Q&A 158: Does a Titan Sample Return Mission Make Sense? And More...

hey everyone welcome to the question show your questions my answers as always wherever you are across my channel if a question pops into your brain just write it down i will gather them up and i will answer them here i we do the show every monday at 5 p.m pacific time so if you want to join live you can but put down your questions anywhere across my channel and i will gather them up and i will answer them here all right let's get into it matthew grotky with ligo how do they tell between bigger collisions farther away and smaller collisions closer ligo of course is the gravitational wave observatory that has been detecting all of these merging black holes neutron stars black hole neutron stars maybe primordial black holes we don't really know yet and ligo is capable of detecting these events across a sphere of space centered on the earth of course and so your question really asked is like like you know when we see a star that's very very bright how do we know that that star is just close or that that star is really far away it's really hard to know which one it is and so it's one of the really tricky challenges that astronomers have had to come up and so they have this idea of luminosity so when you have a a star or a galaxy it's going to have its absolute luminosity essentially the amount of light that is putting out and then you've got its apparent uh magnitude apparent luminosity so from our distance how much light are we receiving and it can be really tricky to know whether the star is just close or it's far it's just brighter the way they determine the distance on gravitational waves is essentially through redshift in sort of the same way that they detect these galaxies that are moving away from us at faster and faster rates this was the discovery made by hubble hubble had to use a method to determine these variable stars that were in these galaxies and use that as a ruler to figure out the distance to these galaxies and then they realized there was a correlation that the faster these galaxies were moving away from us the farther they were and you could sort of double check with these mira variable stars so with gravitational waves it's purely based on the redshift essentially as these two objects are spiraling towards each other and they're about to collide they put out these gravitational waves that then sweep out through space and are detected by ligo and and other gravitational wave observatories here on earth and the frequency of those waves as they pass over because they really are they're like ripples in the ocean and the gravitational wave observatory detects these ripples detects the frequency as these waves pass over and they're able to determine the redshift in other words if it was very close you'd expect one frequency if they're billion light years away you would expect a different frequency and that redshift allows them to calculate the distance and one of the cool things that was done with this ability with gravitational waves to detect distance is they were able to finally confirm the fact that gravity moves at the same speed as light and so back in 2017 there was the kilonova event where you had these two neutron stars collided with each other they let out a blast of radiation and gravitational waves at the same time we saw the radiation and we also detected the gravitational waves at the same time telling us that these things move at the same speed so um that's how they do it red ketchup are all the satellite rovers engines that we sent on mars landed or crashed have they all been sterilized even the first ones that are crashed been sterilized no um like keep in mind that that you've got the americans with nasa you've got the russians who have been sending missions to mars they've all been crashing um the british sent a a rover the europeans have sent or bridge center lander the europeans have sent a spacecraft to mars that's crashed and so many of those spacecraft that were sent to mars were sent earlier than sort of our modern idea of planetary protection and so there were no real cleaning put in place but eventually started to dawn on nasa and the rest of the world's space agencies that there was a risk of microbes from earth contaminating places like mars especially places where there could still be water or there was water in the recent past there could be life there and you want to make sure that we don't contaminate it and so many of the rovers are sterilized the best that they can depending on where they're going to be going so if it's going to go to a place that's very inhospitable they don't do much of a sterilization job because it's very difficult they essentially have to take each part of the rover put it into an oven bake it to an incredibly high heat put the whole thing together in a completely sterile environment it's an enormous pain while if you're just going to build something that you don't have to worry about planetary protection at all you can just slap it together you're concerned about grit and dust and stuff getting into it but you're not concerned about microbes which as we know life finds away and they get everywhere so i would say the older stuff that's crashed onto mars a lot of the soviet spacecraft some of the older stuff sent by nasa weren't protected that well and then stuff that's more modern have been protected a little bit better and i think you're gonna find into the future planetary protection is becoming more and more of a global internationally agreed upon way of of protecting mars from our filthy microbes ruling moss 55 hey fraser love what you do i have a somewhat obscure question say nasa or some other space agency proposed a sample return mission from titan similar to the mars sample return expected in the next couple of years would it be possible to make a launch vehicle capable of lifting off from titan would the atmosphere be too dense to be able to achieve orbit from the surface with the high concentration of methane and titan's atmosphere trigger some sort of explosion if we tried to use a chemical rocket in the lower atmosphere of titan so as you know nasa is planning on bringing samples back from mars and the way they're going to do this is they're going to send a rocket to mars it's going to be empty of fuel it's going to land on the surface of mars and then it's going to fill up it's going to essentially create its own rocket fuel using resources that it finds on mars it's going to be sucking carbon dioxide it's going to be using a chemical process with hydrogen to turn that into methane it will fill the rocket and when it's ready to return the samples it will blast off from the surface of mars meet a spacecraft in orbit transfer the samples to that spacecraft and that spacecraft is going to come back to earth but could you do the same thing with titan and the answer is yes in fact we did an article on universe today feels like about a year ago or so about exactly this that there is a researcher who has put together a mission proposal for nasa on doing a sample return from titan using local resources and as you said right the local resources that you have on titan the rocks the sand the mountains they're actually just made of water ice the seas are made of liquid methane and ethane rocket fuel in many ways so you could go to titan you could land your spacecraft there you could bring in water from the surface somehow you could try to bring in carbon dioxide from the atmosphere or if you could land close enough or maybe if it rained the methane rains then you could collect that and turn that into rocket fuel now you still need an oxidizer and so that's the trick and people always want to know like why doesn't titan just explode because it's got methane all over it and because you don't have the oxidizer the oxidizer is locked away in all of that water so you would need to split up the water using say electrolysis into hydrogen and oxygen and then you could turn that then into rocket fuel or you could essentially use that hydrogen with carbon dioxide to make methane and then get oxygen to be your your oxidizer have liquid oxygen liquid methane use those as your rocket fuel and it would absolutely work the gravity on titan is fairly low so it's actually very easy to launch a spacecraft off of titan the atmosphere is thick so that would definitely pose a challenge but it's not like venus thick it's like 50 thicker than earth's atmosphere so it would be a problem but not that bad of a problem and in fact there's lots of interesting ideas because the atmosphere is so thick the gravity is so low you could say launch an airplane and it could fly to a certain altitude and the rocket could take off from that so you've got a lot of ideas and hopefully as i'm talking about this chat is putting up uh images of the article that we did on universe today so you can check it out and i'll put a link in the comments because it's it's a pretty cool idea and i don't think anybody else talked about it other than us matt legrow being close to a large gravity field slows down time if i found an area without gravity how fast would time go yeah as we all saw in the movie interstellar you spend a bunch of time near a supermassive black hole and for every day that you spend 30 years happen for your friends and mother back on earth even just being down here on the surface of earth we are experiencing time differently than astronauts who are in orbit but the key to this whole thing is that it's about relativity everything is relative so first there's no place you can go in the universe that doesn't have gravity you are experiencing the gravity from every single atom every single photon every black hole every bit of gas in the entire observable universe if you can see it you're being influenced by its gravity so there's really no place that you could go but it all really comes down to the relative amount of gravity so back to the idea of interstellar if you and your astronaut friend were standing on the planet together you would experience the same amount of time together but if your friend was back home on earth and you were down on that planet then you would experience a day and they would experience 30 years so there really is no place that you could go that doesn't have gravity everything's just relative and so when you ask this question you've just got to say compared to what where are you and where is the observer where are you and where is the person that you are comparing yourself to you can calculate a difference of time between those two locations because of the different gravity wells but it's going to be different for you and every other observer in the observable universe double d after seeing a video of an astronaut losing a shield i was wondering if the iss could have a mini eva rc vehicle to go retrieve lost items that's a really cool idea and to be honest i don't know of anything that's been proposed to fly around outside the international space station there have been flying robots that have been sent to the space station to fly inside essentially they're very reminiscent of star wars they're like these little balls that can shoot out little gusts of air and maneuver themselves around inside the space station but they're pulling in air from the space station they're blowing it out again and they're using that to maneuver themselves around but you need something with propellant to sit around outside back with the space shuttle bruce mccandless one of the astronauts there's a very famous picture he's floating free in space with this backpack on and so for a few of the missions they gave the astronauts a backpack that would allow them to fly around untethered to the space station but there aren't a lot of uses for it and so it's not really a necessity but i wonder if there are any plans to have some kind of spacecraft just some kind of utility vehicle that's attached to the space station that could do this kind of work but i don't know of anything right now pole tuck i read recently about a mission that's going to flip some asteroid orbits around another asteroid to study our ability to stop them can't recall what the mission was does anybody know don't know the specific mission but there's the dart mission that nasa is building right now and the purpose of this mission is to impact an asteroid and from that impact nasa will be able to understand how much mass they have how hard they are to move and so you can imagine this spacecraft will smash into this asteroid they'll measure its trajectory beforehand to measure its trajectory afterwards and be able to just get a sense of of how much effort how much energy we can from earth put into an asteroid to try and move it and of course this has a real impact on part of the pun on the dangerous asteroids that could be coming to earth the thing with asteroids is that it's not like we're going to detect some asteroid on a collision course with earth it's that there will be an asteroid that is say 50 years down the road has a potential to interact with the earth's orbit at a bad time and there'll be some probability that that asteroid is going to smack into us and so you've got many many years and so the question is if you've got lots of years what is the most efficient way for us to be able to try and change the trajectory of that asteroid just a little bit to be able to have it not be in the danger zone the high probability zone of hitting us and that's what missions like dart are going to try and help us figure out more questions in a second but first i'd like to thank our patrons bonnie sandler mark greenberg jeff frenenki and the rest of our 786 patrons for their generous support want our videos early with no ads join our community at patreon.com universetoday rafael dominikini if space probes did not have size and weight limitations would it be possible to build them cheaper i like this question because up until this point no one would ever ask that like the cost of the rocket the launcher for your spacecraft was so expensive that you absolutely had to minimize the weight and size of your spacecraft to fit within the fairing to be able to launch on the spacecraft and every kilogram that your spacecraft took up was going to cost you tens of thousands of dollars to launch and so you had to be really really careful the more you could shave off weight and so a lot of the times over the last couple of decades there was just a ton of compromise that had to be made really cool missions really cool instruments had to get thrown overboard because they're too heavy and we're talking like things that are like five kilograms 10 kilograms like very light instruments but still couldn't fit within the weight and now you've got even just with the falcon 9 with the reusability of the falcon 9 the low cost the falcon heavy you've got the ability to be less careful about shaving down the weight of your spacecraft and when starship comes along and you're going to be launching your spacecraft you'll be launching 120 tons or whatever to orbit for a couple of million dollars theoretically it changes everything like you just don't have to be concerned about and so you can then make a heavy spacecraft that is cheap or you can make a big bulky spacecraft that is cheap and so what a revolution in launchers is going to provide is a dramatic decrease in the cost of spacecraft and a cheaper cost means more means more complicated spacecraft going to various places and so i mean i just imagine like if james webb was designed for starship it would be a very different instrument and probably would look similar to hubble and not the way james webb does so i think that we're going to have these compounding effects that are going to change everything and i can't wait to see this play out if it happens come on starship launch already vignesh gopinath i assume we conduct experiments on iss because of microgravity what kind of scientific experiments would happen on a moon base and why that could only be done on the moon and not on earth i've never thought about this before i love this question so what could we do with a moon base that we couldn't do with earth or with the international space station and you're right i mean the main purpose of performing experiments on the international space station in microgravity is to learn what microgravity does to materials to electronics to life to plants to cells all kinds of things right you just want to understand how is microgravity different than gravity and turns out very different we found all kinds of things and there have been a few experiments that have been done to say is there something that you can do in microgravity that you can't do under gravity at all and they've found that you can like grow crystals you can you can make fiber optic cables which are which are pure that are able to to send signals better so so there are a few advantages to to being in in microgravity but if you're on the moon you've got say one-sixth earth gravity what does that get you right and so i think the vast majority of the experiments that will be carried out on the moon will be what does one sixth gravity do to electronics to life etc it's gonna be about learning how to live on the moon there are going to be some experiments definitely some astronomy research that can be done cosmic ray detection but again that's kind of like how can we live on the moon and deal with the cosmic rays i guess it would be like if we could perform experiments with biology on the moon and we could see that say you could take mice to the moon and they could carry their pups to term and they were healthy then that would tell you that mars which has more gravity is probably safe as well so i think moon is kind of like an extreme place you can find out everything that breaks spending time in low gravity that then we would still have to test those out on mars but all the stuff that that still seems to work out okay we could assume that when we go to mars that stuff is going to work out okay as well so i think that's what it's good for sean martin at fraser at the eventual heat depth of the universe will there still be time there's no particle left to decay how would one measure time thanks for just the show as we look into the far far future of the universe and of course katie mack has done an amazing book called the end of everything which it covers all of these issues but for deep time all of the stars are dead all of the black holes have evaporated one of the big questions is then does matter just protons do they decay and if protons decay then you just won't have anything there won't be any matter left in the universe but there will still be the radiation and the various particles left over from the decay of the protons and they will all be spreading apart in the universe just indetectably warmer than the background of the universe which will be close to absolute zero it will be a very sad dead cold place but will time still exist sure time will still exist i mean does time exist if we don't measure it i think yes i mean unless you think that humanity is incredibly important and so just because we use a clock to measure time or whether we use an atomic particle to measure time doesn't mean the time isn't still taking place of course back to that earlier question i mean it's all relative where you are what kind of gravitational influence you're under but yeah time will still go on forever and ever and ever um as the universe expands and cools and dies even more zach perry if a rogue planet was heading towards our solar system could it catch us by surprise or would we definitely know well in advance mike brown and constantine battigan of course uh they have suggested they have calculated that there is a heavy object out in the outer solar system something uranus neptune-sized way out beyond the orbit of pluto and yet so far we haven't detected it and so it's in the solar system it's well within the solar system if it's there it's relatively close compared to the nearest star system and yet we haven't been able to take a picture of it yet probably when the vera rubin observatory comes online we'll finally get that image of planet nine and maybe planet ten and planet eleven but we're still waiting for the telescope to come online like if there was an object the size of earth we probably wouldn't detect it like no one would notice it until it was probably around the orbit of pluto maybe even closer you know pluto was found through a search you can find pluto in a in a backyard telescope but you got to know where to look and so until you have these all-sky surveys that are updating every couple of nights you're just not going to be looking at every part of the sky so it's going to be a chance so if there was an earth-sized rogue planet on its way through the solar system i don't think we would spot it until it was reasonably bright started to get picked up by accident in a lot of the images that astronomers are taking kind of in the way that that supernova get detected someone will be observing a galaxy and then they'll notice that one of the stars is a little brighter and like i discovered a supernova or the way people find comets and so it would need to be relatively close though with probably within the orbit of pluto maybe closer before it got detected matt jonah two would it be better to send a lander that builds its own rovers say a lander that has one pre-built rover that gathers material while the lander builds more rovers that could then explore all of mars you are talking about von neumann probes you were talking about self-replicating robots which would be awesome if we could send a spacecraft that would go to mars and it would have just the bare minimum to be able to exist on mars and then it would gather all of the local resources and begin building more rovers on mars that would be the greatest i would love that but unfortunately we're just not that technologically capable yet 3d printing in space has just barely been tested out on the international space station there's some ideas and you could build physical elements you could build say legs joints things like that but to build some of the more complicated parts the machines the actuators the computer board things like that that would be really tricky so i would say we are decades away from that but the idea of sending a spacecraft that that has like the main parts and then gather stuff from the local resources to build more of itself or copies of itself i like that idea a lot but i wonder if it just makes more sense to just build the thing on earth be able to test it out make sure that it's right with good equipment good machinery because sending it to mars and having try and make a copy of itself or making sub rovers it's a pretty bad workspace for your poor robot like it's out in radiation hot and cold it's only got the terrible tools that you sent it with but there will be a time like there will absolutely be a time in the far future near future far future when spacecraft go to other asteroids planets things like that gather up material locally and they're able to make copies of themselves it would be really cool i can't wait it would be like the baba verse books roy lindsey why don't launch platforms have huge holes beneath them for all of the exhaust launch platforms do have large cavities underneath them for the exhaust to go when you look at say the space shuttle and space shuttle is taking off it looks like it's just sitting on this launch pad the reality is that it's got this huge area underneath and in fact when the space shuttle was launching they would spray water into this area as the rocket was firing its engines and sort of has two parts one is to dampen the sound so it would absorb all of the sound from the rocket so the rocket wouldn't shake itself apart but also to absorb a lot of the energy all of this heat and exhaust that's coming out of the rocket and so all modern launch pads will have some version of that they're not just sitting on the ground they're launching from some place where they can deal with all of the exhaust gases that are coming out of the rocket jack malone what fermi paradox solution is your favorite not the most likely solution but your favorite the solution to the fermi paradox that i suspect is true is that we're alone the one that i fear is true is the great filter that something horrible happens to every advanced civilization when it reaches the rudiments of space flight what's the one that's my favorite i would say the galactic zoo is my favorite the idea that there is an advanced civilization all around us that they are aware of us that they are watching us and they are waiting for us to reach some point in our development with which point they're going to make contact with us kind of like star trek i mean i've definitely been influenced by star trek this idea of the prime directive that you don't interfere with civilization until they've reached a certain level of technological advancement they're attempting to reach out to other worlds and that's the moment when their curiosity is at the highest when they're open to uh finding out what's out there across the milky way that you interact with them and tell them the truth and until then you just keep the wool over their eyes make them think that it's all up to them that's the idea that i like the best but you know it's probably because star trek just sort of messed with my brain all right those were the questions this week thank you everybody for sending them in and for the people who join me during the live show this is super fun i really enjoyed a lot of questions that i'd never seen before which was great so thank you everyone for hanging out i will see you next week if you want a single comprehensive resource for space news you'll want to subscribe to my weekly email newsletter every friday i send out a magazine of space news with dozens of stories pictures brief highlights and links you can find out more go to universetoday.com newsletter to sign up it's totally free and did you know that all of my videos are also available in a handy audio podcast format so that you can have the latest episodes as well as special bonus material like interviews with me show up on your audio device go to university.com audio or search for universe today on itunes spotify or wherever you get your podcast i'll put a link in the show notes thanks to all the moderators and a special thanks as always to chad weber and nancy graziano

Channel: Fraser Cain

Views: 14,695

Keywords: universe today, fraser cain, space, astronomy

Id: EaeHQDGY8UU

Length: 27min 37sec (1657 seconds)

Published: Mon Oct 18 2021