A Realistic Way to Intercept An Interstellar Visitor

if you want to fly to Europe you contact a travel agent and they help you work out the logistics of how to get there or you do it yourself but it's really hard anyway if you want to fly to somewhere in the solar system then you contact the NASA equivalent and interplanetary travel agent and my guest today is one of these he's Dr Damon Landau he works at NASA's jet propulsion lab and he is the person that you will talk to if you want to figure out what orbits trajectories you're going to need to get your spacecraft to any destination in the solar system and he's worked on plotting the trajectories to go to asteroids to Mars to various places around the solar system and most recently he worked out what kinds of trajectories it would take to be able to catch an Interstellar object and actually have a rendezvous mission where you could orbit and analyze this object up close to get a sense of something that formed in an entirely different solar system so our interview is great long range we talk about just orbits in general every extreme gravitational assist and then we talk about what it would take to catch up with an Interstellar object like or Comet borsov alright here's the interview find thinking about orbital mechanics very non-intuitive was there some moment in your mind when you started to think in ellipses ah um yeah I'm I I guess to begin with I'm a very visual thinker uh anyway so when you know somebody comes to me and says you know I'd like to do a mission to to Mars the first thing that I think about isn't necessarily the spacecraft the first thing I think about is okay well what does that that path look like how do we get from Earth to Mars what do we do when we're at Mart um same thing or you know if we want to go to the outer planets visit some of the the moons there if we want to go to a comet or an asteroid and sort of the interesting thing is you know one orbit or one sort of General trajectory family doesn't work for all all of them we have to Hey Hey Taylor our approach to to each um so or or for example to go to Mars Mars is you know the next planet out in the solar system so we don't have to go way out out there and so the the orbit around the Sun is more like the Analytics versus if we want to go to uh for example some of the interstellar objects that have been coming through those things are screaming by with their um on a uh hyperbola and so uh with that it's it's a totally the different approach um but the the the thing that does help Grant it all so you know I mentioned Ellipsis and hyperbolas and so to start with there there are you know just sort of like a handful of basic kind of shapes that we can start with and play around and that was actually my next question it's like what are the what are the raw materials you know what are what's in the toolbox that you have to get around the solar system yeah so um yeah I've I've been developing my my toolbox for a while on it you know like like any uh any good credit right across menu constantly have to own your your act you know uh and so uh there there's a bit of a a a a process that um that that I've developed with with others that uh JPL where we start with sort of a simplified model so we um know where the plants are in in in the solar system and we know that when we're going in between the the planet for the most part the spacecraft trajectory is only influenced by the gravity of the sun they're not really influenced by the planet themselves you know on on the trip they're just on sort of the end point and what we can do is you know use our best engineering judgment on what what kind of approximation can can we take to simplify the problem a little bit in order to do this more broad uh trade space exploration so that's kind of the first steps as we run things in a simplified model we try to run through as much of the trade space as possible so for for a example when we want to look at missions to Mars we might be interested in okay what's happening in the span of the entire 20 20 30. we might run um trajectories for an entire decade in order to start to sift out sort of where the um you know where the the needle in in the haystack is on on a really good trip trajectory and what are you looking for like like I sort of think of an analogy like if I'm planning a trip to Europe right then the first thing that I want to lock down is that flight from Canada to somewhere in Europe that's close to where I want to be and then you've got all these different choices you're like you're this provided that provider these dates those dates and after a while an answer comes out that is like this is the one that's the the least terrible flight that has you know because you know the fewest layovers that I can afford Etc and then once that's locked in then I've started thinking more about the details is that a good analogy yeah that's a great analogy and what what you just described in sort of engineering speak is a multi-objective optimization problem if you've been on top of that if they constrained multi-objective optimization problems so you you have constraints on you know when when when when you want to fly you're like you know okay you're you're your brother's birthday is in June so you know we're we we we want to be you know somewhere for that um so we we we we do the same same thing um on on our end so um some of the things are are very clearly uh on knowledges we will give a a window on the time that that we want want to leave I'll I'll a lot of times you know that that window isn't necessarily um governed by the physics of the solar system it's more a programmatic thing of saying we know that NASA is going to make a a call for proposal sometime in the 20 32 2033 time frame so we start to hone in and look for launches there the departures there the other thing is how long it takes to get there we want to we don't want to take forever in order to get to the destination to get our our science back so we look look at the flight times as well so that gives us a box of sort of the um the the the timed dimensions on on on things we we want to be in there um the the other the the other main currency and sort of on on the trajectory and the space trajectory design is um another uh some of the technical term is our Delta V which is shorthand for change in but but the change in velocity and so that's sort of the equivalent of um our uh of of of of of the distance um that that it takes we're we're not so much worried about um you know the the actual distance itself it's more how much change and speed do do we need the the the Rockets to perform and that translates directly to how much propellant we need to bring on board which translates directly to how big this spacecraft is going to be which translates directly to how constantly is it right so we we run through all the times We compare the the Delta V we'll plot one versus the the other we'll go talk to the scientists and say hey which of these sort of looks good so it's a it iterative process where you bring in different stakeholders where each person sort of cares about a different part of of this multi-objective optimization and and that's for like the simplest flight that's going from Earth to Mars and and if you take the slowest path if you take the fastest path you're not going to have huge differences but but once you consider some of the other tools in the toolkit if you're going to go farther out you've got gravitational assists you've got uh LaGrange points you've got various other factors that are or and and the entry orbit that is requested by the scientists like that will have a factor as as well so so how much more complicated does your job become as you think farther and farther away from from Earth yeah it's it's it's funny you know it's um we're actually just sort of talk about this the the other day at work sort of comparing notes and you know with with each other and um you know there there's kind of like a a fundamental Truth where people will make things as complicated as as possible until it's too complicated for them to to work with um and so it it it builds up so yeah so I was mentioning we start on with the simplified model but then we we can start to throw throw in more more things and so um missions to the outer planets for example Jupiter or or Saturn are good examples of this particularly um NASA jet propulsion lab we're going to launch a mission to a moon at Jupiter called Europa in in in a a couple years and so with that we we look at using gravity assist to get out to Jupiter but then it really gets fun when we start to look at the orbits themselves and so um you have to worry about the initial capture orbit at at the planet how do you line that up um in order to fly Supply by the moons of of of interest and so uh again with that you you can start with a kind of simplified model but then you you you use that as sort of what we call the initial guess in into our more sophisticated tools and you sort of build up your but Fidelity that way and and each each sort of mission has a different tool in in the toolbox so when we're talking about moons of um planets in the outer solar system a lot of times we work with resonances of of those moons where the spacecraft go go for example when the spacecraft goes around the planet like six times in the amount of time that it takes the the moon to go around eight times um or or something like that and so what that allows us to do is to repeatedly and and encounter the the moons and so you start to build things up that way um so sort of using different mathematical constructs um that we found as Engineers are very helpful to allow us to build these these projections and there's some really interesting orbits that I feel have been discovered fairly recently I think one of my favorites is the Tess orbit right this one uh you know orbits in a way that is relatively stable and brings it back to Earth on a regular basis so it can transmit its data but it's kept in lockstep thanks to the interactions with the Earth and the moon so are there some orbits out there that that you are particularly fond of Ah that's a good question um you know I I guess I'm I'm I'm I'm partial to the the orbit that you know gets gets the the science return so it's kind of different um for for for each um I I won't say you know I I sort of mentioned the Resonance of the before I I do find those it's from sort of just you know kind of nerd out here from a mathematical standpoint like number Theory seeing you know how they combine different integers of things to make everything line up and it really gets interesting um when you start to look at um for for example at Saturn um Enceladus and and diony themselves so those are two moons um two of the smaller icy moons at Saturn so those are in a resonance with themselves and then you add a spacecraft in there and so you start to get um I guess yeah we call it a zizzichi when um version this is the different moons light lineup and being able to sort of fit a spacecraft trajectory in there to repeatedly and and encounter the moons um that that really gets interesting same thing happened that Jupiter with the galileans satellites those are in um resonances with themselves which um uh Bridge mathematician LaPlace for sort of found out figured out how that worked and so sort of trying to understand so you can use those resonances of the moons to like stabilize the spacecraft's orbit or to shift its orbit in a way that is scientifically useful over time uh we can use it to do both so yeah that that's a great great question yeah you kind of hit um you know sometimes you want to to stabilize the orbit because you're you're trying to get repeated observations and so you you can set up the the resonance in such a way that it'll that it'll um keep the orbit sort of how how you want it and you brought up test before that's a great example of that where on every other orbit the the moon sort of perturbs the orbit left and then right and so it sort of keeps the orbit um set where you you want it um we we we can also use um these resonance to repeatedly and encounter and sort of change the plane of of the orbit and so uh the Cassini trajectory at Saturn is a good example of that using chitin um to change the the inclination of of the orbit and as you're doing that you also sort of change where the orbit crosses the equatorial oil plane which allows you to intersect different moons um that that way and so we we can line up these different combinations and and we'll pull them together in in such a way to to meet the scientific scientific objectives there are some missions I think of like the is it Lucy but this was done with the Galileo spacecraft that they didn't have enough Delta V to reach their destination and so they used a gravitational assist of Earth but that's where the spacecraft launched from so how how can a spacecraft use gravitational assist of Earth to be able to reach a destination with less propellant yeah that's um a a a a another sort of great um or a classic problem in in or orbit Dynamics and um yeah uh you'll you'll also sort of get a slightly different answer depending on which after dynamicist you you you you you talk to um but the the fundamental thing there or is is what we call it a leveraging transfer so we leverage our speed from launch up to a speed at at the flyby so we'll for example we'll we'll depart Earth at like um say five kilometers per second and then we we set it up again on a resonance so that it'll come back to earth and if we didn't do anything if we didn't fire the pressure of the spacecraft then we would come back at pretty much exactly five kilometers per second again and so that wouldn't really help us but um what we do is um sometime during that that transfer most of the time it's near um one of the the apsis of the orbit either the farthest point from the Sun or the nearest point to the sun will perform a small maneuver that will um change the eccentricity of the orbit you know house Health circular where the the orbit is and what that does is when we re-encounter Earth where we're coming in at a slightly different angle and that angle to the the Earth also affects how much speed we have with with respect to Earth and so we we we basically build energy into the system doing this maneuver so when we come back to earth we have more energy with respect to Earth so we leave at five points per second we come back at like eight kilometers per second and with that we have this additional energy we also use Earth to bend the um the the the the orbit and what that does is it also kicks up the um the appelian which is the the part part of this point so we um so so the uh the the Juno trajectory to Jupiter and also the the Lucy um trajectory does this where you launch and you barely get you know in in into the the aspirin belt so you get up to maybe three eight Au 3 um time three after nautical units you know the distance from her to to the Sun and then when you fly by Earth that kicks your your appealing up so that you can eventually intercept Jupiter or in lucid's case the Jupiter Trojan asteroids right it's playing the the spacecraft energy with the gravitational energy of earth right so like ellipses aren't perfect circles and so you're going at different velocities along the ellipse depending on where you are when you think about comets getting going really fast as you get really close to the Sun and then they slow back down so you're you're using a little bit of propellant to shift the shape of your ellipse and then you're kind of multiplying that when you come back to the Earth is that multiple multiplicative Factor yeah yeah right in timing where on the ellipse you are as you make it back to Earth to to get that boost it's kind of interesting and then I think about some of the using planetary flybys in Reverse to be able to get closer to the Sun so you think about what's happened with say the Parker solar probe and the what was what was done with the messenger spacecraft in the past and to save the solar Orbiter so talk a bit about that about about using planetary cysts backwards yeah um it's it's uh yeah my immediate thought is you know it's it's doing right it uh gravity is that backward it it really is kind of the opposite of you know what we're the the discussing you know getting out to the outer toilet with them so um basically and when you do your your flyby of the planet so for example you apply by Earth instead of flying by the trailing edge of Earth as it circled the sun you'd fly by the Leading Edge of of Earth and so that bends the orbit the other way it takes energy out of the the orbit um in in this case and um and then when you take the energy out of the orbit that means that the orbit will drop more and you can do this repeatedly um and so uh yeah the these orbits I get very close to the Sun or that eventually gets a little bit around Mercury um yeah we want to do sort of a a period of steps down there so first we might do a gravity assist of Earth and then that will be that's enough to measure orbit down through each Venus but we haven't quite reached Mercury yet and then we start to use Venus as our gravity engine and we'll do a few of Venus to kind of take the orbit from something that's entirely outside of being as something that's totally inside of Venus and eventually you can intercept a Mercury and so um that's that's sort of a a another um sort of tool that that we have is to use the the granite sift bodies um be the planets removed that's what it's stepping itself um to to the destination that we were eventually were talking about and is there any limit like the sun is the hardest place to reach in the solar system ironically because you know where on Earth we're going 30 kilometers per second around the Sun and so we would have to remove that 30 kilometers per second to be able to drop into the sun you keep missing the sun when you try to aim for it but could you theoretically just keep canceling your orbital velocity and drive a spacecraft into the sun should you want to um yes um you know sort of the depending on you know how how much time you have so I'll take time and it does take propellant and then um ironically the well what one of the lower Delta V wave in order to get to its sun to you know actually intercept the the time is um you actually don't go towards the sun first you go out you go up um and so you you put a whole bunch of energy into the Sun and then you fly by Jupiter what that does is it fills all the angular momentum so it's it's going left to to right and then you fly by Jupiter and then it's it's like stop and then it just falls directly it's like you're holding a ball and you and you drop it and then right your spacecraft eventually just you know the sun is the floor of the solar system um and so that's how you can get really close to the the Sun and if you survive the trip then you know you get along back out to like you know where that kind of where where you started up by by the sort of classic physics you know go down until they come back up to the same spot that's interesting look I I had read that you could go like on almost an Interstellar like an escape velocity from the Sun go right out to the very edge where your or your orbital velocity is almost zero and then fall back down into the so you know a minor nudge and then fall back into the solar system but I hadn't thought of using Jupiter as a as a kick so you'd sort of save you that time having to go all the way out to the farthest perilian possible that's really interesting what about this technique of using the sun to go faster to go as close as possible to the Sun and then fire your your engines has anyone tried this yet could we use this ah um let's see yeah I am not sure there there probably is an example out there of um let's see yeah doing a close approach to the Sun and then to to kick out um yeah I I don't know if we've used it in practice but um it's it's been known for a while there's um that back in the early 1900s um there is a fellow by the last name of Ober who um was the first one to work out the map of of how this works so we call it the old Earth effect where um what happens is uh to get very close to the a gravitational body so as you're mentioning the ellipse earlier as as you get towards the the focus of the ellipse but spacecraft speeds up and then when you're going very fast a small change in your um in in in your velocity uh given to you by the propellant on on your spacecraft is Multiplied so again we're finding cases where we can sort of multiply the um effect of the of the spacecraft propellant so we get going as fast as as we can getting near the sun we'll do a little bit of um additional energy input from the spacecraft but that from an orbital standpoint gives us a extra boost in terms of orbital energy so that's that's what what will allow it to really scream out towards um for the the outer so for me even right right yeah um and and so I guess this idea of time like if if time wasn't an issue are there low energy like low Delta V Pathways that you can take around the solar system yeah sure there are um yeah so there's there's also yeah so so when we when we start to think about okay what happens if we take you know if we're not worried about time or even worried about sort of like even a lifetime um time you know uh now we can start to think about um which is actually one of the more fundamental things to the questions that um you know and that's what it's looking into it's what how did the solar system form um and and it's it's high because you know the the the physics that affected spacecraft or the same physics that affected sort of the primordial uh so solar system and and so um when when when you look at sort of a given energy level of a part particle being a particle of like operate or a particle of a a spacecraft um there are certain sort of uh energy levels that um can connect between different places in in in the solar system um so there was a lot of um research look looked into this I think it was probably about 20 years ago um one of my colleagues Martin Lowe um I talked about sort of the um uh well the the solar system or Enterprise rates super higher I remember that um jump jump between so when you're looking at doing that with with the planets the time scales are very very long um they're larger than what we want to look at in terms of for a spacecraft but when you look at um systems that have a shorter time scale for example the moons that orbit Jupiter are Saturn those moons have period on the order of date um and in in that case you can make use of of these um we call them low low and low energy transfer between the low energy because you're not really going that fast with respect to them in order to make the to get the most use out of the gravitational potential um of each move and and where those potentials sort of connect allow you to the dance is really good and so you could Drift from moon to moon with the least possible propellant by following this Interstellar or interplanetary uh superhighway yeah yeah um and and so that that's also sort of you know one of the classic traits that we all always look at but getting back to the sort of multi-objective thing you know we we care about how much propellant it takes and how much for about how much time it takes and um you you you you very seldom find a trajectory that gives me both you know right always a trade you know pull one at one against the the other yeah now you know right now humanity is headed back to the moon and people are thinking about Mars but it's even easier to reach many asteroids you did a study a few years back where you looked at the amount of Delta V that it would take to reach different asteroids in the solar system and and what did you find uh yeah so I found that there there are sort of getting back to these that the stepping stone I I idea and so there are a lot of asteroids near Earth we call them near Earth some of them um have orbits that are very similar to Earth and some of them you know have orbits that are closer to Mark or even in intercept Mars and um there's also a a whole bunch there there's a schload of different asteroids out out there and so we can use sort of the strength and numbers there to again sort of look at finding these needles in the haystack so if you have a population of 10 20 000 different asteroids you can start to see which ones come near Earth at the right time and um start to play out okay well it looks like something's going to be very close in 2033 but let's go buy this one but if we happen to not you know get on get on that bus there's another one that's coming in 2013. so you can start to find um you know for each sort of Delta V limit that that you have um where the evaporates lineup and then as you get your Delta V higher as you put more propellant on the spacecraft get the more and more ambitious mission you can start to um get aspirates that are far farther out um you know have longer durations and eventually build up the capability um you know starting with mention suttered what you do at the moon of you know maybe on the order of a month a few things that you need for Mark if you're more in the order of like a year or two so so would you I mean they like drift relatively like as you say they're fairly similar to Earth so once you're in Earth orbit the amount of additional Delta V that you require is minimal like far less than even going to the Moon even though the Moon is right there right yeah you could time things right so you would get sort of a mission of different durations depending on what you're looking for yeah and it's that's also an interesting point um where whereas you're you're also the the other inner theme um characteristic that we that we look at when we look at afterward missions the asteroids them felt are small they're not a big gravitational well which means that um you know it's it's not as much work once we sort of fly by them in order to um land on on them whereas you know when we go to to the Moon as they get very close to them and it means gravity it's going to speed up the the spacecraft so you need to spend more propellant to slow down and so yeah that that's um one of these sort of like one of the many I I already that you get when you look at the the adapter day Dynamics yeah um even though the the aspirate is explained by Earth and not in orbit around or sometimes it's easier to just you know when when you look at the energy perspective of you know let's just you know get the spacecraft on as close to an orbit as the asteroid and then it's kind of easier to close that Gap once you're near it and I guess that idea of the ellipse like because the asteroid is following an ellipse it's moving at different speeds you could have a situation where you catch the asteroid as it's you know you sort of reach ahead reach the asteroid but then Earth maybe laps the asteroid and then you can leave the asteroid again and make your way back to Earth and and not have to use very much propellant at all to make the the journey right yeah and so uh yeah there's a um again but but building up the complications of of the mission so now when we talk about these round-trip trajectory um yeah we we care about um yeah not only getting to the upgrade but then we run a whole series of trajectories from asteroid that that back back to Earth so um you know it works both ways and then we uh once we have these sort of date databases of trajectories out databases the conductory then then we can compare which ones have a date time that is more than zero days and say okay well this is one that looks like it might work for it did you work on The Lucy Mission at all in in plotting that course I did not no okay all right all right I'm just like the I'm I'm very familiar with i i i i with the person who did work work on it um right right yeah but but that like that combination of of seeing a couple of asteroids in the main belt and then being able to see multiple asteroids in one Trojan belt and then a whole bunch more asteroids in the other Trojan belt at Jupiter like that's just gotta feel like an enormous amount of science that could be done comparative science and I wonder like how complicated so I guess when you talk to them how how complicated was this job of of figuring out how to get the most possible science out of these trajectories yeah so um yeah so and if I did discussions with them you know I I also because it was that or is such a cool trajectory um also use that at sort of a test case to own my my own tool so you know I I have the thought for that because I used to develop things and then I see okay well somebody you know has this awesome trajectory let's see if my tool is able to do that oh interesting yeah um the first time you know you run it through it it doesn't it you know it it pops out but then okay well if if I picked up and pick that then then it goes so that's sort of you know how how we build up our our capability we um you know see you know what we'll think that other people are doing and you know like like everybody else they're like hey that's cool I want to try it try it right could I pull that off all right so so your most recent paper and this is the one that sort of had me drop you an email and see if I can interview and we haven't even gotten to that part yet is your were proposing that it could be possible to intercept and rendezvous with an Interstellar object so I mean how extreme are these objects compared to other stuff in the solar system uh I would say that they are the most extreme um you know I I I I've been working uh at Nasa for about 20 years 20 years now and I didn't even conceive that you know this type of mission could be possible even like a few few years ago so the first of these Interstellar objects um it's an afraid called amuamua and um when when it when it came came through it kind of like opened up the eyes to a lot of the scientific community and then that that trickles down to the engineering community because the scientists are like hey there's this really cool classic object out there is there you know how how can we check these things out um and so as as a good engineer you know I've sat down and and think about it a bit and I was like well you know there are we know ways of getting out to the the solar system so these objects the interstellar objects they they come from a different stock they do not originate in inner solar system they're totally new um and so that's you know the draw of them and then the the challenge is you know they don't start in our solar system which means that they're not going to stay in our solar system so they they Zip by and the height I mean very tight on on these things so you know it's it's the opposite of of our interplanetary Super Highway we're you know we're we need to get on an express lane going quick to um wherever this thing going going to be so we we start to put put together different concepts sort of brainstorming um what what what are the different ways of looking at that and um you know we we always start um when when we're doing a new Mission with with the trade space and so I sort of listed out well here's all the different um Technologies you thought I've heard about that that might be but coming around the Horizon and um you know with my background on uh trajectory design it's like well here's to put a handful of trajectories back that I know about let's start to combine the propulsion systems with the trajectory um let's uh talk with the uh astronomy Community to figure out a what types of orbits we do we think these things could be on right now we only have two um board stop but um when we when we reach out and talk to the experts they say okay well here's what the the range of orbits might look like for these things and here's how bright they they might be and so also fully in order yeah this isn't done in in a back team I have to talk to a lot of different experts to sort of see what's going on and then um using some of the techniques that we've developed in our mission concept development here at JPL we go through all the we'll try to look through all the corners of the trade space and see what what pops out and a few different promising art architecture sort of fell out of them well so let's drill into each one of those assumptions that you're that you're talking about so first let's talk about their trajectories so give us a sense like how fast are these things moving and and where are they tending to go through the solar system yeah so they are um they're screaming by at uh so they're they're going by faster than the the Voyager spacecraft have half life so um for for the most part we think in order to to get this type of Mission to work um where we actually catch up to the object they can send um you know a deep amount of time in proximity to it um we need to get a chance cop going faster than the that's in spacecraft yeah so we're gonna have to break out we're going to figure out to break a record um but like well like when I think about like I know like the escape velocity of the sun is like almost what 50 kilometers per second to leave the like the solar system so these have more right yeah they are on an escape trajectory yeah yeah and and so yeah so you so you have to get the spacecraft going even faster than that and so yeah so the the other thing to you know sort of going back to our our classic physics here so yeah Escape Escape speed yeah now you order 50 kilometers per second but that means that when it's very far from the Sun it eventually goes to to zero kilometers per second it you know the potential energy of the gravity of the sun pulls away all that speed now these objects are going so fast that even as they go infinitely away from the planet I'd say you know go to whatever the next star might be they're still traveling that's that several kilometers per second right um yeah so there so you have to kick up even more speed just so that you have enough energy left over as you exit the gravity well of the sun you continue along a course with them and is there any pattern to where they seemingly come from so uh that is a hot topic of of research so um I from what I read and um speaking with with some some of the experts there there is thought to be a um bias towards the direction where where are they coming so there's a a term I I believe I need that it's correctly called the the solar Apec which if if you expand your mind out even more they're not just a solar system but now let's think about the Sun as an individual star in our galaxy orbiting the the Galaxy itself you know sort of mixed in with all these other stars and as a son or orbit there's a um there's a relative velocity of the star with respect of the sun with respect to other stars and so it's thought that the these Interstellar objects might be biased more towards this because it you know you can sort of think of a um you know a boat sort of going through the water you're going to encounter you know stuff you're going to encounter plus them on on the pond in the direction that that you're going within your boat and so and so that and then that toolbox of propulsion systems I mean I'm assuming there's just a plain old chemical rocket isn't going to be quite enough or you just need a really big one right yeah yeah it would it would have to be a really big really big chemical rocket if you were to do it that that way so there's yeah so then we start to look at well what's what different combinations what would work and so yeah we'll start by by looking at more traditional portfolio systems so the tried and true technology is a chemical propulsion we have a fuel we have an oxidizer we burn those to create an energy shoot the exhaust out the back and that's how how you get going um and so that's very um you know as a a very well-known technology that before we start but it takes a lot of propellant to do that the the the my miles per per gallon on that or I guess you know the kilometers per second for per kilogram of propellant aren't um as a good using that and so we we also um have uh been developing what we call electric propulsion systems and so um uh a a good example of this was the Don uh spacecraft which orbited the asteroid Vesta and theory in in the aspirated belt um they're also used you that's propulsion that's there's a lot of propulsions have been falsely used you ubiquitously on communication stuff but like so um you know a lot of GEOS um and so the this is um very interesting and that it's a very efficient from a math standpoint you get a lot of Delta V per kilogram of per pound now the trade-off is that the threat is very low on on on on this particular um former proportion system so you have to do these very long extended um burns like I guess yeah you can call it on work instead of just burning for a few minutes or hours it's months or even years at these things and operate but um when you're looking at objects that are coming from outside to the solar system and if you're spending several years to catch up with them you have the time to use this very efficient form of of protection system which um means that you need to carry less propellant in order to um match that's the uh orbit of of the object which means that you can fit on a smaller launch vehicle in your spacecraft is smaller which means that um you have it it might cost less in in the overall um to do that so you have to look at sort of all steps um was there anything else you looked at did you look at nuclear thermal Rockets uh yeah I I did look look into those as uh as well um and so when when we look at um you know what what might be available in the near term uh we we do think that the nuclear thermal rocket technology will be um available I I I I know that um DARPA the the the the defense um you know research branch is looking to do some some depending on on those um I believe I read in the news yeah I think they're planning to launch one by 2028. with NASA yeah and so um that so so that technology itself I I believe it's going to be a bit available soon now the rub for using that technology for the application of catching up with these objects is on on these trajectories if they take several years um the the issue isn't um with the new nuclear propulsion system itself it's in the propellant so these propulsion system um generally use uh liquid hydrogen as a propellant um there are other options out there but the um I I believe that all the options sort of rely on a uh very cold a cryogenic uh fuel um or propelling in order to make it work and storing um liquid hydrogen in States for years upon n um I I I I I I think that that's that's sort of a push um right are for this particular technology um not so much in in that the the technology itself is um you know Out Of Reach I I believe that we could do that I I don't think that um you know the the policy is in place to develop the technology for that I I believe that they're looking for that for more um uh give me admissions to the moon and Mars and so those you know you might need to throw the propellant for uh a few years maybe three or four years at that most whereas you know the trajectories we're looking at the beginning till our objects are more like pens that we might not actually develop the Technologies for that and so were there any other Technologies you looked at or mainly you you looked at chemical and and solar electric propulsion yeah so so when it comes to the uh electric propulsion yeah so I'm I'm glad we uh yeah you mentioned that and so there's also two flavors of the electric propulsion so there's the electric boxers themselves and those are are more or less agnostic to how they are are powered and so you mentioned solar electric propulsion so that's the technology that um you know we we have today that's that's what's playing but as we go very far from the Sun if you imagine the solar panel don't produce it as much and it's harder to run the Clusters and so the the technology that that I also looked into is using nucleus electrical protein where um so with a nuclear thermal rocket as we were discussing or earlier that uses um thermal energy heat in order to to make the propellant um uh you know you know the the shootout whereas uh you can also use this new nuclear energy to create electricity and um that NASA is looking into or its mission to the moon and eventually marred um to use uh nuclear fission power for the the the power of the um the the on on on the surface so where the uh might eventually land um you know we need that sort of um long duration power source that also happens to give you the same power no matter how far you are away from them so we can bind the nuclear electric power source with an electric Republican Thruster in order to to get um the thrust that that we need even you know out at the distance of net net Neptune and and preclude us to catch up um and and eventually get into close proximity to anything so what did you conclude when you sort of looked at all of the trajectories that you made have to follow and all of the technology that you have to work with to solve this engineering problem what what solution did you come up with yeah so um you know they're a a a good engineer always has plan complain Plan B so um there's you know it sort of depends on where you know the technology development goes in the next few years but if um you know NASA continues to develop this nuclear power source I do think that's the best bet um in in order to do this which I also I I I really like this and this sort of parked in fact even when I was doing my my gr my graduate or looking at what how how can we leverage the technology that not to uh investing in to make you know student exploitment space possible leverage those Technologies to also help out the the inner interplan interplanetary correlation um using robotics based happening so being able to leverage this this power source in order to for interplanetary for trajectories I think that um allows us to make a a spacecraft that um uh doesn't um you know for the for the size of the spacecraft it'll be able to reach the widest variety of of of the interstellar objects um yeah so my my uh analysis point out too um 2025 to up to 40 of the objects that come through if you do have nuclear electric propulsion Technologies you'd be able to Rendezvous with them stay stay in close proximity um if if we don't have this um you know that that technology um for example it becomes too difficult to transition it from surface power to powering a a spacecraft then um we sort of go back to um I guess you know I call like more of a Brute Force where we did throw a bunch of chemical propulsion at it launched on a larger launch vehicle so there we have to Leverage The Investments and like the the SLS which you know decided to make mainly play you know with months ago um or perhaps it's actually Starship one of these giant rocket might be able to help with that um I I will mention one of the interesting things that I I found out um it also it's not just the technology but it's it's how you you use it and I also found that um where we staged the the Rockets also um not something to play and uh in in the case of an Interstellar object um I I do I I advocate first launching the spacecraft to Earth orbit and have it weight in in Earth orbit um with with what they pick stage so that once you actually observe the object you're already launched from Earth you're right ready to go and it takes only a few months to sort of line up the trajectory so that when you do your pick stage out for her you can um you can catch up with the object and the the reason there is um there's a very short window of only a few months between When You observe the object and when it um going to eventually you know go through the inner solar system and turn off the way out for you um really need to be on on the ball um you know you can you'll have to wait until you think it comes in and this is similar like I know the European Space Agency is developing an intracellular object interest Interceptor this is something that would weight at say the L 2. for some object that's on an appropriate trajectory and then it'll attempt an intercept but not a rendezvous not go into orbit and collect data over the long term but just do a quick flyby and take some pictures and send them home which is dramatically different so so let's kind of put this together then sort of in your imagination uh and you know we know that that NASA has no plans currently to to send a mission like this but you know just in our imaginations what would this Mission look like it's like someone has approved okay yeah we do want to Rendezvous with an Interstellar object how does this work then a spacecraft is a chemical or talk me through this right yeah so um yeah the the you you started off with step one is you know to get uh the policy makers interested in yeah unanimously yeah yeah it's not I'm off road you know no no bugs no but but Rogers so so we we we start there and then um you know uh we we sort of you know which which technology we want to push to to be the developed and so if we follow this nuclear electric propulsion path we um we we start to look at okay well what what what what if anything do we need to do to retrofit these surface power reactors or um use in in phase and so we we start to do that technology development on the on on the ground um the the other thing that we do is we start to again negotiate with the the policy makers on things okay we want to build a spacecraft but we don't have a target for it yet we have a type of Target and um the the depending on what we find so the uh there are ruin of Reuben Observatory and um getting the first light yeah um and so if if we start to see these objects come coming by you know like maybe once a year once every other year then we have some confidence that once we do build the spacecraft we'll have you know something to to to to go to and so we we build up the consensus that that way that okay the mission's worth doing so that's sort of you know the first thing is to get the people on board and then uh and and then we um you know do the sort of nuts and bolts in engineering we developed the the fifth graph we build it um and then we launch it from Earth I I I recommend um putting it again into the sort of higher orbit um better so this is an orbit that would intercept um the the the the the moon but not um you know not not until we actually need it to so it it'll allow it'll go other than the moon but then come in and you know and it's also um not trying to in or going through the the radiation development at Earth so we're able to keep it safe um in in orbit for a while and then we we wait um we we we wait until the very Reuben Observatory it says okay here's an object coming in oh look at this it looks like it has a tail let's get everybody to look at it and say okay well what's going on this is a comment and then um we get all the um the uh observers around the earth to look at it you get a fit on on the orbit the first time you you see an object that the fit with the orbit generally very poor like we don't know um how close it's going going to get to the Sun and even less um you you know sort of what time the the department the timing of everything is going to be so you you look at the comic for a a couple of months um did a trail on it and then um once once you sort of know what the orbit of the the comet is you compare that to the capability that you built on board of your spacecraft if if it looks like it's the go then um you know you go to someone like like myself or somebody in my good to run the trajectory we'll say okay well here's here's what we need to do and then once um we we calculate the the right time to launch it's usually sometime near that kind of hit billion um we do the the burns are they're going we turn on our nuclear electric bulking system have it slowly nudged towards the the the the the the comet um the the the other thing that um is really enabling for this is um are getting back to get a regarded system from Jupiter Jupiter as you know it's the largest planet in the solar system that also does driving itself engine in the bullet system so we um have the spacecraft actually applied by Jupiter first um even if Jupiter is a bit out of the way after you apply by Jupiter will print it so that you are now going on the way um the the comment um continue to have your electric propulsion system nudging it and um 10 to 15 years at after launch we're able to get in proximity with it and and um you know get up quotes and personal and see what's going on but and that's the time frame you're thinking like 15 to 20 years of chasing to actually catch up to it yeah um yeah I I limited the the search to a map of like 20 years um they thinking that sort of thing about what are the um you know the current limit limitations of chasecraft and actually not as much of limitations the qualifications to be able to survive um and so yeah it it turns out that you know uh I think 10 10 to 15 years is probably a good time frame if if you really want to be able to have a good chance of running and it feels like there's overlap in in this idea and some of the other missions that are being considered like there's this idea of the interstellar mission that NASA is considering to send a spacecraft out into essentially the same environment to examine what's outside the the the close what's outside the inner solar system and so you're looking at like getting out to say a thousand astronomical units and then the other mission of course is to try and get out to say the solar gravitational lens which is at about a thousand astronomical units so it feels like there's a lot of overlap you could probably do a bunch of related research with one mission yeah that's um you know that that's one of where things get fun is where you look for um yeah so we call it sort of opportunistic but the clients so you know you you have a mission doing one thing but you know on on the way out we we see that uh yeah it's eventually going to be out if you get to it without an Anu let's let's make sure you know it might not be that much of a Delta cost to add an instrument that does sort of the particles and Fields that you want to do out there or or to get in imagery if you do get out to the um the particular solar uh gravity lens um you can also do really interesting finances on the way out as if you're going to look for um there's a um that's a special class of comets called fenpard that or orbit um out outside the orbit of Saturn based sort of inside the orbitals Neptune because they're going through there if you have a a good uh camera on you can sort of start to look for different objects yeah it's really interesting um what about a sample return did you do the math on what it might take to be able to bring a piece of an Interstellar object back to home um yeah I I did look into that a a a a bit um and so uh again you know getting the the sample home is sort of you know what you just have to do what you just did in in Reverse so if it takes place um 10 to 15 years to get out there it's going to take about that long to get back so now we're looking at like a 30-year mission to propellant goes way up because um yeah the the uh um it's an exponential push on how much propellant you have so so basically all the propellant that that you need to return the sample back that is all going to multiply the time to get out because you have to carry all this extra math what I do think would be a a feasible way of getting a sample um is is to do what what we did for uh the startup um Mission which um I think that's probably about 20 20 years ago now where we had a spacecraft fly by a comment we used to capture particles that were coming out out of that Comet um and so I I think that we could do a flyby Mission so so I I think the best way to get a sample back to Earth of an Interstellar object is um instead of landing on it and getting a big big sample to do a flyby if it's um of an active object get some of the sample that's for the material that's naturally um coming off the the surface and have it on on again one of these resonant trajectories so that when it applies by the comments in resonant with Earth back to Earth it's like Dart where you where you impact it release a cloud fly through the cloud gather the samples and then bring that back to Earth yeah yeah so so dark yeah the the the the dart um of approach for a non-active object would be great yeah you make a plume light through the plume that that always comes up as um you know one of the ways to try to get something off the surface especially if you want to get something that's not just scratching the surface of of an object if you have an impact or it can it can push stuff up from a few meters deep do you when you think about orbits just in the Milky Way itself I mean obviously now we're shifting deeply into science fiction land are there any interesting trajectories that we could use I mean if power was no obstacle if budget was no obstacle you know could we use these these methods either the slow moving ways waiting for stars to get close to Earth or finding rogue planets in between or dwarf stars in between us and other places um or maybe doing gravitational assists with black holes like can you expand out what you've mastered for the solar system to the Milky Way to understand yes I mean the physics for the most part still holds so you know we we can use we use the same equations you know to to work yourself through a complex gravity field around a planet as you would become to navigate through a complex gravity appeal than a Galaxy um and and we we actually um did what look into this a little bit we we gave ourselves a toy problem since September years ago it's all the trajectory nerds County myself has had one of them um and every few years we we put out a um a problem we call it the global trajectory optimization competition and that's cool yeah yeah um G Talk for short so yeah if you can Google gtoc and you'll you'll find it uh one of the um one of the problems that that we worked on was how could you eventually um see the solar system with spacecraft um and and and so the equations you know we were able to use some of our tools for that um where things do get interesting so you mentioned you know um doing like a graduate system off of a a black hole so once you're doing that you get the relativistic of vaccine so um you know I I personally haven't looked at that since grad school um because you know we never really need it for the day the day-to-day but yeah we can certainly take an advantage of of those things and to some extent like we we do to in order to navigate that spacecraft that we're navigating now we do actually need to take into account relativity because you know the time you know runs a bit slower you know depending on where you are in the gravitational field which means that um you know if if the clock on the spacecraft is going different than your clock clock at Earth then things are going to be up and so we account for for all of that so um most of the physics required for as you mentioned that's sort of Interstellar exploration is in in our toolboxes now it just hasn't been you know exercised to the extent does your software handle it nicely if you plot a a gravitational assist near a black hole or does it uh does it kind of freak out at you it it would produce a solution but it would produce the wrong one yes I don't have all the relative effects but I wonder like I think about like if if Humanity lasts for tens of thousands hundreds of millions of years then time starts to be on our side again and you think about stars getting closer and farther to the Sun that there are opportunities to to hop from star to star if you're willing to be patient just wait 70 000 years and you can you can reach in here by star because it's going to come close to us yeah yeah and so that yeah that's you know that's a very similar idea of what we're discussing before about the asteroid you know there are there are asteroids out there that every once in a while get near Earth and you know we wait for them to come um you know it once we start to think about things on more of a galactic time scale it's the same thing sometimes Stars come come near near Earth and and you know if we're talking about trajectories that last thousands of years then you know we went to take that into account as as well you know it's it's it's it's the traveling salesman problem but you know everything sort of move moving around right yeah totally uh well Damon it's been a fascinating conversation um if people want to follow your work what's the best place to do that oh um that's a good question uh scholar that's good good I I recommend that that's why you're getting scientific papers done and and so keep it that way yeah awesome well thank you so much for taking the time to chat with me today uh I look forward to that mission and when it does get approved will you let me know oh you'll you'll be the second person to know after me perfect all right thanks Evan you're welcome you can get even more space news in my weekly email newsletter I send it out every Friday to more than 60 000 people I write every word there are no ads and it's absolutely free subscribe at university.com newsletter you can also subscribe to the universe Today podcast there you can find an audio version of all of our news interviews and Q and A's as well as exclusive content subscribe at 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Channel: Fraser Cain

Views: 28,595

Keywords: universe today, fraser cain, space, astronomy

Id: PxYecl2QvT0

Length: 69min 13sec (4153 seconds)

Published: Tue Mar 07 2023