Cunjo Carl

Amidst all the amazing things going on I couldn't help but wonder.... Why did the water tower decide to take a leak at T - 01:30 ? Were they topping it up or something? Maybe an overpressurization from downstream? Of course this is the thing I latch on to!

Fortunately for any prospective passengers on Skylon, the Sabre engine's only designed to go up to mach 5-6 while air breathing, and then slowly leave the atmosphere burning fuel like a normal rocket to reach "Mach 25" orbital speeds. In the case of Skylon, it's kindof a misnomer to use 'mach 25' because the plane should be well up into space by the time it reaches those speeds. That missile on the other hand is something else! Totally agreed. They did get that bit of DARPA funding for the precooler test facility in Colorado, but yeah, funding for the rest of the project would be amazing. That said, major funding from the British government would probably be difficult, and making sure it doesn't get cut the day before their first successful launch would be even harder! ... Alright, I guess I'm just salty about Black Arrow.

Totally feasible! Industrial organic chemistry is like legos up to a point! Where there's a will there's a way. Let's see, for going from methane to specifically aromatics I think the normal answer would be super acid catalysis (normally in a loaded zeolite) to make ethylene, then Pt catalysis to dehydrogenate to benzene. I could probably pull up examples if it's useful, but hopefully this is enough to get started? These chemistries are used on an industrial scale, but the key difficulty is always struggling to maintain high catalyst activity while they're constantly getting covered in coke. That's the main reason you don't see these in laboratories much. The easy approach I learned is to just burn it off, but trying that on a small scale is a bit tricky... Still, if you had JPL on your side...

Ah, different conversation. This was for the Merlin 1D vac on the Falcon Heavy Upper Stage for an idea sevenperforce put forward. @sevenperforce You know, you might actually send the suggestion along to them. The look on the administrator's face was one of someone desperately trying to build as many fallback plans as possible, so sending it their way couldn't hurt. The worst they'll do is ignore it, and it's possible they didn't think of the elliptical orbit rendezvous, which is rather the crux of the thing. [email protected] or maybe https://www.nasa.gov/content/submit-a-question-for-nasa

I like it! And they didn't mention having considered it yet. But would just the docking clamps be enough to keep it all steady during the TLI burn? My quick numbers show the end of the TLI burn would be at ~.9G (39% throttle, 934kN thrust, 41.2t ) . I've heard the new docking clamps are snazzy, but I don't know much about them. (Oh also, could you put Doyouwonda's name on the quote in this post?)

I haven't been following the conversation, I just heard what he said in the video. It sounds like he's considering the idea as a ... maybe a fall back plan is the right feeling. He still has his bets on the SLS, but he thought the FH-ICPS had enough continuing merits for the long term mission (I believe here meaning entry into NRHO orbit with the hoped-to-be Gateway) to be worth seriously considering. It certainly has its difficulties, and he discusses a few of the problems in the video. He also mentions that he hadn't run these things by his lead rocket scientist, who was wearing a decidedly blank and dubious smile. Still, he explains that "It would require time, it would require cost and there is risk involved. But guess what, if we're going to land boots on the moon in 2024, we have time and we have the ability to accept some risk and make some modifications. All of that is on the table." Straight out of the horse's mouth. Not sure what else to say! Right? I love it! Almost could have been the April Fools joke. Original image credit appears to be a Reddit user by the name of DoYouWonda. " To everyone thinking this is a Franken-rocket, you’re right. As are many rockets. The Falcon Heavy is 3 Falcon 9s, the Delta IV Heavy the same. The OmegA is nothing but restocked existing pieces. SLS is a shuttle derived launcher with boosters, core stage, main engines, and upper stage from different rockets. " DoYouWonda

NASA is seriously considering using a Falcon Heavy together with an ICPS (Boeing's second stage for the Delta IV) for the EM-1 mission in order to lift the Orion capsule and European Service Module for a lunar flyby. Bridenstine talks about the idea and the difficulties involved during this town hall meeting. The video starts when the discussion moves to SpaceX-y things, and that particular suggestion is at about 36:00. "Talk about strange bed fellows." NASA's Administrator, Jim Bridenstine.

Technological inertia is surprisingly strong in rocket science. I wonder if it's because rocket science so expensive and difficult, people try to cling to whatever works! Echoing that, the opinion of John D. Clark in Ignition about the initial choice of RFNA over N2O4: " So the first order of business was choosing an oxidizer. ... and Malina, Parsons, and Forman who, with the assistance of Dr. H. R. Moody, did a survey of the subject, considered that N2O4 was impractical. It is difficult to say why, but the extremely poisonous nature of the beast may have had something to do with its rejection. "

I wasn't supposed to do any more typing today, but I'm too curious now. It's a good question. What happens if the Earth and Moon are combined into a roughly spherical body? Angular momentum of body in orbit = m*r*v (v is velocity perpendicular surface) Angular momentum of sphere = 2/5 m r^2 * 2*pi / T (T is rotation period) volume = (4/3)pi*r^3 8.6E4 s per day 3.8E8 m Moon orbit radius 1.0E3 m/s Moon orbital velocity 7.3E22 kg Moon mass 6.0E24 kg Earth mass 6.4E6 m Earth radius Since the Moon's mass is only ~1% that of the earth, the moon+earth sphere would have radius only .33% bigger, so not enough to worry about. The moon has about 4 times the angular momentum of the spinning Earth, so the day of a hypothetical spherical Earth+Moon combo would be much shorter! 5.0 hrs day = [((2/5)*6.0E24*6.4E6^2*2*3.14/8.6E4 + 7.3E22*3.8E8*1E3) / ((2/5)*6.1E24*6.4E6^2*2*3.14))]^-1/3600 Centrifugal force at the equator would be 1.6m/s^2

The KSP forums discourage discussion of contentious non-spacey things, and this presentation is unfortunately dripping with nationalism, politics and religion. However, it also contains mountains of extremely notable changes to US' space programs which will be good things to talk about! I did my best to sort the germ from the chaff here, so let's enjoy the fruits of that effort by not griping about the things we could all obviously gripe about. Thanks in advance. Also, thanks to @Ultimate Steve for bringing up this conference in the NASA Payloads thread! Big conversational items, and the timestamps they can be found at: NTRs and other nuclear space technologies will be developed, including for use in commercial space programs. 0:23:15, and primarily at 0:44:15 NASA is still committed to SLS, Gateway 1:17:30 500M$ Executive request to US congress to put crew on Gateway (seems very small?) 0:08:00 There were many conversations about risk involved in the 5yr plan, both for people and dollars. Notably, speaking about risk in commercial space programs: 1:39:30 They're heavily reducing bureaucratic hurdles for commercial launch 0:47:45, 0:57:15 There was one call to retain LEO presence for scientific research 2:01:30 Prospects of lunar ISRU at south pole are still unknown, though thankfully they realize it's very cold down where the water is. 2:21:30 One contentious issue that I have no idea how to handle discussing is the Space Race v.2 they're trying to start. This unfortunately explains why Roscosmos' proposed contributions to Gateway aren't being accepted. Mods, if you could let us know your thoughts on discussing this topic? For the sake of my blood pressure, let's not discuss it in this thread at least! 0:16:15, 0:38:00, 0:39:45. Also, ameliorating, 1:38:20 The US Space Force is being created provisionally (probably also its own topic) 0:05:30, 0:53:30 And, here's the full rundown of the conference:

My mistake! It was OneSpace that lost a rocket last week. Thanks for the catch.

Not much to discuss, but a new weekly space news show (fittingly called Space News) has been shaping up really well so I wanted to share it. They have a segment for traffic (all launches that week), weather (solar storms, etc) and whatever else is big in the news for space people that week. Most of the hosts are engineers and scientists, but they keep the stories and explanations pleasantly layman. This week's stories: • Launches: Ariane (success), OneWeb OneSpace (lost), Rocket Lab (success) • US Vice Pres announces NASA has coals under its feet to get boots back to the moon • Bennu's surprisingly rocky regolith spurts boulders into orbit • New superbly antibacterial silver alloys tested on the ISS • News-hyped solar storm arrived late, aurora later this week • Teaser: NASA's Dr. Eric Smith coming for an interview about James Webb

Oh hey! I actually use those, they're contact (or thin film) thermal conductivities. Let's do the standard thermal conductivities first, and then convert them to the contact equivalent. The imperial one was the most common thermal conductivity unit in the states up until recently. Now though, we almost always use W/m.K (for bulk materials) or kW/m2K (for contact). Here's the conversion: 6.933 Btu.in/(hr . ft2 . F) = 1 W/m.K = .001 kW/m.K (Thermal conductivity) 0.1761 Btu/(hr . ft2 . F) = 1 W/m2.K = .001 kW/m2.K (Contact/film thermal conductance) Or in other words, divide your imperial value by 176.1 . Depending on what you're working on, typical contact thermal conductances are often on the order of 2-20 kW/m2.K Best of luck with your project! Let me know if I can help any more with the translation

Besides the photos and sample already sent, I'm having a hard time imagining what other experiments they could want to run up in orbit. They can't exactly section the piece of Aluminum off the craft, and the hole's already been filled with a thermoset (very permanent) glue, so what's left to be done? Besides testing specifically the drills up there... oh, that does bode a bit. Edit: I'm realizing that probably came across more serious than I intended it, but still, what else is there left to do in orbit?

It's a page back, so I figured I'd also post here, I missed a factor of 2 on the angle of the Starship cylinder that would be reflecting to the viewer. It should be 2 * 4.5m * sin(0.53deg / 4) making a 2cm strip (half the light). Updating, that puts the brightness at .0048 lx, and the magnitude at -8.1 . Still bright enough to be a show, but not quite as impressive! The astronomers will probably be happier at any rate Sorry all!

My rationale was that there's a big thermal resistance between the engines and the fuel tanks. So, despite the engines absorbing much more sunlight they'd also radiate almost all of the energy away as heat rather than letting it pass to the fuel. Meanwhile, the walls of the starship will reflect most light away, but what they do absorb will probably have a very low thermal-resistance direct path of metal the fuel tanks (because of how the ship is designed for anti-buckling). Totally just a guess! I haven't heard of the barbeque roll, I'll go look it up!

The nose is an interesting question! It's more complicated, so I ignored it . Moonlight reflection is also interesting. Since the moon fills the same area in the sky as the sun, and is about 14 magnitude dimmer, that would put its reflection at magnitude ~ 5, which would be just barely visible if you're far away from cities. Again, lots of uncertainty, so YMMV!

Edit: Made a minor oops, fixed in the bottom paragraph. Because it was interesting, I took a little bit and thought through the math of the maxmimum magnitude of light reflected by starship in low orbit (like with the ISS). I thought it'd need an integral, but luckily it looks like not! I reasoned that any shiny surface can be thought of as n-many flat mirrors. A distant flat mirror will either shine with the full intensity of the sun or not at all (we used tiny steel mirrors in search and rescue for signalling at ridiculous distances, it's an interesting property). Given this, the lux from starship will be the lux from the sun times the ratio of apparent solid angles. The maximum brightness should occur (roughly) at sunset when the Starship is directly overhead with its nose pointing towards the sun and 45 degrees up from the horizon, and with the shiny dorsal side rotated to face down towards us. The light reflected will be from the horizontal axis of the sun right across the middle. Assuming this position, the brightness should cover a much larger area of Earth than say the iridium panels. The part of starship that reflects to us will be the cylinder's entire length (guessing 40m at 45 degrees to us), and around the radius (4.5m) the same angle as the sun takes up in the sky (0.53 deg), making a strip about 4cm across. Apparent Reflective Area = 40m * sin(45deg) * 2 * 4.5m * sin(0.53deg / 2) . The distance will be the altitude of ISS, say, 409km. Let's call its reflectivity at 0.93 like @cubinator suggests. The greyish steel is carbon steel turned grey from FeO, Stainless is shiny! The sun shines at 98000 lux and is 696Mm radius and 150Gm distance. It shines from the apparent area of a disc at pi*r^2 Starship Lux = 98000 * 0.93 * [ 40 * sin(45deg) * 2 * 4.5 * sin(0.53deg / 2) / 409E3^2 ] / (3.14*696E6^2 / 150E9^2) = 0.0095 lx (at max) Finally converting this is about a -8.8 magnitude, so the same as an iridium flare! (about -8 to -9) . If starship is pointing its engines at the sun though, it won't look nearly as impressive. Let's hope the SpaceX execs are the sort of people who like to put on a show on occasion * Your mileage may vary, all this was calculated on a napkin. Also, I used an approximate formula for solid angle, but it's good enough for this case. Edit: Eeek, Sorry all, I missed a factor of 2 on the angle of the Starship cylinder that would be reflecting to the viewer. It should be 2 * 4.5 * sin(0.53deg / 4) making a 2cm strip. Updating, that puts the brightness at .0048 lx, and -8.1 magnitude. Still bright enough to be a show, but not quite as impressive!

I suspect the Starship will orbit with it's engine side facing the sun though, like the BFR with its axolotl solar panels, right? BFR Concept art from SpaceX Axolotl picture from ThreeLeaves on Youtube

Man, I'm painfully slow at writing now. This took almost a week! I finally read the article posted by @Nivee~ and it's pretty uncanny- This exact project has actually come across my desk. I guess I should give some context. I was previously a process development engineer for an academic institution which heavily promoted commercial development (though now I'm much happier just being a physics researcher). I gained a reputation for being able to unstick stuck projects, so people would often bring me problems for unofficial consulting. This project came to me about a year before I got sick, so maybe 2 years ago? I should also preface that I'm not a proponent (I think it's destined to not quite work), but this particular project has people acting in good faith. There are MANY projects presented very similarly which are just scams. It's also possible development's stopped and it's since become a scam, but anyways, on with the story. This was one of two applications for a shoe-string budget project on H2 production, and it actually does have merits. Like everyone else has said, unlike in the article, it's not one weird trick that power companies hate him for , but it does have locations where it's viable. There are, I was told, isolated small communities where Aluminum cans are used in volume (thanks to pepsi co's legendary distribution network), but it's not practical or politically viable to have a sorting/recycling service. In these places, the Al is literally just being tossed into the garbage heaps. There's apparently a lot of places like this. In order to be viable they'd need to crack 3 small breakthroughs. The first being closing the loop on Gallium which is used to 'soften up' the Al, but which is expensive and largely consumed in the process. I ran the numbers back then and showed they'd need at least ~~90% recycling of Gallium to become economically feasible relative to petrol power. Fortunately there's a couple techniques that could conceivably make this possible, including a simple insitu electrochemical cell to recover Gallium within the process directly on to fresh shredded Aluminum presented as the cathode. It's plausible, but would need significant development. Next, I thought fuel cells wouldn't be economically viable given the size scale of their intended application. Keeping those things hot is a pain. It looks like the gentleman in the article is trying to solve the problem with an internal combustion cycle... There's a lot of difficulties to this with Hydrogen. It resists ignition better than gasoline, has a very complicated combustion rate-vs-concentration profile (kinetics), it slowly embrittles steel, and has a nastily negative Joule-Thompson coefficient all of which are kinda unpleasant. Anyways, if some handy engineer figured it out, I'm happy. I'd definitely want to see it running in person, 'cause the devils in the details for a design like that. Lastly is what to do with the waste streams which will be a terrible grey sludge full of old soda, beer and inks. I'm still a fan of @kerbiloid's suggestion! For all the trouble we'd get about a C-cell's worth of power out of each can. Not bad! Also not good. I mentally put the project about on par with grass-roots campaigns to recoup power from compostables outgassing (like here in California), or power generation from burning flammable trash (like in Japan). It's much more difficult than these, but could serve a similar roll specifically for communities where proper recycling infrastructure isn't feasible.

Plenty of good answers already, but I'll add a bit. We actually have an equivalent to the Oberth effect right here on Earth, if you've ever ridden a bike in a hilly area. When faced with a short hill, people will speed up extra at the bottom rather than trying to fight the hill extra at the top. Especially on a bike, our legs act a bit like rocket engines. Our legs can provide a force for a certain time before getting tired, just like rocket engines can provide a force for a certain time before running out of fuel. In either case, that force per time translates into a certain amount of 'speed up'. In other words, if you crank the pedals harder for a little bit, you'll be going faster. Great! So if you're toodling along at a normal speed (say 16kph or 10mph) and you notice the road in front of you has a short but steep incline (say 2m or 6.5ft tall) you'll naturally speed up a bit so that you hit the incline with plenty of speed and whisk over it, rather than needing to spend the extra energy by slowing to a crawl halfway up and cranking your way up the second half. Let's compare how much speed (aka. energy) we come out with if we speed up another 6.5kph (4mph) at the bottom of the hill while we're still going fast rather than trying to use it at the top of the hill after it's too late and we've already slowed down. 1. Use the 6.5kph speedup first to get to 22.5kph and hit the hill: you'll come out traveling 16kph just like originally! This is what people normally do because it's the easy way to ride a bike up a hill. 2. Hit the hill going 16kph, and naturally slow down to 1.5kph by the top. Then use the 6.5kph speedup and you'll only be going 8kph- half your original speed! People don't do this. It's hard! Anyways, the Oberth Effect is all the same things for the same reasons, except IN SPAAAACE . Which is why it seems more magical

Scott Manley talks about the anatomy of the Raptor engine (starting at 1:30), and other recent SpaceX happenings. "I'm not a rocket scientist, but I play one on the internet." So say we all!

Rumor from over at the spacex redit was that the rent was getting prohibitive and the port was trying to strongarm SpaceX into a worse deal so they peaced out. That could explain some of the 'take no prisoners' approach to clearing out the old space.

Eyes in the back of my head would be capital! There's actually ongoing research for that sort of stuff, I helped out a bit with research on biocompatible electrical interconnects to neurons about a decade back. It's a bit invasive for the general public to use, but technology-wise it's not that far out now. Spare hemispheres, maybe a little further... Albeit just as necessary in my case! CNS neuron coupling to nanoporous gold electrical interface, work by Dr. E. Seker et. al Also, technically a reuseable species, but it costs more to refurbish a unit than to just make a new one like on the STS . Being flippant, don't take too seriously, please!