NASA Goes Nuclear // 4% Chance of Hitting The Moon // Big Dark Energy Results

The Dark Energy Survey results are in. An asteroid strike on the Moon would be a boon to science. Mercury might not be totally dead, and NASA continues to test its nuclear rockets. All this and more in this week's Space Bytes. Do you remember Asteroid 2024 YR4? Maybe you don't, and that's because the asteroid slot in your brain was replaced with Comet 3i Atlas. This was this huge asteroid, that had a non-zero chance of hitting the Earth in 2032, and yet now it's been forgotten. Well, while the chances of that asteroid hitting Earth have been dropped to essentially zero, there's still about a 4% chance that it's going to strike the Moon in 2032. That's cool. And in fact, if it does happen, it will be a tremendous boon to science. And astronomers have written a paper where they calculate what we might see when this asteroid crashes into the Moon. It will hit the Moon with the impact like a medium-sized thermonuclear weapon. It'll be about six orders of magnitude more than an impact that we saw in 2013. It'll vaporize rock, turning it into plasma. It will be easily visible from the Pacific, which will have nighttime at that time, watching the Moon. It'll make a crater one kilometer wide and 150 to 260 meters deep with a 100 meter pool of molten rock at the center. And then this melt pool will be visible in infrared telescopes for a while as it slowly cools down. It'll make a moonquake of magnitude 5 on the surface of the Moon. And then it'll hurl material off of the surface of the Moon through space. And some of that will actually enter the Earth's atmosphere. And it's estimated that about 400 kilograms will actually survive entry through the Earth's atmosphere and land softly enough that then scientists can get their hands on it and study. It's a free lunar sample return mission. So while I'm really glad that 2024 YR4 wasn't going to hit the Earth, I really wanted to hit the Moon. Got a story about this from Andy Thomas. Chemical rockets are kind of incredible, like that you can just light things on fire. You can mix chemicals together. It produces exhaust gases. You can use this to go to space and you can use this to go to other planets like Mars. The problem is the exhaust velocity of the chemical rockets, the speed that the gases are coming out the back of the rocket. They're fast, but they're not fast enough. And so you want to have a rocket capable of firing these exhaust gases out much, much faster. That gives you more thrust and an idea that NASA has been working on literally forever. Well, OK, since the 1960s is nuclear rockets. So instead of, say, liquid hydrogen and oxygen that you combust, you have a fission reactor that is very, very hot. And then you use that to blast out, say, hydrogen gas out the back of the rocket at much higher exhaust velocity. It could cut your trip times from Earth to Mars by months. Maybe you could do it in three months, four months instead of, say, nine months. So there are a lot of good reasons why NASA has been testing these nuclear rockets. There are downsides, of course, when you are testing nuclear reactors. And so a lot of the testing came to a halt. And it's only recently that NASA has been starting to consider how they're going to incorporate space based nuclear engines into their flight capability. And then last year, the White House, when it made its budget request, decided to cancel all of the effort into these nuclear rockets. Well, now Congress has overturned that. And so nuclear rockets are back on. And so NASA has recently tested a type of chamber that would be used for one of these nuclear rockets. Now, they're not actually testing a fission reactor. They're testing this chamber that would simulate how the liquid hydrogen would move through the reactor. They're looking for vibrations, looking for oscillations, things that would tear this chamber apart. And then later on, you would get a real fission reactor that is pulling the fuel through and sending that out the back of the rocket. And so according to their tests, the drum was able to handle it. So another step towards some future of nuclear rockets. And, you know, there is no specific missions that are planned for this. There's a lot of separate technologies that are being tested. But we know that Jared Isaacman, the new NASA administrator, is a big fan of nuclear rockets as a way to go to other worlds. And so we're seeing more interest in this idea. And I think that's great. Take them to space, then turn them on, and we should be able to go to other worlds in shorter flight times. A story about this from Mark Thompson. OK, this is a big piece of news that might have slipped past your radar. And so I'm going to get you up to speed. As I'm sure you're aware, in 1998, astronomers announced that the expansion of the universe wasn't slowing down. It was actually accelerating. There's this mysterious force in the universe called dark energy, Nobel Prizes all around. But this was such a surprise. And now astronomers have been developing a range and series of tools to mark the rate of this acceleration over time. And one of the really interesting things that came out of the dark energy survey about a year ago was that dark energy might actually be evolving over time. And this connects quite nicely to this idea of the Hubble tension, that when you measure the expansion rate of the universe in the cosmic microwave background radiation and you measure it in the sort of more nearby Cepheid variables in Type 20 supernova, you get two different numbers and they don't agree with each other and their error bars don't overlap. And so maybe evolving dark energy could be one answer for this. So one possibility is the dark energy is just this constant pressure that you get whenever you have more space, the cosmological constant. The other possibility is that actually the strength of dark energy has been changing over time. So there are four major ways that you can measure the existence of dark energy. The first one is that Type 20 supernova. That is what the Nobel Prize was originally given for. But there are other ways. One is measuring the baryonic acoustic oscillations. These are sort of leftover reverberations of when the universe was in a much hotter, denser state. The slight variations in temperature and density have turned into the large scale structure in the universe that we see today. There are how well galaxies cluster themselves together. And then there is weak gravitational lensing where you can see the effect of gravity on galaxy clusters. You put that all together, you have four separate probes for understanding the presence of dark energy at different times in the universe. And then about a year ago, and I'm sure you remember this, we got this announcement from the Dark Energy Survey that they had found evidence that maybe dark energy is evolving over time. And this is sort of entered the conversation in the last year. But that announcement a year ago, that only came from two of those methods of doing these observations. You've got the galaxy clustering and the supernova observations, but that didn't include the other two. So you've got the baryonic acoustic oscillations and the weak gravitational lensing. And so last week, the Dark Energy Survey released the final data of six years of observation with their incredible telescope. It observed for 750 nights in six years. It observed 669 million galaxies, accounts for about one eighth of the entire night sky. And from that, they were able to provide results for all four of those methods of studying dark energy. So what do they find? Well, the problem is they didn't get a certain answer either way. And in general, what they saw was that the amount of dark energy in the universe still matches this Lambda Cold Dark Matter model, Lambda CDM. But it's a little bit in tension. So the supernova results and the baryonic acoustic oscillation results hint that dark energy is evolving. But the lensing clustering data show this clumping problem that was originally found about a year ago. And neither one crosses that really important five sigma level to say this is certainly the way things are going. And so, you know, if dark energy has been evolving over time, the impact is fairly subtle. It is not this gigantic, obvious result that is just screaming out of the data. What's going on is more subtle. And it's starting to kind of tease apart these separate lines of evidence could very well be that you still have Lambda CDM, but maybe there's different physics and what's causing galaxies to cluster together. Maybe we don't understand how neutrinos work or something like that. So there is definitely new science, new physics to be uncovered in all of this result. And this is like the first big survey out of the gate. We've still got Rubin, Roman, Euclid, Desi. So there's all these other surveys are going to be doing very similar versions of this. And so, you know, maybe 10 years down the road, we'll have a much better answer. We've got a great story about this from Matt Williams on Universe Today. Like as usual, I'm giving you the synopsis, the quick version of this story, even though I went into quite a lot of detail and the article by Matt on Universe Today goes into even more detail and really takes you through the line of reasoning to show where we are today. So if you want to get a better sense, I think this is one of the most important findings of the year so far. You should definitely check out the story. Mercury has always been thought of as a dead planet, but maybe it should be thought of as mostly dead. And that's because scientists have found several bright features on the surface of Mercury that indicate that it might still have volcanic outgassing. These features are called linear and they've been seen on Earth and now it looks like they've been seen on Mercury. So planetary scientists went through one hundred thousand images taken by NASA's Mercury Messenger spacecraft. This was NASA's Mercury orbiter mission that wrapped up. But still, scientists are going through the data and these linear are on the south facing slopes of various impact craters. It looks like there's some kind of volcanic outgassing that is happening. So it means that Mercury isn't dead, is still having some kind of volcanic activity in its center, that it's making its way out to the surface. We've got a story about this from Mark Thompson. Interstellar Object 3i Atlas is now on its way out of the solar system. It completed its closest pass to the sun, its closest pass to Earth, still got Jupiter, but it is getting farther and farther away and dimmer. And so fewer telescopes are going to be able to image it. And eventually we will see our last picture of this comet. And we've been sharing every single picture that we can get our hands on from ground based observatories, space based observatories, rovers on other worlds. And here's another. This comes from NASA's Transiting Exoplanet Survey Satellite, the test mission, which is finding exoplanets around other stars, but was able to make a series of observations 3i Atlas from January 15th to the 22nd. So here's an animation that shows 3i Atlas. You can see the dot, you can see its little tail. And at this point, it was magnitude 11.5, which is about 100 times fainter than you can see with the unaided eye. You definitely are needing a telescope and now kind of a larger telescope to be able to image 3i Atlas. Every week we do a vote on our channel where you tell us what you thought was the best space news story of the week. And the winner last week was the Artemis 2 rollout. So thank you everybody who voted last week, we're going to put this week's vote into the post tab on our YouTube channel. So go there, vote for the story that you thought was the best and we will celebrate next week. Of course, the best thing to do is subscribe to the channel, click on the notifications bell, and then go into the post tab and vote for a bunch of stuff to train the algorithm. You want to see these polls. We're finding more and more examples of supermassive black holes early on in the age of the universe that seem to have gotten way too big faster than the estimates have predicted. Well, it's like how big should a black hole be? Well, it comes down to this called the Eddington limit. And this puts a cap on the growth of black holes that the faster the black hole is pulling in material, the hotter the accretion disk gets around the black hole, the more radiation this puts out and this prevents more material from falling inward. This also works with stars, but you know, the accretion disks around black holes are kind of like stars. And so this same process happens with them. But black holes have been seen breaking this rule with a thing called super Eddington accretion. What happens is that in the accretion disk around the black hole, radiation can get trapped inside all of the hot gas and material. And then as that goes into the black hole, it is taken off the table. And so it can no longer prevent new material from falling in. You also get these incredible jets that are blasting material out of the black holes. And so astronomers have found a galaxy that contains a supermassive black hole, and they're seeing it about one point five billion years after the Big Bang. And it appears to be feeding at 15 times the Eddington limit. And so then if this black hole is feeding at this limit, well, then now your rules are how big black holes can get. It's just like out the window. And so then the question is, has this black hole been feeding like this for a long time? And the answer appears to be no, that they were able to see the jets coming out of this black hole, be able to trace the amount of X-rays and radio waves coming from the black hole and confirm that in fact, these jets are fairly recent. And so it hasn't been just constantly feeding for a long time. It's going through a feeding period right now, but it was very short lived. So there needs to be some other explanation for how these black holes could have gotten so big so early. Got a story about this from Evan Goff. All right, now let's give you some pictures. That's why you really watch these videos, right? This is the surface in this galaxy, which is about 13 million light years away. Sounds far, but actually that is relatively close when you think about how we're seeing galaxies that are billions of light years away. And it hosts an actively feeding supermassive black hole at the heart. It's one of the closest examples of an active galactic nuclei that we have. In fact, the problem is that at the heart of this galaxy, the region where the black hole is and where it's feeding is too bright. And so astronomers had a really hard time picking out the features around the supermassive black hole that's there. You've got attempts from ground based observatories, the Hubble Space Telescope. Finally, James Webb has been able to observe this, and it did this with a technique that was designed for looking at objects much closer to home. Webb has an instrument on board the near infrared imager and slitless spectrograph and has an aperture with seven hexagonal holes that it can then combine light from various sources. It can then do interference on the light from those to block various features and reveal fainter things that it wanting to look at kind of like a chronograph. And so they were able to use Webb to examine the heart of this galaxy, and they were able to reconstruct the size, the shape and the features of the center of the galaxy. What they found was that almost all of the hot infrared emission is coming from hot dust that is really close to the supermassive black hole. Very little of it is actually coming from regions that are farther away. And so the heat coming from the supermassive black hole is concentrated, not spread out across the dust that is surrounding where it's feeding. We've got a story about this from Matt Williams. And then we've got this incredible image of a massive galaxy cluster called Max J 1149. It's about five billion light years away, and it contains at least 300 galaxies, but probably hundreds more. It's a well-known gravitational lens, and you can see all kinds of little arcs and twisted little galaxies. But the one I like the best is right at the very middle where you've got this red galaxy that's being kind of distorted at the center. And that is from the gravitational lens. And for a while, this galaxy cluster contained the farthest ever seen individual star, which was known as Icarus. And then we got this updated thanks to a new gravitational lens where the new stars called Arendelle, which is like a Tolkien reference, just shows you how much this gravity can distort the light that gets too close. Got a story about this from Evan Goff. All right. I hope you're enjoying this week's episode of Space Bites. We've got a lot of stories here this week. But, you know, if you're watching this on YouTube, you had to probably watch an ad at the beginning. Now, we remove the ads in the middle of the videos, the mid-roll ads. I think they're now starting to put ads at the end of our videos. We kind of have no control over this. If we could remove all the ads here on YouTube, we would, but YouTube will no longer allow it. We think it's a much better place where you can watch our videos. And that's over on Patreon. Now, keep in mind, we put all of our videos over on Patreon. They're completely free. There's no ads. There's no you have to sign up. You don't have to pay anything. You just watch it. And to celebrate this, we put one additional story in the episode over on Patreon. And the bonus story this week is how astronomers have solved a longstanding mystery about the nearby expansion of the universe. I'll put a link in the show notes. And so go over to Patreon, watch the video there. If you like that experience, subscribe for free on Patreon. You're now following us and you'll get notifications every time we release a new video. And this is just a fraction of all of the stories that we're covering over on Universe Today. Usually, we cover about 30 to 40 stories every week and a lot of really cool ones this week. And every Friday, I gather up all of the that we covered and then I write an email newsletter that explains all of them. There's no ads in the newsletter and it's completely free. Go to universetoday.com slash newsletter to sign up. I'm going to give you a shout out to another great source of space news. But first, I'd like to thank our patrons. Thanks to Abe Kingston, Andrea Pedretti, Bailey Griffin, Brian Bode, Kerwin, Chuck Hawkins, Commander Baylock, Cy Nielsen, Darkfinger, David Gilton, David Matts, Evan Probe, Greg Feely, James Clark, Jerry Madden, Jim Burke, Jordan Young, Josh Schultz, Marcel Smits, Micah Purcell, Nordspace, OneStepForAnimals.org, Paul Buck, Ren Kaidu, Richard Williams, Sean Sargent, Steven Fowler-Munley, Team 49, Telescopes Canada, Wolfgang Klotz, and Zeldaborg Galactic Defender who support us at the Master of the Universe level and all our patrons. All your support means the universe to us. I know you're looking for good, reliable, honest sources of space news. And there's one that I think is being chronically underwatched and is very high quality. And this is the one presented by my astronomy cast co-host, Dr. Pamela Gay. This is over on the Cosmic Quest channel. It's part of the non-profit organization that she runs. They do the mapping of craters on the moon and Mars, and they were able to help find the landing spot for OSIRIS-REx mission. And she does a ton of space news. Specifically, they do a show called Escape Velocity Space News. And about once a week, Pamela presents all of the big breaking space news of the week, similar to what we do with Space Bites. And so if you're a fan of astronomy cast and you enjoy hearing Pamela, a PhD astronomer, explain stuff about space and astronomy, I think you'll really enjoy this. She is presenting it, writing it, and she knows her stuff. And of course, she's got an incredible voice. And so if you're looking for a show to fall asleep to as well, you may want to put on Escape Velocity Space News, but don't tell her I said that part. All right. We'll see you next week.