Tag: DonaldJohanson

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The science team for the asteroid probe Lucy have now released their names for the features they discovered on the main belt asteroid Donaldjohanson when the spacecraft flew past in April 2025.

The smaller lobe is called Afar Lobus, after the Ethiopian region where Lucy and other hominin fossils were found. The larger lobe is named Olduvai Lobus, after the Tanzanian river gorge that has also yielded many important hominin discoveries.

The asteroid’s neck, Windover Collum, which joins those two lobes, is named after the Windover Archeological Site near Cape Canaveral Space Force Station in Florida — where NASA’s Lucy mission launched in 2021. Human remains and artifacts recovered from that site revolutionized our understanding of the people who lived in Florida around 7,300 years ago.

Two smooth areas on the asteroid’s neck are named Hadar Regio, marking the specific site of Johanson’s discovery of the Lucy fossil, and Minatogawa Regio, after the location where the oldest known hominins in Japan were found. Select boulders and craters on Donaldjohanson are named after notable fossils ranging from pre-Homo sapiens hominins to ancient modern humans.

These names were “approved” by the International Astronautical Union (IAU), which claims the authority over the naming of every rock, boulder, pebble in space. The truth is, however, that future spacefarers are going to accept these names no matter what the IAU had said, simply because these scientists did the first exploration of this asteroid. They get to choose, not the IAU.

The spacecraft is now on its long coast out of the main belt and on to the orbit of Jupiter, where it will make fly-bys of ten different asteroids.

Lucy’s route to the asteroids, with its first picture
of Donaldjohanson in lower right, taken in February.
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The science team operating the probe Lucy are now preparing for the spacecraft’s second asteroid fly-by, set of April 20, 2025, and passing within 600 miles of the surface of asteroid Donaldjohanson.

Lucy’s closest approach to Donaldjohanson will occur at 1:51pm EDT on April 20, at a distance of 596 miles (960 km). About 30 minutes before closest approach, Lucy will orient itself to track the asteroid, during which its high-gain antenna will turn away from Earth, suspending communication. Guided by its terminal tracking system, Lucy will autonomously rotate to keep Donaldjohanson in view. As it does this, Lucy will carry out a more complicated observing sequence than was used at Dinkinesh [the first asteroid that Lucy saw up close in 2023]. All three science instruments – the high-resolution greyscale imager called L’LORRI, the color imager and infrared spectrometer called L’Ralph, and the far infrared spectrometer called L’TES – will carry out observation sequences very similar to the ones that will occur at the Trojan asteroids.

However, unlike with Dinkinesh, Lucy will stop tracking Donaldjohanson 40 seconds before the closest approach to protect its sensitive instruments from intense sunlight.

“If you were sitting on the asteroid watching the Lucy spacecraft approaching, you would have to shield your eyes staring at the Sun while waiting for Lucy to emerge from the glare. After Lucy passes the asteroid, the positions will be reversed, so we have to shield the instruments in the same way,” said encounter phase lead Michael Vincent of Southwest Research Institute (SwRI) in Boulder, Colorado. “These instruments are designed to photograph objects illuminated by sunlight 25 times dimmer than at Earth, so looking toward the Sun could damage our cameras.”

Unlike most of the Trojan asteroids Lucy will study, Donaldjohanson is a main belt asteroid. It is thought to be only 150 million years old, but its history would be expected to be very different than those Trojan asteroids.