Hi, I am Prabhanjan and I'm going to talk about quantum zero knowledge in the concurrent composition setting This is in joint work with Kaiman Chung and Rolando Laplacca Zero knowledge is a notion that we are all familiar with The traditional notion of zero is depletes that the conversation between a prover and a verifier can be simulated in other words The verify doesn't learn any additional information after talking to the prover You know in most protocols we have seen so far the assumption is that the verifier is a classical PPT algorithm However, this assumption has been challenged By the prospect of quantum computers in the last few years Some companies and many governments have intensified efforts towards building quantum computers In the next few decades, we need to brace ourselves towards the possibility that quantum computers could become a reality And towards this we need to start thinking about designing protocols that are secure even after quantum computers come into existence So we're going to look at one such Protocols which is you know, we're going to look at one such notion, which is the notion of quantum zero knowledge So this notion is an analog of zero knowledge in the quantum setting and It roughly says that the conversation between a prover and a quantum verifier Can be simulated by a quantum simulator This notion is not new. I mean people have actually looked at Quantum zero knowledge protocols But they're mostly focused on standalone quantum zero knowledge protocols in the setting we assume that there is a prover and a verifier and You know the execution between the prover and this verifier is run in isolation So in other words, you know, the prover is talking to this verifier, then it cannot talk to any other verifier During this time. So the good news is that there are some feasibility results known. So we do know how to achieve the standalone QZK However, this is not a very realistic setting So if you think about it, it's not reasonable to assume that you know, the prover only talks to one verifier at a time In the real world setting, you know, you have You could have a, you know, maybe like a server who's running He's taking the role of the prover, you know talking to many clients who are taking the role of verifiers At the same time. So more realistic setting that we can consider is concurrency So in this setting we have a prover talking to multiple verifiers at the same time and These verifiers can interleave their messages with the prover in any arbitrary fashion You know, maybe, you know, there's one verifier who starts the execution with the prover And before this verifier sends its second message, maybe another verifier starts talking to this prover And we want the notion of zero knowledge to even hold in this setting you know and the the notion of QZK in the concurrent setting will be called as a concurrent QZK And unfortunately we don't know much about the possibility or impossibility of QZK in the concurrent composition setting But if you look at the classical cryptography literature, there are many many works on you know On on the feasibility of concurrent CK So before we try to understand the feasibility of QZK in the concurrent composition setting, let's first try to formally define what concurrent QZK is So in order to do that, we need to define What is a malicious how does a malicious verifier behave? So in this case, the malicious verifier is a QPT algorithm Let me denote this by we start And we are going to work in the setting where the verifier can be non-uniform So in other words, it can take as input an auxiliary state This auxiliary state denoted here by row can be thought of as A quantum state That has a polynomial number of qubits And this verifier we start can invoke Q sessions or Q verifiers with the pruer p with the honest pruer p And the sessions are denoted by V1 through VQ Okay, so to Be a little more precise about how the interaction between the pruer and the verifier we start goes So we can think of every message computed by V star to be let's say unitary Followed by a measurement where this measurement determines the message to be sent to the pruer Right, and then we can think of every message we start sense to be of the following format So it's message one corresponding to the first session message to corresponding to the second session and so on And then we have q comma message q where q is the number of sessions And then you can do this for all the messages and you know Not all sessions need to You know Be active in any round So for example, the ith session can choose not to you know, send any message to the pruer In some round in this case it will set the message message i to be empty Which which we are going to interpret as saying that the ith verifier is not sending any message in this round and We say that a protocol satisfies concurrent q ck if there exists a simulator such that the following two distributions are indistinguishable The output of the verifier, you know after it interacts with the honest pruer Uh, you know the output of the verifier v star is going to be some state We want this state to be computationally indistinguishable Or rather like a distribution of states to be computationally indistinguishable from the Uh, the the The distribution specified by the simulator, right? So the output of the simulator Describes a distribution and we want this distribution to be indistinguishable from the output of the verifier So it's the same as as a Classical zk except that you know the algorithms here are quantum And and also the advice is as quantum There are two notions of concurrent q zk that we can consider one is bounded concurrency and another one is unbounded concurrency So in in in bounded concurrency the number of sessions q needs to be fixed apri like even before the protocol begins Uh, in the case of unbounded concurrency, you know the verifier the militia's verifier can choose how many sessions to run Um, you know at the beginning of the security experiment So it need not be specified as part of the protocol description So we can also consider another weaker notion which is parallel q zk Um, so in in the parallel setting we want all the verifiers to send the messages at the same time While this is not the most, uh Useful notion in practice Parallel zk is still useful for constructing let's say mpc protocols Okay, so let's let me, uh give a an overview of our results So we initiate a formal study of concurrent q zk Uh, we give a feasibility result of bounded concurrent q zk for, uh, all languages in np And we actually show how to get, uh, quantum proof of knowledge for np Um And finally we also show feasibility of bounded concurrent q zk for, uh q ma So q ma is a quantum analog of ma um, so, um, we say that a relation is q ma relation if You know for Every instance pooling string, let's say x we say x comma some state belongs to this relation If there's a quantum algorithm quantum polynomial time algorithm that on input this instance and the state outputs One with high probability So it's in ma the witness is classical in q ma the witness can be quantum. So that's that's the difference So i'm not going to elaborate on the quantum proof of knowledge and the bounded concurrent q zk for q ma results I encourage you to look at the paper So for the rest of the talk, i'm going to focus on the feasibility of bounded concurrent q zk for np Okay, so, um, let me zoom in on this and expand on this result statement So we show that there exists bounded concurrent q zk for np, uh, assuming The existence of post quantum one-way functions And two nice features about our protocol is that first of all, it's a it's a public coin Uh protocol and moreover, it's a proof system. That is the soundness holds against the unbounded provers So we know that, um There you know, there there was a prior work on bounded parallel q zk argument system for np from f h e for quantum computation Which is going to appear in your record this year So our work improves upon their result in terms of assumption. Also, we get the stronger stronger notion of bounded concurrent q zk Let's dive right into the techniques A natural approach that we can consider is the following So we can start with a classical bounded concurrent zk for np. So we do know how to achieve this So let's start with the construction that we know and then What we can do is, you know, try to come up with a A different proof for the same construction that proves that this construction is actually Secure against quantum verifiers and not just classical verifiers So not to do that, you know, we need to figure out a Way to port the classical simulation strategy to quantum to quantum simulation Right and we're going to focus on revinding based simulation strategies So and towards this, you know, we can ask a more general question What are the classical revinding techniques that can be ported to the quantum setting? So we can identify a quote-unquote Quantum friendly classical revinding techniques. These are the techniques that Can actually be ported to the quantum setting. These are classical techniques, but that can be adapted to the quantum setting And a rule of thumb that we can adopt For identifying this class of quantum friendly classical revinding techniques is the following So we can first ask if the classical revinding technique is oblivious. What do I mean? You know in any round the simulator can You know decide whether it wants to rewind or not And we want the property that You know at any point in time the simulators The distribution on simulators decisions should be independent of the verifier state So it should be the same no matter what auxiliary state the verifier has. So this is the first condition See the other condition is that we want Um the simulator to be no recording. What does it mean? It means that Um the simulator, you know should not learn some information Um and then rewind And then you know continue to use the information that it had gathered from a previous rewind for for future windings So this is the other sort of uh guarantee we need So if I think that these two properties are sort of artificial and you can ask whether do we Know any classical revinding that satisfies these two properties And as it is Yes, there are actually protocols that satisfy uh both these there are actually techniques that satisfy both these properties So if you look at the um the simulator of uh the popular graph isomorphism protocol You can show that that that particular simulator satisfies both these properties You know, there are other examples as well. So this is the um This is sort of like the prototypical example that you can consider Okay, so once we have identified this Quantum friendly classical rewinding the next step would be to combine this with Uh a lemma that was proposed by watrus And we can combine both of them to get quantum simulation. It's a um somehow we can uh You know Merge these two different uh techniques together to get a quantum simulator So this is sort of roughly the strategy we are going to adopt to um Come up with a feasibility result for bonnet concurrent QZK Okay, so towards this you can ask if there are quantum friendly classical concurrent rewinding techniques, right? And then we can try to combine them with watrus And the um answer is unfortunately no, I mean most of the techniques we know in the classical concurrent literature Either violate the obliviousness condition or the no recording condition Um, so which means that we need to really, you know, sort of devise a new um Quantum friendly classical rewinding technique and that's what we do in this work So we propose a technique called block rewinding technique And then we're going to use this technique to prove that the classical protocol of um pass Sing and mix strong Is bounded concurrent QZK Did they showed the existence of classical concurrent ZK? Boundary concurrent ZK, and we're going to show that the same construction Modulo some modifications in the parameters Is also secure in the quantum setting Okay So what is this block rewinding technique um at a high level what we do is we sort of divide the Entire transcript, which is the execution of the pro with all the verifiers into blocks And The simulator what it's going to do is at the end of every block It's going to do decide whether to rewind to the beginning of the block or not with with probability half And since the decision to rewind Um Is oblivious of the very fast state. So the simulator will do this no matter what the auxiliary state was So this particular Step would satisfy the obliviousness condition And when the simulator records, it's going to forget all the transcript. It has remembered so far So when it goes from step i to step j Uh, so sorry when it when it revines from step j to step i then it's going to forget all the messages from i to j And that's uh the this also satisfies the no recording condition So this was a So really vague and high-level Um idea of how the simulator would work. I mean here there are many questions.  You know, will the simulation work for all schedule links, you know Can the verifier somehow interleave the messages cleverly in such a way that the simulator fails and uh Finally, what if the all the verifiers are bought in a single block? Um, will the simulator even rewind that right? So, um If the simulator doesn't choose to rewind then It would end up depending on the verifier state and thus violating the obliviousness condition So we need to also handle the case when all the verifiers are bought in a block Okay, so before Answering these questions. Let's uh look at the protocol description of bass sing and big strong So their protocol is composed into two stages in the first stage. Uh, the pruer p sends a commitment Of a bit to the verifier and the verifier sends some other bit To a back to P So in terms of what commitment we use we are going to use a statistically binding A quantum concealing commitment scheme which can be based on post quantum on my functions And in the second stage, uh pruer proves to the verifier that either it knows the witness for this instance or Uh, there are enough number of uh executions in stage one Where the verifiers bit agreed with the pruer's committed bit So we're going to use the term matchings. Uh, so we say that, um, you know, a particular execution of stage one has been matched if Uh, the verifiers bit is the same as the pruer's committed bit Like in other words, if bi prime is the same as bi and if you can we can replace this Condition as saying that the number of matchings has to be at least l over two plus q to the four, uh lander So roughly, you know, uh in expectation l over two executions will have The verifier spit to be the same as the pruer spit What we are asking is something that is slightly more than, uh, roughly half of the executions of stage one okay So we're going to use the you know, we're going to call a single execution of stage one to be a slot So let's first consider the setting when the simulator is, uh Uh, when the verifier is classical and then You know, we're we're going to see how to port the ideas developed here to the case when this verifier is uh going to Okay Okay, so we're going to divide the the transcript into b size blocks. We're going to fix, uh, b soon So what we are going to do is for the ith message of v star Um in in a block what we are going to check is if uh, this message Is a is a last message in a block. Okay So if this message is the last message in the block Then you see how many of the sessions, uh contain a slot in this block b Okay, so you're going to consider all the slots that are completely contained in this block And then you're going to pick one of these slots uniformly at random, right? Um And so there are let's say there are l verifiers Whose uh slots are contained in b then you're going to pick one of the verifiers uniformly at random Um, you know, of course a single verifier could have multiple slots Just pick one of them at random And then you're going to check if this slot has been matched in other words if bi prime is the same as bi So if that is the case then you mourn to the next block Otherwise what you're going to do is you're going to rewind Uh rewind to the beginning of the block Okay So let's first assume that Um somehow the verifiers interleaving strategy says that Uh one slot in every block contains at least one slot If this is the case then you can see that the probability that the simulator rewinds Uh is going to be roughly half Right. Um, so now we can ask what if a block doesn't contain any slot If a block doesn't contain any slot then You know, what you're going to do is the simulator is going to just You know pick a bit uniformly random This is a dummy bit and if this bit comes up as zero then it goes to the next block Otherwise it's going to rewind to the beginning of the block And why do we have this? Uh, remember we need to satisfy condition called obliviousness that says that the simulator's revinding Um, the the decision to rewind should be independent of the verifier state Right. So this you know, it could very well be the very very well be the case that the verifier has Interleaved it its messages in such a way that There does not exist any slot in a block Uh, and if the simulator does not choose to rewind then Um, then its decision is depending on the verifier state, right and that violates obliviousness So we're going to add this condition as well in the description of the simulator Okay, so now what if uh, you know the The the message that you're considering is the intermediate message in the block In this case, you know, if it is a stage one message, then you're going to behave like the honest pruer You're going to just send a commitment of a random bit if it is a stage two message Then you check if the number of matchings Uh, is at least l over two plus this additional q to the four lambda or not if it is less than that then you're going to abort Otherwise you have sufficient number of matchings now you can use these matchings to complete the wi phase So what is left is to show that the probability that the number of matchings Um, is at most l over two plus q to the four lambda is uh negligible, right? Because if this happens then the simulator is failing and we want to show that the probability of this event is low So the intuition is that for every verifier vi the number of blocks that contain at least one slot of vi is at least six Um times q to the five lambda so you can you can show this using a counting argument Similarly, you can also show that the number of blocks in which a particular verifier slot is picked is also sufficiently high Then you can use both combine both these facts to argue that with high probability using churn up on um At least three times q to the four lambda of these slots are matched Um, you know, this is by the simulator um employing the rewinding strategy On the other hand, you know, there are still l minus three q to the four lambda slots remaining and you know even You know, even if the simulator doesn't try to match them just by sheer luck Uh, half of them are going to be satisfied in expectation And again using churn off you can show that the number of slots that are satisfied with high probabilities At least l over two minus two q to the four lambda So if you add both of them up These two quantities up you're going to get um the desired bound right so you can argue that This is in fact negligible Right, so that's how we complete the simulation strategy so What is remaining is to show that uh the verifier is um We need to show the case when the verifier is q p t and the quantum Uh simulation strategy is very simple, you know The quantum simulator is just going to run the classical simulator and the verifier in superposition. So it's not going to measure anything um Except at the end of the block at the end of the block It's going to measure something and based on that it decides to rewind Uh, and how does it rewind it employs the rewinding strategy proposed by waters? So this is the rewinding that's going to be uh given to us by the waters lemma Right and we can show that a careful repeated application of waters. Uh lemma implies a successful simulation against a quantum verifier Okay, so with this, uh, let me conclude this talk We initiate a formal study of concurrent q z k We showed a feasibility of bounded concurrent q z k for np Couple of results I didn't talk about is quantum proof of knowledge for np And we also show the feasibility of bounded concurrent q z k for q ma So what is open is to show the possibility or impossibility of unbounded concurrent q z k Um, and also post quantum concurrent, uh, secure computation With this, uh, I conclude. Thanks


Coming up, two crews launch into space. Juno has a hiccup. I have an interview with Dave Mastin in studio. And I crack up on air thanks to our live audience. All of that and more coming up on this week's episode of Tomorrow. And welcome to Tomorrow, episode 9.34 for October 22nd, 2016. Now before we get started with our episode, we want to thank all of our patrons on Patreon who give us $10 or more per episode. These folks are our tomorrow premiere patrons. They get access to everything in our Slack channel. So thank you to these patrons. And if you would like to help consider crowdfunding the shows of tomorrow, head on over to patreon.com slash t-m-r-o. Now of course I am your host through the news, Jared Head. And next to me I've got Space Mike from the mythical lands of Arizona very far away from us here, of course, in the studio in Anaheim. Now we're going to get started with you, Mike, because we've got a nice array of exciting things to start off with. So go ahead, Mike. That's right. We try to start each show at the top of it with Space launches and we have quite a few of them. First up we have a Long March 2 F rocket which launched the Senzo 11's capsule into space. This launched on Sunday, October 16th at 2330, coordinated universal time. From the G-Quan Satellite Launch Center in China. This carried two Tyconauts on board bound for the Tiangon 2 space station, which we'll talk about a little bit later. They could have taken three crew members on board, but they wanted to take up more supplies instead, so they only had two crew members on this particular mission. And then next up we have a Cygnus, or rather an Antares launch, which launched the Cygnus cargo vehicle. This launched on Monday, October 17th at 2345, coordinated universal time. From the Mid-Atlantic Regional Space Port at Wallops Island, Virginia. I love the shaking on that first part. This was the first Antares launch since 2014. The first launch with the new Russian RD-181 engines. And it carried the sixth Cygnus cargo mission for the commercial resupply services program, but it was designated OA-5 and also called the SS Allen Point Dexter. So congratulations to Orbital ATK for that successful launch. But then next up we have a Soyuz launch, which launched on Wednesday, October 19th at 805 coordinated universal time from the Baikonur Cosmodrome. And this was launching a Soyuz capsule, specifically the MSO-2 capsule, which carried with it cosmonaut Sergei Regikov, Andrei Borosenko, and also the astronaut Shane Kimbra, and this was going to be bound for the International Space Station, which we'll talk about in a few moments. So congratulations to Roscosmos and to NASA for this successful launch. Yes, a fantastic week of launches happening throughout the world. Although we do have a little bit of an issue with something that's occurring off of the world about a billion miles away from us with NASA's Juno probe. So engineers at the Jet Propulsion Laboratory here in the Los Angeles area are troubleshooting the issues. It's currently in orbit around Jupiter and in testing for preparation for an engine burn to place it into its 14-day science orbit, delivered data showed that two valves on board were operating significantly slower than needed. These valves control the helium pressurization system for the main engine, and they are designed to open a few seconds, but it took several minutes for the valves to open during the test. So mission managers opted to skip that burn and take an extra 53-day orbit before attempting another burn to put it in a 14-day orbit, but then during the close-pass to Jupiter, Juno went into safe mode, and all science from that orbit was lost. So Juno is perfectly fine, but unfortunately any science that was done on that orbit is gone. So, yeah, there goes the data. Now, Mike, we want to get back to talking about Shenzhou 11, so go ahead and take it away. Well, just two days after launch, they successfully rendezvoused with the Tian Gong-2 space station, and they were able to successfully dock with the space station on October 18th, which was Tuesday, at 1924, a coordinated universal time, and this docking happened automatically. On board, the two Taikunots were a veteran Jing Haipeng, who has previously been on Shenzhou 7 and the Shenzhou 9 spacecrafts, and also a first-time Taikunot, Chen Dong. They will spend 33 days in space total preparing the lab for experiments and a refuel operations test next year. Now, some experiments will be conducted during this visit, and they will do lots of public outreach and also guest reporting for the Chinese media. So that's going to be interesting, and so congratulations to the Chinese Space Agency for the successful mission so far. I hope the rest of it goes well. But over to the International Space Station, that Soyuz vehicle that launched also was able to successfully rendezvous with the space station two days later, instead of the new four-day rendezvous they've been doing. This took place, the docking took place at 9.52, coordinated universal time, and as I said before, the crew members on board, MS02, are Cosmonauts Andrei Borisenko and Sergei Rajikov, as well as the astronaut Shane Krimbra, and they will be joining the crew of Anatoly Ivanishin, Tokoya Onishi, and Kate Rubins, who will be departing the space station on October 29th. Now this new crew, during their stay, a Cygnus vehicle and a Japanese HTV cargo vehicle will be docking with the International Space Station, and I love that shot right there, so beautiful. And during the time, there's also going to be at least one spacewalk planned. And then the next three crew members, who will be replacing Ivanishin, Onishi, and Rubins, should arrive in mid-November before the Japanese HTV cargo vehicle arrives in December. So congratulations to NASA and Roscosmos, and everyone involved at the International Space Station for having these successful docking operations. Yes, now turning our way back out to the solar system, the European Space Agency probes Venus Express returned a lot of data, and scientists are still scouring that, and they found a very interesting result coming from that. Now there is a very large mountain on Venus called Inan Mons, and the use of an infrared mapping sensor has showed that what was originally thought to be a heat anomaly actually is layered on this topographical map, and it puts it squarely on top of Inan Mons. Now what that means is that scientists think that we're essentially looking at fresh lava flows on the surface of Venus coming out of this. Now this isn't direct evidence, if you will, of actual current lava flows on Venus, but scientists in Germany were actually able to extrapolate the data and determine where those lava flows would actually be at at different times, and this is a nice little image of that chart right there. So some very interesting scientific results that do need a little bit more scrutiny, but are sort of showing that maybe Venus really is sort of Earth's evil twin in that it does have volcanism potentially on the surface even today. Now we're going to go from Venus to Mars. Mike, tell us a little bit about something that happened at Mars this week. Yeah, and also speaking of the European Space Agency's Planetary Exploration Program, we're talking about the Trace Gas Orbiter, which successfully entered orbit around Mars on Wednesday. And it successfully entered, but what we're talking about today is the Schia Pirelli Lander, which this is an animation that you're seeing on screen of what should have happened during its re-entry or rather entry in landing operations. And this whole thing, they were partnering with Russia to have a future lander in rover. But with this, the data so far looks like that something went wrong and the Schia Pirelli Lander crash landed into Mars instead of making a safe landing. The European Space Agency doesn't yet know what happened, but the initial data looks like that the last signal was received 50 seconds before the expected landing time. And it also looks like the parachutes were released earlier than planned. Now some reports are even saying that the landing thrusters only fired for three seconds, but that hasn't been confirmed by the European Space Agency yet. But even so, this lander as a technology demonstrator and from an engineering standpoint, the European Space Agency will have a lot of useful data to pour over that the Schia Pirelli was able to broadcast before going silent. Now there was a couple of images that were actually taken by one of NASA's Mars orbiters that showed the predicted landing site, and there's kind of a before and after that shows where it possibly landed. And just based on the scale that they give us up at the top right-hand corner, it looks like it's kind of a large landing zone, even like a crater. That's just what it looks like to me, though. But it's really interesting they were able to capture this and even the opportunity rover was supposed to be able to take a couple pixels of the landing. It'll be interesting to see if they were able to capture that. Congratulations for getting the Trace Gas Orbiter into orbit, but unfortunately I feel really bad for the Schia Pirelli not being able to land successfully. Yeah, tough luck. Mars, very difficult place in order to land. Now talking about flying and landing, when we come back from the break, we're going to be having Dave Mastin from Mastin Space Systems here in the studio with Ben doing that interview. So stay tuned. We'll see you right after this break. Welcome back to tomorrow. Now before we get started with our interview with Dave Mastin, I wanted to give a huge shout out to all of the patrons of tomorrow who've done to make this specific segment of this episode happen. These are people who've contributed $10 or more to get access to absolutely everything. We've also got our tomorrow producers. These are people who've contributed $5 or more. They're going to get access to After Dark and a bunch of other really great rewards to find out those reward levels and how you can help crowdfund the shows of tomorrow. Head on over to patreon.com slash T-M-R-O. Long time guest to the show. Dave Mastin, you're back on. Welcome. Thank you for driving down from the mythical lines of Mojave. So unusual, pleasant weather and everything. It is weird. It is weird. So for those who don't know, who is Mastin Space Systems? So Mastin Space Systems is a small company up in Mojave. We've been, like to say, we're the hipster rocket company. We've been doing reusable since before it was cool. You have. You did like the Northrop Grumman Lunar Land... What are we calling it now? It's the Northrop Grumman Lunar Land or X-Prize. They change it every year. It's the Lunar Land of Challenge as far as I'm concerned. And it was a wonderful thing back in 2009. We demonstrated a small rocket-powered vehicle essentially doing what it would be doing on the moon with a landing and then take off and land again. And the big things were it was be able to do two of them within a very short period of time. I think it was 45 minutes to do two flights. As far as I know, no one's really done that yet, right? So you were landing five years before any of the other big players were doing that. Yes. But you were also then reusing it within, like, an hour. With it, yeah. A very short period of time. Turn around and launch again. We've done a number of times where we've done multiple flights in a single day. I think our record is, for a flight period, is like 12 flights in less than a week. That's a pretty good number, yeah. That's a pretty good number. So, hipster company. So, anyway, since we've been doing reusable for so long, we've now been working on launch vehicles with DARPA and doing the XS1 program. And the XS1 program, as DARPA wants to do, not just a reusable launch vehicle, but a launch vehicle is truly airplane-like in operations. And one of the requirements is to do 10 flights in 10 days. We've already done that. Of course, they want to launch a larger vehicle when we've done before a little higher performance. So, for our competitors, Northrop Grumman and Boeing, their challenge is to actually get a reusable vehicle and doing 10 flights in 10 days. They've already done the same size or bigger. Whereas for us, well, we've already done the 10 flights in 10 days. We just have to do a larger, more higher performance vehicle. But in that XS1, you're going to a higher altitude. You see more performance. That's what you mean. Not just higher altitude, but a higher velocity as well. So, yeah, XS1 is a full go-take-a-satellite-to-orbit type launch vehicle, where we have not done that. Pretty much suborbital vehicles, very low performance type of vehicles up until now and now. We're working on this, you know, actually a launch vehicle. It's a small to medium-size launch vehicle. And NeuroPilot in the chatroom says, are you still working on winged reentry vehicles? That's what this XS1. So, XS1, our initial concept drawing that we gave out to the press and DARPA sent out to the press actually had wings on it. We have a difference configuration. I prefer to think of them as fins, but they're kind of large even for fins. But, yeah, we do need some amount of aerodynamic surfaces for what we're trying to do with it, in terms of basically doing the reusability and still maintain some performance levels. So, have you changed the orientation of launch or landing then? We still do vertical takeoff, vertical landing. That is, Mastin will not do anything, but you just, you can't land horizontally or takeoff horizontally from the surface of the moon. So, why do I want to do that anywhere else? NeuroPilot also asks, is Lynx still a partner or is that all dead in the water? So, XCOR was a partner for the XS1 in the early parts of phase one, but what they were doing was they were literally just a, how to say, they were the what to do in case some of our technology development didn't go as well as we expected. So, there was sort of a redundancy level to it, and we got to a point in phase one where DARPA agreed with us that we actually had bought down enough of the risk that we didn't need to carry another performer along with us to mitigate that risk. So, basically they did what they needed to do, which was come in and do some of the work and make sure that we didn't have some technology risks, and we got to a point where we didn't have those technology risks, and so, they said, oh, hey, you did a great job. Thank you for helping us out, and have a nice day. Well, they kind of have met, they're not totally gone ex-core, but they kind of met the same fate that a lot of new space companies meet, which is a lack of funding, and it seems like they've kind of really shut down their links program, which was their reusable space plane. So, they're kind of moving on, but you seem to be doing all right. We're doing okay so far. We're holding on, and it's basically, I think we've found, we've found a little niche that gives us enough money to keep going, and we actually have customers, which helps and are actually able to fly those missions. In fact, one of those missions, actually a series of missions that we flew for JPL has resulted in the technology that we were helping JPL test get selected for Mars 2020. Which is basically the curiosity reborn. Yeah, the next curiosity mission, essentially, which we'll be launching in 2020, that's Mars 2020, and yeah, so that, I have a little piece of technology going to Mars. Well, not just going to Mars, landing on Mars. So, landing on Mars, yes. We've created an impact creator, but we've already proven out the sky crane model. Well, it's some knock on wood here, because what we did was actually help them test out some of the technology, train relative navigation, and hazard avoidance technologies that some of that is going to be used for the new mission. So, hopefully it does enable a nice soft landing and doesn't mess up in... Why is that important? Why is train navigation important? So, train relative navigation and hazard avoidance technologies are really important because we need to go someplace a little less boring on Mars. Because we're choosing flat areas that we can easily land in. Huge flat areas that you can easily land on just are not, apparently, they're not scientifically exciting. They may be deep canyons where water may have once gone. That's a little more interesting. Apparently, geologists think that mountains and canyons and ravines are interesting. So, we need to see that type of geology and that geography. So, we need to be able to land in a much tighter band that landing ellipse needs to be brought down in size. Once you have a smaller landing ellipse, you can do a lot more science with that. And that's train relative navigation and hazard avoidance should enable that. So, there was a tweet when we announced that you were coming on the show. I was like, oh, I hope they talk about hiking because you and your wife love to hiking. So, let's talk about hiking. Exploration! Exploration is how I like to call it. That's what it is though, right? You're talking about hazard avoidance but you're going to need this so for a long time we're not going to have humans on board but even when we do have humans on board autonomous landing is a good idea. And then you have intention of going to Mars yourself. I would love to go to Mars. So, I consider myself an explorer. I'm not the pioneer. I'm not the guy who's going to go there and stay. I do have no intention of staying on Mars when I get there. I want to come home. So, I'm going to go there. I'm going to survey. I would love to survey Elon's retirement home. And when I get done with the survey maybe hike around maybe explore some mountains. You know, that hiking and mountaineering stuff that I do is there's the largest mountain in the solar system. So, let's go hike to the top of it. You mentioned something before the show that I didn't know. The top of Olympus Mons which is the mountain on Mars is in space. It actually extends above the quote-unquote sensible atmosphere. So, you actually have more of the so, you know, despite the hard vacuum of space there is actually an atmosphere everywhere. It is the solar wind is what you're going to quote-unquote feel. It is what you have there. If you have the instrumentation to detect it it's more of the solar wind than it is the Martian atmosphere at the top of Olympus Mons. So, you're basically out in space on top of Olympus Mons. The little secret is climbing Olympus Mons once you're at the edge of it apparently at the base of it is like just a very long and it's a long, gradual, easy to walk up slope. It's not mountaineering at all. And then when you're at the top you can feel that solar breeze rushing against your helmet I guess at that point. So, you're going to go there and come back on a Mastin vehicle? I would hope so. That's what we're working towards. So, to that end, what Jack asks what is the ultimate goal of Mastin Space Systems? So, the ultimate goal of Mastin Space Systems is we're a space transportation company. It is our intention to have provide the transportation services anywhere in the solar system. If you're going to a solid body or maybe even a liquid surface we'll take you there. And it doesn't matter where in the solar system. Maybe even outside the solar system too. Interesting. I feel like I should poke at that a little bit. Well, I mean, you know, hopefully someday we'll figure out how to go, you know, get to the higher performance rocket engines and, you know, maybe figure out fusion or fission or something and get some higher performance and, you know, there is an effort of I don't know, I can't remember his name now, Russian billionaire and send a little tiny spacecraft to Alpha Centauri. Love to help him with that. So, that leads into another question from user Little Blind Crippled Girl who asks, what is your dream rocket? Can it do, like, three flights a day? What kind of load can it do with a low-earth orbit on a daily basis? Like, Dave Mastin budget is no constraint. Time is no constraint. You can build it. What is your dream rocket? I know the two things that are always the huge constraints that keep everything down, but let's illuminate it for a moment. So, I don't know that I have a single dream rocket. There's, it's sort of like what's your dream car?  For certain routes, use Canada's, Canada Air regional jets. And, you know, there are routes with everything in between. We see the same thing. There are certain places where, you know, a small sat-launch vehicle is the perfect thing to do and makes sense, and so that's what we'll do. In other places, you know, we need something where, you know, even Elon's not thinking big enough. But that's, you know, that's somewhere way down the line. That's a pretty big rocket. That's a large statement. Who knows where that will end up being?  You also have super tankers that are hundreds of thousands of, millions of gallons of petroleum at a time. You need the whole range of things, so, you know, I think we're going to have to do the whole range of things. You mentioned a super tanker, so I have to mention the tweet that you sent out, which was, you were out looking at, what was it, an Atlas or Delta launch? It was a launch, of sorts, with your team, and mentioned, you may have figured out how to turn a super tanker into a rocket. It was, you know, it's a Friday, Friday afternoon, bunch of guys around the water, cooler talking, and recent, and Atlas 5, I think, launch, I don't recall, but, yeah, and I just was like, what is the propellant mass fraction of a super tanker? At which point somebody else jumped on Google and started looking and was like, about 80%. 80%, well, that's pretty close to, you know, reasonable rocket range, you know, normally it's 90%. Well, that does include the diesel engines, so we take out the diesel engines and we put rocket engines in instead and rocket engines have this thrust weight ratio and you'll need about this amount of thrust. And the next thing you know, we've got a concept design for a rocket based on a super tanker. Now, that's very similar to something that we've brought up on the show before, which is C-Dragon. Would there, is this you guys just talking like, hey, wouldn't this be neat, or do you think there's actually something there? So, I'm not sure that there's a number of questions that still need to be answered. There's maybe there's something there, maybe something that big really does need to occur. And so, yeah, I mean, we basically just you know, sort of an afternoon a group of guys thinking about what does what does a concept design like that look like? There's still some questions, but maybe maybe it's not too unreasonable. Would you, so if you were thinking about you floated out to sea and then like tip it down like you would sea launch, would you? Oh, that was one of our guys was like, yeah, you know, we could use our Zeus technology that you know, where we land a Centaur on its side and so you have your side thrusters, plus you have your main engines. So maybe you take it out to sea and when you get out to where you know you've got your trajectory doesn't crossover land, you need and you're pointing at the right inclination. Maybe you're down at the equator. You can you can light the engines up in the front. You can basically pop a wheelie, light your main engines and get going. I want to see that. That would be amazing. That would be amazing. Just being a little much smaller vessel out at sea, like, oh, that's a very large, are they firing rocket engines? Yeah, there's some serious questions about that, but you know it was a controls guy, so the controls guy thinks it can be done. It might actually not be. I would love to see you working out in the middle of the Mojave desert, just this giant super tanker with like the Mastin logo and a pirate flag on top or something like that. The pirate flag comes after we raise up the battleship Yamato and turn that into a spaceship. All right. For those who grew up in the 70s. All right, so going backwards in time a little bit, just structure 1701 says in the chat room there are a lot of questions about MXP 351. This is the first I've heard of it. Please describe it. Okay, so I'm not going to give you as much description as you want. It's a hypergolic, a propellant combination. It is green for whatever definition of green we want. Basically it's really about you don't need the full scape suit when you're handling propellants like you do with the traditional hypergols. You still need some protective equipment. So for those who don't know hypergolic fuels will basically react with anything like water. So hypergolic means that you have the oxidizer component and the fuel component and when they touch they ignite. You don't need an igniter. You don't need an igniter. It's they will ignite, they will and what the satellite industry loves about that is that they touch they will ignite, you will your engine is going. They love that you don't need an igniter. You don't have a point of failure out in space. You don't have a point of failure out in space. They're extremely reliable. So we've come up with a combination. We've been working. This is a lot of the work has been done in conjunction with NASA on the catalyst program and we've basically worked out a way of getting these two particular chemicals. They come together they ignite. They're actually very easy to handle instead of a full scape suit. All you need to do is basically wear eye protection and gloves. We do one of the an MSDS for one of the things said maybe you might want to wear a respirator. So we said, okay, we'll wear a respirator. Not a big deal. So but generally it's the stuff is non-toxic. You can handle it. If you were to inhale it you're not going to die in the next couple of seconds. You don't have to go to the hospital. If you Well, wait, if you inhale a hypergall like today, there is not going to a hospital right? I mean you're... It depends on which of those two you inhale. One of them you're pretty much dead. You're gone. The other one you may have to go to the hospital. I guess that's the one I'm used to work considering with aerospace. They basically react with anything. It will react with anything including the tissues in your lungs. Exactly, it's not a fun thing. The hydrazine is not necessarily a terrible thing. I've understand that some people have accidentally breathe hydrazine and are talking about it. On the other hand, the the red fuming nitric acid is a little bit worse. So, yeah, it's the... and there's a lot of details because we don't actually use hydrazine. It's more like aerosine which is some weird combination of hydrazine and other things that makes it worse. So, it's much greener, so better for the environment because traditionally hypergols are not super awesome.  It's very toxic. That's generally the hypergolic fuels. So, it's green but what about... it's easier to work with so it's safer, but are there any words on like prices? Is it less expensive? Is it more expensive or is that it well? Well, just because it's easier to work with makes it less expensive. The actual cost of buying the chemical is in the noise compared to the cost of actually loading it onto a satellite and actually working with it. So, yeah, it's because it's easier to work with, it makes it a lot cheaper. Alright. Let's move even further backwards, kind of to the beginning of the interview because we're jumping all around with the chat rooms. Okay. What is the maximum altitude you've achieved with your vehicles and how long can you provide flight kind of flight-provided microgravity? So, how long can you stay in... So, we haven't actually gotten to microgravity levels yet. Our highest flight shoot we just had this discussion in an email conversation we were like trying to figure out what our highest altitude was because we think we came very close to it this past week. I want to say it's around successful flight it was around 500 meters. So 1600 foot. We hear Elon and SpaceX talk about this a lot it's not the altitude, it's the velocity that is the hard part, right? Because you're talking about doing low-earth orbit missions with like XS1, that's not height, that speed. Yeah, it's all about the velocity at that point and to a certain extent up to a point, say 100 kilometers or so or the velocities up to about, you know, getting to space, it's speed and height are one and the same. Once you're starting to go to orbit, then it's all about the velocity after that and altitude has little to do with it. But that impacts your recoverability as well, right? I mean, that's what makes reusability, I mean you're known for reusability but this is a nut that you haven't cracked yet is it not? So, it is something that we haven't gone really fast yet. We haven't done the really fast. But, I mean, there's a lot of different things you have to deal with for reusability. One of the things is can you even get a rocket engine to shut down and light again? Repeatedly. And then how often can you repeat that before you have to take it apart and do maintenance? You know, between shuttle flights, that was one of the things. Now, early in the shuttle program, they absolutely positively had to take the shuttle engines apart and rebuild them every single time. Now, my understanding is by the end of the program by the time they retired shuttle they did, but they really didn't have to take the engines off. Like, they took them apart, they checked it out, rebuilt it, but they really didn't have the wear and tear. So, like, maybe they're thinking, hey, you know, maybe we are getting to a level of reusability that might be, you know, more like an airplane where you land. You don't tear apart an airplane engine every time you land. Right. So, that's an interesting question. And I don't know SpaceX and Blue Origin, how much time do they spend on engine rework after they land? Are they just inspecting or do they have to clean the heck out of them? Or even tear them apart and rebuild them? How about you? How much time? I mean, obviously you're being able to fly within 45 minutes, so I have to assume the answer is like zero. We figured it out to where you don't have to take apart an engine. You don't have to, you know, you just sort of look at it and say, you know, that still looks like an engine. So, what is, this is from Tarantula. What is the biggest challenge for quick turnaround of your reusable vehicles? So, I think the biggest challenges are in the propulsion system. And then once you start doing things like going to space and doing much higher velocities thermal protection systems. Hmm. Is there a danger that you don't burn up? Don't burn up on reentry, yeah. And that's sort of the hard part. That's sort of the part that we need a lot more work on, quite frankly. Why is it hard? It feels like there are a billion different thermal protection systems. You got the tiles from the shuttle, you got blankets, you've got pica from NASA. So, you have things like pica from NASA which aren't so reusable. It's ablative. Sure. So, by definition, you're burning up a portion of it and you can reuse it a second or third time if the reentry wasn't as bad as you expected. But, you really need something where you're not going to replace it after every flight or every two flights.  And that becomes difficult. Now, on the shuttle, the shuttle used a lot of what RCC, let's say, a carbon-carbon composite. It had the problem of if you the reentry part might go just perfectly fine, it lost a lot of tiles. They had constant problems with losing tiles, so that's a bit of an issue. So, you had that replacement work. But also, you couldn't land in the rain because just a raindrop hitting it was going fast enough and the carbon composite, the carbon-carbon is so brittle that a raindrop hitting it will crack it. Oh my gosh, I had no idea. I did not know you could not land in the rain. So, yeah, they couldn't land in the rain. That's why they oftentimes had to land at Edwards. Huh. It's because, oh, it looks like it's going to rain and it's going to keep raining through our entry window. So, let's shift to Edwards so that we can land this mission. That one time at White Sands. They landed there once and they said, we're never doing that again. So, yeah. There's a lot of materials issues about doing a reentry. And I think we actually have some answers for that. I'm excited to see that in the future. Do you have any, are you allowed, are you able to give out any timelines? Because I know that XS-1, it's done in phases and the first phase is basically done and we're kind of waiting on phase two. Are you going to move, do you need them to do phase two or can you just continue moving forward without that? What other ultimate decisions are we're going to keep moving? We may change direction a little bit like we might change the size of the vehicle. I'm not sure that, I mean DARPA's XS-1 vehicle may be a little larger than what we really, really, really want to do. Okay, so what do you really, really want to do then? So right now I really, really want to concentrate on small set launch. I think there's a really nice opening there and that's...  What do you define as a small set? Well, traditionally small set is anything that's 100 kilograms or less for a satellite size. I'm stretching that a little bit. I think maybe 250 kilos, 300 kilos is probably a sweeter spot for launch capability. But generally, looking at most of the market is less than 100 kilos, there's enough of the between 100 and 300 that we think that makes a more sensible size. XS-1? So XS-1 was 3,000 to 5,000 pounds to orbit, so about 1,400 or so kilos. So quite a bit more. So quite a bit more. But that's all... XS-1 is single stage to orbit. Well, it doesn't have to be. But it's definitely reusable. It is definitely reusable. If you did multi-stage to orbit, do all stages need to be reusable? No, it's just the booster stage for XS-1. There's sort of another change there is I want to make that upper stage reusable. And so there's a little bit... Well, because in your initial drawings it looked like you were single stage to orbit, like with the wing diversion, right? A giant airplane looking thing. So we had a wing, but it was a booster. So when the XS-1 program started there were two missions for it. There was the go-to orbit, and it was also a do-a-mock-10 kind of a vehicle that could carry a scramjet experiment. Okay. So basically hypersonic experiments for the Air Force. The Air Force is really interested in doing a lot more testing in hypersonic environments. And they thought that if you could go to orbit then well obviously you can do a mock-10 hypersonic experiment. As we got through the program well no that's not really true. You want to dedicate a vehicle for hypersonics. And it's either for launch or it's for hypersonics you're really not going to do the same vehicle for both. So they sort of dropped the hypersonic requirement towards the end. And then you would actually take it. If phase two doesn't happen or if you're not selected you would take it and scale it down even more. We're just going to scale it down and do our own...  That's what massive space is. Yes, exactly. So an interesting comment from Lars von Braun maybe you can speak to. He says I really want to like mass and space systems but I feel like they're not very far along feels like they're more dreamers than anything else at this time. Are you just talking about this stuff? Are you building this stuff? Where are you? Because we don't hear a lot about you, right? We're building stuff we're launching stuff you know we're not we're not billionaires we're not backed by a billionaire so it's just taking a little bit more time and unfortunately because the government has been helping us with contracts so our launch vehicle we're getting a lot of assistance from DARPO through the XS1 program to do a launch vehicle then yeah guess what we can't tweet about it well we can but in order to tweet about something exciting that we did for XS1 for example we recently did some engine testing for for XS1 in order to tweet about it I have to put in a request for media release to the bureaucracy it feels like it's hilarious that you have 140 characters you have to have this request yes and two weeks later I get a question about it you know social media nowadays is you have a four hour relevancy window you know if you're not talking if you don't tweet it out in four hours you're not relevant so if I got way too weeks forget it so our social media is just you know taking a dive basically I think we pretty much tweet about being on tomorrow and we tweet about job openings so you're kind of for lack of a better term in blue origin mode right now where there's a lot of stuff but no one can see what you're doing exactly and then someday once you're able to do it these floodgates will open and be like oh actually we have all of these vehicles because you have engines you are flying things you're making stuff you're bending hardware you're not just talking about it you actually have a whole campus now up in yeah we have a whole campus we have five buildings now you know our staff is growing considerably we're about three or four times what we were a couple years ago because we're working a lot more with the government we're actually getting government contracts to support a lot of our development activities you know we have to go through this whole long spiel for getting stuff you know to tweet about stuff and so it doesn't get us talked about as much you know let's keep working we can do that they don't stop us from doing that alright a couple last questions we're going to bounce around a little bit again one more is that you really got the chat room all riled up over mxp 351 so if you can, yeah I know you're like oh come on join us this question don't answer it if you can but determined it's cheaper safer but can you produce it off of earth so let's say you go to mars and you want to build a vehicle and refuel it on mars could you go to mars and create it there from only elements found on mars well I mean technically it is you know elements that are found just about everywhere in the universe so yes we could how much effort would it take I don't know it's probably not as easy as just cracking water to get hydrogen and oxygen although one of the components pretty much if you have water we can make you one of the components but yeah no I you could all the elements are there but the question we don't have any technology to make propellants off earth right now anyway so no you can't and I don't care if you sleep but theoretically you could but no I don't think anybody actually has that technology right now alright this is a great question to take us into break so this will be the last question for you this one's easy I promise and that is from structure 1701 do you have any job openings right now I don't think we're hiring right at the moment but if you do in the future where should people go for that information in the future Mastin.arrow A-E-R-O did you know that there's a dot space top level domain now you can actually own Mastin.space I'll make sure to let our people know we found that out the other day so yeah there's a whole new slew of things so that'd be pretty cool Dave it is always fun having you on the show thank you so much hopefully that was not too painful alright we're gonna take a quick break and when we come back comments from last week's show stay tuned we'll be right back we've always looked to the stars they guide us give us comfort help us find our way we see ourselves out there when we look up it inspires us we long for something we don't yet know we yearn to go there so we venture forth we choose to go to the moon in this decay and do the other thing not because they are easy but because they are hard because that gold will serve to organize a vision of this the eagle has landed welcome back for man welcome back for this the exploration of space will go ahead whether we join in it or not many think we stopped exploring but we know our journey didn't end we've only just begun come with us and explore tomorrow welcome back to tomorrow now before we get started if you have any viewer comments from this last week's show I did want to give a huge shout out to all of the patrons of tomorrow who helped to make this specific segment to this episode happen these are people who have contributed $10 or more to this specific episode they're going to get absolutely everything we've also got our tomorrow producers they've contributed $5 or more to this specific episode and the people who are going to get access to after dark early that's going to be our tomorrow Patreon plus subscribers these are people who have contributed $2.50 but wait this little is $1 per episode and get your name in the show to find out more information all those different reward levels head on over to Patreon.com slash T-M-R-O alright and a huge thank you to all of our patrons for helping to make all of that happen let's get started with some comments from last week's show what was our topic last week it was data is beautiful we're talking about flight club IO and how you can do thanks it was and how you can do some beautiful graphing and like real-time charts of where the rockets are and whatnot so capcom take us away first one comes off of YouTube this one comes from Fabio Malone says we only know the human body behaves under two conditions one G and no G we need more samples before we can say or predict anything about how the body will react in other conditions the moon one 6 G the Mars the Mars the Mars is the Mars that's the one 5 so might as well be the Mars one third G may provide more entry points to this chart yes right Dave you'll you'll help us with that right yeah yeah Dave Dave gives us a thumbs up yeah and you know we did have experiments for space station that were like a centrifuge and other ways to do these you know tessie since we built them and they're sitting in Japan right now is that correct and they will never fly unfortunately or at least there are no plans to have them fly at this time so you're right we do need to do these tests and understand what's going on there and we have the experiments we're just for whatever reason choosing not to send them up which is I think somewhat sad alright next up capcom next one also comes off of YouTube this one comes from Stuart Young President Obama it's gratifying to see president taking some time to participate in some boyhood fantasy dreaming at this extremely difficult point in history it always shocks me how gray he's become that happens to all the presidents have you ever noticed yeah well eight years under super stressful situations you try to not turn gray but they do they age like 20 years and eight it doesn't matter anyway offhand I think it's I can't think of a president who's taken more of a consistent interest in space since Lyndon B. Johnson which was 1965 to 1969 for those of you who don't know well I mean I think it's great that he is showing this interest and has you know tried to be consistent and you know we say consistent but a lot of people complain when he changed the plan when his administration took office that it was somewhat vague but you know as we were talking about the new story that I was talking about this with I mean I feel that his legacy is helping to enable all of this public private partnerships and having the commercial crew program the commercial cargo program his legacy all these other things but didn't start out with his program but he was something who was able to further that and give support to that and urge Congress and the Senate to vote in favor of programs like that whereas before they didn't they didn't necessarily want to throw out as much money towards programs yeah I mean and to be clear the COTS program started under the brush administration to searcher 17 oh one says Abel Lincoln no interest in space exploration at all totally worthless sorry I just that's true George Washington didn't care about space at all but you know COTS in the commercial space stuff really started mostly under the bush administration specifically under Mike Griffin's NASA administration they're the ones who kind of help you know dream that up and then it was the Obama administration certainly did help but I think there was a really big push from deputy administrator NASA administrator Harvard who really championed this quite a bit and took it and ran with it and like made it kind of like their thing like we shouldn't be doing this and she really fought I mean she fought for it yeah she fought in my opinion she fought for it more than administrator Bolden did I mean she was the one who really made it happen and yeah yeah I mean President Obama certainly kind of had some space stuff but he helps sort of define the funding that is necessary I guess I just felt like his administration like his view of space was uninspired and just boring lackluster it was lackluster and I mean it's neat that he enjoys this stuff but I was constantly disappointed for better or worse go back to the moon oh I forgot to ask Dave we'll have to ask him in after dark we're trying to ask everyone moon or Mars first I'm the reason I forgot to ask David because I know the answer but yeah we so anyhow this is me Curian Crack I'm Dave you guys are all so he's in the studio what am I trying to say he's in the control room and he just like stands up and he's a formidable guy and he's wearing a shirt that says moon first and he's like eh alright so there you go I don't know and maybe I'm wrong maybe maybe the Obama administration did a lot more than I'm not giving them credit for if that's the case and you do know something there certainly post it in the comments and let me know why I'm wrong but otherwise I just I feel like really it was even you know the Bush administration did help start some of these cost programs what not but every every program has been underfunded so I mean yeah great you can have an idea and you can go hey let's do this but if you're gonna steal all the funding and drop it on a giant rocket that won't fly I don't it yeah it's very difficult to understand that alright next up next up oh my god you're kidding I didn't how many pages is this four pages hang on while we go to this I'm just gonna stare at Duda the entire time Duda the hair okay so this one comes off of reddit I'm gonna have a drink you probably should you could probably go to the bathroom actually during all this you're gonna have some time people this one's from Brandon Mark hmm oh oh oh another US president who has another Mars plan slated to happen and oh you guessed it about 20 years I wish I could attend a speech like this and throw a pie in the guy's face you know what bold into I feel like every single US president in my lifetime is a promise we go back to the moon and then Mars and every single time it's 15 to 20 years away Reagan Bush Clinton Bush Obama same story every single time why should anyone take these people seriously it's like Charlie Brown and Lucy with the stupid football I'm convinced politicians by and large really don't care about spaceflight they want DOD contractors to stay in the black while they want US missile engineers to stay in practice and as far as NASA and its dreams it's no it's good PR vehicle to convince millennials to pay their taxes also of note 20 years is convincing conveniently far enough in the future that nobody will remember or care where the president said in 2016 and Obama certainly won't have to shoulder the responsibility for the policy or the spending to make a Mars mission happen double convenient and my bitter hell yeah I was promised an awesome future time and time again I'm older but the awesome is still frustratingly quote-unquote only 20 years away I think I'd rather keep my tax money thank you very much and I'd rather pin my hopes on fickle politicians I'll just watch Elon Musk demonstrate how worthless these 20 year plans really are we accomplishes it in far less maybe it won't be 10 years maybe it'll be less than 15 I had enough time to go into the other room grab a soda and a mug that was a long comment Dutta although a fairly passionate plea and that's why and that's why Dutta yells fairly passionate plea and not necessarily wrong you know I'll argue that today's guest Dave Mastin may be able to do it in less time as well I don't know yeah I don't know that it's politicians that don't want to see success you know you just need to understand what their role here is and that's that they want to create jobs for their district and they don't want their constituents to be out of work because then they're not going to get reelected yeah and I mean in the space industry we hate that that sucks we don't want to see that but you can understand where they're coming from at least right so I would make the argument that what we need to do is change the idea and concept that instead of building big rockets to know where that will keep people employed if we instead create new industry you'll employ even more people in your district by letting the market mature into a way in which we're not just working here on earth but we're also working out in space and I think that will create all new jobs all new industry all new manufacturing at a scale of which we have not seen before and I think that scale is so large that they can't even fathom it and I think that's part of the problem but if we can do that then then and convince politicians of that and actually work towards that model then I do think government would play an incredible role in making that happen also you look at small space companies NASA new space companies NASA and even Dave good chunk of that funding is coming from government so they're not it's not that they're evil it's just that there are certain very small factions they're doing that have a lot of control over money they're doing things that we disagree with yes there you go I think that kind of goes back into the whole public private partnerships you know all these new space companies that could accomplish the goal of going to the moon and Mars in you know less than 20 years like you said are getting a lot of their funding right now from NASA and I think that that you know the past eight years have kind of helped to foster this kind of new contracting that they have instead of doing cost plus contracting you know it's fixed price contracting to do a certain goal and and I think that it's for the better for all the reasons that you that you just said and because this is the political system that we have we need to work within that system and I think that just the amount of successes that we've seen in the the recent past is starting to convince more and more politicians that maybe this is such a good idea and will create an industry that's just my opinion anyway and that gets me into my whole cost plus isn't necessarily a bad idea you just can't use it everywhere and it can't be abused there actually is a that's a different conversation for a different time though it's kind of like the solid the solid fuel versus liquid fuel argument yes there are places for each one of them each one of them has their pros and cons you just have to understand them and apply them appropriately and when you don't do that bad things happen yes so alright I don't know how I want oh hey I'm being told to do this there you go alright next up or is this the last one yeah alright last one capcom also comes off of youtube this was from josh willis says it's a little screwed up to be so flippant about the theories around tabby star we don't know what it is so at this point a Dyson swarm is still on the table though very very unlikely biases can influence the way data is perceived so it's very important to not let our own lack of knowledge color what the data may very well be saying Jared well I mean I'll throw this out here which is that Carl Sagan once said extraordinary extraordinary ideas require extraordinary evidence so in science we don't jump to the fantastical immediately when we're working on things we work but we want to do you want so fantastic so much better story it's like the best thing ever to just say aliens and then work with it but there's a problem with that which is that in science you have to first look at the obvious and that's really what you do you throw the obvious guess at it and you see if that sticks on the wall if it sticks on the wall there you go you found it unless somebody else comes in and looks at your obvious guess and says no that's wrong here's another one and then that sticks to the wall okay maybe it sticks a bit better than the other one did so you compromise with it so sorry you know I'm not here to sugarcoat or try to try to give you some kind of Star Wars answer with everything I'm just going to tell you what we know and the fact is with Tabby Star we don't know but the chances of it being a swarm of comets is probably a lot higher than it being aliens so just throwing that out there sorry it's I mean I would love for it to be nice and sphere and we find out that there's intelligent life out there but guess what it's probably not what it is and because that's not and because the chances of that are so much smaller than any other potential answer nobody's really going to pursue it because you're not going to be able to fund the study to even think about you know doing stuff like that you know it's going to be fun in early December Fraser Kane of Universe Today is going to be on and he and I have somewhat different views on the possibility of intelligent life out there and he actually basically says no it's not out there it's almost certainly just us and I am of the opinion that there's almost certainly intelligent life out there it's just never been here yes so that taking that conversation like I think that is going to be a fascinating fun show yes because he actually has very compelling arguments so hopefully my arguments are as compelling as his slash he's smarter than I am so he might just win that by debate December 3rd December 3rd is when that particular debate he was actually going to be on a couple weeks ago but our bandwidth issues unfortunately prevented him from coming on so I'm excited for that debate to actually occur yeah yeah absolutely alright next week show we're going to have a long time viewer and contributor to the show Emery Stagmer also known as Vax Headroom he's going to be on and we're going to be talking small sats so very apt to go from Dave Preston to Emery who also actually this is a really great transition because he also has been on talking about Sea Dragon before and you know some of the floaty super yeah exactly right so that's going to be that's going to be a lot of fun so everyone thank you so much for watching after dark is up next if you're a patreon plus subscriber you're going to get that as soon as it's posted on demand everyone else had to be available at about a month and we'll see you guys next week


Okay, it is time for hem facing. We have front hem facing and a back hem facing. That's exactly what it sounds like. The back hem facing goes along the back and then up the side and the front hem facing does the same thing on the front. This I'm going to work on the front hem facing first. So you have two of these and they make this little L shape, right? Let me move this out of the way. Like this, you're going to sew the little short end together at your seam allowance and then once that's done, press that open and you're going to finish this long edge, which will eventually, by this point, look like this. Okay, so it's very, very long.  Now you're wondering, how do you do an internal corner on a serger? I get it. It seems a little complicated. Depending on the flexibility of your fabric, you can do a move like this where, see how straight that is? And you just kind of like, you know, press that out a little bit, just enough for the serger stitches and then that's it.  Just attaching this at my seam allowance, which should be half an inch. Okay, so once you've got your hem facings sewn together on that short edge and finished, then we're going to attach the facings to each other, but only like the littlest bit. So right sides together. Okay, so this little notch here, this notch to the edge is all we're stitching the front and the back together. Okay, just that little bit. So find the short edges, put them together, right sides together, like so. And again, you're just going to sew at your seam allowance from, and you're going to do that on both sides. So these should be right sides together. For what it's worth, if you've gotten yours mixed up, I think that the back is a little bit shorter than the front. Okay, so again, we're just stitching right through here. All right. Okay, and once you've got that done, now we are going to clip into these. I know this part is always so nerve-racking even for me, but you're going to clip into the area where the notch is, and you're going to clip up to your stitching, like really up to it. Where's the other one? Okay, now you can bring your skirt hem down. This is my front skirt. Okay, so now we're going to lay this right sides together. I'm going to start over here because that's also where we're going to start sewing. So come up through here, untwist, untwist. This is going to go around the back of the dress, like so. Okay, so now this raw edge, the shorter one comes up to here. Perfect. Yes. Okay, and then pin, and all you're going to do is sew from this dot down, pivoting, come around, and go back up the other side, and then repeat the same thing for the back. It's not a continuous seam per se, but just lots of pinning and then, all right. So again, we're starting at one of the dots, and at our seam line, we're just going to come straight down and pivot and go around. Now, once the front is done, you're going to break your stitches, and we're going to switch it to do the back side. Okay, and when you remove all your pins, I'm going to show you what it looks like at the table. We're going to come right back over here and do understitching, which is actually my favorite, one of my favorite sewing techniques, sewing skills ever. I just think it makes such a big difference. But yeah, let me show you what this looks like at the table. Okay, so we are trimming seam allowances, right, and you can trim the straight ones too, not just the corners. I, with this fabric, I kind of want to leave them just to keep adding weight to the hem, so it's not too lightweight. I also think it makes, you know, the understitching a little bit better on lightweight fabrics, so I'm going to leave mine. We're going to go to back to the machine, and we are going to understitch. Understitching is sewing, repeat after me, the seam allowance to the facing, okay, or the lining or whatever you're doing. So it's going to go like this, where the face, the seam allowances are being pushed toward the facing, right, and then you stitch very, very, very close to that seam line right there, and you're not going to be able to go all the way around. Like in these corners, it's just going to get too tight, but go as far as you can in every direction, and that'll help pull that seam line to the wrong side of the dress, so you'll never see that seam line. It really, really, really does work. Okay, okay, and when you're done with your understitching and you turn everything to the inside, it just, you can tell, it just does not want to roll. That seam line does not want to roll to the outside at all. So go and press this, and then we are going to topstitch this down. I do think that is pretty much necessary for everyone. I guess there's a way that you could probably tack it at the seams if you wanted, but I just think that would just, I don't know, probably get on my nerves. I don't know about you, though. Maybe it depends on your fabric, or you can do a hand, you know, to make it a little bit more invisible if you want to keep the clean line. I am a little bit upset that I'm going to put a stitch right through here, but I don't know now. I might save that decision for another day, but you guys understand what the goal here is. It's just to run a stitch over this to hold all this down into place. You will see it on the right side, though. That's my dilemma. Let me think about it while I'm getting all of this looking pretty. I'm going to continue on with the next video that we're going to finish up the dress, really. We're going to put on our straps. We're going to put on the lining and finish up what's left of the instructions on this pattern. I'll see you back for that one.


Here's another activity for comparing and contrasting the tenses, focusing here in this activity on the present perfect and the present perfect continuous. So in the activity, students will start at the start and roll a die. Perhaps they could roll a five. They will read something you've been learning for a long time. The appropriate sentence may be, I've been learning English for a long time. The next student may go and roll a four. They read a beautiful place you've visited. Then, rather than the present perfect continuous, they would use the present perfect tense. I've visited Paris. You could encourage students to even ask follow-up questions which would also include other tenses. What was so beautiful about Paris? Now this activity will be particularly good for your more advanced students who are capable of using various tenses accurately. It's also good in the beginning of your course when students perhaps don't know each other very well and they're using this as a way to learn about their past experiences.