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The only thing I can state at this point in time--the asteroid retrieval mission strikes me more as a "make-workee" program in order to justify the enormously expensive SLS. This smacks of a Bush-II Constellation project technology rescue mission. I don't have any enthusiasm for it, and it's burning through lots of scarce NASA cash. The SLS should be utilized a couple times for a Apollo 8 Redux, and then quietly retired.
There really isn't much of a scientific payback for asteroid retrieval.
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Here is the topic we have here: SLS and what asteriod will we go to
I agree that we do not need make work programs but its congress that needs to grow up....They are the one's that resurected the constellation program and are forcing it to execute the law that was passed....
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The only thing I can state at this point in time--the asteroid retrieval mission strikes me more as a "make-workee" program in order to justify the enormously expensive SLS. This smacks of a Bush-II Constellation project technology rescue mission. I don't have any enthusiasm for it, and it's burning through lots of scarce NASA cash. The SLS should be utilized a couple times for a Apollo 8 Redux, and then quietly retired.
There really isn't much of a scientific payback for asteroid retrieval.
Why would you want such a massive orbiter around the Moon? How about a Titan orbiter and rover? SLS is a massive Saturn V type rocket, how about using it to explore the outer planets?
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To answer the question "SLS is a massive Saturn V type rocket, how about using it to explore the outer planets?":
Short form: SLS will be too expensive to use.
Long form follows:
Even if you believe NASA's estimate of 0.5B/launch, and a 100 ton cargo to LEO (initially only 70 ton with the smaller second stage), that's about $5M/metric ton delivered, flying full. That's where we are today with 13-20 ton payloads on Falcon-9, Atlas-5, Ariane 5, etc, averaging $5.5M/ton. Ranges from just under $5M/ton to a little over $6M/ton. Payloads sort-of average near 15 metric tons to LEO. That's 23.5 degrees inclination out of Canaveral, to something around 300 km altitudes.
Falcon-Heavy looks to deliver 54 tons to LEO at about $100M/launch. That's about $1.9M/ton delivered to LEO. Call it $2M/ton, which is less than $5.5M/ton, so there really is an economy of scale to this.
NASA's critics suggest SLS will cost closer to $1-2B per launch. OK, split the difference and call it $1.5B/launch. That's 15M/ton delivered to LEO. At least 10, possibly 20.
Why would anyone EVER want to fly their stuff on SLS unless it was just too large to fly on Falcon-Heavy at ~$2M/ton? And given that current probes will fit on an Atlas-5 at 15-20 tons and ~$5-6M/ton, same question!
OK, current unit price is near $5M/ton at something like 15 ton. Falcon-Heavy should be ~$2M/ton at 54 ton. If you try to scale linearly with payload tonnage, you get a negative $M/ton at 100 ton sizes. So, clearly this economy-of-scale thing is a diminishing-returns thing, not a linear extrapolation.
But, the point is, at 100 ton deliveries to LEO, we should be looking at very small unit prices: perhaps actually under $1M/ton!!!!!
If you believe NASA, SLS will be delivering 100 tons to LEO for $5M/ton. If you believe the critics, that's closer to $15M/ton. It should be very crudely $1M/ton, if done by the commercial guys who build the current fleets.
So I reiterate: why on Earth would anyone EVER want to fly ANYTHING on SLS, unless it was just too damned big to fit a commercial launcher?
Especially, when most of the time, you could just split up your item into smaller pieces, launch its pieces on commercial launchers, dock those pieces together in LEO, and STILL SAVE MONEY TO BOOT! The launch price difference ($500+M vs $62M) way, way more than covers the launch price of a Falcon-9/Dragon v2 crew to go up and dock it together for you.
Or you could use the ISS crew to do the dockings for you. They need a second mission like that to justify keeping the place open.
"Bigger rocket" is not necessarily better, especially when the unit price is higher when it should be lower. NASA evidently still knows nothing about low-priced launch. The commercial guys do.
Now, since Boeing and Lockheed are doing SLS as well as Atlas-5 (as ULA), doesn't the SLS/Orion program begin to smell to you more like a giant corporate welfare state thing (extreme pork barrel largesse) than anything with logical thought or a real use behind it?
It should! Stinks to high heaven for a lot of us.
GW
Last edited by GW Johnson (2017-01-24 13:22:07)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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I believe the cost per ton to LEO will ultimately go far below the cost calculated by GW Johnson, based on the ability to recover at least the 2 strap-on Falcon 9 booster stages with a high degree of probability, and also the central core, probably on the drone ship.. Elon Musk has stated on one of the webcasts that they cost SpaceX about $16 Million each, so 3 x $16 Million saved from the initial throwaway price of $98 Million a launch is essentially halved, if we don't calculate the refurbishment and profits. A second recycle of a stage becomes even more friendly w/r cost to LEO. There's simply NO WAY the SLS system can compete. ULA better make their money now, because their rice bowl is vanishing...
Compare what the CEO of Lockheed-Martin has agreed to do w/r the F 35 Multirole fighter.
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I do not think any hardware for the retrieval unit has been made as of yet so ya cancelled that at least to free up funds for using it to make a lunar base....
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Oldfart, recovery also reduces the payload significantly, so the savings per tonne of payload won't be that great.
"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony
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Since we have a few SLS built, we might as well do something with them rather than let them rust in a museum. If were going to go with Falcons but we've already built some SLSs, we are not going to get the money we spent in building hem back if we don't use them, so if we don't plan on using it for manned missions, how about using it for a mission to the outer planets, with all that tonnage it can deliver to low Earth orbit, we should be able to get to Saturn quicker, instead of having to rely on gravity assist to get there.
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Terraformer-
Even after consideration of the 36 ton to orbit based on complete recovery of the booster stages of the Falcon heavy, rather than the 53 tons to LEO as a throwaway, this is pretty good bang for the buck. That calculates to $2.72 million per ton. After we adjust for first stage recovery by deducting $16M/ stage recovered from the cost by making a second launch cost $50M, that subsequently reduces the price per ton delivered to LEO all the way down to $1.39 M. A second re-use of the boosters should reduce the cost per launch even further, and as GW has calculated, around $1 M per ton. Or less, if we give a basic cost to range management, refurbishment of stages between flights, and roughly $200,000 for RP-1 and LOX per stage per flight (Musk's figures). Maybe we use a figure of (just a WAG!) of $20 M per launch with all ancillary costs included for a completely amortized set of stages, brings us down to a figure of ~ $500,000 per ton to LEO. There's simply NO WAY that ULA can compete with the SLS. This is bringing down the cost of...gasp!...Orbital Tourism!
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Terraformer-
Even after consideration of the 36 ton to orbit based on complete recovery of the booster stages of the Falcon heavy, rather than the 53 tons to LEO as a throwaway, this is pretty good bang for the buck. That calculates to $2.72 million per ton. After we adjust for first stage recovery by deducting $16M/ stage recovered from the cost by making a second launch cost $50M, that subsequently reduces the price per ton delivered to LEO all the way down to $1.39 M. A second re-use of the boosters should reduce the cost per launch even further, and as GW has calculated, around $1 M per ton. Or less, if we give a basic cost to range management, refurbishment of stages between flights, and roughly $200,000 for RP-1 and LOX per stage per flight (Musk's figures). Maybe we use a figure of (just a WAG!) of $20 M per launch with all ancillary costs included for a completely amortized set of stages, brings us down to a figure of ~ $500,000 per ton to LEO. There's simply NO WAY that ULA can compete with the SLS. This is bringing down the cost of...gasp!...Orbital Tourism!
but we already spent money on the SLS, so lets recover that money by launching them, if not for manned missions, how about missions to the outer planets?
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Pork barrelling makes politics go round.
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The cost numbers I presented were for expendable launches at full payload. It remains to be seen whether reusability will be fully achieved, but if it is, unit costs to LEO might drop below the expendable trend by a factor of 2 to perhaps 3, eventually. Who knows?
The Falcons are only semi-reusable. There is no recovery planned for second stages. It remains to be seen whether reusability will be practical with the first stages at their low inert mass fractions. Other reusable flight structures have had far higher inert fractions, over the last century.
It's a question of "how many times can it fly?" A few won't buy you a whole lot of cost reduction. 10's of thousands will, but I doubt 5% inerts will ever be made to fly more than a very few times. Fingers on one hand sort of thing.
The MCT design incorporates re-use of the second stage. If they build it, and if it successfully re-uses the way planned, then Musk's price tag of $150 K per person or per ton to Mars might become realistic. We'll see. But at least they are trying, and at something more challenging than suborbital spaceflight.
If the cost of spaceflight really does drop, then there is no longer a need to preserve the old shuttle workforces, as that kind of technology is not going to be the way it will be done. So ends the need for the super-massive pork barrel politics that cripples NASA. Again, we'll see. This will take several years to play out.
Meanwhile, I'm thinking it's a decent bet that Musk will beat NASA to Mars, by more than a decade. I'm hoping he starts sending Red Dragon probes next year, like he promised.
But I sure would like to see him add artificial gravity to the MCT. A ~6 month voyage at 1 full gee means you are fully fit to endure gee challenges upon arrival, whether outbound or coming home. That strategy avoids a lot of complications for the base designs on Mars (or the other destinations).
GW
Last edited by GW Johnson (2017-01-25 11:39:49)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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It's the coming back that is the problem here. Astronauts visiting the space station for 6 months are fit for earth return, as clearly demonstrated. Astronauts' fitness after 6months no g several months 0.38g and another 6 months no g has not been demonstrated. This is why we should have a Mars gravity simulation in LEO. If people are not then fit for direct re-entry to earth we need a better plan. Probably including a stop in LEO.
If return missions are bringing samples, they should be offloaded to a station in LEO anyway, for the avoidance of contamination both ways.
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So if Nasa and partners are not going to do the studies under real conditions then its up to the commercial industry to step up to the plate....
Cash crunch for anti-Armageddon asteroid mission
2022, the idea is to launch a 600-kilogramme (1,300-pound) NASA spacecraft at Didymos, an asteroid some 13 million kilometres (eight million miles) from Earth, after a two-year self-guided journey through space.
The craft will crash into the 800 metre-wide Didymos' tiny satellite, Didymoon, at a speed of about six kilometres (3.7 miles) per second.
The aim would be to "redirect" the 160-metre moon -- the first time humans would have altered the course of a Solar System body.
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If things go the way they usually do, the outcome will differ greatly from that planned. "Didymoon" is small enough to have somewhere between trivial and zero ice content. If that is true, it is a flying unconsolidated gravel bar, and will fly all to pieces when hit by the impactor.
It's only my opinion, but I think the spectrum of mechanical properties is highly variable, even in one "spectral class". If there's little cohesiveness, they fly apart easily, whether hit by an impactor or a nuke.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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The spiders solved this one a few hundred million years ago. Catch it in a net, then wrap it to stop it escaping. Tow it back to your lair or stash it for later if you aren't hungry right now.
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So that would be a kevlar thread net....and that might work for the large chunks but not for dirt or gravel to pea size stone....
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That does depend on the mesh size.
I was only intending to point out that we can learn from evolution. Evolution hasn't come up with a better answer than spider web and we will struggle to do so. We should start by just copying it as best we can.
Spider silk comes in many different types depending on the required physical and chemical properties. Web silk is very elastic so it can stick to large high speed flying objects, bring them to a halt and spring back.
Kevlar has the stiffness, but doesn't have the elastic behaviour of web silk. I don't know whether it could be made sticky and whether that stickiness would survive in a vacuum.
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For objects very limited size and very limited spin rate, you combine the spider idea with the plastic bag idea. You envelop the object with what amounts to a reinforced trash bag, strong enough not to rip when the object comes all apart as you exert torgue to de-spin it.
The strength has to come from "ropes" embedded in the bag sheet structure. Because of limits to what we can practically build, this will limit you to the capture of objects under about 10 m in size, maybe under 1 m (just guessing). And I have no idea how to deploy and control such a thing about a spinning object, hanging in space like that. Much less how to exert torque and de-spin it.
The first time up for such a stunt probably ought to be a manned thing, not a robot thing. Why? Because: it WILL NOT turn out the way envisioned, that's Murphy's Law in action.
To succeed, the procedure and techniques will have to be adapted on-site, real-time. Robots don't do that. Tele-operated gear does it, but poorly, especially poorly when speed-of-light delays are long. Up close and personal with people works best (which could include tele-operated stuff in-situ along with direct EVA's and other stuff, too).
If small bodies turn out to be something worth mining, then this sort of capture problem must be solved. Period.
THAT provides a reason for men to visit NEO's, in situ, not 0.1 m boulders brought back to near the moon inside a glorified tuna can.
THAT ALSO provides a reason to develop better means for manned interplanetary travel than that idiotic SLS/Orion thing that cannot take men there without a spacious long-interval habitat and additional propulsion stages, neither of which it has.
THAT IN TURN justifies thinking outside the box. Way, way outside the box of Apollo, which is where we still are 50 years later after committing to a moon landing. One launch/one mission thinking only barely works for the moon, guys.
Consider this: any vehicle that can safely take men on voyages of many months in good health from Earth orbit to Mars orbit, can also take men from Earth orbit to NEO's. Unlike Mars, for an NEO, you don't need a lander. Why not build one common vehicle design as a reusable long-life item, and then use it again and again for multiple trips to both destinations? And more besides?
The old guys who dreamed up mission architectures exactly like that in the late 1940's and early 1950's maybe weren't so dumb after all, no? They lacked the technology and experience we have today, but their basic ideas are still quite good.
Here's another reason for men to go out there in situ to the NEO's: You have to "tinker" with a whole variety of these things to understand wildly-varying physical properties well enough to push on one without tearing it apart (something also required to anchor mining stations on larger bodies). Robots don't do "tinkering", men do. Speed-of-light delays make tele-operated "tinkering" so impractical as to be next-to-impossible.
But until you understand these things well enough to deflect them without tearing them apart, you cannot mount an effective defense against one threatening to hit the Earth. Murphy's Law says we won't have years of warning, we'll have days to weeks.
That close in, tearing it apart means all the bits hit you like a shotgun blast instead of a single bullet strike. The damage is actually worse because it is more widespread.
Exploring Mars, learning to mine asteroids, learning how to deflect "killer" asteroids on short notice. All can be done with exactly the same orbit-to-orbit transfer vehicle.
So can going to Mercury, Venus, the main asteroid belt, and later perhaps the outer planet moons if we can get "hotter" propulsion working to retrofit our vehicle. Just like putting turbo-prop engines on a DC-3.
NOW does what I suggest for mission architectures make more sense?
GW
Last edited by GW Johnson (2017-01-27 11:31:59)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Ya hefty cinch sack of course multi layered stretched across a support system that gives but not breaks to slow as it captures the object slowly tied to an ION drive tug to pull it to where ever you want. Matching speed in the same direction of course gradually slowing with contact to allow for the capture of the NEO rock....
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This discussion has pretty well dealt with the "hows," but in general failed to justify the mission on the basis of science. I just cannot somehow get my head to justify the huge expense of the SLS as a "throwaway."
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Well, what NASA wants to do is all throwaway expense for a rather small scientific return. What are you going to learn from one 20-to-50-cm-size cobble? At ~$1B per SLS launch?
What I suggested is made from 3 modules that are variations on Bigelow B-330 modules, plus dumb NTO-MMH propellant tanks that plumb together into a layered, long baton shape, with an engine cluster at one end and a Dragon v2 or two as Earth return/emergency bailout capsules.
You arrange some of the tanks, and all the water and wastewater tankage, about the flight control station and the sleeping quarters as radiation shielding. You spin it end-over end for artificial gravity while coasting.
It uses a LOX-LH2 expendable kick stage to leave LEO. You shoot the return propellant ahead as clusters of tanks sent by solar-electric or nuclear-electric propulsion, depending upon your destination. Same thing for any landers and their propellants. The manned vehicle return propellant supply tank farm is big enough to recover the thing in LEO.
I proposed this for a crew-of-six Mars mission that would visit up to 12 sites for a month each while at Mars, with 3 in orbit watching over 3 on the surface, and alternating roles as new sites get explored. The landers were single stage reusable, refueled on-orbit from the tank farms sent ahead. They're quite large, so the surface crew lives in the lander while on the surface.
A month on the surface with a drill-rig-equipped rover car, and 3 men. That's enough to get started on true exploration: finding out what all is there and where exactly it is. And doing this at up to 12 sites; important since they will all be different, just like here at home. That's a huge return for a much smaller price.
You leave the landers in Mars orbit for the next crew to use. So all you need to send is more of their landing propellant, next time. The only expendables here are empty tanks and the LOX-LH2 kick stages for departure.
On the assumption that launch costs were 20% of program costs, and nothing needing more than a Falcon-Heavy for assembly in LEO (most of it Atlas-5 and a mix of Falcon-9 and Falcon-Heavy), I crudely estimated $50B for this mission. But not if the "usual gang" is tasked to build it. Then it would be closer to $500B.
As I said, this same vehicle could take men to the NEO's to do science and exploration in situ. You just don't need the landers. You take your gear to "tinker" with the thing instead. Once again, a big return for not much price.
I posted this as "Mars Mission 2016" over at exrocketman.blogspot.com last year. It's jst a feasibility rough-out, not a detailed design.
GW
Last edited by GW Johnson (2017-01-28 10:57:34)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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GW--
I like the idea of getting something a lot more valuable than another chunk of space debris. I would not hesitate to state the new administration should examine your proposal. On the other hand, why not just make the SLS a launch vehicle for the proposed Mars version of the ISS? A SMALL version, however. Didn't either Boeing or Lockheed-Martin suggest something like this? It would not take until 2028 if they used this existing hardware. I believe (and strongly hope!) that the Asteroid Redirect/Retrieval will die from disinterest. The future of manned space exploration is shifting from the "usual players" to SpaceX. Once Falcon Heavy begins flying, we can all rejoice.
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Hi Oldfart1939:
The "Mars version of ISS" you mentioned may be the "reference mission" that ULA priced out to NASA at then-$450B. It showed up as the giant spaceship in the movie "The Martian". One site, no drill rig, one-shot throwaway Mars ascent vehicles, one-shot throwaway base hab.
Only a little further toward a real scientific return than an Apollo flag-and-footprints mission. Which is exactly why I don't buy spending so much for so little.
My mission and Musk's MCT transportation concept are two sides of the same coin. Unlike me, he is focused on one site. Unlike me, he is betting lives on producing 1000-ton quantities of return propellant on Mars. Other than that, we are both focused on reusability.
I also have an article on "exrocketman" about his revelations for the MCT approach from the Guadalajara meeting. I do wish he would spin the thing for artificial gravity, it is big enough. He does his mission design with fewer launches of a giant rocket than I do. He does require on-orbit refueling, with cryogens. I do the same, but with the easier room-temperature storables.
GW (another old retired fart)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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So I am thinking about how to turn the SLS solid and first stage into a recoverable reuseable rocket to get costs down...
The same rules for falcon 9 means that we must have residual fuel in the stage to land on a barge, a heavier constructed tank I would suspect all of which under the 70 mT payload design would lower this...50 to 60 mt depending on recovery location....
SpaceX estimates that the payload needs to be 15% below the max weight in order to recover downrange, and 30% below the max to return to the launch site.
Another cost reduction would be to use the rs68 upgrades engine for flights not for manned use instead of the expensive rs25 redux..
I figure that would drop use of SLS to nearer to the 400 million price tag....
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