Lucy, Discovery Mission 13 - a grand tour of the Jupiter Trojans Options

[PhilipTerryGraha...]

Obligatory new thread for the Lucy mission, now that it has been selected by NASA to launch as Discovery mission 13! Lucy will launch in 2021, and will perform a flyby of a main belt asteroid in 2025, before making flybys of at least six Jupiter trojans from 2027 to 2033. The mission, led by the Southwest Research Institute and Principal Investigator Harold F. Levison, will send a spacecraft carrying updated versions of New Horizons' LORRI and RALPH instruments.

Be sure to check out r/lucymission on reddit as well!

EDIT: I have made a mistake. Could a kind mod please move this thread to the "Cometary and Asteroid Missions" subforum?

ADMIN: Done.

Note for the new members: Generally speaking, please consult a member of the admin/mod team before creating new topics. Not a hard rule, but it does help to keep the place tidy. Also, we encourage all members to review this welcome post for orientation purposes. Thanks!

[Patteroast]

Very excited for this mission. I'm a sucker for seeing new worlds, and I didn't realize Patroclus-Menoetius was a target for Lucy until it was selected. And so many others, too!

[Mongo]

This new paper on arXiv suggests that Jupiter formed past Neptune and then migrated inwards to its current orbit, sweeping up the Jupiter Trojan asteroids with it. They make a compelling case, that explains the otherwise inexplicable asymmetry between the leading and trailing Trojan clouds.

This would mean that there is an incredible compositional diversity within the Trojans, due to their origins ranging from the inner Kuiper belt to the location of the current Hilda asteroids. So the Lucy mission has the opportunity to visit bodies originating throughout the middle and outer solar system, which makes it even more important for understanding the history of the solar system.

[Holder of the Tw...]

They are ready to start building the spacecraft.

Link: Lucy passes Critical Design Review

[Explorer1]

Cool news a satellite discovered around one of the flyby targets!
https://www.nasa.gov/feature/nasa-s-lucy-mi...bates-satellite

[stevesliva]

Turns out Lucy might get pretty darn close to said Satellite:
https://twitter.com/plutokiller/status/1401894522859122694

(Tweets from June)

Lucy scheduled for Launch in October.

[mcaplinger]

Some open-access papers about the Lucy mission here: https://iopscience.iop.org/issue/2632-3338/2/5

[propguy]

Lucy launch is only 2 days away. We are now powered for the last time and this AM moved to the pad at LC41 and looking at a nice early AM launch on 10/16 (0934 UTC, 0534 EDT) with great weather forecasat. Hope everyone is going to get up early with us for launch. There was a very good pre-launch press briefing yesterday that is on YouTube (sorry for all the commercials I could not find any alternate hosting sites,YouTube video link). Hope you have a chance to watch the launch live (or after getting up for those in the US). I have seen some questions on forums such as reddit asking what propulsion elements Lucy has (All of the following info is not export controlled so I can provide these answers here). We have eight 1 N and six 22 N mono-propellant thrusters for ACS and the majority of the trajectory correction maneuvers (up to 50 m/sec). For larger burns we have a 470 N bi-propellant main engine (Leros 1C). The propellants are hydrazine and dinitrogen tetroxide. There are currently 4 burns over 7 years that will use our main engine. We won't need to use that engine till mid 2024 (large DSM to target Earth for an Earth flyby). Go Lucy!!!

[john_s]

Some of us here are on the science team too- happy to (attempt to) answer any science questions.

At the Cape, trying to type with fingers crossed!

John

[Explorer1]

Sure, we really appreciate it, having representatives from both side of the mission coin on here!

Having watched the briefing from earlier; will the geometry of the Earth flybys allow for some great (colourful) views for L'LORRI (or even during commissioning)? LORRI on New Horizons never looked back at Earth even to this day....

[john_s]

Imaging the Earth will likely be done for calibration, but we might have saturation issues, so don’t yet know how pretty the pictures will be. The moon will also likely be a calibration target and less likely to saturate. The geometry will depend on our launch date, so we’ll know soon!

John

[Ron Hobbs]

Watched the Science Press Conference today. Excited to follow this mission.

GO LUCY!!!

[Holder of the Tw...]

Hmmm. Since this Atlas launch will be without any SRBs, a couple of shock diamonds might be just barely visible in the far end of the exhaust of the rocket.

If so, I can think of a caption for that photo ...

[nprev]

Hoping to keep my eyes open long enough to watch the launch tonight.

GO LUCY!!!

[Explorer1]

Go up early to watch the launch! Beautiful! All the best to the team, and looking forward to the first images!
1 year to Earth flyby....

[Floyd]

I also watched the launch this morning--it is always breathtaking. I understand the huge solar panels unfolded properly.

[Tom Tamlyn]

The best general media article I’ve run across concerning the Lucy Mission is this one in the New York Times. (I assume it’s paywalled, although the NYT is a little more generous with free articles than it was.)

https://www.nytimes.com/article/nasa-lucy-t...-asteroids.html

The article is nicely written, features some particularly good graphics, and most importantly, feels more comprehensive than is typical for the twenty-first century NYT science section.

This was a mild surprise. I’m a life-long reader and admirer of the New York Times science desk. However, since the MER rover missions renewed and intensified my interest in planetary science in 2004, I’ve frequently felt that the NYT’s fine writers were not allowed enough ink to do do justice to planetary missions. I began to rely much more on specialist journals and online sources, especially Emily Lakdawalla, and particularly during her time at the Planetary Society, and of course this forum.

The article's author, David W. Brown, is a freelancer who has apparently just published a book on the Europa Clipper mission with the following title:

THE MISSION, or: How a Disciple of Carl Sagan, an Ex-Motocross Racer, a Texas Tea Party Congressman, the World's Worst Typewriter Saleswoman, California Mountain People, and an Anonymous NASA Functionary Went to War with Mars, Survived an Insurgency at Saturn, Traded Blows with Washington, and Stole a Ride on an Alabama Moon Rocket to Send a Space Robot to Jupiter in Search of the Second Garden of Eden at the Bottom of an Alien Ocean Inside of an Ice World Called Europa (A True Story)

I'm not a fan of goofy long book titles that don't include useful search terms in the first few words, or in this case, anywhere at all, but on the strength of Brown's article about Lucy, I'm going to read his book.

[Explorer1]

I posted a minor review of the audiobook in the Europa Clipper thread: http://www.unmannedspaceflight.com/index.p...st&p=251818
He's a good writer, though naturally he can only write about non-confidential subject matter, so he is limited to some degree.

[stevesliva]

Re: NYT: this reads like a Science Tuesday section front page, and that's where I'd expect to see it in print.

[JTN]

Hmmm. Since this Atlas launch will be without any SRBs, a couple of shock diamonds might be just barely visible in the far end of the exhaust of the rocket.

I think this tweet (direct image link) might show such.

Also, the Spaceflight Now article has "A tiny diamond buried deep inside the L’TES spectrometer acts as a beam splitter".

[Decepticon]

https://spacenews.com/nasa-investigating-is...cy-solar-array/

[Explorer1]

They're optimistic that it's not a major issue: RCS thrusters worked already, main change has been a delay in deploying the instrument platform:

https://spaceflightnow.com/2021/10/18/nasa-...lar-array-snag/
EDIT: More details, directly from the team:
https://blogs.nasa.gov/lucy/2021/10/19/nasa...s-solar-arrays/

[Hungry4info]

Lucy update. We're now in cruise mode, with the instrument platform deployed. They're going to turn the spacecraft to various attitudes to try to use the current measurement from the stuck array to determine how far it deployed to better inform how to fix it. https://scitechdaily.com/nasa-issues-update...ay-problem/amp/

[Explorer1]

https://blogs.nasa.gov/lucy/2021/10/27/lucy...in-cruise-mode/
Next attempt to fully deploy no earlier than November 16th. Instrument checkout going on as planned, some minor manouvers have been completed.
Array is 75 - 95 % deployed, team estimates.

[lcs]

Something similar happened on Galileo. Possible explanation?

https://www.mdpi.com/2075-4442/9/8/72?type=...e&version=2

[stevesliva]

The mechanisms are different, and Galileo was in storage for too many years.

The status report above mentions a 'lanyard'. There is a timelapse video from a deployment test here: https://www.youtube.com/watch?v=6vjK9vGEw5Q

My guess is that the lanyard they mention is seen here. It starts pulling around the fulcrum at the center of the array, and then pulls across the screen, and then is off screen.

[Explorer1]

Lucy was never in storage for an extended period due to delays. I'm sure they're thinking over every possibility. Although we all hope the array finishes deploying, I have been thinking that if this isn't fixed by the time of the Earth flyby next year, the low altitude combined with the size of the arrays, might make it possible to resolve the stuck array directly with Earth-based imagery?

[mcaplinger]

...possible to resolve the stuck array directly with Earth-based imagery?

See https://www.jpl.nasa.gov/nmp/st8/tech_paper...20NGU%20ST8.pdf for some information about how Ultraflex arrays work (BTW, ST8 never flew as far as I know). I don't know what kinds of position information or other telemetry (e.g., motor current) they get during deployment. What's been said suggests that all they get is a single binary flag showing full latching, but I doubt that's true.

It's not at all obvious to me if images, especially ground-based, would be of any use whatsoever to fixing the problem. The TTCAM cameras could in theory produce out-of-focus images of the spacecraft, but I don't know if their placement and platform articulation would allow anything useful of the panel (links to a paper on those cameras upthread.)

There's a lengthy, mostly off-topic discussion of this at https://forum.nasaspaceflight.com/index.php?topic=46685.0 if you're into that kind of thing.

[JRehling]

An object 300 km from a telescope on the ground might enable imagery with resolution as good as about 10 cm per pixel… but that assumes a lot, including good weather at the sub-spacecraft point, which is completely beyond anyone's control or ability to predict, as well as two geometric factors that are knowable in advance, but not known to me: Will the spacecraft be near closest approach over land vs. the 70% of Earth that is water, and will the spacecraft be in sunlight at the time of closest approach, but not lost in daylight? This all sounds well below 50% probability, but not impossible.

[mcaplinger]

An object 300 km from a telescope on the ground might enable imagery with resolution as good as about 10 cm per pixel…

Color me skeptical that this is 1) possible or 2) useful, but feel free to check out the geometry -- the best trajectory info so far is https://naif.jpl.nasa.gov/pub/naif/LUCY/ker...-TCM36-P_v2.bsp

[Floyd]

With the low cost and weight of small cameras, I'm surprised there were not two cameras dedicated to viewing the solar arrays and documenting their deployment.

[mcaplinger]

With the low cost and weight of small cameras, I'm surprised there were not two cameras dedicated to viewing the solar arrays and documenting their deployment.

The overall system cost is probably not as low as you think, and it's not at all clear that documenting the deployment would help you fix a problem. Without knowing the details of the system it's impossible to know. There's more than enough poorly-informed discussion of this at the link I provided above.

If you want small space-rated cameras we would be happy to sell you some, and in fact there are two on Lucy: https://www.msss.com/news/index.php?id=131

[JRehling]

I don't have the software to turn that kernel data into the flyby specifics, but I'll emphasize that it seems unlikely that a best-case scenario for ground imaging would occur.

If it did, I still maintain that decimeter-scale resolution is possible, at least if we were trying to determine the degree that the solar array had deployed, from a continuum of known possibilities. Measuring the separation between two linear features measuring many pixels long allows for much greater accuracy than trying to image an unknown object. It would be quite similar to the situation where Vernier acuity is measured. As the Wikipedia article (accurately) states, "vernier acuity exceeds acuity by far."

https://en.wikipedia.org/wiki/Vernier_acuity

Here is an image of the ISS that approaches the best case resolution. As a comparison, this telescope has something like 3x the aperture of HiRise, which images subjects 300 km away.

https://m.facebook.com/MilroyCoonabarabran/...8555909/?type=3

But, again, there's no reason other than hope that a single opportunity would achieve results like the best of virtually unlimited opportunities to image the ISS. I don't predict a productive outcome for such an effort.

[bobik]

The overall system cost is probably not as low as you think, and it's not at all clear that documenting the deployment would help you fix a problem.

Is that so? The BepiColombo project added 3 small monitoring cameras to a completely integrated spacecraft less than two years before launch, and ESA - especially ESA's Science Programme isn't known for swimming in money. Yes, however, 20 percent uncertainty of the deployment state doesn't help to fix or assess the problem either.

[mcaplinger]

The BepiColombo project added 3 small monitoring cameras to a completely integrated spacecraft less than two years before launch, and ESA - especially ESA's Science Programme isn't known for swimming in money.

Unless you can produce an actual cost figure then this is at best circumstantial. I have a pretty good idea of how much it would have cost on Lucy, but can't discuss specifics.

This is all 20-20 hindsight. What I don't know is how much telemetry of the array state they get. Obviously they weren't expecting a problem.

[Marcin600]

"...The test data and findings suggest the lanyard may not have wound on the spool as intended. Testing continues to determine what caused this outcome, and a range of scenarios are possible. The team isn’t planning to attempt to move or further characterize the current state of the solar array deployment before Wednesday, Dec. 1, at the earliest."
"...Checkouts for the Lucy instruments were successfully completed Nov. 8, and all instruments are working normally..."

https://blogs.nasa.gov/lucy/2021/11/18/lucy...-checkout-a-ok/

https://twitter.com/NASASolarSystem/status/...393961629757450

[JTN]

NASA Zeroing in on Path Forward for Lucy Solar Array (8 Dec)

NASA now has data on all 10 gores confirming they are open, producing power as expected, and not stuck together.

[MahFL]

NASA Zeroing in on Path Forward for Lucy Solar Array (8 Dec)

Sounds good.

[Decepticon]

Update on Solar array.

https://spacenews.com/cause-of-lucy-solar-a...lem-identified/

[john_s]

We're planning the first step of the Lucy solar array re-deployment attempt on the week of May 9th- see this blog post for details. Fingers crossed!

John

[john_s]

Two Lucy items of interest:

1) The first step of the solar array redeployment test was completed last week: https://blogs.nasa.gov/lucy/2022/05/10/nasa...oyment-attempt/. Data analysis is under way.

2) We'll be making a movie of tonight's lunar eclipse! As far as I know, this will be the first movie of a lunar eclipse from deep space, though someone here might be able to correct me. See http://lucy.swri.edu/2022/05/12/LunarEclipse.html

John

[Explorer1]

And here it is! https://www.nasa.gov/feature/goddard/2022/n...a-lunar-eclipse

[StargazeInWonder]

What a beautiful result. It might be surprising to people who've spotted a lunar eclipse and could easily see the Moon during totality that the eclipsed Moon is much darker than the full Moon, by a factor of hundreds or more. So, in a video that does not adjust the brightness to compensate, the Moon will seem simply to go black.

[john_s]

Here's a repeating version, which I prefer to the version that was posted on NASA.



John

[JTN]

Tidbits on Lucy solar array deployment:

NASA’s Lucy Mission Continues Solar Array Deployment Process (Lucy blog, June 8): not latched yet, but four attempts (May 9, May 12, May 26, June 2) all show array continuing to open and stiffen. More attempts are possible.

Efforts continue to fully deploy Lucy solar array (spacenews,com, also June 8) has quotes from Hal Levison:

“That’s allowing us to make significant process towards latch, but we’re not latched yet,” Hal Levison, principal investigator for Lucy at the Southwest Research Institute, said in a presentation at a meeting of NASA’s Small Bodies Assessment Group June 8. “We are seeing significant tensioning of the array.”

That tensioning, he said, is a positive sign even though the array has not latched into place. “It makes it likely that, even if we don’t get the thing latched, we’ll be able to fly the mission as-is,” he said, noting the array, in its current configuration, is generating more than 90% of its planned power.

[Explorer1]

New moon of Polymele discovered (due to a recent occultation)!

Good summary here, including of the array issue:

https://spaceflightnow.com/2022/06/14/nasa-...asteroid-probe/

One of the Trojan asteroids on Lucy’s tour, named Polymele, has a companion. Scientists discovered an apparent satellite of Polymele during a ground-based occultation observation in March, when Polymele briefly passed in front of a star, temporarily blocking its light from reaching Earth.

The occultation observations were intended to help the Lucy science team determine the shape of Polymele, which only appears as a point of light in telescope images.

“We got a really nice projected shape of Polymele, and then we were very surprised to detect an object about 200 kilometers (120 miles) away from Polymele,” Levison said last week in a presentation to NASA’s Small Bodies Advisory Group. “It’s 5 kilometers (3 miles) in diameter, and it’s sitting almost exactly in Polymele’s equatorial plane.”

[Explorer1]

Good news for the array:

https://www.nasa.gov/feature/goddard/2022/n...llions-of-miles

The mission now estimates that Lucy’s solar array is between 353 degrees and 357 degrees open (out of 360 total degrees for a fully deployed array). While the array is not fully latched, it is under substantially more tension, making it stable enough for the spacecraft to operate as needed for mission operations.

[Steve G]

Has there been any estimates released on the orbital period of the newly discovered moon? Specifically, are they mutually tidally locked to the other?

[Toma B]

Does anybody know when do we get the first images from Earth's gravity assist?
This should be a great test of what those cameras can do.
Can Lucy take better image sequences than Galileo or Messenger spacecraft during this flyby?

[mcaplinger]

Does anybody know when do we get the first images from Earth's gravity assist?

Speculation as we have no operational role in this mission --

DSN Now shows 20 kbit/s down, most likely on the LGA/MGA due to spacecraft orientation. I doubt if we will see anything until after the flyby is complete and they can send the data back at a higher rate.

It took about 2 months before the 14 Feb 2022 star images were released ( https://www.nasa.gov/feature/goddard/2022/c...lucy-spacecraft ) but hopefully some flyby images will show up more quickly.

[john_s]

We'll be imaging the Earth and Moon a few times during the flyby, but no Galileo-style color movies- the science cameras are rather limited in what they can do at 1 AU, due to overexposure. We're hoping for some nice images of the Moon after Earth closest approach, however.

I'm hoping to see the spacecraft itself with binoculars on Sunday morning, from Western Nebraska where we've come to avoid clouds in Colorado. It should be much brighter from north-west Australia, just before closest approach, for anyone in that part of the world. See http://lucy.swri.edu/SpotTheSpacecraft-EGA1.html

John

[mcaplinger]

I doubt if we will see anything until after the flyby is complete and they can send the data back at a higher rate.

Lucy downlinking now at 353 kb/sec to DSS14.

[mcaplinger]

https://www.nasa.gov/image-feature/goddard/...-gravity-assist

I was sort of expecting science instrument images to be highlighted over T2CAM images, but I'm not complaining.

[john_s]

It's just a matter of what was ready when. Science camera images will follow shortly.

John

[Bill Harris]

snip

I'm hoping to see the spacecraft itself with binoculars on Sunday morning, from Western Nebraska where we've come to avoid clouds in Colorado. It should be much brighter from north-west Australia, just before closest approach, for anyone in that part of the world. See http://lucy.swri.edu/SpotTheSpacecraft-EGA1.html

John

Still, 6th-7th mag from North America shouldn't be that impossible with binocs. Seems that the "proper motion" of the spacecraft won't be all that large.
Even if you get clouded out, there are still 2 flybys to possibly try again.

--Bill

[john_s]

For the record, I didn't catch it in my binoculars, but we saw it live with an 11" telescope, which was quite thrilling. We followed it for about 30 minutes until we lost it in twilight- it got rapidly slower and dimmer during that time as it climbed away, in the general direction of the Moon.

John

[climber]

Here is the Moon : https://www.nasa.gov/image-feature/goddard/...-views-the-moon

[Hungry4info]

We're getting a bonus flyby! Lucy will visit the small main belt asteroid 1999 VD57 on 01 Nov 2023.
https://www.nasa.gov/feature/goddard/2023/n...asteroid-target

[Explorer1]

Combined with the new moons discovered fro the primary targets, I think they're trying to beat Cassini's record...

[john_s]

Here are the first Lucy images (movies, in fact) of four of our five primary Trojan asteroid targets:

NASA image release

John (Lucy deputy project scientist)

[Brian Swift]

Here are the first Lucy images (movies, in fact) of four of our five primary Trojan asteroid targets:

NASA image release

And a camera-shy asteroid scooting out of frame in the upper left of 4th video.

[john_s]

Here's our first view of Lucy's first asteroid target, Dinkinesh. Only 49 days till encounter!

John

[jasedm]

Thanks for the update John, I was checking in on Lucy's progress only yesterday.

Can anyone advise on the sort of visible resolution to be expected during closest approach? Will it be Mathilde/Steins/Arrakoth standard of resolution? (I guess with LORRI heritage it may be substantially better)

It will be exciting if the terminal tracking system pans out as expected.

Fingers crossed for a successful encounter for all those involved.

Another awesome mission!

[Explorer1]

Some details on resolution estimates here (PDF)

If all goes well, we expect to obtain 2 m/pixel panchromatic images, 15 m/pixel color images, 24 m/pixel near-IR spectra, and thermal measurements, on what will be the smallest main-belt asteroid yet encountered by a spacecraft.

[jasedm]

Thanks for the link Explorer, this sounds awesome - can't wait!

[john_s]

an anyone advise on the sort of visible resolution to be expected during closest approach? Will it be Mathilde/Steins/Arrakoth standard of resolution?

To answer directly, we expect somewhat fewer pixels than the best Arrokoth images (maybe 500 pixels across, instead of 900), but much better exposed images, due to being at 2.3 AU rather than at 43 AU! In fact we have some risk of overexposure of the lowest-phase images. The Lucy LORRI camera has very similar performance to the New Horizons LORRI camera.

John

[mcaplinger]

It will be exciting if the terminal tracking system pans out as expected.

It will be more exciting (but not in a good way) if it doesn't.

[Roby72]

With Lucys first encounter coming very soon, a question about the solar power on board the spacecraft. I not know the latest status on the unfold process - is it now fully deployed yet or still not ?
Any info is appreciated !
Thx !

[Explorer1]

They decided not to bother any more in January. Over 98% is more than sufficient and unlikely to cause any problems.

[vjkane]

A journal paper on the L'Ralph instrument capabilities and implementation is available

L’Ralph: A Visible/Infrared Spectral Imager for the Lucy Mission to the Trojans

The paper is open access.

[Marcin600]

Only two days left until the asteroid Dinkinesh encounter (November 1, 12:54 p.m. EDT)
https://lucy.swri.edu/
https://whereislucy.space/
https://science.nasa.gov/missions/lucy/nasa...asteroid-flyby/

Attached thumbnail(s)

 

[Hungry4info]

2 hours to go. Should a new thread be created for Dinkinesh?

[Marcin600]

Well, after a close-up. We have to wait another 2 hours until the antenna is turned towards Earth again and communication with Lucy is re-established. Then data transfer will start. When we receive them, we will know whether the asteroid tracking system worked properly and whether we have good images of Dinkinesh.
Two more links:
https://blogs.nasa.gov/lucy/
https://twitter.com/LucyMission

Attached thumbnail(s)

 

[mcaplinger]

Down signal on DSS14 at 232 kb/sec.

[kenny]

Nice animation of the gyrations of Lucy to keep the instruments pointed at asteroid Dinkinesh.

Dinkinesh encounter animation

[jasedm]

Nice animation of the gyrations of Lucy to keep the instruments pointed at asteroid Dinkinesh.

Dinkinesh encounter animation

Seems counter-intuitive to see the spacecraft pivot around the camera platform like that, but wow! Thanks for the link Kenny.

[Marcin600]

https://blogs.nasa.gov/lucy/?fbclid=IwAR08J...9NvWR23oF6tUvP4
quote: "The Lucy operations team has confirmed that the NASA’s Lucy spacecraft has phoned home after its encounter with the small main belt asteroid, Dinkinesh. Based on the information received, the team has determined that the spacecraft is in good health and the team has commanded the spacecraft to start downlinking the data collected during the encounter. It will take up to a week for all the data collected during the encounter to be downlinked to Earth. The team is looking forward to see how the spacecraft performed during this first in-flight test of a high-speed asteroid encounter."

[jasedm]

Can't wait to see the results - good luck to the team!"

[stevesliva]

Googling for information, whether there is a press conference scheduled, etc... found this article about sifting through WISE data to do a study:
https://www.nasa.gov/missions/lucy/data-fro...roid-dinkinesh/
... small enough to be detectable, but not detected, per se. Will be interesting to see if these images are novel or not. It's such a small object...

[john_s]

Closeup Dinkinesh images (with a surprise!)

John

[nprev]

Amazing! How cool is that? Gotta love serendipity; it's the "s" in science!

L'LORRI sure seems to perform quite well, and of course the entire integrated autonomous targeting process obviously did too. Nice win for the team.

[jasedm]

Fabulous! Wonderful stuff. Another unique little world(s)

The terminal tracking system seems to be more than capable of dealing with 'distractions'

[stevesliva]

Closeup Dinkinesh images (with a surprise!)

Nice!

Dinkinesh is about 1/2 the size of Dactyl so even taking moons into account, it is indeed setting records for Dinki...ness.

[kenny]

Fabulous and amazing result...!

And it does look like Dinkinesh might have an equatorial bulge like both Bennu and Ryugu ...
(assuming that the spin axis is vertical in the new photo.)

[Explorer1]

Lucy is having quite the ride multiplying asteroids! At this rate, I don't know what to expect at the trojans! Interesting how the satellite evaded prior observation, (presumably it would be visible via an occultation, but none happened, did they?)
Definitely a curious shape on the moon, seems like another giant boulder on its southern hemisphere (and an equatorial ridge, perhaps?)
And presumably we can get a mass measurement too....

[Bjorn Jonsson]

This is amazing. I wasn't expecting anything really unexpected from this flyby so this is a very nice surprise.

[stfletch]

What a cool surprise!

Is this the first time we've discovered a moon of an asteroid only during the flyby since Ida and Dactyl?

[Phil Stooke]

Yes, that's right. Lots of other binaries have been detected using earth-based radar and telescopes but this and Ida/Dactyl are the only two discovered in the flyby data.

Phil

[mcaplinger]

The terminal tracking system seems to be more than capable of dealing with 'distractions'

One of the primary Lucy targets (617 Patroclus) is a binary so this always had to be considered. But for this flyby distance and target size I doubt it mattered much.

https://ntrs.nasa.gov/api/citations/2022000...d%20Mission.pdf for more details.

[Phil Stooke]

"And presumably we can get a mass measurement too.... "

We might get a mass estimate if the moon's orbit can be determined reasonably well, but that could be very difficult given the rapid flyby. The spacecraft trajectory is not going to be altered by this small object so the moon's orbit is the only hope.

[ngunn]

I wonder if the two objects are tidally locked. Will we have enough data from the flyby to determine this?

[StargazeInWonder]

It seems like the close up imagery could be used in combination with subsequent ground observations to characterize the orbit. If a light curve can be derived, then that would nail down the orbital period. The Lucy imagery characterizes the semimajor axis. And both of those combined, would give us the mass.

[fredk]

And the release says that the team had noticed brightness changes in the preceeding weeks, so those certainly could pin down the orbital period.

[john_s]

More weirdness at Dinkinesh: NASA release

John

[Marcin600]

More weirdness at Dinkinesh: NASA release

John

How many more surprises await us? Something incredible!!!
Lucy rules!

[StargazeInWonder]

The mind reels. Did Dinkinesh have two slow-revolving mini-satellites that came together, or did an existing contact binary get captured? It seems like something even weirder must have happened. Baffling.

[Explorer1]

I was just joking in my post from last week about Lucy's multiplication abilities!
There was that hint of weirdness in the southern hemisphere. Turns out to have been a horizon, with the back end peaking out from behind.
Much like Arrokoth, it must have been a low velocity collision to merge the two moons into one.

[Marcin600]

Here you can find a slightly larger version of the recently published picture:
https://lucy.swri.edu/DinkineshEncounter.html
https://lucy.swri.edu/img/Dinkinesh_satelli...trajectory2.png

Some of my attempts to enlarge:
Credit to original picture: NASA/Goddard/SwRI/Johns Hopkins APL

Attached thumbnail(s)

 

[Marcin600]

(...) Much like Arrokoth, it must have been a low velocity collision to merge the two moons into one.

Let me just remind you of the theory of the formation of the equatorial ridge and small satellites presented in this article (I have already linked it regarding Ryugu): https://www.isas.jaxa.jp/home/research-port...eway/2022/1125/

The animation of the formation model posted there shows great potential for creating "contact binary mini-satellites":
https://youtu.be/Bj_TZYYSWKQ

[Hungry4info]

Dinkinesh's satellite has been named Selam.
https://www.wgsbn-iau.org/files/Bulletins/V...ll_V003_016.pdf