The whole subject of planetary defense has a somewhat nebulous rationale. Despite the recent bolide collision in Russia, which spawned a number of quasi-hysterical press reports, the risk of a life-altering asteroid collision is actually quite low. Check out this diagram from The Economist your risk of being killed by an asteroid impact is roughly 1 in 75 million. For comparison, your risk of being struck by lightning is about 1 in 500,000, of being attacked by a shark is 1 in 11 million, and being killed in a terrorist attack is about 1 in 20 million. You are actually more likely to die in an asteroid impact than you are to win the Powerball lottery (1 in 175 million). Is it logical or prudent to make asteroid defense an integral part of NASAs mission, given that its likelihood is of such low probability?
I disagree with this part of the article. Lightning strikes and shark attacks don't normally wipe out cities (unless it's a Sharknado ) much less the whole species. So just comparing the odds like that isn't really a sensible comparison. You have to consider the potential harm that could be done as well as the chance of it happening, to decide whether to do anything about it.
It's so frustrating from a biotech perspective. Year over year, we can do so many more things at only a slightly elevated cost. No so with space development, it seems. We need some type of cultural shift, the same thing that allowed affordable cars and computers.
Uranus is a naked eye object in some places. Being new to this, I've never seen it, but I know Uranus is magnitude 5.something. You're in Queens, so I'm guessing its out of range for you, but not in more rural areas.
However, every source I've seen says it can never be seen with the naked eye (Even though its magnitude is sometimes lower than 8), and of course, I have no idea where you'd find a sky that dark anyways. I'm curious if it can theoretically be spotted under absolutely perfect conditions. I'm absolutely certain that Uranus can.
I disagree with this part of the article. Lightning strikes and shark attacks don't normally wipe out cities (unless it's a Sharknado ) much less the whole species. So just comparing the odds like that isn't really a sensible comparison. You have to consider the potential harm that could be done as well as the chance of it happening, to decide whether to do anything about it.
Well, personally I think that a 1 to 75 million chance of being killed by an asteroid is pretty damn high (it's just four times less likely to occur than me being killed by some terrorist wackos, which is entirely a human-controlled issue).
And as you correctly pointed out, it's about the scale of the disaster, which wholly transcends individual interests. Yes, I as a person have a much greater chance of being killed by a lightning storm. But if that were to happen (knock knock on wood), the rest of humanity would hardly notice the disappearance of my prodigious personality
On the other hand, should a 10 km asteroid hit Earth, it would pretty much mean the end of human civilization and the death of perhaps as many as 99% of humans alive, not to mention the mass extinctions and environmental chaos that would follow.
Thus, since it is a catastrophe we can't afford to suffer (as callous as it sounds, we can afford thousands of people being killed by hurricanes or terrorists each year, partly because we can't do much more about them than we already are doing, and partly because their loss doesn't threaten the whole of mankind), it seems sensible to me to at least get ready to do something about it. The cost isn't that steep.
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Now, what Spudis was saying in that article was, that the proposed asteroid capture mission does very little to prepare ourselves for the possibility of a real asteroid deflection. Moving essentially a medium-sized boulder with a mass of several hundred tonnes is very different from deflecting a mountain-sized asteroid weighing millions of tonnes.
I think that if NASA wants an asteroid mission, they should do a NEO mission. That would test all kinds of stuff, including manned interplanetary spaceflight, rendezvous and landing on a large asteroid, drilling on an asteroid (why not try it while we're there?), ISRU (we could at least find out whether it's doable on an asteroid), etc. Personally, I would even have them carry a nuke there and set it off near the rock when the crew is in safe distance, to measure what kind of a kick it gives. Or test other deflection methods (mirrors, electric thrusters on the surface, etc.). Such a mission would both be interesting, worthwhile, and increase our experience with the kind of operations we would need to do in case a killer asteroid was really heading our way.
-> He talks a lot about SLS, how it came into being, why the space programme is in such a mess and what should be done next. He seems to have quite a good understanding of the matter.
Controversially, he claims that SLS was designed the way it was by the Senate not because of any political malice, but because NASA was dragging its feet and didn't supply its own study of how to achieve heavy-lift. I totally did not know about that. He also speaks about why Congress keeps wanting NASA to return to the Moon, that's also VERY interesting. Not least he speaks about the so-called "new space" companies in the US and gives some very good arguments as to why should one be sceptical. ("If Falcon 9 is so wonderful and cheap as SpaceX people claim, why haven't they flown a single commercial satellite yet?").
Really recommended. If anybody does listen to it, let me know what you think.
An International Collaboration of FACom researchers and astronomers of the University of Texas (El Paso) and New Mexico State University have discovered a physical mechanism that could make binary stars more hospitable to habitable planets than single stars.
The discovery could imply a modification in the estimations of the number of planets potentially harboring life in the galaxy and in the future selection of targets for the search of life elsewhere.
I read the paper, but I'm not sure how this might apply to my favorite star, Delta Trianguli, but from the figures provided, I take it the components (1.09 Msun G0V / 0.75 Msun K3V / P=10 days SMA=0.11146 au) may likely have ended up with the forever young effect and potentially diminishing habitability? Or am I being too pessimistic, since I noted Kepler-47 was in the middle range?
Aren't such planets pretty rare? I mean, what mechanisms even create close binaries? If one of the stars "migrates" towards the the other during the early stages of formation of their planetary systems, I'd guess most planets will be either swallowed or ejected out of the system (similar thing probably happens if a gas giant migrates inwards).
BTW, it's interesting how everything points us to Sun-like stars (K,G, colder Fs) as the best candidates for habitability. M-class may be by far the most numerous, but it seems pretty hard for a planet to get everything right in order to be habitable (by Earth-like life, anyway).
Sweet Jesus, this looks absolutely great. I am so going to see this in a cinema, if only for the CGI (anything beyond that goes above my expectations and I am getting ready to pick the film's plot apart).
If anything, this film might give people *some* idea of what it is like to really be in space.
The director's quote that there won't be sound in vacuum (except for what the characters can actually hear) leaves me hopeful And I am positively happy that someone decided to make a real (well, realistic looking) space fiction, instead of all the totally unrealistic action Hollywood crap people are normally being fed (starting with Armageddon, continuing up to now with all the comic-book adaptations crap).
(At the risk of sounding like an old fart in my 28 years of age, I see the modern CGI-extravaganza as detrimental to our cause. If people are "educated" by action-packed, senses-saturating CGI films, the "real" space travel as shown in broadcasts by NASA or ESA seems boring and mundane. Getting excited about space is possible on two levels: (a) the "wow" factor of seeing stuff like the Earth from 450 km altitude, observing planets through high-resolution photos, etc., and (b) understanding the significance of it all.
For b), a certain level of education and insight is needed. I have this issue with my girlfriend - I tell her something I've read about or seen in an excited manner, implying how great and interesting it is, and she's just looking at me with this blank expression on her face. She doesn't get WHY is it exciting. For someone who follows space exploration, things like "they've found methane in Mars' atmosphere!" or "they've found a planet orbiting Alpha Centauri!" is "OMG, awesome, that's just great!". For people who don't follow this, it's "hm, okay, I guess, but so what?"
Therefore, a) is that much more important. But it's hard to achieve if people's expectations are unrealistically high as result of all the CGI action crap that passes for entertainment these days. If people expect us to be travelling around the Galaxy in a starship full of young attractive males and females, how do you get them excited by the real space travel, or even the kind of space travel we can realistically achieve? A transit to Mars would be 6-8 months of pure boredom (you can't even see anything interesting from the windows), followed by fumbling around a dusty desert, looking for things people can't see. "So why is finding some stupid bacteria so important? Don't we have plenty here on Earth? Why do I pay my tax dollars/euros/rubles/yuans for this nonsense?"
Space cadets like us would be drooling, but what about the "civilians"? It's their money paying for this, so we can't ignore them.)
Have you caught Europa Report yet? If not, you should, it's excellent hard sci-fi.
Yeah Although I am sometimes pretty frustrated by my utter inability to properly convey the wonder and excitement I feel about this stuff. I should be able to do it, somehow, but since it requires some prior knowledge, it would take a lot of lecturing, and you clearly can't do it with everyone.
BTW, I did a little experiment in lalala-land virtual rocketry.
It occurred to me, what if we made a semi-SSTO out of the Shuttle main tanks? SLWT is EXTREMELY lightweight (dry mass fraction only 0.035). Now, I say it now that this would require HUGE LOx-LH2 engines to even lift off the ground - if I calculated it right (probably not), we'd need an engine with 5.75 MN sea-level thrust, which is only slightly less than the Saturn-V's F-1, and 3 times as much as the SSME. I'd *guess* it's doable and with modern technology it could even be reasonably light (about 8 tonnes). Oh, and we'd need to cluster 7 of them together
The core would be a slightly strengthened space shuttle main tank with the engines underneath and payload on top. Another four space shuttle tanks would be attached radially to the core, feeding fuel to the engines. These external tanks would jettison after having fed all their propellant to the core. Optionally they could be fitted with parachutes and recovered later for reuse (after all, it's a big dumb tank, how hard would it be to make it reusable?).
The core would have a dry mass of roughly 150 tonnes (as opposed for the normal shuttle tank's dry weight of only 26.5 tonnes) to account for the engines and additional structural modifications. Originally, I assumed the whole core stage would re-enter and land pretty much like the SpaceX "grasshopper". I was inspired by the Skylon re-entry profile, which is more benign due to its large volume-to-mass ratio, and wondered if perhaps something similar could not be used here (less re-entry heating and g-loads - lighter thermal protection systems and more lightweight structure). There would be no large wings, the core would simply drop down and in the terminal phase use one of its large engines to burn a little remaining propellant to slow down and land vertically on a pad.
If that was too difficult, then perhaps the engine pod could be separable from the core and capable of re-entry and parachute landing. The engines are by far the most expensive part of the rocket, so re-using them is a priority; everything else is optional. Oh, if I haven't said that already, the engines would be designed to be reasonably re-usable (say 5-10 times).
I used the Launch Vehicle Performance Calculator plus my own guesstimate calculations and was positively surprised - this would not only get to low Earth orbit, but also lift a CONSIDERABLE payload - as much as 150 tonnes! I tried various more pessimistic (higher dry mass) versions, and the payload never dropped below 70 tonnes (which is still very good by today's launchers standards).
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Which makes me wonder why nobody has tried this before. I know there were some ideas about using the Saturn-V's 2nd stage (the S-II) as an expendable SSTO. What really makes the difference here is using LOx/LH2 propellant mixture. Even with relatively inefficient high-thrust hydrogen-oxygen engines, you get a specific impulse of 410 seconds and better (the cutting edge is about 460 seconds). This is far better than the best you get from kerolox engines. Now I understand that liquid hydrogen is a **** to work with, but with modern-day materials, we should be able to do a pure-rocket hydrogen-oxygen SSTO (yeah, I am not counting the external tanks as a separate stage).
Also, I do appreciate that real rocketry is far more complicated than "LEGOing" pieces together on paper, but... wouldn't using one piece 5 times on one launch vehicle be inherently cheaper than designing a rocket made of many separate pieces requiring totally different manufacturing processes and numerous facilities and many more people working in them? This would basically only use two variants of the Shuttle Main Tank - manufacturable in one facility, one type of engine, plus some accessory stuff. With a lift capacity of 150 tonnes and limited reusability, it would be far preferable to the super expensive, totally expendable SLS. And it would still be Shuttle derived, technically speaking!
(Also, this would never fit in the VAB. OK, back to the real world now )
A slightly dated BBC documentary about the ISS. Pretty interesting as far as the history of the project is concerned (I loled when I learned that NASA originally sold the project to Reagan claiming it would cost 8 billion dollars ).
It is also interesting to ponder the reasons why Russia was invited to join with the US and Europe in building a space station in the first place. We can cynically say that it was because the US was concerned what all the Russians rocket scientists and designers would do if they lost their jobs (which they would have if not for Western money being poured into the Russian space programme), like, say, work for Iran or North Korea or any number of crackpot regimes on their ballistic missiles.
But the documentary correctly suggests that the reason was more practical. NASA really had almost zero experience with building modular space stations and making them work. Their experience with life support systems and other stuff was limited. The first 8 billion dollars given to NASA were totally wasted as a standing army of NASA employees scratched their heads trying to figure out how to build a space station that comes in more than one piece.
So, Russia injected the much needed experience in the project. Of course, today the Western part of the ISS pretty much eclipses the Russian part in its functionality, but without Russia, there probably would be no space station at all.
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BTW: Notice by the end how the British bias against human spaceflight seeps into the documentary I mean, it is of course relevant to know *why* we have built the ISS and whether it was worth the cost. But I really dislike the simplistic take on human vs. robot exploration. This has been discussed ad nauseam so I won't ramble about that, but if anybody else wants to comment, I am willing to engage in such a debate
BTW: Notice by the end how the British bias against human spaceflight seeps into the documentary I mean, it is of course relevant to know *why* we have built the ISS and whether it was worth the cost. But I really dislike the simplistic take on human vs. robot exploration. This has been discussed ad nauseam so I won't ramble about that, but if anybody else wants to comment, I am willing to engage in such a debate
I've never understood how people can say with a straight face that robotic exploration is either cheaper or better than manned exploration. Sure, there are a lot of missions where robots make sense. But when it comes down to it, all of the science that Spirit and Opportunity have done in the years they have been on Mars could have been done by a single scientist in a couple of days, no joke. Maybe an individual robotic mission is cheaper than a manned mission but if science is truly the most important factor than there is simply no comparison between robotic and manned exploration. All of the robotic missions have returned samples measured in grams, while just six moon landings brought back nearly a ton. Plus, nearly every robotic mission has been capable of doing just a handful of experiments - experiments that often fail because the robots are incapable of adjusting them to suit local conditions. You just don't have that issue with manned missions.
That's why I say safety and more importantly, cost have been the driving force behind robotic exploration with science coming in third.
In my opinion, you can't do that because you'd end up modifying the tanks so much that they'd have little resemblance to the original tanks. You'd wind up with all of the costs associated with a brand new system. I'll explain:
SLWT is EXTREMELY lightweight (dry mass fraction only 0.035).
Because they were designed to be expendable and they don't have to bear most of the thrust load throughout their structure the way they would if rockets were at the bottom instead of side mounted as the Space Shuttle's engines and boosters were.
Now, I say it now that this would require HUGE LOx-LH2 engines to even lift off the ground - if I calculated it right (probably not), we'd need an engine with 5.75 MN sea-level thrust, which is only slightly less than the Saturn-V's F-1, and 3 times as much as the SSME. I'd *guess* it's doable and with modern technology it could even be reasonably light (about 8 tonnes). Oh, and we'd need to cluster 7 of them together
Everything but the cluster is pretty reasonable. A new engine of that class would be hella expensive but it could be done. No one really has experience with that kind of clustering though, it's a much bigger challenge than adding on a bunch of SRB's or even just two extra cores Delta V Heavy-style.
The core would be a slightly strengthened space shuttle main tank with the engines underneath and payload on top. Another four space shuttle tanks would be attached radially to the core, feeding fuel to the engines. These external tanks would jettison after having fed all their propellant to the core. Optionally they could be fitted with parachutes and recovered later for reuse (after all, it's a big dumb tank, how hard would it be to make it reusable?).
Those tanks won't survived even a suborbital reentry without significant reengineering to add heat shields and significantly strengthen the structure. Then there's the foam issue: that stuff is going to break off during reentry and on impact and I don't know of any good way to put it back on without stripping it all off and reapplying, which I don't think would be very easy. IIRC most of the work hours put into those tanks was in foam application so if you are having to strip it off and reapply you might as well build another whole tank that won't have any defects from reentry/splashdown.
The core would have a dry mass of roughly 150 tonnes (as opposed for the normal shuttle tank's dry weight of only 26.5 tonnes) to account for the engines and additional structural modifications. Originally, I assumed the whole core stage would re-enter and land pretty much like the SpaceX "grasshopper". I was inspired by the Skylon re-entry profile, which is more benign due to its large volume-to-mass ratio, and wondered if perhaps something similar could not be used here (less re-entry heating and g-loads - lighter thermal protection systems and more lightweight structure). There would be no large wings, the core would simply drop down and in the terminal phase use one of its large engines to burn a little remaining propellant to slow down and land vertically on a pad.
You won't be able to turn it around very easily I think but I'm not sure. Plus, your asking for a restartable engine because you don't want to be trusting when you flip it around to slow down. That alone ups the difficulty behind engineering the thing considerably. You would need some sort of ullage system to settle the propellent before engine restart. Then you'd need some sort of spool-up system to get the turbopumps up to speed again. In most large rockets that's done by systems on the pad and by auxiliary high-pressure helium systems that basically force the turbopumps to turn over and start pumping. That's a big weight cost and adds to the complexity of the system.
The other problem is that you can't really get away from using a thermal protection system when the tank is falling from altitude as it will still be falling with ridiculous velocity. Of course, the necessity for thermal protection is going to depend on the particular flight path so I don't rule out that you could get away with not having it.
If that was too difficult, then perhaps the engine pod could be separable from the core and capable of re-entry and parachute landing. The engines are by far the most expensive part of the rocket, so re-using them is a priority; everything else is optional. Oh, if I haven't said that already, the engines would be designed to be reasonably re-usable (say 5-10 times).
If you are talking a parachute landing on the ground, you might be able to do this. If you are talking about a parachute landing at sea then you can rule out reusable engines because if there is one thing machines hate it's sea water. I wouldn't risk an astronauts life putting him on a rocket that has flood damage! You could try and enclose them but that's another engineering problem with associated mass penalty. Plus, if you are talking about a US or EU rocket, then it's going to have to be a wet landing because we don't have a poor neighbor lol: Kazakhstan) that we can dump our spent stages on like the Russians do.
Another thing is that re-usable engines don't really work nor do they save you that much money. The SSME's got about 3 reuses IIRC before they were replaced. Even then, reusing them meant stripping out and replacing a ton of parts and was extremely costly just because of all the man-hours and parts needed. It's probably going to be cheaper to design engines that work extremely well and reliably once and then are easily swapped out for fresh ones. I think that would save a lot of money over a reusable engine in the long run.
Now I understand that liquid hydrogen is a **** to work with, but with modern-day materials, we should be able to do a pure-rocket hydrogen-oxygen SSTO (yeah, I am not counting the external tanks as a separate stage).
I think you are right and I think H2/Lox lower stages are the way NASA plans on going from now on. Once you have mastered H2 systems there is really not much reason to not use it.
Also, I do appreciate that real rocketry is far more complicated than "LEGOing" pieces together on paper, but... wouldn't using one piece 5 times on one launch vehicle be inherently cheaper than designing a rocket made of many separate pieces requiring totally different manufacturing processes and numerous facilities and many more people working in them? This would basically only use two variants of the Shuttle Main Tank - manufacturable in one facility, one type of engine, plus some accessory stuff. With a lift capacity of 150 tonnes and limited reusability, it would be far preferable to the super expensive, totally expendable SLS. And it would still be Shuttle derived, technically speaking!
-> He talks a lot about SLS, how it came into being, why the space programme is in such a mess and what should be done next. He seems to have quite a good understanding of the matter.
Controversially, he claims that SLS was designed the way it was by the Senate not because of any political malice, but because NASA was dragging its feet and didn't supply its own study of how to achieve heavy-lift. I totally did not know about that. He also speaks about why Congress keeps wanting NASA to return to the Moon, that's also VERY interesting. Not least he speaks about the so-called "new space" companies in the US and gives some very good arguments as to why should one be sceptical. ("If Falcon 9 is so wonderful and cheap as SpaceX people claim, why haven't they flown a single commercial satellite yet?").
Really recommended. If anybody does listen to it, let me know what you think.
I listened to it and it was good. I do have to note that he is pretty heavily biased though. He's basically taking the Zubrin approach and advocating for a destination (the moon) and an architecture he thinks works best and discounts everything else to nearly the point of absurdity. Also, his libertarian bent stuck out like a sore thumb and really turned me off. I really wish I could remember the quote I'm thinking of but he blasted 'new space' companies by talking about how wrong it is for the government to fund them in any way shape or form. That's all fine and dandy in theory but the reality is that if we want to get these companies off the ground they need a ton of upfront investment because the barrier to entry into this market is astronomically higher than in any other industry. He's just not realistic when it comes to that at all - I don't advocate funding them unconditionally forever but there is no reason we can't fund them by buying their services while they get their feet on solid footing. Rockets are not like computers, you're not going to find the Steve Wozniak of Rocketry plugging away in his mom's garage banging together the next best thing in space launch technology. He knows better, he is a smart man with a lot of experience but his ideology is twisting his reality very similarly to how Zubrin's mind works.
I really wish I could remember the quote that set me off, I'm going to have to go back and listen to it.
Also, he completely dismissed the value of the currently-planned asteroid mission. I'm not saying it couldn't be done better, but the man literally said we know all there is to know about asteroids and that meteorites we have on the ground tell us all we need to know about asteroids. I'm sorry but that was pretty stupid! It's like saying that I saw a bunch of mummies in a museum once and now I know everything about Egypt. We can really only guess as to the true composition and geological features of the asteroids and there is so much to be learned by exploring one or even capturing one and moving it around. Sure, there could be better ways to go about it, but I have to say his bent on returning to the Moon was blinding him to true value of the mission. He is just like Zubrin in that he has a destination in mind (the moon) and he's going to attack everything that 'distracts' from that. I too have a favorite destination but if NASA chooses to go somewhere else then I'll support that rather than try and stop the whole program in order to refocus them on going to my favorite place. They already have enough distraction and funding issues, trying to throw wrenches in the process simply because you don't like where they are going is pretty selfish. He also chastised a caller for his 'fantasy architecture' (the caller had an idea for a reuseable rocket) while not realizing he has his own fantasy architecture (space fuel depots and his version of a heavy lift rocket) and he's using that fantasy architecture to attack what NASA is doing. Again, the criticism is welcome but let's not be hypocritical about it and attack random callers for doing what you do yourself.
Finally on the private companies: he's way off IMO. I am not SPACEX IS THE BEST FALCON9!!!!!111!!!1! nut myself, but he's pretty unforgiving and unrealistic in his analysis. He did point out that the Falcon 9 hasn't flown a commercial payload yet, but he dismissed out of hand the fact that Falcon 9 does have a manifest of launches that they will deliver on. He had nothing to say to that other than 'well they haven't done any commercial launches yet!' which is an overly simplistic assessment. He knows darn well the engineering challenges required behind building a new rocket. He also dismisses the fact that the programs that are funding Antares and Falcon 9 development are not bottomless pit arrangements that Boeing, Lockheed et al got when they were developing their systems. They have development deadlines and competitive funding, they can't just blow up 50 rockets on the pad and turn to the government and ask 'May I have some more sir' the way the older companies did. The failure rate of Atlas, Delta and Titan systems was absolutely atrocious but they just kept getting cash thrown at them until they worked it out. The newer companies don't have that luxury in that the government isn't going to pay for multiple failures and the market investors will dump the companies if that happens. So that's why I say he was unfair, I am most decidedly not rahrahrahSPACEX, but the situation isn't as simple as the picture he painted.
He also dismissed out of hand the need for SpaceX et al to do lots of demonstration flights before insurance rates become reasonable enough for companies to buy launches from them. He really had nothing to say on that and that is a mistake because insurance rates are one of the biggest challenges any space launch company faces, particularly when they are new and don't have a huge launch history behind them.
Anywho, all in all it was a very good listen and it made me think a lot. I appreciate the link.
When does the next episode of the Space Show come out?
Edit: I didn't mean to knock on the guest for being libertarian. I could care less, I just think his political beliefs tint his take on the space program in a very contrarian way and led him to ignore reality in some sense.
Edit 2: Found the quote: (on the government/private enterprise COTS program)
I have a philosophical objection to this. The government runs GM....
I am sorry, I am going to be replying in a piecemeal fashion (lack of time). If I quote just a part of your post, it's for brevity sake, I've read it all. I may return and comment some more.
Because they were designed to be expendable and they don't have to bear most of the thrust load throughout their structure the way they would if rockets were at the bottom instead of side mounted as the Space Shuttle's engines and boosters were.
Well, I would have used them exactly in the Shuttle way - mount them to the side of the core stage, which would bear most of the load. But good points about the foam and other stuff - so scrap reusability, just drop them in the ocean. Or, at some payload penalty, carry some of them up into orbit and use them to build space stations
Another thing is that re-usable engines don't really work nor do they save you that much money. The SSME's got about 3 reuses IIRC before they were replaced. Even then, reusing them meant stripping out and replacing a ton of parts and was extremely costly just because of all the man-hours and parts needed. It's probably going to be cheaper to design engines that work extremely well and reliably once and then are easily swapped out for fresh ones. I think that would save a lot of money over a reusable engine in the long run.
About engine reusability - I was surprised to read on astronautix and other sites that the Russians actually managed to produce large reusable engines, even though they operate at insane chamber pressures and temperatures, use oxygen-rich propellant mixtures and otherwise stress the engine components. Their RD-170 was apparently capable of withstanding up to 10-20 burns.
If the Russians have managed that with a kerosene engine more powerful than the F-1, I would *guess* that someone in the West who is prepared to spend some money and adopt some of the Russian know-how (which boils down to breaking a lot of stuff, until finally you make things that work not only well, but even excellently), it *should* be possible to design a powerful LH2/LOx engine capable of many consecutive restarts without extensive refurbishing after each flight. After all, this fuel mixture is pretty clean, so it doesn't clog with sooth or anything like that. It doesn't even have to be all that efficient; an Isp of over 420 s is acceptable, anything above only increases the payload.
I also read about the work Reaction Engines Ltd. is doing concerning the expansion-deflection nozzles. If that pans out, it could potentially lead to pretty significant improvements in performance, as the Isp/thrust losses at lower altitudes would be reduced.
I've read in many sources that the aerospace industry is hopelessly conservative. They do things that they know work, but are very risk averse, which has been identified by many as the chief reason behind the lack of progress in launch vehicle developments. One of the main contributions of SpaceX so far in my opinion was to demonstrate that a judicious infusion of innovation into what's essentially 1960s era technology can lead to pretty spectacular results. Now imagine we went a little farther...
(Oh, my proposal would definitely require government money, lots of it. The launch vehicle would be huge, beyond the ability of smaller companies to fund on their own. The bottom line is, I as a layman see no reason why this should be in principle impossible. Furthermore, even if SKYLON or Grasshopper or similar concepts work, we will only have reusable vehicles in the 10-20 tonne to LEO range. There will still be a need for heavy lift, if we are to go to Mars or build large bases on the Moon. It seems logical to me, then, that the US should, instead of going down the "big, complicated, expendable" route, focus on innovative concepts for achieving heavy lift. In the end, the initial investment would more than pay off later.)
I listened to it and it was good. I do have to note that he is pretty heavily biased though. He's basically taking the Zubrin approach and advocating for a destination (the moon) and an architecture he thinks works best and discounts everything else to nearly the point of absurdity. Also, his libertarian bent stuck out like a sore thumb and really turned me off.
Oh, he definitely *is* biased I am a Mars nut myself, so listening to his cruel reasoning isn't comfortable to me either, but I do have to (reservedly) agree with him. I ran a few simulations in my head and this is how it went:
Suppose for the sake of the argument that Zubrin catches a magic gold fish which grants him his wish to have Mars Direct implemented. OK, so the US invests the 50-100 billion dollars in a 10 year Apollo-style "let's go to Mars before this decade is out" dash and in mid-2020s first humans land on Mars. Then what?
The programme is far too expensive for the bean counters in Congress to sustain for long. Zubrin believes that once we get to Mars, everybody will be magically interested in keeping the programme running forever. But I think a much likelier scenario is that once the initial goals are met - we have men and women on Mars, planting flags, shooting videos for schoolkids, and doing science - the interest would quickly wane. It would get ordinary, like the ISS flights. Further Mars Direct missions would essentially be doing the same all over again, at least in the eyes of the public and their representatives in the American government. People would ask - what's the benefit for us here on Earth? What are the tangible gains to our economy, international standing, national security, etc.? Politicians would point out that nowhere in the space policy documents does it say that the goal of NASA is to colonize space, therefore using that justification is politically imprudent to say the least.
Therefore, the likely scenario is that Mars Direct would end the same way Apollo did, cancelled after a few missions, with further plans for settlement "deferred" until later time, when we have the "technologies" to do it "cheaply" and "safely" [the quotation marks indicate the sarcasm in my voice]. Mars exploration may be exciting, but it is hardly sustainable unless you somehow make the government adopt space colonization as a priority goal.
What Spudis and his camp propose is clever in the way that it *may* just be sustainable. Once a milestone is achieved, it leaves behind capabilities others can build on. Once you, for example, have propellant factory on the Moon, you'd have to be insane not to use it. And once you have that capability, it opens many possibilities you didn't have previously. It's a slow, not-so-exciting, but incremental process of establishing a permanent presence in space, starting close to Earth where the money is, servicing down-to-Earth needs of humankind. The more robust the cis-lunar infrastructure, the lesser the likelihood of it all being cancelled one day.
You have to admit there is logic in that, even if that means our dreams of (manned) beyond-Moon exploration would be put on hold for Gods-know how long.
I really wish I could remember the quote that set me off, I'm going to have to go back and listen to it.
Oh, yes, he's absolutely missing the point there, I completely agree. Public-private partnership is nothing to scowl at, especially not on "philosophical" grounds. The government(s) will pay private companies to do it one way or another (unless the US goes communist and nationalizes all aerospace industry ), so it may just as well do it in a cheaper way - trickle-feeding private companies to develop products and services which they will then sell to the government. Encourage private enterprise to fill the gaps in capability.
It makes no sense for him to oppose that, but I guess it's a result of his view of the NewSpace companies, which according to him are mostly selling hype, not delivering, and constantly asking for money and expertise and technologies from NASA for free. That may be true for many, perhaps most, but there are some which are serious partners.
(Not the suborbitals, I wouldn't give them a single dollar/euro of public money, because theirs is a dead end.)
Also, he completely dismissed the value of the currently-planned asteroid mission.
That's actually where he convinced me. The way he explains it (especially in articles on his blog), the asteroid capture mission was selected *against* the better judgement of many in NASA itself, and its main goal is to give NASA *something* to do, since return to the Moon or going to Mars is off the table. It's pay-off in terms of science and experience really seems pretty weak and not really worth it compared to other things NASA could do. Zubrin pointed it out too - for this kind of money you could send tens of probes to tens of NEOs and return samples for them.
He also chastised a caller for his 'fantasy architecture' (the caller had an idea for a reuseable rocket) while not realizing he has his own fantasy architecture (space fuel depots and his version of a heavy lift rocket) and he's using that fantasy architecture to attack what NASA is doing. Again, the criticism is welcome but let's not be hypocritical about it and attack random callers for doing what you do yourself.
Hm, I read that part differently. He said something like "We all have fantasy programmes and we like to talk about them, but the real problem is to manage the real space programme in a real world." Unless I am mistaken, he's a sort of a historian of the US space programme, so I trust his experience. Before reading stuff from him about the Vision for Space Exploration, I thought (like many in the Mars crowd) that returning to the Moon was unnecessary, a political boondoggle to distract from the good things we should do in space. Spudis, however, makes a very good case for sticking with the Moon, because it is pretty much the only programme which can be made sustainable and provide benefits to Earth relatively quickly. I recommend his 5-part article on the history of the VSE, it was pretty illuminating.
Finally on the private companies: he's way off IMO. I am not SPACEX IS THE BEST FALCON9!!!!!111!!!1! nut myself, but he's pretty unforgiving and unrealistic in his analysis.
Yeah, I agree. Or... well, OK, I am a sceptic (some people say cynic) by nature. So I share some of the motivation behind his comments. As in, "I'll trust them when they actually prove they can do this and that for that kind of money." It is true that SpaceX has a large flight manifest, but until they actually start putting payloads in orbit for the money they claim, on schedule, and reliably, we should take their statements with a grain of salt. I am sure you would agree with that too.
Anywho, all in all it was a very good listen and it made me think a lot. I appreciate the link.
Yeah. I don't listen to everything on the Space Show, only to some things that sound interesting from the description, but I found that the things that are most interesting to me are those I initially vigorously disagree with Because it makes me think harder, evaluate, and try to come up with counter-arguments. And when I can't find many, you have to admit the possibility this or that speaker is actually right about some things.
Of course there are many there who are just plainly wrong, living in fantasy world, or insufficiently aware of what's really happening in space, you just have to filter them out.
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) much less the whole species. So just comparing the odds like that isn't really a sensible comparison. You have to consider the potential harm that could be done as well as the chance of it happening, to decide whether to do anything about it.
And I am positively happy that someone decided to make a real (well, realistic looking) space fiction, instead of all the totally unrealistic action Hollywood crap people are normally being fed (starting with Armageddon, continuing up to now with all the comic-book adaptations crap).
Although I am sometimes pretty frustrated by my utter inability to properly convey the wonder and excitement I feel about this stuff. I should be able to do it, somehow, but since it requires some prior knowledge, it would take a lot of lecturing, and you clearly can't do it with everyone.
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