NASA has confirmed that its New Horizons space probe has successfully flew by the Kuiper Belt object cataloged as 2014 MU69 and nicknamed Ultima Thule. After completing its second mission, New Horizons turned to Earth, communicated a series of telemetric data that allowed to confirm that it’s in good health and started sending the data it collected.
The first photos sent by the New Horizons space probe were actually taken when it was still approaching Ultima Thule, which took it only 3,500 kilometers (about 2,200 miles) from this object. Each new photo brought improvements in quality and therefore in the reproduction of its shape, which remained mysterious until the very end. Estimates of the size at approximately 32-35 for 15-16 kilometers (20-21 by 9-10 miles) are substantially confirmed, but there are still uncertainties about everything else.
The image (NASA/JHUAPL/SwRI, sketch courtesy James Tuttle Keane) on the left side of a composition of two photos taken by the Long-Range Reconnaissance Imager (LORRI) still left a doubt as Ultima Thule could still be composed of two asteroids very close if not in contact or be a single object with two lobes as the nucleus of the comet 67P/Churyumov-Gerasimenko. Objects with two lobes are not rare because they can be the result of the union of two smaller bodies that collided at low speed or the result of erosion and sublimation phenomena of frozen volatile compounds. On the right side there’s an artist’s concept of Ultima Thule as a 2-lobed object with the axis of rotation indicated by the arrows.
A more precise estimate of the rotation axis obtain thanks to the latest photos suggests that it points more or less to the New Horizons space probe’s approach direction and this would explain why it didn’t show any significant changes in brightness over the last few days. Again, there are some uncertainties that should be eliminated with the arrival of the photos taken at shorter distances.
For some days, more and more interesting data will arrive but then there will be an interruption of the transmissions for about 10 days due to the fact that the New Horizons space probe will be too close to the Sun from the Earth’s point of view to have reliable communications. It will be only a brief blackout after the long preparation period of the Ultima Thule flyby, its second flyby after Pluto’s. At this point, if the instruments worked correctly, a lot of high quality data will arrive about the farthest object reached so far by a space probe.
