alleph_od124.bsp ) has a end date of September 2018
nprev
Alan just reported on FB that they finished their last nav meeting a few minutes ago, so possible that there might be a REAL fresh one available soon.
Bjorn Jonsson
Interesting tidbit in the Spaceflight Now live-blog from Hal Weaver, there are some hints that Ultima Thule is a quickly-rotating object.
Aldebaran
QUOTE (Bjorn Jonsson @ Dec 30 2018, 11:25 PM) *
Interesting tidbit in the Spaceflight Now live-blog from Hal Weaver, there are some hints that Ultima Thule is a quickly-rotating object.


Could that explain the lack of light curve? (temporal resolution constraints)
Bjorn Jonsson
QUOTE (Aldebaran @ Dec 30 2018, 10:56 PM) *
Could that explain the lack of light curve? (temporal resolution constraints)

I doubt it - some of the light curve observations probably include images taken with a short time interval between the images and probably also a variable interval.

But if it turns out that UT really us a quickly rotating object that must be good news since it means NH will be able to observe a bigger part of UT's surface.
MahFL
0.9m miles now.

Failsafe 1 images download starts at 8:31 pm EST.
dudley
How fast would Ultima Thule have to be spinning, I wonder, so that the light curve would be smeared out into one consistent light level?
Hungry4info
It doesn't appear to be a binary object from this image.
(Processed by Daniel Bamberger (stacked, deconvoluted, enlarged)).
Explorer1
DSN Now shows 1.06 kb/ sec download! This is 'Failsafe 1', right?
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