The best image we now have of Ultima Thule (2014 MU69) still isn’t the best image New Horizons captured on its New Years Day flyby. Seven minutes before its closest approach, the spacecraft’s wide-angle Multicolor Visible Imaging Camera (MVIC) snapped this image
New Horizons was about 4,200 miles at the time the image was captured. Closest approach was 2,200 miles. The best is still yet to come.
Let’s take a closer look at the image.
We can see what appear to be small impact craters along the terminator, or day/night line. These possible impact craters have a much more round shape we typically see resulting from long ago meteorite impacts. But those huge depressions riddling the surface are still a mystery.
“This new image is starting to reveal differences in the geologic character of the two lobes of Ultima Thule, and is presenting us with new mysteries as well,” says New Horizons Principal Investigator Alan Stern.
The depression on the smaller lobe stands out the most. It measures about 4 miles across. New Horizons’ team isn’t sure if it was caused by an impact crater or something else. It could also be feature known as a ‘collapse pit,’ caused by volatile materials venting long ago. The bright ‘collar’ where the two lobes appear to be attached is another intriguing feature. What is it, and what caused it are questions scientists hope to answer as better images make the more than six-hour journey back to huge satellite dishes back on Earth.
You can watch the data come back over at the Deep Space Network website. To give you an idea of the patience required by the New Horizons team, you can see the data coming back from Hayabusa-2 right now. One of the satellite dishes at the Goldstone Deep Space Communications Complex in California is receiving data at a blistering rate of 4.10 kb/sec (the data rate does fluctuate but don’t expect Comcast speeds).
Yep, that’s kilobytes. And Hayabusa-2 is only 352.74 million kilometers away compared to 6.64 billion kilometers for New Horizons.
Getting the image you see back to Earth happened over a two-day stretch (Jan. 18 – 19).
We’ll have to wait a little longer for New Horizons to start answering all the questions we have about Ultima Thule. What’s it made of? How long have the two lobes been attached? Were they always in this configuration? I ask that third question because the larger lobe has a circular outline near the center that almost looks like it matches the size of the large depression on the smaller lobe.
New Horizons will keep reaching out to Earth over the next 20 months to reveal Ultima Thule to us.