NASA’s Lucy spacecraft has discovered some new information about asteroid Donaldjohanson. This asteroid is a peanut-shaped space rock, and it may help scientists understand the early solar system better. They are also researching the role that water played in its foundation. When water is found in anything in space we stand up and take notice because for us humans, water is the foundation of all life. Meaning – there could be evidence of other lifeforms out there. Which is always the hope when a discovery like this comes up.
During a close flyby in April 2025, Lucy discovered that the asteroid is made of two lobes. These lobes likely merged after a collision which was estimated to have happened about 155 million years ago. It was also found that the asteroid tumbles through space. Rather than spinning smoothly, this wobbling motion may have been slowly altered over millions of years by something called the YORP effect. In layman’s terms that means the subtle force of sunlight was able to change the way it moved.
Evidence of Liquid Water
The most exciting discovery however was the evidence that Donaldjohanson’s original body once contained liquid water. Lucy detected iron-rich clay minerals on the asteroid’s surface. Iron-rich clay can only form when rock intermingles with water. And we can tell how long it did so by studying the elements in the clay. For example because the clay is iron rich we know that it only briefly interacted with water. If it had a standing body of water on it there would be evidence of other elements such as magnesium.
One thing they’re still trying to figure out is why the water left so quickly. It could have been evaporated by heat. They think that one possibility is the asteroid formed later, when there was less radioactive heat available to melt ice into liquid water. Another is that it formed with less water to begin with. Researchers also think the asteroid may have originally formed farther from the Sun. Eventually it would move to the inner asteroid belt, preserving a record of a very different environment.
Lucy continues its journey toward Jupiter’s Trojan asteroids. All the while making discoveries like this asteroid. Scientists are piecing together how water, rocky worlds, and the building blocks of planets formed billions of years ago.
