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DART & HERA, NASA/ESA Asteroid Redirection Missions
Marcin600
post Nov 5 2022, 08:34 PM
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Yes, LICIACube has quite limited technological capabilities - we have to remember that this mini-satellite is about the size of a microwave oven, but the opportunity to "squeeze" more scientific results out of it is exciting!

BTW, there is a new potential opportunity to hear about the new LICIACube results from the Dimorphos impact observation:
Festival delle Scienze 2022 = Science Festival 2022, November 21, 08:00 - November 27, 17:00
https://www.asi.it/event/festival-delle-scienze-2022/

Saturday, November 26 at 19:00, Guest Room: "LiciaCube" conference:
„...A few months after the detachment of the LICIACube nanosatellite from the DART probe, the meeting will present the contribution of the Italian scientific community to the NASA mission at the Festival. A successful mission that opens up new perspectives in asteroid monitoring and exploration policies in the context of planetary defense...”
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bobik
post Nov 14 2022, 06:58 AM
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An instructive paper on the two Hera Cubesats and their integration with the Hera spacecraft.
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bobik
post Nov 22 2022, 07:55 AM
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Reportedly, Hera has completed its system CDR (Critical Design Review) last week. Though I am not fond of ESA's way and venue to communicate such important project milestones, the reply section of this tweet is somewhat funny. rolleyes.gif
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Marcin600
post Dec 17 2022, 08:37 PM
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AGU22: Press Conference "Pioneering Planetary Defense: What Comes Next After DART’s Asteroid Impact?" Decmber 15, 2022
https://www.youtube.com/watch?v=FF-5B7_FMfY
https://dart.jhuapl.edu/News-and-Resources/...php?id=20221215
https://www.asi.it/2022/12/un-prestigioso-r...mento-per-dart/

Some quotes from the presentations given at the press conference:

Andy Rivkin (DART Investigation Team Lead, Johns Hopkins Applied Physics Laboratory)
"...An estimate of how much material was blasted off of Dimorphos by DART and we think it is about a million kilograms of material at the least. So this is enough to fill six or seven railway cars of gravel (...) This number is a minimum, it could be twice that, it could even be as much as 10 times that according to same estimates..."

Cristina Thomas (DART Observations Workin Group Lead, Northern Arizona University):
"...The two spectra [of Dimorphos and Didymos] looked very similar. Thay have a lot of these consistent features (...) which are consistent with it being an analog for something like an ordinary chondrite (...) So, we see that these two objects [Dimorphos and Didymos] are in fact similar in composition. You'll notice that there are some slight differences that are tied to a lot of other questions that we are going to be investigating in the coming months, but they do not actually impact the way that we think about it compositionally..."


Alessandro Rossi (LICIACube Science Team Member, Instituto di Fisica Applicata Nello Carrara):
"...[LICIACube] startet science operations 71 seconds before impact (...), [and was] 58 km from the system at closest approche...

...Enhanced color images: the left one was taken about 3 minutes after the impact, (...) we are looking at the south pole of Didymos and you see the ejecta cloud almost face on. A few seconds after LICIACube has moved and we see the plume from a different perspective and we clearly notice the cone shape of the ejecta coming out of the surface of Dimorphos and we also can notice a kind of dark arc over the surface of Dimorphos which we believe is related to the shadow of the plume itself on the surface of Dimorphos....

...We can enhance the level of saturation of the images and it is in this image you see the saturated part of the image in black, but in that way other features of the ejecta plume come to your vision, and here we clearly see some very interesting structure in the ejecta plume. You see linear filaments of material being ejected from the surface, but we also see clumps of materials possibly related to agglomerates of two particles in the process of being disrupted and also nodules that we attribute to the presence of larger boulder being ejected. Take a looking at images at different times we can be able to compute the velocities of these objects, which we count on the order of tens of meters per second in these cases...
"


Andy Cheng (DART Investigation Team Lead, Johns Hopkins Applied Physics Laboratory) - on the results of momentum transfer calculations

Credit: ASI/NASA


EDIT: I replaced the second picture with a better quality one - officially published on the NASA website (but with a wrong description, which concerns the first picture, not published there by NASA): https://www.nasa.gov/feature/imagery-of-ear...-s-dart-mission

The yellow circles indicate: "two clumps of materials possibly related to agglomerates of two particles in the process of being disrupted" and two possibly "larger boulders being ejected".
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Hungry4info
post Jan 27 2023, 11:06 PM
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Some surface features on Dimorphos have been assigned names, with the theme being drums from various cultures.
Drums because we hit the asteroid ... get it?
https://planetarynames.wr.usgs.gov/Page/DIMORPHOS/target


--------------------
-- Hungry4info (Sirius_Alpha)
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fredk
post Mar 3 2023, 12:19 AM
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Some results published in Nature. One number reported is that the momentum imparted to Dimorphos was around 4 times that of DART, due to the ejecta.

QUOTE (fredk @ Oct 20 2022, 11:35 PM) *
One other relevant energy scale in the system is the orbital kinetic energy of Dimorphos. With a (pre-impact) orbital velocity of around 0.17 m/s and the above mass, I get around 6*10^7 J. So DART had roughly 200 times the KE that Dimorphos did. So it's not surprizing that DART could change the orbit significantly, subject to all the same caveats about dependence on mechanical properties of the moon etc. as we discussed above.


Repeating this calculation for momentum, the ratio is flipped right around, due to the different dependences on velocity. I find the momentum of Dimorphos to be around 7*10^8 kg m/s. around 200 times DART's momentum of 3.6*10^6 kg m/s. Momemtum isn't subject to uncertain losses do to heating etc, just to what the ejecta carries, so this is a better measure than KE of what effect you'd expect DART to have on the moon's orbit. 1 in 200, or 4 in 200, sounds about right.
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Marcin600
post Mar 3 2023, 06:32 PM
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And here and here is a model showing the DART's alignment as it hits the surface of Dimorphos
"...the spacecraft body hit between two large boulders while its two solar panels impacted those boulders..."
Credits: NASA/Johns Hopkins APL
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Tom Tamlyn
post Apr 21 2023, 05:15 PM
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Nature has published a cover story about DART, with five open access papers.

https://www.nature.com/nature/volumes/616/issues/7957

QUOTE
Crash course
Although currently there is no known threat to Earth from asteroids, strategies to protect the planet from a collision are being explored. On 26 September 2022, NASA and the Johns Hopkins Applied Physics Laboratory successfully tested one such approach: the Double Asteroid Redirection Test (DART) spacecraft was deliberately crashed into Dimorphos, a moon orbiting the small asteroid Didymos, resulting in a change in the moon’s orbit. In this week’s issue, five papers explore the test and the effects of the collision. One paper reconstructs the impact; a second looks at the change to Dimorphos’s orbit caused by the impact. A third paper reports observations from the Hubble Space Telescope of the material ejected during the collision. A fourth paper uses modelling to characterize the transfer of momentum that resulted from the impact. And the final paper reports on citizen science observations before, during and after the collision.


H/t to Shannon Cofield @MarsRoverMapper, who tweeted the link.
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Phil Stooke
post Nov 15 2023, 04:14 AM
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I have made a set of LICIAcube images of Didymos (plus one from DART itself). All LICIAcube images are from ASI.

The sequence starts at bottom left and moves to the right, then up a row and to the right again.

Also an image pair showing common features between the DART and best LICIAcube images (latter showing the south polar area)

Phil

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... because the Solar System ain't gonna map itself.

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NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain)
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Marcin600
post Dec 9 2023, 03:45 PM
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QUOTE (Phil Stooke @ Nov 15 2023, 05:14 AM) *
I have made a set of LICIAcube images of Didymos (plus one from DART itself)...

I missed this post, but I have to comment on this...

Great job Phil, this is a fantastic and very informative "mini-atlas" of Didymos!!!
While waiting for HERA (and that's still at least 3 years), this is the most complete overall picture of this body. Thanks for that!

I don't know why NASA (and ASI) doesn't do and publish things like this - after all, it is part of the legacy of this mission...
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Phil Stooke
post Dec 10 2023, 07:36 AM
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Thanks! It's really the mission teams that should get on this, not the agencies. It would only take a willing grad student with access to the images.

Phil


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... because the Solar System ain't gonna map itself.

Also to be found posting similar content on https://mastodon.social/@PhilStooke
NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain)
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Phil Stooke
post Feb 12 2024, 09:40 PM
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Here is an experimental map of Didymos, made for my LPSC poster. The coordinates are from a preprint by Barnouin et al.:

https://www.researchsquare.com/article/rs-3399230/v1

Two names were recently added.

Phil

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... because the Solar System ain't gonna map itself.

Also to be found posting similar content on https://mastodon.social/@PhilStooke
NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain)
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bobik
post Feb 25 2024, 02:12 PM
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Interesting, the opto-mechanical design of the flight model of Hera's Planetary ALTimeter (PALT) (p. 13bl) instrument seems to be quite different to the widely-published design. huh.gif
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