Emily Lakdawalla Profile picture
Sep 26, 2022 42 tweets 20 min read Read on X
Thar they are! Right now Dimorphos and Didymos are both this bright dot of light. They’ll separate into two dots in a little while. #DARTMission

I’ll add photos on to this thread periodically as approach continues.
At the moment, this is the only source for the approach images. If they have not appeared on a website by the time of the post-impact press briefing scheduled for (I think) 5pm Pacific time, I will ask! #DARTmission
So one hour prior to impact, or roughly 35 minutes after this tweet, the #DARTmission photos should start separating the two components of the Dimorphos system.
Meanwhile, Didymos and Dimorphos are still just one bright dot to the #DARTMission DRACO camera.
Under 75 minutes to impact. Still a dot. #DARTMission
Under 70 minutes.
It’s a very narrow angle camera — a long lens — so constant teeny pointing adjustments are being made autonomously by the spacecraft to pointing to keep the asteroid system in the center of the field of view. #DARTmission
Under 65 minutes. Should be separable soon. I’m looking at them under bright sunlight on my iPhone so I can’t really tell, sadly! I’ll be in better viewing conditions closer to impact time. #DARTmission
Under an hour. I’m noticing that the live image feed is behind the impact time by a few minutes. That could be for a variety of reasons, but regardless, I’ll stick with the timeline as reported on the DRACO image feed.
Under 55 minutes
Under 50 minutes
Under 45 minutes to #DARTMission impact
Under 40 minutes to impact, at least on the DRACO image feed.
Under 35 minutes now!
Of course both asteroid and spacecraft are in motion. Spacecraft is steering both with course corrections and with pointing changes (rotation of spacecraft to get target in camera crosshairs)
Under 30 minutes to #DARTMission impact.
Under 25 minutes. I can even see Dimorphos from my phone screen now, a much fainter dot up and to the right of Didymos.
23, 22, 21, 20 minutes to #DARTmission impact (don’t know if I’ll be able to keep this up but I’ll do my best)
19, 18, 17, 16
Lost lock briefly but now under 12 minutes
Under 9 and now clearly targeting moon Dimorphos
Under 7
5
ccoooooollll stuff visible now
cant keep up with tweeting ack
rrrrubbbble pile!!!
Ok I’m now firing up computer to listen to commentated broadcast
Gonna see if I can make a shared album of these screen grabs for people to play with
In the meantime, here are some tweets of highlights:
And here’s the final frame I grabbed off of the #DARTMission DRACO camera live stream before the DART spacecraft ate it in a 6.1 km/s impact. Now waiting for the #LICIAcube images, which will come in much more slowly.
My first and barely-thought-out response is, gosh that looks like Itokawa and Ryugu and Bennu! Gravel pile asteroids in the few hundreds of meters in size are all pretty similar in surface texture.
Gravel-pile NEAR-EARTH asteroids, I should say. These things share a history that includes a perhaps violent event that sent them out of the main belt and onto Earth-crossing or Earth-near paths. They may not look like 100s-of-m bodies still in the main belt.
On the accuracy of #DARTmission's targeting of Dimorphos:
A common phrase around space engineers: "Better is the enemy of good enough." 17 meters off target is just as good 0 meters off target for a 170-meter body; no need for better targeting than that. Stay the course, steady as she goes.
Cheers and well done to the #DARTMission team! I’ll end this particular thread here, but please follow me for more images and commentary, and please consider supporting me at Patreon.com/elakdawalla if you enjoyed my live coverage today.

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More from @elakdawalla

Oct 5, 2022
Nice coffee break at #DPS2022, caught up with a bunch of people and now I'm off to Pluto, where Leslie Young is talking about a recently observed occultation with her habitual dry-as-desert wit.
Leslie Young: "One site only got data on egress; they were supposed to be part of the picket fence [a closely spaced line of telescopes] but their RV was infested by ants." #AstronomerProblems #AustraliaProblems #DPS2022
No scientific results to report yet, but Young shows they got absolutely gorgeous data during the 1 Jun 2022 occultation of Pluto by a magnitude 13 star, multiple chords with two showing a spectacular, strong central flash. Despite the ants. #DPS2022
Read 4 tweets
Oct 5, 2022
Gooooooood morning London! Today at #DPS2022 I'll be checking out Uranus and Saturn's rings, changes at Pluto since the New Horizons flyby, interstellar traveling rocks, outer planet irregular satellites, and keeping an ear out for early JWST results.
I barely made it to the rings session in time to see Matt Hedman show off some new results on a big brightening of a dusty ring at Uranus, revealed in part by some terrific reprocessing of Voyager data by an amateur, @IanARegan. Nice work, Ian!
It's a little too early in the morning for me to comprehend Bill Hubbard's talk, but the idea that the rate that Titan is receding from Saturn, the precession of Saturn's spin axis, and the cyclical change in tilt of Neptune's spin axis are all linked is...wow. #DPS2022
Read 9 tweets
Oct 2, 2022
It’s always very sad to lose a spacecraft, but MOM was essentially a technology demonstration for India, its first ever deep space mission, designed and built on a shoestring budget. To have lasted nearly nine years is an achievement to be very proud of.
India oversold scientific capabilities & achievements of MOM, and undersold and underused its ability to photograph the full globe of Mars in stunning color and detail, which I’ll always be sad about. But getting to Mars and surviving for so long on the 1st try is amazing.
I hope this isn’t India’s only trip to Mars. I hope to see future collaborations that will make the most of India’s experience and capability in affordable, reliable access to space combined with real collaboration with the international scientific community.
Read 8 tweets
Sep 27, 2022
Here's the replay of the DRACO camera view of the #DARTMission impact onto Dimorphos, the moon of Didymos earlier today. Now time for me to play with some images...
Read 16 tweets
Sep 27, 2022
OK y'all #DARTmission post-impact press briefing is live now here:
nasa.gov/nasalive
"Once we got a look at Dimorphos, we were very confident we were going to hit." (If Dimorphos had been a contact binary like comet Churyumov-Gerasimenko or New Horizons' target Arrokoth, a nearly direct hit on its centroid could've turned into a miss. Fortunately, it was round.)
I tried to call in to the press briefing to ask a question about image release plans, but, technical difficulties. There was one question on the briefing about LICIAcube plans... 1/n
Read 11 tweets
Sep 26, 2022
Less than seven hours til #DARTsmash! Live countdown and links to official streams are on the mission website here: dart.jhuapl.edu
And I’ve got you covered with links to background information on the mission to answer all your questions about #DARTMission #DARTsmash on my Patreon: patreon.com/posts/72349462…
Just six hours to #DARTMission #DARTsmash now. The live feed from DART's DRACO camera will pick up at 2:30pm California time, a little more than 4 hours from now. eeeeeeeeeeeeeeee
Read 5 tweets

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