When NASA’s Lucy mission flew past asteroid Dinkinesh on November 1, 2023, it made the surprising discovery the asteroid had a tiny moon. Then came another surprise. This wasn’t just any moon, but a contact binary moon, where two space rocks are gently resting against each other. Of course, this new and unique moon needed a name, so the International Astronomical Union (IAU) has just approved approved “Selam,” which means peace in Ethiopia’s language.
But, everything’s connected here. Dinkinesh is the Ethiopian name for the Lucy fossil, and Selam is named after another fossil from the same species of human ancestor.
Ever want to play a game of cosmic billiards? That’s commonly how the DART mission was described when it successfully changed the orbit of a near-Earth asteroid last year. If you want an idea of how it works, just Google it and an Easter egg from the search giant will give you a general idea. But DART was more like trying to brute force a billiards break – there are many other things you can do with a set of asteroids and impactors on the galactic stage. One of the more interesting is to try to force two asteroids together to form a “contact binary” – the goal of a mission design put forward by a group of scientists from Cornell in a recent paper in Acta Astronautica.
While preparing for the threat of an asteroid strike might seem like a hypothetical exercise, it’s really not. The Solar System has calmed down a lot from earlier times when impacts were more frequent. But it is only a matter of time before an asteroid heads straight for Earth. The probability of an impact is not zero.
Equally as difficult as determining when one will come for us is the task of getting humanity to cooperate and prepare for it.
I cannot for the life of me remember when it was or what it was but a fair few years ago I remember positioning a telescope to observe an asteroid as it silently and perhaps slightly eerily drifted between us and the Moon. I say eerily as this asteroid had the ability to cause widespread damage had it hit but of course we knew it posed no threat. I remember at the time thinking it was mind blowing that even today, we still use mathematics with roots (pardon the pun) centuries old to calculate the position of objects in our Solar System. We get to see evidence of this again on 12th December when something rare happens!
By discovering two interstellar objects (ISOs), we know that asteroids and comets from other star systems pass through the Solar System from time to time. By inference, some of these must have crashed into the Moon, creating impact craters. If we could study the impact sites, we might be able to learn about the star systems that they came from.
A new paper suggests there could be a way to determine which lunar craters came from interstellar object impacts. The authors say that young, small craters with high-melt volume near the Moon’s equator are likely the best candidates for ISO-generated craters on the lunar surface.
Lucy’s images of asteroid Dinkinesh are the gift that keeps on giving. First, it was the discovery of a smaller companion. Now, it turns out that the companion itself is a contact binary. That’s two smaller objects touching each other as they orbit with Dinkinesh. So, how did they get that way?
Landing safely on an asteroid is no mean feat. Despite several recent successes, there have also been notable failures – most famously, the Philae lander to 67P/Churyumov-Gerasimenko. Admittedly, that was an attempt to land on a comet rather than an asteroid, but those two bodies share many of the same landing hazards. One of the most prevalent of those is “inhomogenous” gravity. To tackle this problem, researchers from the Harbin Institute of Technology in China recently released a paper detailing a framework for performing “soft landings” on asteroids, which might help make exploring these rocky worlds much more accessible.
In about one year from now, the European Space Agency will launch its Hera mission. Its destination is the asteroid Didymos, and it’ll be the second human spacecraft to visit the 390-meter chunk of rock. NASA’s DART mission crashed a kinetic impactor into Didymos’ tiny moonlet Dimorphos as a test of planetary defence.
Hera will perform a follow-up investigation of the binary asteroid to measure the size and morphology of the impact crater on Dimorphos. To help it along, it’s taking two tiny CubeSats that will land on Dimorphos.
When a giant meteor crashed into Earth 66 million years ago, the impact pulverized cubic kilometers of rock and blasted the dust and debris into the Earth’s atmosphere. It was previously believed that sulfur from the impact and soot from the global fires that followed drove a global “impact winter” that killed off 75% of species on Earth, including the dinosaurs.
A new geology paper says that the die-off was additionally fueled by ultrafine dust created by the impact which filled the atmosphere and blocked sunlight for as long as 15 years. Plants were unable to photosynthesize and global temperatures were lowered by 15 degrees C (59 F).
In July of this year, an asteroid roughly 30 to 60 meters across passed Earth to within one-quarter of the distance to the Moon. It posed no threat to our world, but if it had struck Earth it would have created a blast three times greater than the 2013 Chelyabinsk impact. And we only noticed it two days after it passed. It’s a good example of how sizable asteroids still miss detection. Not ones large enough to threaten our extinction, but large enough to threaten millions of lives. If a similar asteroid was detected just days before impact, could we stop it? That’s the question raised by a recent study in the arXiv.