DART & HERA, NASA/ESA Asteroid Redirection Missions Options

[Daniele_bianchin...]

So we wouldn't have more pictures of Didymos? :- /
I tried to compare Didymos ad DimorphoS with other recently visited asteroids:

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[jasedm]

That's a brilliant montage Daniele!, thanks for your time composing it

It's easy to forget that the reconnaissance of the asteroids in our solar system is fairly well-advanced these days. Psyche and Lucy will really add to our knowledge in the next decade.

I feel really lucky to be along for the ride in this era of discovery. On the year I was born (1967), we had some pretty decent images of the moon, and that was about it.

[Marcin600]

Media briefing at 2 p.m. EDT, Tuesday, Oct. 11 - https://www.nasa.gov/press-release/nasa-to-...ry-defense-test

As Italian Space Agency (ASI) President Giorgio Saccoccia will be among the participants of the briefing, I really hope to see some new pictures from LICIACube (and other pictures) ...

And maybe some new results from telescopic observations (?)

EDIT:
Tuesday, Oct. 11 at 20:00 Italian time - https://www.asi.it/2022/10/alla-conferenza-...arlare-della-m/
The conference will be broadcast live on the ASI TV website at: https://www.asitv.it/media/live

[john_s]

I missed the briefing, but I see remarkable images like this one posted at https://www.nasa.gov/feature/nasa-dart-imag...arget-asteroid:



Is the bright limb on Didymos due to dust kicked up from the impact of ejecta from Dimorphos? Was this addressed in the briefing?

John

[Tom Tamlyn]

I'll let you know when I've watched the whole briefing; I only caught the last third or so, and it wasn't mentioned during that portion.

The briefing video is here: https://www.youtube.com/watch?v=Zhzn0U2m5wQ&t=2352s

[mcaplinger]

Is the bright limb on Didymos due to dust kicked up from the impact of ejecta from Dimorphos? Was this addressed in the briefing?

I didn't see the briefing, but this seems very unlikely. The exposure time of the images seems all over the place, I'm still not sure what the strategy being employed was.

[Hungry4info]

Is the bright limb on Didymos due to dust kicked up from the impact of ejecta from Dimorphos? Was this addressed in the briefing?

My interpretation of that image is that we're seeing their night hemispheres, and that the bright part of Didymos' limb is the very tiny "crescent" of the asteroid that's in direct sunlight. The illumination of half of Didymos is coming from light reflecting off Dimorphos and scattering off the impact plume. The most convincing bit of evidence for this is the apparent shadowing of the impact plume by Dimorphos apparently centered around Dimorphos rather than angled off to the side.

[Explorer1]

Great new images; we can see a bit of the other side of Didymos too! Some enormous boulders on that side too (unless it's the same ones from a different angle)

[john_s]

My interpretation of that image is that we're seeing their night hemispheres, and that the bright part of Didymos' limb is the very tiny "crescent" of the asteroid that's in direct sunlight. The illumination of half of Didymos is coming from light reflecting off Dimorphos and scattering off the impact plume. The most convincing bit of evidence for this is the apparent shadowing of the impact plume by Dimorphos apparently centered around Dimorphos rather than angled off to the side.

Hmmm.. not sure I buy that explanation. Dimorphos is displaced a long way "below" the line perpendicular to the apparent terminator on Didymos- if it was the source of the illumination, the terminator ought to be roughly perpendicular to the direction to Dimorphos. The bright "crescent" also looks rather too diffuse to be be sunlit portion, which should be vastly brighter than the Didymos+plume lit part. I agree the "hole" in the ejecta is peculiar, but it's not clear that it's easily explained as Dimorphos' shadow on the ejecta either, as the shadow should be the same size as Dimorphos.

I don't think dust kicked up on Didymos is an unlikely possibility- some of the ejecta is certainly going to hit Didymos at fairly high speed, and in zero g it could plausibly generate a lot of secondary dust.

We'll know more soon...

John

[Marcin600]

So:

1. DART slowed down Dimorphos by over half an hour - 32 minutes (although it was assumed that 10 minutes would be a success) and the tiny moon now orbits several dozen meters closer to Didymos

2. Dimorphos survived - it is still in one piece (against some fears) and ready for HERA's arrival :

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[mcaplinger]

I don't think dust kicked up on Didymos is an unlikely possibility- some of the ejecta is certainly going to hit Didymos at fairly high speed, and in zero g it could plausibly generate a lot of secondary dust.

We'll know more soon...

I don't think some dust being kicked up is unlikely, I guess, what I find less likely is that the bright areas are anything more than the bright low-phase edge of Didymos. At least based on the movie at the top of https://www.nasa.gov/feature/nasa-dart-imag...target-asteroid

But I agree the outbound images look stranger than the inbound, so maybe you're right.

Not sure when we can expect to see the full LICIACube dataset.

[Marcin600]

Not sure when we can expect to see the full LICIACube dataset.

"...LICIACube took a total of 627 images, 326 of which reached Earth. Once all the pictures have been received, they will become the subject of scientific research that will provide us with more information about the cloud resulting from the impact, and in particular characterize its structure and evolution..." - https://www.asi.it/2022/10/nasa-presenta-gl...-missione-dart/

[Hungry4info]

The twitter user landru79 created a couple of animations from the available imagery here and here which show in splendid detail the 3D geometry of the system just after the time of impact. Truly glorious work, and enough to show that my interpretation of the images was quite wrong.

[john_s]

Those animations are very instructive- thanks for the link! It really looks like the "anomalous" brightness of the Dimorphos-facing side of Didymos extends above the surface, consistent with it being due to kicked-up dust. Fascinating...

John

[Tom Tamlyn]

Is the bright limb on Didymos due to dust kicked up from the impact of ejecta from Dimorphos? Was this addressed in the briefing?
John

Not addressed in the briefing. The LICIACube images were acknowledged and admired, but not analyzed.