Here goes one of our occasional space and astronomy roundups!
First some personal science news. I will be speaking about the search for extraterrestrial intelligence (SETI) twice, early in 2015. (1) at the conference of the AAPT - the American Association of Physics Teachers, January 4 - 6, 2015, in San Diego...
... then (2) I'll be the "con" arguer in a debate over "messaging to aliens" at the American Association for the Advancement of Science - AAAS Annual Meeting - the greatest scientific conclave on the planet, from 12 - 16 February 2015, in San Jose, CA.
And now... cool stuff!
== Are we a target? ==
... or rather... really hot stuff! Did you hear that a solar storm spewed forth a major spray of energetic, charged particles that passed very close to the Earth, a while back? Read up on the 1859 Carrington Event that fried telegraph systems -- if it struck today, our electronics-dependent civilization could suffer real damage. Contemplate that... then consider this. There may have been a truly monumental coronal mass ejection around the year 775 that hit the Earth with a strength that was about 20 times the 1859 Carrington Event.
And yes, the solution is to get out there! Members of Congress introduced a bill to protect property rights for commercial exploitation of asteroids. The bipartisan legislation, introduced by Rep. Bill Posey (R-FL) and Rep. Derek Kilmer (D-WA), is called the American Space Technology for Exploring Resource Opportunities in Deep Space (ASTEROIDS) Act. Alas, during our current civil war, there is no chance of an actual political process in the USA. But when this phase ends, as it must, the bill will be ready for action by a restored, scientific and forward-looking nation.
Have you heard stories about this supposed reactionless drive, “unveiled” at a NASA conference in Ohio? I've put in a query to Geoff Landis - NASA scientist and renowned SciFi author, who promised to watch developments and give us the straight dope... or poop. To be clear, there are some places where we already can do a version of this -- turn solar energy directly into motion, without using reaction mass or rocketry -- e.g. by applying electrodynamic tethers to leverage against the Earth's magnetic field...
First some personal science news. I will be speaking about the search for extraterrestrial intelligence (SETI) twice, early in 2015. (1) at the conference of the AAPT - the American Association of Physics Teachers, January 4 - 6, 2015, in San Diego...
... then (2) I'll be the "con" arguer in a debate over "messaging to aliens" at the American Association for the Advancement of Science - AAAS Annual Meeting - the greatest scientific conclave on the planet, from 12 - 16 February 2015, in San Jose, CA.
And now... cool stuff!
== Are we a target? ==
... or rather... really hot stuff! Did you hear that a solar storm spewed forth a major spray of energetic, charged particles that passed very close to the Earth, a while back? Read up on the 1859 Carrington Event that fried telegraph systems -- if it struck today, our electronics-dependent civilization could suffer real damage. Contemplate that... then consider this. There may have been a truly monumental coronal mass ejection around the year 775 that hit the Earth with a strength that was about 20 times the 1859 Carrington Event.
And yes, the solution is to get out there! Members of Congress introduced a bill to protect property rights for commercial exploitation of asteroids. The bipartisan legislation, introduced by Rep. Bill Posey (R-FL) and Rep. Derek Kilmer (D-WA), is called the American Space Technology for Exploring Resource Opportunities in Deep Space (ASTEROIDS) Act. Alas, during our current civil war, there is no chance of an actual political process in the USA. But when this phase ends, as it must, the bill will be ready for action by a restored, scientific and forward-looking nation.
Have you heard stories about this supposed reactionless drive, “unveiled” at a NASA conference in Ohio? I've put in a query to Geoff Landis - NASA scientist and renowned SciFi author, who promised to watch developments and give us the straight dope... or poop. To be clear, there are some places where we already can do a version of this -- turn solar energy directly into motion, without using reaction mass or rocketry -- e.g. by applying electrodynamic tethers to leverage against the Earth's magnetic field...
…but only where there is an electron rich zone like the Van Allen belts to close the circuit loop. Interestingly, electomagnetic tethers work in exactly the realm you must climb through before deploying a solar sail. (See this process illustrated in both my short story “Tank Farm Dyamo” and in the first chapter of EXISTENCE, which I read aloud for you, here.)
Meanwhile. NASA released high-quality footage of their experiment in near-space in June, deploying the agency’s Low-Density Supersonic Decelerator (LDSD) and experimental parachute systems that will be helpful in maneuvers and landings near planets, like Mars. Way cool footage!
Oh but we really need to get out there! Dig this — “Within a two-week period in August 2013, astronomers observed three massive volcanic eruptions on Jupiter’s moon Io. The grand finale was an eruption they say was one of the brightest volcanic eruptions ever observed in our solar system. These astronomers are speculating that these eruptions on Io – which can send material hundreds of miles above the little moon’s surface – might be much more common than they previously thought."
Oh but we really need to get out there! Dig this — “Within a two-week period in August 2013, astronomers observed three massive volcanic eruptions on Jupiter’s moon Io. The grand finale was an eruption they say was one of the brightest volcanic eruptions ever observed in our solar system. These astronomers are speculating that these eruptions on Io – which can send material hundreds of miles above the little moon’s surface – might be much more common than they previously thought."
We should have a satellite observatory in-residence above Jupiter, permanently.
Meanwhile, researchers have found a microbial menagerie that thrives in tiny water worlds floating in oily tar pits ... perhaps a model for life on Titan?
== And yet more from space! ==
From beyond the solar system: Cosmic grains returned by the Stardust mission predate the solar system -- and may be our first samples of interstellar dust. This is amazing. And crowd-sourced amateur science played a role!
Are many asteroids “rubble piles” held together by molecular forces, in addition to very weak gravity? It seems that is the case for near Earth crosser 1950 DA… and the implications — for resource-mining as well as countering potentially dangerous ones — are very complicated. It is a good thing we are forging forward to find out. Alas, the Space.com reporter might need to get straight the meanings of “centripetal” vs “centrifugal.”
Under ideal conditions, the upcoming James Webb Space Telescope (JWST) should be able to detect two kinds of chlorofluorocarbons (CFCs) in the atmospheres of alien worlds, if atmospheric levels were 10 times those on Earth. In other words, if aliens are self-destructive fools, we might catch them during the brief window of time. But only if it is orbiting a very dim star.
Are many asteroids “rubble piles” held together by molecular forces, in addition to very weak gravity? It seems that is the case for near Earth crosser 1950 DA… and the implications — for resource-mining as well as countering potentially dangerous ones — are very complicated. It is a good thing we are forging forward to find out. Alas, the Space.com reporter might need to get straight the meanings of “centripetal” vs “centrifugal.”
Under ideal conditions, the upcoming James Webb Space Telescope (JWST) should be able to detect two kinds of chlorofluorocarbons (CFCs) in the atmospheres of alien worlds, if atmospheric levels were 10 times those on Earth. In other words, if aliens are self-destructive fools, we might catch them during the brief window of time. But only if it is orbiting a very dim star.
Is the Universe a Bubble? If two pocket “universes” make physical contact, there are several possibilities. M-brane theorists think the collision would release so much energy that the resulting bang would wipe out any galaxy-style realms that existed before. On the other hand, researchers at the Perimeter Institute for Theoretical Physics, think the interaction could be mild and show up in the maps we are now making of the microwave background. “We start with a multiverse that has two bubbles in it, we collide the bubbles on a computer to figure out what happens, and then we stick a virtual observer in various places and ask what that observer would see from there."
Want more about the multiverse? See Exploring the Multiverse -- a talk given by astrophysicists Brian Keating (UCSD) and Andrew Friedman (MIT)... and me.... We covered the ELEVEN different ways (that we have thought-of, so far) that this cosmos we observe may be just one of many! The event took place at the Arthur C. Clarke Center for Human Imagination at UCSD on July 29. Here's a photo from our panel discussion: Brian Keating on the left, Andrew Friedman in the middle, me on the right:
== Space is also for dreams ==
Finally... do you miss the "final frontier"? The notion of a hopeful future of unbounded possibilities? Do you like well done sci fi and drama and neat effects... in a terrific Kickstarter-level production? Have a look at the 20 minute "Prelude to Axanar." All of it aimed at a high quality, semi-pro indie Star Trek film.
You have to hand it to Paramount Pictures. They figured out that you don't have to be jerks about policing a copyrighted franchise. Start Trek has always had a close and friendly relationship with its fans and Paramount has kept a very loose and tolerant attitude toward "unofficial" productions, many of which have been well-written and entertaining... and which ultimately kept Paramount's valued core healthy. A true win-win.
But Axanar looks likely to be something special. This is Star Trek at its best. The danger and tension and action... mixed with joy and optimism that you get nowhere else, these days. This is worth your support.
I've a quick question concerning asteroids and these "rubble-piles" - one "concern" about detonating a nuke on one of these asteroids is that it would cause multiple smaller impacts on the planet. However, is this necessarily a bad thing?
ReplyDeleteLet's take an asteroid that is large enough to destroy a city or devastate a region. If you destroy it, suddenly you have a rain of asteroid material impacting the planet... except much of this WON'T hit the planet because we have this nice little shield called the atmosphere.
Thus wouldn't destroying a non-planet buster asteroid actually result in a rain of material, most of which will burn up in the atmosphere? There would be multiple objects that could cause explosions in the upper atmosphere as they become fireballs, but it would cause far less damage than letting the entire thing hit in one region.
In essence it's the difference between a shotgun slug and a group of shotgun pellets... with numerous pellets never teaching the target. Would the damage be worse in this situation?
Rob H.
Tell the people of Chelyabinsk that their meteor never reached its target. Asteroids burning up in the atmosphere still impart energy to Earth. That could literally set the world on fire. Plus it may be harder to deflect a soft pile of rubble compared to a solid rock.
ReplyDeleteBut I think the key here is uncertainty since we don't know the composition of most asteroids (except this one) and any mitigation efforts we want to make rely on that kind of knowledge.
We should have a number of science stations peppered all around the solar system watching for things like eruptions on IO, landslides on Mars, and CME's from the sun, but the cost of putting them out there has to come down if it's going to happen in a reasonable time frame. That happens if the engineering efforts (private and public) get prioritized and funded properly. Io will still have erupting volcanos in future decades, I suspect, but we won't be there watching if the cost of getting to orbit doesn't come down a lot.
ReplyDelete"If two pocket "universes" make physical contact, there are several possibilities. M-brane theorists think the collision would release so much energy that the resulting bang would wipe out any galaxy-style realms that existed before."
ReplyDeleteSo the big bang could have been caused by the last collision between our brane and a neighbour, wiping out the previous version of our universe? And the dark energy accelerating expansion could be due to the approaching return of that (or another) neighbour? So we need to figure out how to jump into M-space itself in the next few billion years or we're toast.
Crisis!
" 'We start with a multiverse that has two bubbles in it, we collide the bubbles on a computer to figure out what happens, and then we stick a virtual observer in various places and ask what that observer would see from there.' "
Science. Yo!
"You have to hand it to Paramount Pictures. They figured out that you don't have to be jerks about policing a copyrighted franchise."
There was a learning curve. Back in the BBS and early internet days, they often attacked fan created sites and resources. It took them awhile to realise that attacking fans cost them vastly more than the perceived loss of control over their IP.
Experimenters: "We've created conditions consistent with an M-brane incursion 5 million light years from your current position and commencing 10 million years ago. What do you see?"
ReplyDeleteVirtual Observer: "AIEEEEE!!!!"
Robert,
ReplyDeleteIf you break up a rubble-pile asteroid, the pieces won't necessarily be reduced to gravel. A 1km asteroid is the equivalent of a thousand 100m asteroids. So you could end up with hundreds of >100m impactors, plus thousands of 20-50m impactors, all arriving roughly the same time. If your 1km civilisation killer was going to hit land (the best possible scenario) and instead you break it up, you would create hundreds of tsunami-causing ocean impacts, across the globe. Only slightly less devastating to that initial target area, but much more devastating to the rest of humanity. Still worth doing if you can do it early enough to cause most of the impact mass to miss Earth (by smearing it out over a wider area.)
And as Scott says, nuking a rubble pile is going to be more like hitting a beanbag with a hammer. Less a Bang!-shatter than a flumph-rustle.
Alex,
ReplyDeleteRe: Cost of multiple observatories throughout the solar system.
Every probe/lander/telescope is always a unique bespoke spacecraft, with very little overlap. We need to create a generic version of a planetary observatory that can be designed once and then just run off a production line by the dozens for $20-50m each. Even if each observatory was less capable than a specialised one-off spacecraft, being able to buy dozens of the things for the price of a single major traditional mission more than makes up for it. I believe this will also save costs for instrument makers, because they can build to a standard interface, so over time you develop a modular mix'n'match spacecraft design that can be customised to missions without actually needing a custom spacecraft. You can also start as simple as possible, incrementally upgrading the design as your designers learn from practical experience.
One of the things preventing this is that NASA contractors always retain the IP for the design of any spacecraft. So, for example, you can't start with a stripped down version of the Juno probe or the MRO as your initial design because Lockheed Martin owns both those designs.
Re: Launch costs.
Compared to the typical cost of a mission, launch costs are not that great. With SpaceX, costs are already dropping, and if SpaceX cracks either reusability or heavy-lift, prices will plummet. If they crack both, the game changes entirely.
It's already getting to the point where it may be cheaper to test components in space than to test them in special chambers mimicking space. For example, the program to upgrade the J-2 rocket engine required a huge new test stand which was capable of maintaining a vacuum while the rocket was firing. (I can't even begin to fathom the engineering of that.) The cost was over $600m just for the stand, not including the actual operating costs or the cost of the test engines. Meanwhile, SpaceX's Falcon9 costs $57m per launch to reach actual space.
Multiverse theory (which postulates the simultaneous existence of multiple universes) is inherently problematic as the term 'universe' (derived from the Latin 'ūniversus meaning 'all together') is defined as 'the aggregate of all existing matter, energy, and space, including the earth, the galaxies and the contents of intergalactic space', meaning that the very idea of a 'multiverse' (and/or multiple universes) is as semantically absurd as multiplying infinities into a 'mega-infinity' (or adding many haystacks together into a single 'multi-stack').
ReplyDeleteAnd, as it is a logical impossibility to create a 'mega-infinity' out of multiple (?) infinities, it is similarly irrational for there to be more than one 'all-inclusive' universe as the term 'universe' means that there can be only 'one' all-inclusive whole.
Semantically speaking, of course.
Best
Tales of climate change, volcanic eruptions, coronal mass ejections & asteroid strikes share these commonalities:
ReplyDelete(1) Things that have happened, can happen; and
(2) Things that can happen, will (eventually) happen.
In addition, all these subjects (and the discussion thereof) tend to rely on faulty conditional logic, arguing that information equals control even though knowledge and mastery are non-equivalent concepts.
Best
Completely OT, but Miami is now looking into police (and meter maids) wearing cameras.
ReplyDelete@alfred (and paul451 who meant to reply to alfred, not me). The cubesat phenomenon man be exactly what is needed to pepper the solar system with sensors. They are standardized platforms and cheap. There are ideas to fit them with high performance thrusters and sails (solar and electric). While they cannot do the science tasks of the flagship probes, they can do a lot of work. We should be able to create lots of them and accept that a percentage will fail. If Moore's law drives the surveillance capability, it should apply to space systems too.
Interesting point about engine tests. You are suggesting that an instrumented J-2 attached to fuel and oxidizer be launched and tested in space, rather than on the ground. One problem with than is if it breaks, the space debris problem is worsened. It also might be hard to inspect the remains to analyze the failures. But your point is well taken.
locumranch,
ReplyDeleteI get your semantic 'complaint', but it turns out there are different kinds of infinities (countable, uncountable, etc) and a way to define 'universe' so you can have more than one of them. Try to imagine the world before Galileo pointed his telescope at Jupiter. Back then we had the word 'Moon', but 'moon' and 'moons' would have made little sense. We could have given the small bodies in orbit around other planets a different name, of course, but that's not the way language expands most of the time. We recognize a new analogy and simply change the meaning of the term. 'Universe' becomes 'universe' and 'universes' because it makes sense relative to what we've learned recently.
(We do this ALL the time even with proper nouns. Who would be the pope of science finction, for example?)
Read Hofstadter's most recent book for a really neat demonstration for how we do this with lexical items and other elements of our languages. You'll never think of language the same old way again.
This may be a bit off subject, but I was going back over my previous calculations for terraforming Venus and it occured to me that Venus is a great source of energy as is.
ReplyDeleteWe have a signficant temperature difference (551 deg F/306 deg C)between the aerial comfort zone where the floating colony would go (at 70 deg F/21 deg C) and the surface hot enough to melt lead (at 621 deg F/327 deg C).
Can we use a version of OTEC to tap this heat differential and generate energy? In this version, the heat source would be on the bottom not near the surface. And is there enough energy to power mass drivers that could launch payloads of carbon fiber mined from the CO2 atmosphere (and stronger than steel) into space for use in builidng sun shades for Venus - or components for space ships, asteroid mining or manufacturing facilities?
Alex,
ReplyDeleteI've been involved in the entrepreneurial space movement on and off since the mid-90's and the Cubesat effort has produced a long lasting impact that surprised a number of us. If you are in the game for long enough, you get to see all sorts of ideas come and go as dreamers and wannabees think up their ultimate solutions only to see them fail in the market or fail to grab mindshare. I've backed more than one failure myself, so it is easy to become cynical. Cubesats have survived and deserve a great deal of credit.
We came up with a couple of acronyms to make a point about market success, though. CATS and FATS are fundamental. Cheap and Frequent Access to Space determines whether or not the price for payloads will be elastic. The huge comm sats that sit up at GEO make multiple billions of dollars for their owners, so the price they pay building them and getting them there doesn't really have to come down. Their business model closes better if they spend more for reliability, so cost per kg to orbit isn't a relevant metric until they face competition that reduces their ability to derive income from the birds.
It's the little stuff and the frequent stuff in the commercial market that will matter if we want to fly flagship science stations. Fly all the little stuff and we get CATS and FATS and the budget reductions that come with them. I’m not trying to argue for reducing science budgets, of course, but the political argument is easier to close if we can accomplish the same science on a few less $$.
Venus has a deep gravity well like ours. I'd be suspicious of any argument made supporting the space uses of carbon from its atmosphere relative to mining from asteroids.
ReplyDeleteUsing the carbon ON Venus is obviously worth considering, but getting the carbon to rain out of the air is probably a better target if your intent terraforming. Venus already reflects most the incident sunlight, after all.
Locum any Sophomore in maths would excitedly tell you about the different layers of infinities.
ReplyDeleteThere's an infinite number of integers. BETWEEN each integer is an infinite number of rational numbers.
BETWEEN each rational number is an infinite number of irrational numbers. nd so on.
As a brief aside, Dr. Brin, I thought you'd be amused that one of the Trading Guilds on the MMORPG "Elder Scrolls Online" was named "Adam Smith's Trade Guild" - he was actually pleased that I knew who Adam Smith was (and was grumbling about the "illiterate bastards" who complained about him using his own name for the guild rather than realizing it was a historical reference).
ReplyDeleteRob H.
You are pals with Adam Smith??? Can I have an autergraf?
ReplyDeleteDon't tell me I butchered the English language and the rules of grammar again....
ReplyDeleteMMORPG Hawker: "Markets! Get yer free market samples here!"
ReplyDeleteAh, looking back I see I left out a sentence. The "he" in question was the chap who formed the guild, not Adam Smith himself. Look, I've been dealing with insufficient sleep for a week as I'm hosting relatives including two children under 10 who enjoy stomping around... and the only functioning bathroom (due to ongoing house repairs) is the one next to my bedroom. I think you can understand how not getting enough sleep can cause sentences to slip by unnoticed....
ReplyDeleteI got it. Just funning' on ya man....
ReplyDeleteAnd here's an article from a Libertarian friend of mine I've tried to get onto the blog before concerning the Market Basket grocery store and the ongoing strike by non-union workers to get their CEO back. I rather like her comment about businesses being cooperative in nature, and while this might be a tad idealistic, she's on to something here.
ReplyDeleteRob H.
Alex, (well, I'm pretty sure this time)
ReplyDelete"One problem with than is if it breaks, the space debris problem is worsened."
You can use a low orbit with a short lifetime until reentry. You only need a few days to fire the engine after orbital insertion.
"It also might be hard to inspect the remains to analyze the failures."
Before they mothballed it again, the J-2X engine was tested on the existing outdoor stand. The giant vacuum stand would just test the exhaust properties (and associated efficiencies) in a vacuum to check if it matched computer models. Blow-it-up-and-analyse-the-pieces testing happens during non-vacuum testing. You really don't want anything blowing up inside a vacuum chamber.
re: microbial menagerie that thrives in tiny water worlds floating in oily tar pits ... perhaps a model for life on Titan?
ReplyDeleteI don't see that. We have an environment in a tar pit that is warm with liquid water. Really just the same as bugs living in an oil bearing rock formation. Titan however, is cold, and the water is rock hard ice. You would need to show that Titan has a warm interior with liquid water deep beneath the surface so that it would be a carbon rich version of Europa.
@Paul451 - I bow to your more logical thoughts on the vacuum testing of rockets. So what are the reasons that a huge vacuum chamber ground testing facility is being built? Surely not "pork" or conservative thinking.
re: "Prelude to Axanar."
ReplyDeleteImpressive. Really good references to Star Trek lore, especially Garth. Great dialog. I really hope this can be pulled off as I would definitely watch the movie and buy the DVD.
Dr Brin, I had a friend with a question that touched on the world of novels and publishing. I thought maybe you would have a clue?
ReplyDeleteLast year, I published a book with a small publisher. This year, they folded and sent all rights back to all authors. The book is listed on Amazon and Smashwords. I have been in contact with SW and they told me how to get the book changed over from the publisher to my account (he has to do it, and it’s easy to do). I cannot find instructions on Amazon for how that would be done, but it seems like such a core action that there has to be a way. Does anyone here know how to reassign marketing/promotional rights on Amazon? I am concerned that if I simply republish I will lose the reviews that are on the book already.
To respond to those credulous individuals who accept the validity of absurdities like 'Infinity to the Nth power', I have a little parable for you:
ReplyDeleteThere was a crackerjack salesman named Joe who sold a product called 'Everything' which he described as the sum-total of the universe, spirit, soul and existence, and ever now and then someone came buying:
'Do you really sell 'Everything?', that individual would ask.
'Yes indeedy,' Joe replied 'as long you accept the flexibility of word meaning and the human lexion. Would you like a free sample?'
'Of course,' replies the individual, 'As I curious individual, i would like to know and experience everything'.
'Here you go,' says Joe.
'Hey,' replies the individual, 'This is just a bag of manure'.
'Spot on,' says Joe, 'that's what you get when you allow others to change word meanings in mid-conservation ... How many sacks can I put you down for?'.
Best
Not an expert or anything but wouldn't ice grinding against each other and/or rock produce small liquid habitats just like these bubbles in tar? They would be small but such habitats are small here as well and still hold life. Not sure how it might get started but once started, it would probably carry on in the littlest habitats.
ReplyDeletelocumranch:
ReplyDeleteHeh. I'm sure I've bought a sack or two from that fellow, but you are demonstrating a significant lack of understanding for how human languages work in practice. There are no objective definitions to any of our terms and dictionaries don't even come close to representing what we do in live situations. We DO change terms in mid-conversation. We do it all the time.
I'll offer a counter-story to help. I'm paraphrasing from Hofstadter's book.
A two year old girl is being taught a few things about feeding herself. Her mother is trying to show her that the fruit in the bowl on the kitchen table is there for when someone wants something small and quick. The mother wants to teach good snacking habits. Later in the day, the girl demonstrates her new skill and excitedly tells her mother about it. She says "Look Mommy! I undressed a banana by myself!"
Did the two-year old girl make a mistake? It won't surprise a listener fluent in English if when they hear the next part of the story they learn that the mother decided it wasn't an error, but it WAS an opportunity to teach the girl about the verb 'to peel'.
Now imagine the same girl grown up a few years telling her mother that she undressed an orange all by herself while wearing a well-defined smirk on her face. Did she make an error? Probably not since the smirk signifies humor and the intention to use the wrong verb, but is it REALLY the wrong verb? The two-year old girl would not have thought so prior to being corrected. Language corrections are very subjective, though.
Now imagine the same girl as a grown up of 20 years sitting on a California beach and watching a surfer guy come up onto the beach and partially peel off his wetsuit. What verb should she really be using for what he is doing? What are the odds of the smirk returning to her face?
Sociotard sorry, I haven’t a clue.
ReplyDeleteLocum, very blithe and folksy… and irrelevant. If you cannot grasp that there is one infinity of countable integers and a completely different kind that is all the rational numbers BETWEEN each integer, then all your folksy dismissal does is show your laziness.
Alfred you are a good storyteller!
===
Now onward...
Alex,
ReplyDelete"So what are the reasons that a huge vacuum chamber ground testing facility is being built?"
Rocket exhaust expands differently in a vacuum, which affects combustion chamber pressures, which affects Isp, which affects fuel/payload ratios. If you optimise an engine for sea-level air pressures, you lose efficiency above 100km. (And vice-versa.)
And to be fair to the developers, a low cost launcher wasn't available at the time. I'm just using it as an example of what is becoming possible.
But, that said, every other upper-stage development (including the J-2's original Apollo era development) managed to avoid vacuum testing. Most of the time you just test an upper-stage at sea-level pressure and just guestimate an optimal vacuum design based on modelling.
J-2X was intended as an upper-stage engine for the Constellation program's Ares V launcher. When that was cancelled, it was then intended to serve as the upper-stage engine for the third version of the SLS; but since that won't fly until at least 2032, the program has been mothballed after spending $2.1 billion. There's no real need for vacuum testing to gain that last few percent efficiency, but Constellation was The Big Program, Apollo-redux, and everyone had their hand in it. SLS inherited many of its... quirks... since SLS was intended to resurrect as much of Constellation as possible, to preserve the pork.
For example, when the J-2X was slated to be mothballed until the late 2020's, the politicians from Mississippi (where Stennis is) guaranteed funding for the vacuum test stand was continued to completion, before it too will be mothballed, having never been used.
Alex again,
ReplyDeleteRe: Life in tar pits != life on Titan
Agreed. If would be more relevant to Titan if the bacteria were surviving without water, by using the hydrocarbons themselves.
Re: Prelude to Axanar
It always amazes me that computer effects have are so much cheaper than practical effects, to the degree that it's vastly cheaper to work on a sound-stage green-screen for a room than to find a suitable real building/room/site and work there. And using shaky plastic models for spacecraft scenes is more expensive than using CG. Once upon a time, using a lot of CG was a sign of a big budget movie/TV-show. Now, shooting in real sets, or even better in real locations, is a sign of a high-budget production.
It's also amazing that 3d printing is starting to turn that back around in favour of physical models and practical effects. (Along with affordable hand-held 4k cameras for location shooting.)