A cool little tidbit on the 5 day data windows that each spacecraft have to talk with earth for you. While it is of course possible to do the mission as stated in the video, this means that one of the spacecraft could be up to 10 days out of contact with Earth. This would violate the requirements for "low-latency" measurements needed for that example shown of LISA predicting a merger hours or days before it is visible to LIGO or optical/radio/x-ray telescopes. To solve this, the optical links that perform the picometer distance measurements, yes picometers over 2.5 million km 😉, also transfer data. They do this by piggybacking on the system that is used for absolute ranging measurements needed for giving the initial conditions for the noise reduction pipeline. This system uses PRN code tracking, like an optical version of GPS. Like GPS, you can do funny things with modulations on modulations. This provides a data link, like a "local network", between the spacecraft. It allows a transfer rate of a whopping 78 kbps... This is actually fine, since the LISA measurements are made at 4 Hz! It is designed to be sensitive to waves of up to 1 Hz so this is more than enough. With this optical data link the spacecraft all do a sort of Dropbox like sync folder thing with the spacecraft currently talking with Earth, and thus, 1 hour latencies (or lower) are possible! Source: Me, one of the tech leads on the scientific payload computer that does this 😁.
Oh, also, the UV light on the test masses are from LEDs, not lasers. Though it makes no practical difference really. LEDs are just easier and you can buy them in the right wavelength from companies that sell them for killing germs 👍.
I would be very interested in knowing how long it would take to re rotate the spacecraft for earth communication. Or in other words how long the „measurement blackout“ for said operation would be.
@@arctrix765 Good question, this I do not know specifically. However, it is somewhat irrelevant since any movement will interrupt the science measurement, which would create a discontinuity in the observation run. While I am sure this is not catastrophic for some particular types of measurements scientists want to make if the realignment was fast (< a few minutes), it could be for others. Since we are trying hard not to mess with it at all, since we don't even know the full gamut of what we are hoping to detect yet... we are designing the system to measure for the longest length runs possible. Any movement at any time for any length is to be avoided if at all possible, which with this system, it is!
Level of technical precision it takes to do this is frightening! The logical part of my mind says, "Cool! Can't wait for the data to come down." The emotional side of me says, "What? They can filter a signal from all that background noise? That's completely nuts!!"
It's hard to exaggerate just how precise the measurements in something like LIGO are. It can measure changes in length that are 1/10000th of a proton in size. Not in absolute terms, but periodic relative changes in some frequency range after filtering, but that's still insane.
@QuantumHistorian I can wrap my mind around, LIGO. Ridiculously high precision static facilities monitoring phase shifts of lasers. Facilities on a scale that you could walk around in an hour or two. I get that... But a constellation of three satellites spaced eight light seconds apart, monitoring their relative distances with an accuracy of ~10^-12 m?! WOW!
Fun insider/nerd fact from 20+ years ago: my colleague who was working on the attitude control system/gnc for LISA (an early design at the time) was finding the performance requirements especially challenging, and in particular the simultaneous need for very accurate position _and_ speed estimation. And he got to wonder: are those specs even physically meaningful? So he worked out how far these were from the Heisenberg uncertainty principle. It turns out, there were still a few orders of magnitude of margin. But not that many. That's a very roundabout way of bridging the gap between general relativity and quantum physics:)
@@_MaxHeadroom_ there's a key principle in quantum mechanics that you can't know the position and velocity of a particle with arbitrary precision at the same time. At some point, it's a trade off, and you can only refine your knowledge of position at the expense of more error on speed, and vice versa. The funny bit here is that my colleague was applying this to a macroscopic system, not an elementary particle, and verifying that when multiplying together the ESA requirements for positioning accuracy and velocity accuracy, he was still within the limits prescribed by the uncertainty principle. He was, but not by a lot (at least compared to what we are used to dealing with in other space projects)
It's such a bonkers mission. The problems it has (ie, inertial positioning) are so difficult, that even the solutions they have to it were orders of magnitude beyond state-of-the-art when they were first proposed. That the pathfinder actually worked and they'll go ahead with the full thing is an incredible technical achievement.
Scott, this was a PHENOMENAL video, from a layman's perspective, you did an amazing job at making the complexities REALLY relatively easy to understand, without dumbing it down. Should be proud of this one and much appreciated from a long time subscriber and fan!
Yeah the programmers for this spacecraft's computer probably don't just copy/paste random code they find on Google like I do. I bet they even understand most of the code they're adding in this thing... lol
I'm glad that there are people with the mental fortitude to take on these problems. Just listening to the things that need to be solved to gather measurements of this kind makes me want to throw my hands up in the air and suggest we go back to eating bananas in the trees.
@@Alfred-Neuman I was smugly thinking to myself just recently how well I'd written a complicated piece of control software... Then I read this and suddenly I feel like an utter noob. While I'm rationally convinced they can pull this off, there's still a part of my brain that thinks it's impossible. Truly amazing!
LISA is for the European Space Agency what the James Webb Space Telescope was for NASA: a mission so technologically ambitious, entire systems had to be invented from scratch to make it feasible. Here's hoping it'll be just as successful!
Personally, I wouldn't call Webb a success. With the time and budget over runs, it's a project that never should have been completed. A lesson NASA and their contractors never learned, which has lead to all the problems with SLS and Starliner. Here's to hoping LISA doesn't have the same complications.
@@enadegheeghaghe6369 Not in my book. If we can't do it efficiently, it's a failure. That attitude has already lead to further problems, SLS is just the tip of the iceberg. We're in a race with China and they're kicking our ass on many levels with a smaller budget. If we don't make changes, China will pass us and the set goals will never be reached.
Lasers from 2,5 million kilometers aimed at a 30cm mirror. I don't know what is more bonkers. That precision or the nanometers and micrometers per second velocity changes inside the devices. Sounds like a ASML EUV Lithography device in space.
Scaled down it compares to hitting the sharp point of a nail across the atlantik. Just free floting while balancing the inner free floating masses and the outer disturbances and keeping track of all the disturbances. Mind boggling
@@Metenos Hmm. Well, lasers are just lights, so it seems like having less precision would work better (think a spreading flashlight beam). You just need enough photons hitting the reflector to be discernable from background sources, which should be easier to filter given the precise wavelength band.
A working spacecraft late is better than a brick on time. Hard to understand unless you're in the business, there is not much room for error in these systems.
@@colinbrown4903given that Scott has a very slight cleft chin it has to be one of the two with beards and no glasses. My bet is the one with the leather jacket on the left
It's nice to see LISA finally happening. I think I first heard about it during my PhD, maybe first post-doc IDK. I do like that ESA does seem to do these quite unique missions like LISA, GAIA, etc. that seem really quite niche but really are revolutionary in the science that they enable.
It helps when you have budgets that do not rely on election cycles 😉 I've read about LISA (maybe it was different name then) when I was in Grade 5 or so in Astronomy magazine. More than 30 years ago! I would love to see it fly.
Thank you for this video, Scott! I am eagerly anticipating the LISA mission for about 10 years already and this video is a gift and a marvel for anyone who is exited with gravitatinal astronomy. Cheers!
Hands down the best commercial interruption in a while. "That's great, because you can make audible chirps from the gravitational wave signals------". 🎶 Heavy dubstep advertisement 🎶
Physicists are going to have a field day with the data from something like LISA. Just studying the ineraction of the planets might bring on some interresting discoveries. You're studying the fabric of the universe. Amazing.
I thought of doing something similar many years ago. My idea to use Lagrange points was very naive and would not have worked. I forgot the simplest thing, that all things are moving in space as your video shows. I guess you could stop completely if you got far enough away from most masses, but then you might be out where Pioneer is, with long comm times. I did get the part where it had to be huge. Great video, glad people came up with real solutions.
Great video as always Scott! I am doing my PhD on LISA science, it's nice to see people talking about the project. There's a lot of very cool stuff both on the engineering and on the science sides. You didn't even have time to mention my favorite thing about LISA: it might be possible to detect a gravitational wave background of cosmological origin with it (think CMB, but instead of microwave radiation it's gravitational waves, and instead of coming from the recombination epoch, it comes from all the way back to basically the big bang). This would allow us to see evidence for crazy things like cosmic strings, phase transitions in the early Universe, and cosmic inflation. Right now it's looking very difficult if possible at all, due to all the sources of noise and other signals piled on top, but it's an enticing possibility.
Test-drillings for the Einstein-telescope are currently taking place right next to my house in the border region between Belgium, Germany and the Netherlands. Great to see you cover this topic Scott!
Definitively most interesting mission. I was tracking it since early 2000s, and was worried they will never get proper funding, or solve all the issues in my lifetime, but finally we are going, and everything looks feasible. So awesome.
When I first heard of LISA, I wondered how the positional accuracy would be achieved between free flying spacecraft but never researched it. The test masses, filtering out of band signals and "rate of change of the change" are very clever.
@zacklewis342 They've spent about 30 years planning this. All the detailed engineering that Scott goes into in this video showcases a lot of PhD theses by some amazing people. The level of detail is incredible.
This is some next level engineering right here. The precision required to just make this stuff work is insane, but then to maintain this precision throughout the missions life really boggles the mind. It makes the super heavy catch look like child's play LOL.
It's not really engineering - it's physics. Engineering is about building useful things. Physics is about measuring things. While these experiments have limitations imposed by our current engineering techniques, it's the physics part that tries to side-step these limitations and still get the measurements required. Super heavy catch is definitely about engineering, and very useful one at that.
this is the coolest telescope ever. someone should write a sci-fi story about how when we turn it on we suddenly receive an alien message encoded in gravitational waves
wow, just wow. every time i thought i had gotten the full idea, something came up that i didn't think about.. like moving the antennas and their impact on the measurements. a truly monumental technical achievement, this experiment is.
Very cool. This reminds me of a NASA proposal to build a giant pinhole camera out of two free-flying spacecraft, one of which would have the collection sensor and the other would have the "pinhole" aperture to focus the image on the first. The idea was that they'd be able to see extrasolar planets in enough detail to make out seas and continents. Each spacecraft would have to flown extremely precisely in order for the two to aim at distant point subjects. I think it was an idea from the late 90s that never got funded.
Fascinating stuff! I’m amazed not only by the precision and complexity of the system, but by the fact that equipment of this sensitivity can be launched into space without destroying it.
The extension of observation into the infra-red, X-ray and gamma ray, and now gravitational wave and cosmic ray regimes makes this a golden age for astronomy, yielding mind-blowing science. Multi-messenger astronomy has already profoundly influenced our understanding of nucleosynthesis and promises deep new insight into the nature of universe.
A few years back I had a look at this for my MSc dissertation (asking the question of what would be needed to see different frequencies of gravitational waves). I wasn't involved in LISA itself at all, but it was wonderful to see the amazing science behind it all and take a real deep dive on it
How would it help us pin down the kind of particle that makes up dark matter? Would axions leave a different kind of gravitational waves signature than WIMPs or something?
@@petergerdes1094My professor said that primordial black holes are a better, more likely theory for dark matter, and this is something he said LISA was going to help find
The test masses are really cool. Reminds me of that episode of Stargate SG-1 where they pull a space mine into their ship's hull and have to pilot the ship to keep the mine relatively stationary so they can work on it... The whole mission is really cool and I don't want to wait 11 years for it to launch. If we're ever going to stumble across new theories of astrophysics with potentially civilization-changing results, it's going to be these sorts of missions that do it.
Just wanted to say this was one of your better videos. Concise and to the point but enough to inform someone who's not familiar with the subject. I appreciate a lot of your videos, just found this one to be among the better ones.
The comment on the electric thrusters is wrong, they expelled droplets of a polarized colloidal fluid accelerated by a high voltage. The FEEPs didn't make the cut in the end, but you got the company right for the colloids!
This is so cool! The amount of amazing engineering and physics that goes into this is wild, and the scientific purpose is awesome as well. Thanks for this video, Scott!
One engineer is not the other. Is simpletons can only ask, couldn't you? And the smart ones awnser, good idea, yes we can. Doing stuff in their head, I can't do on a computer. Many sorts and levels of engineers.
Proud to say I’ve worked on the bid for LISA. The accommodations of the equipment and the technology used is so challenging and incredibly cool. This is going to be such an amazing mission.
It's not about "space race" -- this is about science. NASA funding is not predictable enough so they withdrew from these long term projects. ESA funding is mostly secured and away from politics.
If we had better launch vehicles, these types of missions could have been a lot more frequent and ambitious. Trying to close the edge of physics instead of improving the basics is really impressive, but also myopic.
@@hardopinionsThe space race is about science and I'm not sure how you can pretend it's not, specially seeing as if it never began you wouldn't see any funding, or the infrastructure capable of launcing these instruments into space today. ESA barely has any launch hardware of their own even today.
15:43 I wonder how bad idea would be to have a 4th spacecraft being like a communication center - let each LISA use some short range communication only between and with that 4th one, and let it handles long rage talking.
better idea: make it 4 identical craft, each capable of all roles (measuring together with two others, short range comms between them, long range comms to earth), and let one of them handle the earth comm part, and the other three do the measurements. in case one cannot perform its assigned task because a system failed swap the craft around. also the short range comms should be redundant, cause with this approach its the weakest link.
The problem is the launcher constraint of mass and volume. Adding the fourth data relay spacecraft is not efficient and does not leave enough resources for the science s/c.
If LISA's successor is built as a tetrahedron, it should be able to provide direction of source and some redundancy and error correction. Around year 2050
This was a great video it was greatly appreciated and discussed by LISA scientist on our regular conference call today. I cannot tell you how valuable it is to have a content creator tell the world about what we are doing it the way you have. I have personally thought of LISA in very abstract and theoretical terms. What it can or can't possibly measure and how we will learn about fundamental physics from it. I never really thought of how big of an instrument this is going to be really.
I love how the test masses are a gold platinum alloy, like was that really necessary? I'm sure there was a legitimate engineering reason for that, but it just sounds like they were trying to see how expensive they can make a brick and that's kinda hilarious.
In today's world, I would argue that engineers are the true geniuses. It's like they are making machines that can perform magic. JWST is a excellent example of this. So complex, yet Ariane got to it's deployment position and deployed so well it gained over a decade of performance-lifetime. These machines surpass advanced scientific math. Another example would be ASML's EUV lithography systems able to produce chips at atomic-scales. One company in the world possesses this technology, thanks to its engineers.
It is definitely an inextricable partnership. Scientists need to figure out specific ways to prove their hypotheses that are implementable, and then the hard work of the engineers starts in finding clever ways to achieve that. But I do agree that in most of these situations the engineers end up doing the vast majority of the hard work
I think that is an unfair assessment. Engineering and theoretical sciences are two different disciplines, to argue that scientists can't be geniuses because they need engineers to test their hypotheses seems very narrow-minded. What does it even mean to surpass maths?
Your all overlooking the trained and certified technicians who do all the assembly, testing and validation before they hit the pad. The scientists are not allowed to even touch the unit, mostly because they are idiots.
Thank you so much for this video. Every time someone mentions LISA, i have always wondered how they were going to accurately measure "drift" between the satelites
Would it not make sense to fly 4 satellites in a tetrahedron to get resolution in every direction? I would think that the satellites have a blind spot perpendicular to their plane
Had a thought the other day… With starlink satellites now using a laser communications, would it be possible to ‘see’ gravitational waves by analysing the data of ping round trip times between the nodes? It would be significantly less accurate? ..but there’s thousands of nodes and in a sphere! Doesn’t match the scale of Lisa though.. ?
I made the SAME comment just -12min before- _20mins after_ yours! 🤣 _[edit: YT comment timestamps didn't update correctly until I clicked into this thread]_ Since yours is getting more traction, in case anyone might know, I also asked if using GPS's crazy accurate timing would he possible, or if it *needs* to be optical?
I think the path time between the individual satellites might be too short for starling. Something that goes unsaid in the video is that the laser isn't only bounced once down the arm to pick up the signal. It gets a bit complicated with optical cavities but I think the mirrors bounce the laser back and forth a few hundred times for it to be effected enough... Gravity waves have a very light touch
@@Twitchi If LIGO can get away with 4km arm lengths, I see no reason why satellites even in LEO will struggle with arm length challenges. They will however need to account for various external factors that influence the satellite distance relative to each other which would be especially challenging for satellite in LEO as tiny sliver of atmosphere actually does exist there and drags the orbit of LEO satellite back down to Earth; which I think would be the reason why it won't be able to detect Gravitational Waves as the output data would be severely polluted, even if in theory it *might* be capable of it.
@@stayfrost04 but that's the point I was making.. LIGO is 4km, but it uses something called a Fabry Perot cavity to bounce that laser back and forth down the arm many times.. Its hard to say how many as its a resonance chamber like a laser that superimposes the signal back on itself until a certain power is reached.. But the effect is to lengthen the arms several times, tens if not hundreds of times.. making that 4km into MUCH more
Wow, these is so much science and engineering and math involved. Teaching about the craft would be a cool way to introduce students to these principles with a real world application.
2:51 I was listening to the video in background, and after creating anticipation for the audio chirp YT trolls me switching to a fashion ad with electro-ambiance music. And I'm like: WOOOO!
Imagine putting 3kg gold-platinum alloy blank in your CNC. And setting 0 incorrectly lol. Also you would probably buy new machine just for this. The price of chips would offset the cost :D
@@richhyde4834 Cool! I knew that Gravity Probe B used a inertial reference mass, but hadn't realized that the GPS satellites used them. Do you have a reference for that?
@@kalmanbalazs While I have not watched Eraserhead that is not a match for any of the t shirts I can find nor does it look like the usual Eraserhead shot I have seen many times.
This is probably the greatest technological and engineering marvel ever created by humans. Not even by shier complexity, but the diversity of engineering that went into it.
@Scott Why do we need 3 Sattelites or why do we need 4 Sattelites around the sun? do we do a "quadrat" that changes in plane, but then you can do it with 2 additional sattelites^^
The internal gravitational requirements of the three individual probes reminded me of the complex rotating super-dense masses that had to be used in Dr. Robert L. Forward's outstanding hard SF book "Dragon's Egg." This is really fun stuff that we are embarking on!
A cool little tidbit on the 5 day data windows that each spacecraft have to talk with earth for you. While it is of course possible to do the mission as stated in the video, this means that one of the spacecraft could be up to 10 days out of contact with Earth. This would violate the requirements for "low-latency" measurements needed for that example shown of LISA predicting a merger hours or days before it is visible to LIGO or optical/radio/x-ray telescopes. To solve this, the optical links that perform the picometer distance measurements, yes picometers over 2.5 million km 😉, also transfer data. They do this by piggybacking on the system that is used for absolute ranging measurements needed for giving the initial conditions for the noise reduction pipeline. This system uses PRN code tracking, like an optical version of GPS. Like GPS, you can do funny things with modulations on modulations. This provides a data link, like a "local network", between the spacecraft. It allows a transfer rate of a whopping 78 kbps... This is actually fine, since the LISA measurements are made at 4 Hz! It is designed to be sensitive to waves of up to 1 Hz so this is more than enough. With this optical data link the spacecraft all do a sort of Dropbox like sync folder thing with the spacecraft currently talking with Earth, and thus, 1 hour latencies (or lower) are possible!
Source: Me, one of the tech leads on the scientific payload computer that does this 😁.
Oh, also, the UV light on the test masses are from LEDs, not lasers. Though it makes no practical difference really. LEDs are just easier and you can buy them in the right wavelength from companies that sell them for killing germs 👍.
Thanks for this very interesting and informative comment
Great, thanks for the insider insight. Kudos to you and the team. This seems like a nearly impossible mission.
I would be very interested in knowing how long it would take to re rotate the spacecraft for earth communication. Or in other words how long the „measurement blackout“ for said operation would be.
@@arctrix765 Good question, this I do not know specifically. However, it is somewhat irrelevant since any movement will interrupt the science measurement, which would create a discontinuity in the observation run. While I am sure this is not catastrophic for some particular types of measurements scientists want to make if the realignment was fast (< a few minutes), it could be for others. Since we are trying hard not to mess with it at all, since we don't even know the full gamut of what we are hoping to detect yet... we are designing the system to measure for the longest length runs possible. Any movement at any time for any length is to be avoided if at all possible, which with this system, it is!
Level of technical precision it takes to do this is frightening! The logical part of my mind says, "Cool! Can't wait for the data to come down." The emotional side of me says, "What? They can filter a signal from all that background noise? That's completely nuts!!"
It's hard to exaggerate just how precise the measurements in something like LIGO are. It can measure changes in length that are 1/10000th of a proton in size. Not in absolute terms, but periodic relative changes in some frequency range after filtering, but that's still insane.
@@QuantumHistorian Like measuring the distance to Proxima Cen to within a human hair's width variation. 🤯
This *is* physics 🙂 The science of measurement.
" Level of technical precision it takes to do this is frightening! " did we not say this before Hubble was launched....
@QuantumHistorian I can wrap my mind around, LIGO. Ridiculously high precision static facilities monitoring phase shifts of lasers. Facilities on a scale that you could walk around in an hour or two. I get that...
But a constellation of three satellites spaced eight light seconds apart, monitoring their relative distances with an accuracy of ~10^-12 m?! WOW!
Fun insider/nerd fact from 20+ years ago: my colleague who was working on the attitude control system/gnc for LISA (an early design at the time) was finding the performance requirements especially challenging, and in particular the simultaneous need for very accurate position _and_ speed estimation. And he got to wonder: are those specs even physically meaningful? So he worked out how far these were from the Heisenberg uncertainty principle. It turns out, there were still a few orders of magnitude of margin. But not that many. That's a very roundabout way of bridging the gap between general relativity and quantum physics:)
got to love the long term planning - 20 years ago control was being worked on , with science operations concluding perhaps 20 years from now ...
Can someone ELI5 what this means for someone of average intelligence please?
@@_MaxHeadroom_ there's a key principle in quantum mechanics that you can't know the position and velocity of a particle with arbitrary precision at the same time. At some point, it's a trade off, and you can only refine your knowledge of position at the expense of more error on speed, and vice versa. The funny bit here is that my colleague was applying this to a macroscopic system, not an elementary particle, and verifying that when multiplying together the ESA requirements for positioning accuracy and velocity accuracy, he was still within the limits prescribed by the uncertainty principle. He was, but not by a lot (at least compared to what we are used to dealing with in other space projects)
@@andytroo Not so much long term planning. More like science being the bastard child and doesn't get proper funding.
@@_MaxHeadroom_nothing to do with intelligence mate, you’re here curious about this stuff just like everyone else, so cheers.
It's such a bonkers mission. The problems it has (ie, inertial positioning) are so difficult, that even the solutions they have to it were orders of magnitude beyond state-of-the-art when they were first proposed. That the pathfinder actually worked and they'll go ahead with the full thing is an incredible technical achievement.
Scott, this was a PHENOMENAL video, from a layman's perspective, you did an amazing job at making the complexities REALLY relatively easy to understand, without dumbing it down. Should be proud of this one and much appreciated from a long time subscriber and fan!
The scientific and engineering knowldge involved to make this work is just incredible.
Yeah the programmers for this spacecraft's computer probably don't just copy/paste random code they find on Google like I do. I bet they even understand most of the code they're adding in this thing... lol
@@Alfred-Neuman “ most “
The science seems way simpler than the engineering, in this case.
I'm glad that there are people with the mental fortitude to take on these problems. Just listening to the things that need to be solved to gather measurements of this kind makes me want to throw my hands up in the air and suggest we go back to eating bananas in the trees.
@@Alfred-Neuman I was smugly thinking to myself just recently how well I'd written a complicated piece of control software... Then I read this and suddenly I feel like an utter noob. While I'm rationally convinced they can pull this off, there's still a part of my brain that thinks it's impossible. Truly amazing!
LISA is for the European Space Agency what the James Webb Space Telescope was for NASA: a mission so technologically ambitious, entire systems had to be invented from scratch to make it feasible.
Here's hoping it'll be just as successful!
Personally, I wouldn't call Webb a success. With the time and budget over runs, it's a project that never should have been completed. A lesson NASA and their contractors never learned, which has lead to all the problems with SLS and Starliner. Here's to hoping LISA doesn't have the same complications.
@@ADAMJWAITEWeb was launched and is functional. That is a success
ESA is also part of the JWST collaboration. NASA was also a Part of LISA until they bailed out due to funding limitations.
@@enadegheeghaghe6369 Not in my book. If we can't do it efficiently, it's a failure. That attitude has already lead to further problems, SLS is just the tip of the iceberg. We're in a race with China and they're kicking our ass on many levels with a smaller budget. If we don't make changes, China will pass us and the set goals will never be reached.
NASA and ESA collaborate so frequently, at times it's difficult to differentiate one from the other.
Lasers from 2,5 million kilometers aimed at a 30cm mirror.
I don't know what is more bonkers. That precision or the nanometers and micrometers per second velocity changes inside the devices.
Sounds like a ASML EUV Lithography device in space.
THIS!
Scaled down it compares to hitting the sharp point of a nail across the atlantik. Just free floting while balancing the inner free floating masses and the outer disturbances and keeping track of all the disturbances. Mind boggling
The video at 15:27 looks like the laser is big enough to hit the other spacecraft completely. Still a crazy precision needed though.
@@Metenos Hmm. Well, lasers are just lights, so it seems like having less precision would work better (think a spreading flashlight beam). You just need enough photons hitting the reflector to be discernable from background sources, which should be easier to filter given the precise wavelength band.
haha ikr
There's people in my lab working on LISA, so nice to have you talking about it :D
It's such a cool project !
Why it can't be launched in 2030, what's missing?
Tell them to hurry tf up. Taxpayers time.
So officially, is it LIE-ZUH or LEE-SUH? 😅
(not poking fun at Scott, I'm sincerely curious)
A working spacecraft late is better than a brick on time. Hard to understand unless you're in the business, there is not much room for error in these systems.
@@DUKE_of_RAMBLE Your second guess is closest. The "i" is pronounced more like i for interferometer
I love stuff like LIGO, it is so sensitive it detects trains KM away. They actually keep track of the train schedule so they know false reading
The most precise measuring Instrument to detect train delay humanity has developed yet.😂
@@torstenmautz195ahh you must be a fan of Londons Piccadilly Line
also the Moon passing overhead and waves breaking on distant shores!
I think it's pretty neat that it's a "telescope" where the earth doesn't block their view at all. Neutrino detectors are the same way.
8:08 watch out for the scott with hair jumpscare.
Literally can't pick him out. Where is he in the photo?
@@colinbrown4903 Top row, second from the right
@@colinbrown4903 I think he's the gentleman with the Eraserhead shirt in the back row
@@colinbrown4903given that Scott has a very slight cleft chin it has to be one of the two with beards and no glasses. My bet is the one with the leather jacket on the left
@@colinbrown4903 obviously the dude with the long hair in the front row
It's nice to see LISA finally happening. I think I first heard about it during my PhD, maybe first post-doc IDK.
I do like that ESA does seem to do these quite unique missions like LISA, GAIA, etc. that seem really quite niche but really are revolutionary in the science that they enable.
It helps when you have budgets that do not rely on election cycles 😉 I've read about LISA (maybe it was different name then) when I was in Grade 5 or so in Astronomy magazine. More than 30 years ago! I would love to see it fly.
"You are tearing me apart LISA!" -the secrets of the universe probably.
Oh Hi Mark.
Thank you for this video, Scott! I am eagerly anticipating the LISA mission for about 10 years already and this video is a gift and a marvel for anyone who is exited with gravitatinal astronomy. Cheers!
Hands down the best commercial interruption in a while.
"That's great, because you can make audible chirps from the gravitational wave signals------".
🎶 Heavy dubstep advertisement 🎶
You're making me almost wish I didn't block those ads... almost.
Physicists are going to have a field day with the data from something like LISA. Just studying the ineraction of the planets might bring on some interresting discoveries. You're studying the fabric of the universe. Amazing.
I thought of doing something similar many years ago. My idea to use Lagrange points was very naive and would not have worked. I forgot the simplest thing, that all things are moving in space as your video shows. I guess you could stop completely if you got far enough away from most masses, but then you might be out where Pioneer is, with long comm times. I did get the part where it had to be huge. Great video, glad people came up with real solutions.
Great video as always Scott! I am doing my PhD on LISA science, it's nice to see people talking about the project. There's a lot of very cool stuff both on the engineering and on the science sides. You didn't even have time to mention my favorite thing about LISA: it might be possible to detect a gravitational wave background of cosmological origin with it (think CMB, but instead of microwave radiation it's gravitational waves, and instead of coming from the recombination epoch, it comes from all the way back to basically the big bang). This would allow us to see evidence for crazy things like cosmic strings, phase transitions in the early Universe, and cosmic inflation. Right now it's looking very difficult if possible at all, due to all the sources of noise and other signals piled on top, but it's an enticing possibility.
Test-drillings for the Einstein-telescope are currently taking place right next to my house in the border region between Belgium, Germany and the Netherlands. Great to see you cover this topic Scott!
Definitively most interesting mission. I was tracking it since early 2000s, and was worried they will never get proper funding, or solve all the issues in my lifetime, but finally we are going, and everything looks feasible. So awesome.
When I first heard of LISA, I wondered how the positional accuracy would be achieved between free flying spacecraft but never researched it. The test masses, filtering out of band signals and "rate of change of the change" are very clever.
Incredible precision. I'm lost for words. Hats off to all involved. And to Scott; fantastic video. Bravo!
Hats off for what? It doesn't exist yet.
@zacklewis342 They've spent about 30 years planning this. All the detailed engineering that Scott goes into in this video showcases a lot of PhD theses by some amazing people. The level of detail is incredible.
This is some next level engineering right here. The precision required to just make this stuff work is insane, but then to maintain this precision throughout the missions life really boggles the mind. It makes the super heavy catch look like child's play LOL.
It's not really engineering - it's physics. Engineering is about building useful things. Physics is about measuring things. While these experiments have limitations imposed by our current engineering techniques, it's the physics part that tries to side-step these limitations and still get the measurements required.
Super heavy catch is definitely about engineering, and very useful one at that.
@@hardopinions Building scientific equipment is engineering.
Meh. Superheavy catch is 1990's technology, if that. We just didn't apply the proper funding before now.
@@zacklewis342 If superheavvy catch is 1990 technology, then firearms is 150 AD technology
@@zacklewis342Our computers alone are magnitudes more capable than they were back then. Do you have any evidence to back your claims up?
this is the coolest telescope ever. someone should write a sci-fi story about how when we turn it on we suddenly receive an alien message encoded in gravitational waves
8:08 Scotty with hair. Unbelievable 🤣🤣
Which one is he?!
@@treva31 Supposedly top row, second from right. But I want to believe he's front row next to Paul McNamara, with the long hair.
@@TWeaK819 yea that was my guess lol
wow, just wow. every time i thought i had gotten the full idea, something came up that i didn't think about.. like moving the antennas and their impact on the measurements. a truly monumental technical achievement, this experiment is.
Very cool. This reminds me of a NASA proposal to build a giant pinhole camera out of two free-flying spacecraft, one of which would have the collection sensor and the other would have the "pinhole" aperture to focus the image on the first. The idea was that they'd be able to see extrasolar planets in enough detail to make out seas and continents. Each spacecraft would have to flown extremely precisely in order for the two to aim at distant point subjects. I think it was an idea from the late 90s that never got funded.
Fascinating stuff! I’m amazed not only by the precision and complexity of the system, but by the fact that equipment of this sensitivity can be launched into space without destroying it.
The extension of observation into the infra-red, X-ray and gamma ray, and now gravitational wave and cosmic ray regimes makes this a golden age for astronomy, yielding mind-blowing science. Multi-messenger astronomy has already profoundly influenced our understanding of nucleosynthesis and promises deep new insight into the nature of universe.
A few years back I had a look at this for my MSc dissertation (asking the question of what would be needed to see different frequencies of gravitational waves). I wasn't involved in LISA itself at all, but it was wonderful to see the amazing science behind it all and take a real deep dive on it
Talked about this yesterday in my astro class, I really hope this helps solve the dark matter mystery and the dark energy stuff
What institution ?
@@03bugeye Mental
How would it help us pin down the kind of particle that makes up dark matter? Would axions leave a different kind of gravitational waves signature than WIMPs or something?
@@petergerdes1094My professor said that primordial black holes are a better, more likely theory for dark matter, and this is something he said LISA was going to help find
@@joyl7842 Thats kinda the opposite of what her latest video says.
24 years ago "
I"was a student... love it.... you're always a student!!!!!
The test masses are really cool. Reminds me of that episode of Stargate SG-1 where they pull a space mine into their ship's hull and have to pilot the ship to keep the mine relatively stationary so they can work on it...
The whole mission is really cool and I don't want to wait 11 years for it to launch. If we're ever going to stumble across new theories of astrophysics with potentially civilization-changing results, it's going to be these sorts of missions that do it.
We already waited 30 .. what's another 10? 😉
Instantly one of my favorite videos you’ve made Scott! Great information and definitely excited to see this project develop through the years/decades!
Our dog turned his head when you played the gravitational wave chirp. For quantum effects I will need a cat.
Just wanted to say this was one of your better videos. Concise and to the point but enough to inform someone who's not familiar with the subject. I appreciate a lot of your videos, just found this one to be among the better ones.
The comment on the electric thrusters is wrong, they expelled droplets of a polarized colloidal fluid accelerated by a high voltage. The FEEPs didn't make the cut in the end, but you got the company right for the colloids!
This is so cool! The amount of amazing engineering and physics that goes into this is wild, and the scientific purpose is awesome as well. Thanks for this video, Scott!
As an engineering student, my take-away is that high precision science is a catastrophic pain in the butt, and an interesting challenge.
please, you are an engineer, do the math, see it, see it! watch it! find it out! please! see it for yourself! please I beg you!
Yes, anything beyond the paltry is a royal pain, thus the size of the paycheck...
One day we might actually be able to model the atom! Maybe... :)
One engineer is not the other. Is simpletons can only ask, couldn't you? And the smart ones awnser, good idea, yes we can. Doing stuff in their head, I can't do on a computer. Many sorts and levels of engineers.
@tjallingdalheuvel126 your literally 8 years old, get out, it is literally against tos
Proud to say I’ve worked on the bid for LISA. The accommodations of the equipment and the technology used is so challenging and incredibly cool. This is going to be such an amazing mission.
And yet, people are joking about ESA for not being relavant in space race. Even though they build things like this.
because they take forever to do it
It's not about "space race" -- this is about science. NASA funding is not predictable enough so they withdrew from these long term projects. ESA funding is mostly secured and away from politics.
Microns of accuracy over a million kilometers is absolutely wild, it’s literally brain breaking
If we had better launch vehicles, these types of missions could have been a lot more frequent and ambitious.
Trying to close the edge of physics instead of improving the basics is really impressive, but also myopic.
@@hardopinionsThe space race is about science and I'm not sure how you can pretend it's not, specially seeing as if it never began you wouldn't see any funding, or the infrastructure capable of launcing these instruments into space today. ESA barely has any launch hardware of their own even today.
I love the level of detail we get on these deep dives
15:43 I wonder how bad idea would be to have a 4th spacecraft being like a communication center - let each LISA use some short range communication only between and with that 4th one, and let it handles long rage talking.
better idea: make it 4 identical craft, each capable of all roles (measuring together with two others, short range comms between them, long range comms to earth), and let one of them handle the earth comm part, and the other three do the measurements. in case one cannot perform its assigned task because a system failed swap the craft around. also the short range comms should be redundant, cause with this approach its the weakest link.
@@unitrader403 Four spacecrafts arranged in a Tetraeder shape. The system could fall back to a triangle if one of them fails.
The problem is the launcher constraint of mass and volume. Adding the fourth data relay spacecraft is not efficient and does not leave enough resources for the science s/c.
@@benjaminhanke79 thought of that but not sure if you can find stable Orbits that fullfill this criterium..
put a larger harddrive on one of them and you can send data whenever you like/a meaningful detection is made
Contemplating the complexity and precision required makes me want to scream. AHHHH!
Amazing!
If LISA's successor is built as a tetrahedron, it should be able to provide direction of source and some redundancy and error correction. Around year 2050
As a Layman I think this is very cool. I get most of it, but man so cool!!! Thanks Scott for always giving us awesome space videos
Astonishing! Looking for the noise in the noise. You just have to recognise the tune!
Kind of like trying to pick out a single story while all the grandkids are talking excitedly at the same time.
This was a great video it was greatly appreciated and discussed by LISA scientist on our regular conference call today. I cannot tell you how valuable it is to have a content creator tell the world about what we are doing it the way you have. I have personally thought of LISA in very abstract and theoretical terms. What it can or can't possibly measure and how we will learn about fundamental physics from it. I never really thought of how big of an instrument this is going to be really.
I love how the test masses are a gold platinum alloy, like was that really necessary? I'm sure there was a legitimate engineering reason for that, but it just sounds like they were trying to see how expensive they can make a brick and that's kinda hilarious.
Probably resiliency and inertia, you don't want your mass to move around or degrade. That's my speculation though.
Also reactivity - gold basically doesn’t react with anything. There’s actually plenty of stuff out in space that materials can interact with.
That level of precision is insane, I knew about LISA, but didn't know the tolerances were in micrometers.
In today's world, I would argue that engineers are the true geniuses. It's like they are making machines that can perform magic.
JWST is a excellent example of this. So complex, yet Ariane got to it's deployment position and deployed so well it gained over a decade of performance-lifetime. These machines surpass advanced scientific math.
Another example would be ASML's EUV lithography systems able to produce chips at atomic-scales. One company in the world possesses this technology, thanks to its engineers.
It is definitely an inextricable partnership. Scientists need to figure out specific ways to prove their hypotheses that are implementable, and then the hard work of the engineers starts in finding clever ways to achieve that. But I do agree that in most of these situations the engineers end up doing the vast majority of the hard work
@@falxonPSN Of course, the science comes first. But the minds of engineers are key in every step afterwards.
I think that is an unfair assessment. Engineering and theoretical sciences are two different disciplines, to argue that scientists can't be geniuses because they need engineers to test their hypotheses seems very narrow-minded. What does it even mean to surpass maths?
Found the upset mathematician that wished he was an engineer 😂
Your all overlooking the trained and certified technicians who do all the assembly, testing and validation before they hit the pad. The scientists are not allowed to even touch the unit, mostly because they are idiots.
Incredible telescope. Excellent explanation. Something to look forward to in 10 years.
Now that I know that there are gold/platinum cubes at L1, I know where my treasure map has an "X" mark.
i'd rather get them while theyre still around
Thank you so much for this video. Every time someone mentions LISA, i have always wondered how they were going to accurately measure "drift" between the satelites
Would it not make sense to fly 4 satellites in a tetrahedron to get resolution in every direction? I would think that the satellites have a blind spot perpendicular to their plane
The level of work to achieve a project that clever, is amazing. Great job!
Had a thought the other day… With starlink satellites now using a laser communications, would it be possible to ‘see’ gravitational waves by analysing the data of ping round trip times between the nodes? It would be significantly less accurate? ..but there’s thousands of nodes and in a sphere! Doesn’t match the scale of Lisa though.. ?
I thought about that too!
I made the SAME comment just -12min before- _20mins after_ yours! 🤣 _[edit: YT comment timestamps didn't update correctly until I clicked into this thread]_
Since yours is getting more traction, in case anyone might know, I also asked if using GPS's crazy accurate timing would he possible, or if it *needs* to be optical?
I think the path time between the individual satellites might be too short for starling. Something that goes unsaid in the video is that the laser isn't only bounced once down the arm to pick up the signal. It gets a bit complicated with optical cavities but I think the mirrors bounce the laser back and forth a few hundred times for it to be effected enough... Gravity waves have a very light touch
@@Twitchi If LIGO can get away with 4km arm lengths, I see no reason why satellites even in LEO will struggle with arm length challenges. They will however need to account for various external factors that influence the satellite distance relative to each other which would be especially challenging for satellite in LEO as tiny sliver of atmosphere actually does exist there and drags the orbit of LEO satellite back down to Earth; which I think would be the reason why it won't be able to detect Gravitational Waves as the output data would be severely polluted, even if in theory it *might* be capable of it.
@@stayfrost04 but that's the point I was making.. LIGO is 4km, but it uses something called a Fabry Perot cavity to bounce that laser back and forth down the arm many times.. Its hard to say how many as its a resonance chamber like a laser that superimposes the signal back on itself until a certain power is reached.. But the effect is to lengthen the arms several times, tens if not hundreds of times.. making that 4km into MUCH more
Absolutely amazing program and stellar reporting. Thanks Scott!
Honestly one of the most goated science projects ever. Proud Europe is leading this.
This is one of the coolest projects I have ever heard of. Great video, thanks
Wow, these is so much science and engineering and math involved. Teaching about the craft would be a cool way to introduce students to these principles with a real world application.
WOW YOU ARE D AND U AND M AND THEN A B that really describes you
Outstanding video. It challenged what I remember from my physics courses in college long ago.
hey scott, it's me paul, thanks for the video!
Ok Bruno
I love such a historical sounding headline coming from such a logical and correct man
Proof Scott was in school before they invented colors. 😂
2:51 I was listening to the video in background, and after creating anticipation for the audio chirp YT trolls me switching to a fashion ad with electro-ambiance music.
And I'm like: WOOOO!
Imagine putting 3kg gold-platinum alloy blank in your CNC.
And setting 0 incorrectly lol.
Also you would probably buy new machine just for this. The price of chips would offset the cost :D
You answer me❤. You definitely know your stuff but your ability to communicate it is even more impressive. Always enjoy your videos.
I'm really glad a few of my tax dollars are supporting this research. This is exactly the kind of thing NASA should be working on.
And it’s not NASA paying for this. It is the National Science Foundation - NSF. And Caltech, MIT and others
NASA from now on will be doing what Elon wants it to do
A lot of this tech is borrowed from the GPS says that first used contained masses to have sats maintain positions
@@richhyde4834 Cool! I knew that Gravity Probe B used a inertial reference mass, but hadn't realized that the GPS satellites used them. Do you have a reference for that?
That's just INCREDIBLE with that precision! Simply Amazing! Cheers from Texas!
This whole thing is insane.
Truly amazing video... way way way way way WAY out of my league. Nicely explained.
So, I'm a space antenna?
Indeed! 😂
That or a Simpsons character.
Or the director of the princeton plainsboro teaching hospital.
This project is a beautiful expression of the human spirit
8:08 who is on the T-shirt?
My shirt? I have no idea, I've been trying to figure it out myself.
@@scottmanley Eraserhead, as a vigilent commenter pointed out. My bad I didn't know
@@kalmanbalazs
While I have not watched Eraserhead that is not a match for any of the t shirts I can find nor does it look like the usual Eraserhead shot I have seen many times.
@@kalmanbalazs I don't think that's right though.
This is amazing! I’m praying everything goes perfectly
This is got to be the most sci-fi esque project humans do for quite a while.
STARSHIP?????? and it is a real real thing of the real reality instead of this gar and a bage
@@NeroDefogger never heard of it
@@Coriander1988 lol
Great presentation of the mission, Scott!
by 2035 they wont launch on an Arian 5, they will put all 3 in one starship and launch all 3 at the same time for a fraction of the cost.
Why wouldn’t they want to launch on one of their own rockets?
Ariane 6
@@oberonpanopticon Because they suck? Lol
Setting an alarm for 15 years, you better still be producing videos!
This is going to be incredible!
Thanks Scott!
Great presentation and that is some impressive science!!
Thankyou for taking on these cutting edge areas Scott.
"this is way beyond me" - the one part I understand and agree with
This is probably the greatest technological and engineering marvel ever created by humans. Not even by shier complexity, but the diversity of engineering that went into it.
You are tearing me apart LISA!
LISA will allow us to study in details what we can not see from down here on the ground. An amazing achievement.
Thanks, Scott, for your viewpoint about the future of NASA, space flight and politics.
Thanks, Scott. Awesome one!
@Scott
Why do we need 3 Sattelites or why do we need 4 Sattelites around the sun? do we do a "quadrat" that changes in plane, but then you can do it with 2 additional sattelites^^
The internal gravitational requirements of the three individual probes reminded me of the complex rotating super-dense masses that had to be used in Dr. Robert L. Forward's outstanding hard SF book "Dragon's Egg." This is really fun stuff that we are embarking on!
LOL, the sounds at the beginning reminded me of my UofG Bachelor thesis work for audiolisation of GW signals for education and outreach purposes
Love the engineering and details on these devices
This is staggeringly insane. Absolutely wild what humanity is (hopefully) capable of when smart people work together.
This is insanely complex. Astounding.
Thanks for explaining this so well.
incredible precision. just wow!
Always great videos
[QUESTION] Can you use this orbital method to build a giant interferometer radio telescope satellite fleet?
this vid was indeed exceptionally good