Looks good. Applause and hugs. Science downlink expected 2000 GMT today.

Happy, happy New Year!

How bright is Ultima Thule to an observer with human eyes? (If we can get a common frame of reference and not the math.) As bright as the light from a full moon? Or, if I had a camera with ISO 100 at F4, what would be my shutter speed?

With the news that New Horizons has survived its close encounter with Ultima Thule, with all systems intact, a dense particle cloud now seems to have been rendered very unlikely.

Awesome news, apparently the spacecraft did everything it was supposed to do.

Do you mean, if you were located at a position where it took up the same amount of steradians as the moon does from Earth? Is this in a scenario where it's at 1AU like the moon, or where it actually is at present? I don't think we can give an answer to either scenario yet (has the albedo been determined?)

It's around 43.4 AU from the sun, so sunlight at its surface would be close to 1/1900th as bright as at Earth. That corresponds to nearly 11 photographic stops fainter. So still quite a bit brighter than under a full moon at Earth, which would be around 18 or 19 stops fainter than full sunlight.

Latest image on NASA TV! Looks like a bowling pin.

Hal Weaver says the pole is facing us (explanation for the light curve mystery).

Failsafe 2.

We can see the rotation. Rotation period is either 15 hours or 30 hours.

More like somewhere between 15-ish and 30-ish hours - they didn't observe it at the higher resolution for long enough to pin the rate down well.

They said they're still not sure whether it's one or two bodies. Now that we have a (crude) rotation rate and a good size, it shouldn't be hard to estimate whether the periodicity is consistent with Kepler for two bodies, assuming something about density...

Though of course the uncertainties on linear size are still large, and the uncertainties on volume (and hence mass) will scale like the cube of the linear size (and depend on the full 3-D shape), so will be huge.

Another round of high-fives for Alan Stern and his team.

Looks to me that this might indeed be a binary.

When using this equation: P^2 = [ 24 pi R^3 ] / [ G rho (D1^3 + D2^3) ]
(with P = period -- 15 h or 30 h; R = range between component centers; G = 6.67e-11 m3/kgs2; rho = object density; D1 = diameter of larger, D2 = diameter of smaller component),

then, a P near 15 h can be achieved with the following values:
Assume rho = 0.6 g/cm3 => values for the range and sizes:
R ...12 -- 13 -- 14 -- 15 km
D1... 9 -- 10 -- 11 -- 12 km
D2... 7 -- 7 -- 8 -- 8 km

For P ~ 30 h and rho ~0.5, possible values are:
R ...16 -- 17 -- 18 -- 19 km
D1... 9 -- 9 -- 9 -- 10 km
D2... 5 -- 6 -- 7 -- 7 km

For a density similar to Phoebe's (1.6 g/cm3), the 15 h period might work like this:
R=18 km
D1=10 km
D2=7 km

The 30-h period at 1.6 g/cm3 does not appear to look compatible with the image to me:
R=18 km
D1=6.5 km
D2=4 km


Not surprising, it appears that we need the better images (plus the exact period) to get solid numbers. In the meantime, excitement remains that Ultima Thule might indeed be a double object.

~~ Tilmann

If it is a double object, they should dub the two parts "Ultima" and "Thule." (Like Buda and Pest.)

The ground illumination should look like about 10 minutes after sunset on Earth.

this is amazing... to the New Horizon Team! To the builders, the managers, the engineers, and to the thousands running the infrastructure that to talks to that little beauty! We need more of these machines... to bring our eyes out there! Well done!

https://planetary.s3.amazonaws.com/assets/i...tation_f233.gif

Here, it really looks like a contact binary. We will see...

Quick Crop:

Very interest the hypotetical luminosity over these astronomical distant corps.

I hope in a low distant binary, not in contact ��

Me too :-)

If the rotational axis is not pointing toward the observer, but rather somewhere in between of "toward observer" and "perpendicular to observer", then a binary might make sense also with respect to the non-detection of a lightcurve. In the animated-gif, "Ultima" passes in front of (or behind) "Thule", but the two components do not yet occult each other (at least not significantly). As long as the individual components are rather spherical, this would result in a rather shallow lightcurve because no "additional surface parts" would appear while the components move toward maximum elongation. Since no occultation took place, the characteristic dips of binary lightcurves are not there. Same for lightcurve features from potential eclipses since the sun is behind the observer.

Another 2 cents...

DSN Now is reporting start of the NYT 1 ("New York Times") data downlink. Signal strength is in the about -147.5 to -149 dBm range, as usual, and bit rate is shown as 841 bits/sec. The first post-flyby science data download has begun!

If you've witnessed a near-total-eclipse, you may well have spotted something 'odd' with the light and shadows. A slither of Sun casts much sharper shadows than the full half-degree disk. At Ultima Thule, whilst the daylight will be dimmer, by about 8 magnitudes, the shadows will be very much sharper.

Andy

That's not a useful analogy because it ranges from pitch black to daylight depending on season and latitude. It's more like a very dark rainy day.

Non lo sapevo. . incredible!

Looks like a raw peanut in shape. How long before we know if the peanut is in one piece or broken?

First I want to say congratulations to Alan and all the team for this flyby. Again in Spain has been a trending topic during the afternoon today.

I have made a quick and dirty way to look to all the images that are going to be downloaded from New Horizons that is useful if you want to sort by distance, date or exposure. The database will be uploaded as soon as there are new images avaiable: http://nahumchazarra.com/ultimalorri/viewer.php

Post-sunset brightness also depends upon transparency (humidity, dust). It's still useful, if not precise, for relating to all of us that it is certainly bright enough to see things.

Terrestrial sunlight is 400,000 times brighter than a full Moon, so the sunlight at Ultima Thule is about as bright as 210 full Moons. None of us, I think, have ever seen 210 full Moons at the same time, but as it's possible to read by the light of the full Moon, it certainly conveys that it's not such a dark place.

Put another way, it's about half as bright as sunlight at Neptune. If you've ever seen Neptune through a telescope, you can see that it's quite adequately lit for seeing shape and color.

Just about out of time for wild speculation, so Iʻll give it a last minute whirl....

Methinks that a close binary orbit would be short-lived (on the age-of-solar-system scale) because of small dissipative forces in the "neck" area. Debris could gather there and bounce around.

I am sure there would be cratering events in the history of MU69, but ice condensation/evaporation features cold also be present, plus solar wind and cosmic ray "processing". What the result of this looks like is truly anybodyʻs guess -- the best answer is "we donʻt know, but we will find out soon"....

I can be a bit more specific if it will help. If a spot on UT is normal to the sunlight, the illumination is about the same as a typical location on Earth in cloudless conditions with reasonably clean air having the sun about 1.5 degrees below the horizon. While it's true that aerosols and other factors change this I think the illumination normal to the ground will usually be within a factor of 2 of the nominal value. Perhaps I should try and check this with my sky simulation software and/or some pyranometer measurements.

It's kind of rare for a rainy day to be this dark (<0.1% of full zenithal sun) unless the sun is fairly close to the horizon. I'd place more typical values in cloudy/rainy conditions at 3-10% of the full sun case.

Disspiative forces even in case of a doubly-synchronous binary system with perfectly circular orbits?

A "wild speculation" for the moment:
Ultima Thule is a binary with two similarly-sized (but not equal-sized) components in a doubly synchronous rotation state with a period at the order of 16 hours and a pole-axis orientation that is approximately 45 to 60 degrees away from the observer (aka ~30° to ~45° tilted to the ecliptic plane). Diameter of larger component ~14 km, of smaller ~10 km; center range ~21 km, density ~0.8...0.9 g/cm3.

(Ok, this is really speculative...)

Hmm, we're expecting to see the oldest solid surface yet found in the solar system...
A cold classical Kuiper-belt binary, which has been in basically the same orbit for billions of years.
Hmm, this should be the first time we see what happens when sunlight and solar wind are the main weathering mechanism.

That should be a red-tholin-surface dominated by space weathering on the sunward side.
Might have some interesting long term torquing effects if material evaporates or sputters from the sunward side and collects on the dark side, might even have a "lake" of dust collecting in the neck between the main lobes.

The full moon produces about 0.1 lux illumination, so sunlight at Ultima Thule would be around 21 lux. This is between "twilight" (~10 lux) and "very dark overcast (~110 lux). Dimly lit publlc areas run between 20 to 50 lux, and home interiors are around 150 lux.

Im not very expert but unfortunately I think that two object very close aren't stable. I think necessary almost 30km space between two 10-15 km binary object for stability. But if they were two bodies so far away they were already resolved divided. This is why I believe that they will be two bodies in contact as a skittle or an hourglass.

I expect like-sand dune area like same little area over 67P comet

NYT 1 data download should be on the ground now.

As of a few minutes ago, NASA's DSN-now webpage showed the s 70 meter antenna at Goldstone had just finished a downlink with New Horizons...

LORRI gallery still showing 57 images down, 52 available to browse...
http://pluto.jhuapl.edu/soc/UltimaThule-Encounter/

And NYT 2 downlink has begun, with stable signal and an indicated data rate of 1.06kb/sec. Should be a good news conference tomorrow :-)

Will be interesting to see how close the prior predictions are...


Great Expectations:
Plans and Predictions for New Horizons Encounter with Kuiper Belt Object
2014 MU 69 (‘Ultima Thule’)
submitted to Geophysical Research Letters, June 14, 201

Well done project team!

Anybody seen an announcement for the next news conference, presumably sometime tomorrow morning East Coast US (2 Jan/GMT-4)? Been looking, haven't found anything.

Emily's post says 2:00 PM EST, and that's what I'm counting on. Her table hasn't been wrong yet!

Yes, that is classic Emily. Was wondering if perhaps there was gonna be a pop-up coinciding with the initial data reception, but a- of course there must be some preparation and more importantly b- the team probably should get some sleep since they've been up for like a week or so.

Thanks!

The New Horizons web site at http://pluto.jhuapl.edu/News-Center/Where-to-Watch.php also still shows press briefings at 2:00-3:00PM EST on both Wednesday 2 Jan. and Thursday 3 Jan.

The news briefing tomorrow (Wednesday) will happen while the NYT 3 downlink is still in progress; hopefully we'll see those LORRI + MVIC images on Thursday, and maybe even some first LEISA and SWAP/PEPSI results.

A tweet from James Tuttle Keane: Finishing a long night of analyzing new images of #UltimaThule. I can’t wait for you all to see. For now, here’s a teaser...
Click to view attachment

In case you don’t follow James, he draws sketches...
Hard to make hypothesis but at least it seams UT is not white only !

NYT 2 just finished. Signal dropped at Canberra at about 08:35UTC.

Indicated signal strength was as low as about -150 dBm for a short period, but was in general very stable at previous nominal levels throughout the 6 hrs 45 min. The entire communications pass was via the Canberra 70m dish.

Noticed that data rate dropped to an indicated 841 bps just before 05:51 UTC, and then to 501 bps at about 07:26UTC. Very stable after each change.

It appears we all are now part of a modern ("spacy") version of the Marshmallow Test...

Click to view attachment

From the "Failsafe 2" raw-image data set (2x zoomed; co-registered to inertial stars)

A pile of pencil shavings?

I now have this mental image of a brave little group of icy bits huddled up in a little gravity well for comfort against the cold, dark void.

I guess I can anthropomorphize anything...

My not-so-educated-guess:

Large lobe has a jagged appearance (pencils) - maybe with a single "spike", small lobe is "lumpy" (pencil shavings) and the middle is regolith-like fine material.

Ummm
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