Lucy's Flyby of Asteroid "Dinky" Already Showing Surprises

Asteroid mission Lucy successfully flew by asteroid Dinkinesh yesterday, as detailed Tuesday, and I posted a late edit to Tuesday's post last night quoting the NASA blog for Lucy. 

The word from NASA's Lucy mission blog is that "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."  They estimate it will take "up to a week" to download all the data.

The data on the small asteroid, now becoming affectionately known as Dinky,  has started pouring down and showing up on various news sources.  Here you can still be among the first in the world to see the first image of Dinky.   

Image credit: NASA/Goddard/SwRI/Johns Hopkins APL/NOAO

That also means you're among the first in the world to see that Dinky is part of a binary system.  

Yes, binary system means the smaller body, looking for all the world like a small fish with its mouth open in the small image above, is an entirely separate little body as this smaller, lower-res, animated .gif shows. 

Wednesday's flyby was an important test for the mission, verifying Lucy's terminal tracking system designed to allow the probe to autonomously track an asteroid during a high-speed flyby. (Lucy zoomed past Dinkinesh at a relative speed of about 10,000 mph on Wednesday.) 

"This is an awesome series of images. They indicate that the terminal tracking system worked as intended, even when the universe presented us with a more difficult target than we expected," Tom Kennedy, a mission guidance and navigation engineer at Lockheed Martin in Littleton, Colorado, said in the same statement. "It's one thing to simulate, test and practice. It's another thing entirely to see it actually happen."

Though the encounter was primarily a test, Lucy did gather some interesting data about Dinkinesh. For example, the probe helped nail down the size of the two asteroids. The larger rock is likely about 0.5 miles (790 meters) across at its widest point, for example, while the smaller one is about 0.15 miles (220 m) wide, NASA officials said.

Consider those sizes to be preliminary estimates, likely to change as the data processing continues. Remember, they said they'd be downlinking data from Lucy for about a week. I honestly didn't expect any images yet. Expect more data to be coming for perhaps a couple of weeks; one to download and one to process a bit better.  

In the mean time, Lucy continues on a looping trajectory that now has the satellite heading back toward Earth for another gravity assist and loop back out toward the asteroid belt.  The next target is a main belt space rock named 52246 Donaldjohanson . (Donald Johanson is the co-discoverer of the famous human-ancestor fossil Lucy, after which the NASA mission is named.)  Tuesday's flyby was just over two years after Lucy's launch. The next flyby is expected in 2025, two years from now, after which Lucy will fly on to Jupiter's Trojan asteroids. That's expected in another two years, 2027.