Tulika Bose: What would happen if a giant asteroid started hurtling toward earth? Would we all be headed for impending doom like the dinosaurs some 66 million years ago?
NASA: 4-3-2-1. Oh my God. Wow. Awaiting individual confirmation… and we are making an impact! A triumph for humanity in the name of planetary defense!
Bose: Hailed as a smashing success (no pun intended), at least five studies in the scientific journal Nature have been involved in making clear exactly how our gut’s heavenly punch worked.
NASA: What a moment. Very few words could capture this moment. Beautiful to watch.
Bose: Hi Lee.
Charges: Hello Tulika.
Charges: Correctly. Ideally – and we’ll get into reality in a moment – this is as simple as playing pool: Throw one pool ball at the other and the target ball flies. The more momentum you can transfer, the more movement you have. So you want to hit close to dead center. And, in DART’s case, it aimed for the sunward “direction” of Dimorphos, which it hit at more than 14,000 mph.TThe hat is about three-quarters the speed of General Zod’s starship in Zach Snyder’s Man of Steel.
General Zod: Now. Kneel before Zod.
Bose: Uh, okay. So, now tell us about the two asteroids.
Leeward: Ah yes the two asteroids. Dimorph is a moon of the larger asteroid Gemini – sometimes I call Dimorph “Gemini” just for that, right. This helps measure the effects of DART – think of Dimorphos a bit like the second hand on a clock where Didymos is the hour hand or the clock itself – it’s easier to see small changes by watching how the smaller object moves.
Bose: Okay, it’s too long.
Charges: But for those of us steeped in modernity, I mean it’s about twice the size of a standard football field and weighed about 11 billion pounds.
Charges: While DART is just a 1260 pound spacecraft – about the size and weight of a dairy cow. The fact that the DART made a dent was actually due to its impact at high speed, which we already said was 14,000 miles per hour. And all of this was after a journey through deep space to the point of impact, more than 7 million miles from Earth.
Bose: So, is it like a dairy cow crashing into a great pyramid?
Cow: Moooo [splat.]
Charges: Basically. It’s getting messy.
Bose: Ha. So, let’s get back to science. We know that getting more details helps astronomers understand why this crash was so successful. What are some of the new details about this impact that have been found – and what surprised the scientists? What was NASA’s original goal here?
Leeward: This is a great question Tulika. And the answer was that the surprise was how well it worked. NASA’s official success criterion was to shift Dimorphos’ orbit by just 73 seconds. The original predictions – if it really was a pool ball, for example, all solid rock – the predictions were that maybe DART would push it for about 7 minutes. Instead, we got 33, 33 minutes!
Leeward: Yes! And tThe difference is that Dimorphos is not a billiard ball at all. It’s a loosely tied pile of junk. as the DART closing images showed. So when DART slammed into it, it threw up a huge plume, a long tail of debris, containing more than 2 million pounds of material, which knocked back, basically, Gemini. It’s a bit like a shotgun kick.
Bose: Wow. Well, that really helps me visualize it a little more. So DART was this $330 million spacecraft the size of a golf cart—and it disappeared completely from that asteroid in a matter of microseconds. Scientists seemed pretty confident that this was a success – but what else would we need to ensure that any more dangerous earth-bound asteroids don’t wipe us out?
Leeward: Good question, Tulika. What we really need is better situational awareness. How many of these items are out there? What are they made of? Where is?
Bose: And who is working on it now?
Many different people. The key is to get a catalog of different object sizes, their different trajectories, maybe even what they’re made of, and figure out which ones are the most threatening. So in terms of some short-term projects, we have Hera, it’s the first dimension. This is a project of the European Space Agency. Named after the Greek goddess who married Zeus, I believe, the queen of the gods.
Bose: The Queen!
Charges: The Queen, the Queen. Now, Hera was originally supposed to arrive around the same time as DART at Gemini. Instead, due to delays, it won’t be released until late next year, it’s due to arrive sometime in 2026. But that will still tell us a lot about the aftermath of this era. Now, there are other things to mention. One project I’m excited about is NASA’s NEO surveyor, the Near Earth Objects Surveyor space telescope. That’s an infrared space telescope that’s slated to launch maybe sometime in 2028. And it’s going to be a very big step toward building that catalog of objects and getting a better sense of what’s really out there and what the threats are. And on the ground there is something similar to the Vera C. Rubin Observatory. One thing that is very important about this mission is that we will be doing the same kind of work from the ground. It will take these full, panoramic, high-resolution images of the sky several times a night, each night making almost a high-definition movie of the skies above. And it will be able to see small points of light moving around, some of which could be asteroids that threaten Earth.
Bose: Oh, and then she was named after Vera Rubin, right.
Invoicing. Actually. I believe one of the discoverers of dark matter, right?
Bose: Yes Yes. We also know that researchers with the help of amateur astronomers continue to examine the DART data to learn more about the physics, geology and chemistry of these two asteroids. Lee, what are you most looking forward to learning in the near future?
Charges: Well, honestly, I kind of found Gemini and Dimorph a bit done and dusted. We’ve already hit the space rock, we’ve seen what’s happened. I am interested in obtaining this catalog. I’m interested in learning more about the properties of a wide variety of asteroids, because it might not be a pile of rubble that comes our way every time. What if it’s a big ball of metal? What if it’s made of ice? I do not know.
Bose: This is true.
Charges: So clearly, the answer is just to bang more cows into pyramids, send more of these kinds of missions, and get a sense of what happens when we bang things real hard in the solar system. That said, I have to say, I don’t think this will be enough to save us. There are many situations where something could hit us really hard and fast and the DART certainly wouldn’t save us.
Bose: I will definitely be quiet.
Charges: I hope you do.
Bose: Thanks for listening to Science, Quickly. I am Tulika Bose
Invoicing — and I’m Lee Billings.
Bose: Science Fast is produced by myself, Tulika Bose, Jeffrey DelViscio, and Kelso Harper. Don’t forget to subscribe to Scientific American wherever you get your podcasts.
Charges: And head to Scientific American.com for more in-depth science news and analysis.
Charges: And head to Scientific American.com for more science news and in-depth analysis.