Can't help but feel this is a bit of a disappointment. NASA expected to find (sedimentary) lake deposits at the bottom of Jezero crater. Sedimentary rock might tell us more about the Mars environment as it was when there was still running water. However, it only found igneous rock (produced by volcanic activity below or above the (then) surface). If sedimentary rock ever existed, it must have eroded away by dust-laden wind.
Honestly, I was not expecting any positive result in the upper strata regarding possible "fossiles" or even the presence of sedimentary deposits; not a case that the Nasa is fully relying on the reclamation of those samples (the drilled ones I mean) to give a sure answer to the question if there ever was life on Mars. We have to be patient and wait for a decade still, if not more. Anyways, not all is lost, radar scanning (down to 15 mt) has shown multiple strata of volcanic rocks which are interrupted by (supposedly) sedimentary deposits.
It is also interesting to notice that there's controversy about the "erosion" effect: in fact Mars has a very thin atmosphere and a relatively small size, both elements that negatively impact the possible speed and strength of wind (averagely is very slow, only in rare cases it can get up to peaks of 50 m/s, 180 km/h, roughly 100 kn, and that starts those global storms): the usual movie tempests we see in many movies are pretty fictional, plenty of equipment has been brought there and the hasn't been any real damage, only some issues with dust deposits on solar panels (such as it happened with Insight). Anyways, a small drop of water can drill a hole in a rock over the time, and Mars wind had billions of years to work on removing those upper sediments.
It is also interesting to notice that there's controversy about the "erosion" effect: in fact Mars has a very thin atmosphere and a relatively small size, both elements that negatively impact the possible speed and strength of wind (averagely is very slow, only in rare cases it can get up to peaks of 50 m/s, 180 km/h, roughly 100 kn, and that starts those global storms): the usual movie tempests we see in many movies are pretty fictional, plenty of equipment has been brought there and the hasn't been any real damage, only some issues with dust deposits on solar panels (such as it happened with Insight). Anyways, a small drop of water can drill a hole in a rock over the time, and Mars wind had billions of years to work on removing those upper sediments.
It is also assumed it lost much of its atmosphere, is it not? Wind erosion may have been more severe in the past.
"Lay these words to heart, Lucilius, that you may scorn the pleasure which comes from the applause of the majority. Many men praise you; but have you any reason for being pleased with yourself, if you are a person whom the many can understand?" - Lucius Annaeus Seneca -
It is also assumed it lost much of its atmosphere, is it not? Wind erosion may have been more severe in the past.
Yes indeed, but as I said there's controversy even on that.. it is believed by many that the evaporation of liquid water on the surface and the dissipation of the atmosphere have gone hand in hand, so to say. However, even on Earth erosion takes million of years, and we have stronger winds, rain, snow, etc.. Mars' dry thin atmosphere makes erosion a very slow process, but again it had billions of years. In any case if not for the slow erosion it would have had not sense at all to search for past life's evidences, after like 2,5 (or more) billions of years.
Since 2003, the black hole at the center of the Perseus galaxy cluster has been associated with sound. This is because astronomers discovered that pressure waves sent out by the black hole caused ripples in the cluster’s hot gas that could be translated into a note – one that humans cannot hear some 57 octaves below middle C. Now a new sonification brings more notes to this black hole sound machine. This new sonification – that is, the translation of astronomical data into sound – is being released for NASA’s Black Hole Week this year. In some ways, this sonification is unlike any other done before […] because it revisits the actual sound waves discovered in data from NASA's Chandra X-ray Observatory. The popular misconception that there is no sound in space originates with the fact that most of space is essentially a vacuum, providing no medium for sound waves to propagate through. A galaxy cluster, on the other hand, has copious amounts of gas that envelop the hundreds or even thousands of galaxies within it, providing a medium for the sound waves to travel. In this new sonification of Perseus, the sound waves astronomers previously identified were extracted and made audible for the first time. The sound waves were extracted in radial directions, that is, outwards from the center. The signals were then resynthesized into the range of human hearing by scaling them upward by 57 and 58 octaves above their true pitch. Another way to put this is that they are being heard 144 quadrillion and 288 quadrillion times higher than their original frequency. (A quadrillion is 1,000,000,000,000,000.) The radar-like scan around the image allows you to hear waves emitted in different directions. In the visual image of these data, blue and purple both show X-ray data captured by Chandra.
Can't help but feel this is a bit of a disappointment. NASA expected to find (sedimentary) lake deposits at the bottom of Jezero crater. Sedimentary rock might tell us more about the Mars environment as it was when there was still running water. However, it only found igneous rock (produced by volcanic activity below or above the (then) surface). If sedimentary rock ever existed, it must have eroded away by dust-laden wind.
Now, let's go in order. First I'm honestly shocked that CNN uses the term "organic matter", because it is not. Looks like they quoted a Nasa scientist, but I doubt that Mr Farley would have used that term. However, what Perseverance found are "organic molecules", or "the building blocks of life, such as carbon, hydrogen and oxygen, as well as nitrogen, phosphorous and sulfur." In other words, the news here is that Perseverance actually found and dug into sedimentary rocks (hence why I quotes Muizer's previous post) and that they found some molecules which might have been created by "life". Anyways: "Not all organic molecules require life to form because some can be created through chemical processes."
All in all that's the most basic discovery possible related to past life, we still have some hope when the samples will be send back, to find some fossilized bacteria or the like (that would definitely be the proof, since actually organic molecules can be found on comets as well and life hasn't certainly developed on them).
I'm not optimist to be honest, there's still a chance some basic forms of bacteria have evolved (looks like the oldest fossilized bacteria on Earth are like 3.45 billions of years), but my sensation is that we won't find anything like that on the surface of Mars.
“DART’s success provides a significant addition to the essential toolbox we must have to protect Earth from a devastating impact by an asteroid,” said Lindley Johnson, NASA’s Planetary Defense Officer. “This demonstrates we are no longer powerless to prevent this type of natural disaster. Coupled with enhanced capabilities to accelerate finding the remaining hazardous asteroid population by our next Planetary Defense mission, the Near-Earth Object (NEO) Surveyor, a DART successor could provide what we need to save the day.”
Not long ago we had a discussion here about this mission, I'm still very skeptical about the effective reach of the project to be honest. Sure, we hit an asteroid, but that's not a great news either, since Rosetta and Philae already managed something similar over 6 years ago. As far as I understood, even if they are already checking about the effectiveness of the impact using telescopes from Earth and orbit, the real extent of the success will only be validated with the Hera Mission, in four years from today.
To me, there's way too much enthusiasm about this whole project, and my reason is simple: awareness of the threat, coupled by actual effectiveness of the method. As far as our knowledge goes, there are two kind of threats we have to look upon: smaller, closer asteroid that can hit with almost zero forewarning and cause local wreckage, and very large comets (I mean, VERY large, in the order of tens or hundreds of kilometers, Hale-Bopp was 60 km wide, just saying), that can potentially cause a mass extinction event. Everything in between is being mapped already, and none of them really represents a threat in any foreseeable short term.
So, from one side, we have smaller objects with which this technique could be effective, but that we can't prevent at all, from the other we have very large objects that we will be aware of months (possibly even a year) in advance as they approach the inner solar system from the Oort cloud, but that, looking at their possible sizes, would be very much invulnerable to this technique.
As I said already, we are hundreds of years far from when we will be effectively able to defend ourselves from this kind of threats.
Not long ago we had a discussion here about this mission, I'm still very skeptical about the effective reach of the project to be honest. Sure, we hit an asteroid, but that's not a great news either, since Rosetta and Philae already managed something similar over 6 years ago. As far as I understood, even if they are already checking about the effectiveness of the impact using telescopes from Earth and orbit, the real extent of the success will only be validated with the Hera Mission, in four years from today.
To me, there's way too much enthusiasm about this whole project, and my reason is simple: awareness of the threat, coupled by actual effectiveness of the method. As far as our knowledge goes, there are two kind of threats we have to look upon: smaller, closer asteroid that can hit with almost zero forewarning and cause local wreckage, and very large comets (I mean, VERY large, in the order of tens or hundreds of kilometers, Hale-Bopp was 60 km wide, just saying), that can potentially cause a mass extinction event. Everything in between is being mapped already, and none of them really represents a threat in any foreseeable short term.
So, from one side, we have smaller objects with which this technique could be effective, but that we can't prevent at all, from the other we have very large objects that we will be aware of months (possibly even a year) in advance as they approach the inner solar system from the Oort cloud, but that, looking at their possible sizes, would be very much invulnerable to this technique.
As I said already, we are hundreds of years far from when we will be effectively able to defend ourselves from this kind of threats.
On this matter, this is a clear example of what I mean with "unpredictable".
Airplane-sized asteroid found 2 days after brush by Earth. So, an asteroid of 60 meters, more than enough to cause an explosion of various hundreds of kilotons, should have it reached the Earth surface (for reference, meteor crater in Arizona, is 1200 meter wide and 170 deep, and it is said to have been generated by a 43 meters asteroid - "Little Boy", the nuclear bomb dropped on Hiroshima, was about 16 kilotons), passed by at only 100.000 km from us (close to 1/4th of the distance between Moon and Earth). Now the interesting part about this asteroid, 2023 NT1 that's its name, is that we only discovered it 2 days after it was passed that close to us, yes 2 days after.
Why we didn't see it? First, because despite being able to potentially kill millions, it's still a relatively small object, hard to spot in general. Second, because since it was coming from the direction of the Sun, it was impossible to "see" it in the spectrum of the visible light (the standard method used to look for "new" asteroids and comets).
Now, with regards to our actual capacity of anticipating and possibly preventing meteoric impacts on the atmosphere or on the surface, that's a big red flag, a huge one actually. As already mentioned, most of those smaller object (below 100 mt) are still undetected (and so unpredictable) and the Sun is actually occupying a large portion of our "sky". It's also important to understand that 100.000 km is absolutely nothing in terms of distance in space, this was really a close shave under any aspect.
But what are "we" doing? ESA is developing a new mission, the NEOMIR. This satellite will be put on the L1 region (the same where WEBB and other space telescopes are) and pointed towards the sun: it will use infrared rather than visible light to spot any asteroid or comet coming from that direction: this because any object interacting with the sun's radiation does emit both visible light and infrared light, the latter being able to be revealed despite the Sun's immense emission of the same. That's also the very reason why this satellite has to be put on the L1 zone, because, just like WEBB, its capacity could be seriously hindered by the Earth's atmosphere and local emissions of infrared light.
The NEOMIR mission is, anyways, just in the very early stage, potentially it could be launched in 2030, but it has the same chances of being canceled, for what we know...
I think you're right. Willingness to invest in a planetary defense system would face the rather huge challenge that the odds of an impact for meteorites large enough to do substantial damage are very low. You're talking about an incidence of once every several thousand years at most. A frequency that would be reduced further if you incorporate the likelihood of it impacting in a densely inhabited area. And even further if you consider it a national responsibility. You can then ask whether nations/civilizations are be willing and capable of maintaining undoubtedly highly expensive sophisticated engineered system on such timescales. I think you can guess what my answer would be.
"Lay these words to heart, Lucilius, that you may scorn the pleasure which comes from the applause of the majority. Many men praise you; but have you any reason for being pleased with yourself, if you are a person whom the many can understand?" - Lucius Annaeus Seneca -
Indeed. That's why I was not impressed at all by the DART mission.. I mean, the NASA demonstrated that they could hit an asteroid (but that's not a news per se, we had the technology for that since early 90s and by early 20s we were already able to land on them, 433 Eros - NEAR Shoemaker) and modify their orbit (again, not a surprise at all), but at the same time it's evident that that method could only be used as a desperate attempt to deviate any largish (100 to probably 1000 meter) body that might be on an impact trajectory with Earth. Anything smaller would probably not be worth, anything larger would probably be immune unless a very huge projectile is going to be used.
What it also demonstrated is that NASA completely messed up the calculations about the effects of the impact, to the point that the magnitude of the orbit change is 22 times what they expected. They also undervalued the effect of the tail of debris on further slowing down the orbital period. On the positive side, of course, is that consequent to this mission, we are now developing new knowledge that will help expand future missions on this regard, and that's great obviously.
What I can't stand is the news (supported by NASA itself) that the mission was a complete success, because it wasn't. And honestly that's strange for NASA, because they are usually very available to recognize their mistakes. I have the maximum respect for what NASA is doing and in this particular mission I can also brag about having an all Italian element (the LICIACube), still the excessive enthusiasm around the mission's results I see them just as propaganda, which again is very strange for the NASA. Lol, let me tell you this funny fact, just to put what I say in perspective.
If I type "missione dart" on Google, what I get is an animation of the DART probe crossing from left to right on the page
Spoiler Alert, click show to read:
and hitting the right side, that leaves the page tilted
Spoiler Alert, click show to read:
Never ever seen anything like that before
Now, if really want to make a full analysis of the matter at hand, what would I say?
- First, about spotting in due time every possible menace: as of today we are very far from that, as recently demonstrated by 2023 NT1, and will probably never be able to achieve a 100% coverage, unless AI and very powerful computers will be used, supported by a network of multiple systems, which will cost, all summed up, an uncountable amount of money. On the feasibility of such a system I share the same sentiment as Muizer, in all due honesty. And I'm even more skeptic about the political side of it, to be honest. Science fiction.
- Second, on the ability of being able to react to any menace in due time: as of today, we would need to have a quite a lot of different launchers ready with different size/weight probes, to react accordingly to the real magnitude of the menace. And most probably, two of every kind of them (since a failure at launch is somewhat a concrete possibility even today, you don't want to risk an apocalypse just because that launcher failed and the probe couldn't reach the space at all, don't you?) if not three... And they should be close to ready to be launched (which probably means, loaded on the launch tower with only the fuel missing), because loading up a launcher on a tower can take days (depending on the size of it even weeks) and in the case of a short forewarning, that would render the system useless. Again, the economical cost and the political implications of this makes it something good for Science fiction.
- Third, on the actual need for a similar system: as already pointed out above, and previously as well in this thread, significant asteroid impacts are very rare in terms of human life scale.
From WIKIPEDIA
And those are the smallest ones, the largest ones, those capable of causing an event of mass extinction, are way rarer than that (millions and tens of millions of years). That being said, the Chelyabinsk event showed that we not safe at all and that minor events, that can cause local wreckage, are likely to happen (and have already happened in the historical past, such as the case of Tall el-Hammam which probably inspired the Biblical account of Sodom). Once again, is my understanding of human nature and politics that makes me tend towards the idea that nothing even remotely close to a global defense system will ever exist, considering the overall minimal impact over humanity (and even less over economy).
- Fourth, on the real effectiveness of the DART system: as I said above, if we see it as a "better than nothing" solution and a "desperate attempt at saving Earth", then I can say that it's an effective system, but still with limitations and secondary issues. Main limitation is the reaction time, which will make it useless in the event of any "sudden" treat: most likely any possible impact with less than a couple of years forewarning is going to be missed, because between calculating the orbit (you need at the least two precise measurement over a span of few week to be sure of the orbit of any approaching body), the speed (probably 3 or more measurements), the volume, the expected mass (purely speculative unless one knows the exact composition) it will take months just to understand if it's a real menace or not (will be easy to calculate if clearly not, but in the event of a close call case, it will take more and more measurements in order to be sure if it could impact or not). Sometimes it takes YEARS to calculate that, ask NASA. Add to that the reaction time to calculate the best possible intercepting orbit, to maximize the chances of a positive result, calculate the mass of the projectile, putting up the launcher and so on and on.
Considering that many of the smallest objects (less than 150-200 meters), which are more likely to hit anytime soon, are spot in terms of weeks or months, that gives you an idea of how useful that system is.
As per the possible secondary issues, there's one thing to consider: it's not just about "pushing them away", but rather about "putting them in a new orbit that is safe for the Earth and will not interact with any other body and that might cause secondary, unpredictable issues", that is. On this regard we are absolutely far from being able to grant that it will be the latter, for 2 reasons mainly: first, we can't know with precision the mass of an asteroid (an absolutely must to have data if one wants to be as precise as possible in knowing in advance the result of a calculated impact) if we won't send another probe to investigate the asteroid, and that will add more money and time needs to the mission, rendering it even less likely to be on time, so we are likely going to shot in the dark and just hope that we don't have made it worse; second one, is the effective composition, size and direction of debris that's impossible to calculate, due to both lack of precise info on composition, size, speed, mass, rotation etc of the asteroid, coupled with the computing power needed to make that calculation that I doubt exists today on Earth. A solution would be that to send a manned mission (or AI) with a spacecraft supplied with all the needed instruments to make those calculation and the same time equipped with the necessary weaponry to cause the precise needed impact... once again, that is science fiction and anyways that's not what the Dart mission is, as of today.
So as I said, a desperate solution is what we are talking about here, extremely likely to be too late to be of any use and even if that's not the case and it hits, will be likely causing secondary effects that can render the very mission useless. Complete success my ass.
Last edited by Flinn; July 19, 2023 at 09:25 AM.
Reason: typos
I think you're right. Willingness to invest in a planetary defense system would face the rather huge challenge that the odds of an impact for meteorites large enough to do substantial damage are very low. You're talking about an incidence of once every several thousand years at most. A frequency that would be reduced further if you incorporate the likelihood of it impacting in a densely inhabited area. And even further if you consider it a national responsibility. You can then ask whether nations/civilizations are be willing and capable of maintaining undoubtedly highly expensive sophisticated engineered system on such timescales. I think you can guess what my answer would be.
From a simplistic point of view, maybe. Yet, detection of asteroids is not needed purely for defensive purposes. As we start to wonder outside of Earth we need better detection for guidance and resource collection. It won't be too long before we start placing observation points around the solar system to make sure we know where each object is. Even with our current capabilities, with proper willingness to spend resources, we can cover quite a lot.
Yet, the likelihood of a threat to Earth is not as low as you made it to be and its very hard to calculate such events. Perhaps you're looking at planet killer ones when there are many other sizes that can cause a lot of damage if they hit population centres. Two main events come to mind; Tunguska in 1908 and Chelyabinsk in 2013. Either event happening in over New York or Tokyo would have drastically different outcomes.
There is also the idea that none of these detection efforts are one dimensional. They come with efforts to better optics, guidance systems, construction methods, power management, propulsion systems, etc.
Re: The Astronomy Thread
Originally Posted by Muizer
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