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Nasa is developing a "modern F-1" mega LOX/RP1 engine, but they haven't done much beyond technical study phase. Building a brand new launcher, thats man-rated, in two-three years before the OSP CTV deadline is probobly impractical. Nasa has already all but decided to use the current EELV launch vehicles with man-rated modifications. I expect they will make a formal decision about specific Delta 4/Atlas 5 varients early next year.
http://www1.msfc.nasa.gov/NEWSROOM/news … 3-119.html
As far as a late-stage malfunction on launch, a winged OSP can't return to The Cape because it can't turn the booster around to push it back. What it could do is go accross the Atlantic and come down on a Shuttle emergency strip. This sounds alot better to me than trying to find a capsule over one or two thousand miles of ocean... as far as early-stage launch malfunction, both types of craft would have to come down in water. The HL-20's wings are also not all that big, and if you do have to abort late-stage, then you don't need jet engines because you are moving so fast already, up in the higher mach numbers. Shuttle doesn't need turbines to achieve its 3000mi re-entry crossrange.
Although in a 4-seater OSP would suffice for the basic "US Core Complete" ISS, there ought to be contingency to expand that crew to 6. Further, since the CRV and CTV vehicles will have to come online at almost the same time, and since the cost of building OSP will be fairly high, I really don't think that Nasa has neither time nor money to develop two radicly different craft. Whatever the CRV is, the CTV will be almost identical, so it will be capsules or wings... not both.
I agree, hyper- or supersonic ejection should simply not be planned for unless OSP launch weight without escape pods is far far lower than it seems like it will be. Also, considering the small size and relativly low weight of the craft, it would be easier to simply harden the vehicle itself and equip it with emergency landing systems than it would to figure out how to build the thing around a half dozen ejection seats.
From what I have been gathering, OSP will almost certainly come in one of three forms, with dedicated CRV and CTV varients and possibly with a cargo varient:
-HL-20 lifting body:
http://www.astronautix.com/craft/hl20.htm
-"Big Gemini":
http://www.astronautix.com/craft/bigemini.htm
-"Averikan" version of Russia's Zarya:
http://www.astronautix.com/craft/zarya.htm
None of these vehicles at launch weight with all equipment and 1,000kg payload will be able to ride on the Delta IV Medium class rockets (~16,000kg, too much for 12,000kg Delta), but then all these are designed to seat ten or haul >3 tons of bulky cargo, so if their weight were reduced by 25% along with the crew to 6 then its possible. I am also wondering if OSP or a dedicated cargo varient could be used as an American ATV and launched on a non-man-rated Heavy booster to help replace Shuttle's cargo ferry role. Various big issues include...:
-Due to ISS's "diagonal" orbit, it will be expensive to operate the multiple recovery sites for a capsule to meet the CRV emergency return role, but HL-20 could glide 2000mi or so. Recovery of a capsule on the ground is also a less percise undertaking, and the very limited crossrange of a parafoil would probobly not be signifigant. Note how this situation is much different than the near-equitorial orbit of Gemini/Apollo.
-A capsule will unavoidably subject the crew to higher G-loading on landing, around 3.5-5G probobly, as opposed to HL-20's 1.5G. Impact for a capsule is also an issue, where using air bags or simple retro-rockets to soften landing would help, the Zarya's "near hover" rockets are heavy, produce massive vibration, and use non-storable liquid fuel.
-A capsule system cannot easily recover its OMS engines, as they have to ride behind the heat shield practicly while they can on HL-20, but the cost of replacing versus reuseing this system is unclear.
-Unless the Pentagon can perfect its Kerosene/Peroxide recycler engine, the CTV version of OSP will probobly have to use conventional N2O4/Hydrazine engines, since these are almost off-the-shelf, and cryogenic propellants like Methan/LOX are not storable. The CRV version of OSP would probobly best rely on a X-38 derived solid rocket OMS engine to maximize on-orbit life span in my opinion.
-The heat shielding on HL-20 or a capsule could probobly be re-used a similar number of times, but the HL-20 experiences much less heating, which could permit the use of a METAL heat shield for the majority of the craft if there is signifigant launch weight margin, other than some RCC on the nose and wing edges. Tile technology has also improved considerably (Boeing X-37) however and they are much stronger now, so this combined with low chance of damage on launch should perclude any "Mini Columbia" calamity.
-HL-20 would probobly be too big to ride in a payload faring of either the Delta or Atlas rockets, even if it were several feet narrower, nor would you want HL-20 to ride in one due to how much harder it would be to escape from a running booster. This is also a reuseability/mass concern, where the launch escape system on either HL-20 or a capsule is heavy, and would have to be thrown away on each flight.
-Although a capsule has very good areodynamics, it could probobly not survive re-entry unless it were at least roughly aligned with its re-entry vector, percluding a no-computer return (Apollo 13 had the Lunar Module to align it first), and would be very hard to recover from a bad allignment when the air starts to get thicker. HL-20 would be the opposit, that re-entry is a much more delicate operation, but with its control surfaces would make correction possible though difficult. With the proven Shuttle system (provided its heat shield works...)
-Both HL-20 style or capsules would definatly have the equipment to perform an emergency water landing, like parachutes and air bags for floatation, but the HL-20 would be able to glide much further, perhaps all the way across the Atlantic, whereas a capsule may have to ditch in the middle of it if there were a booster failure.
Thoughts? Other ideas?
More progress on the STS stack puts us that much closer to an effective launcher powerful enough to expose the true heresy of calling the tripple-barrel Delta-IV or quad-SRB Atlas-V a "heavy lifter" (*spits*).
With the lighter Li/Al main tank, and these new super-SRBs, any idea how much additional payload could be lofted in an entirely expendable Shuttle-C style SDV powerd by a trio of SSMEs or a pair of RS-68s (which would produce comperable thrust for much less cost)?
If you add a few more tons of LH2 to orbit for a Mars ship NTR, or a larger reactor for a VASIMR engine, then we can scrap any additional "long term human study" stuff since it wouldn't take that long to get there. More mass for a payload "buffer" too.
Wow, is OSP going to really have that much Earth-to-orbit mass that will require a Delta-IV HLV or Atlas-V HLV? Even Soyuz-TMA only weighs 7,250kg and the X-38 around 8,000kg (sans trans-stage componets). Surely NASA isn't seriously going to build OSP with a mass of 20,000kg! If a large 10-seater HL-20 weighs a shade over 10,800kg and a Soyuz even less, then that means NASA must be being forced into having compatability with the Delta-IV series. The maximum LEO payload for a Delta-IV Medium+ 5,4, the largest single-barreld version, is 11,500kg whereas the Atlas-V 552 is around 20,500kg... The low "big Delta" performance makes me wonder if Boeing wasn't intending for the HLV to be the standard vehicle in the first place, since it costs $80m more.
Anyway, therefore the OSP must weigh alot more in either capsule or lift body form or else Nasa must be really really wanting to avoid a capsule for some reason. Perhaps the amount of trouble it would be to maintain worldwide global backup recovery sites for a capsule is adding up quickly?
Another possible reason that NASA wants the lifting body version... that when Shuttle is retired after the next few launches to finish ISS, Russian Progress-B and ESA ATV cargo ships will probobly not be able to carry enough cargo to sustain a 4-6 person crew + science. ISS uses a rediculus amount of water, which is quite heavy, and what of experiments? Perhaps NASA intends to fly a strip-down OSP full of cargo very often? The reason why a capsule would not be prefferd for a cargo role is quite obvious: Apollo has about 6 m^3 of pressurized volume as opposed to HL-20's 16.5 m^3. Such a scheme would save NASA from having to build their own ATV, buy them from Europe, and would be resuseable. Several tons to the ISS is not unrealistic.
As far as heat tiles are concerned, HL-20 has much less heating than Shuttle and could use -metal- heat tiles, made from Titanium, Nickel, and foamed Aluminum which are about a foot square and attach with bolts. As far as the leading edges and nose cone though, there aren't any alternatives light enough to Shuttle RCC that I know of. RCC would not be so much a danger since debries from launch will all be below it.
A Super Skylab style space station launched on a Energia-M or Voolkain mega-booster or two would have been ideal for quickly building building a robust, inexepnsive, and highly useful space station.
Which is exactly why the idea was scrapped.
I believe that the whole point of the ISS was not science, but rather to maintain a human presence in space at the highest possible cost and duration in order to keep LM/Boeing/STS in business while also getting other nations to help out all planetary-group-hug diplomacy style. Government agencies are like zombies, they will do really dumb stuff to continue justifying their scope/exsistance.
One issue with launching Super Skylab with an Energia booster, is how would you get the thing into an equitorial orbit without a severe payload penalty?
As far as flight two and from LEO and the ISS, this is a perfictly sensable strategy. Russia (and perhaps the USAF...) were thinking about designing an unmanned nuclear/ion tug that would perform that sort of function but be able to do it many times or with very heavy payloads rather than having to refuel or risk a crewman in a manned chemical tug.
But for anything beyond low earth orbit of signifigant mass, like a Mars ship or pieces for a Lunar city, even the Boeing-daydreamed "Delta V" 5-CCB rocket or the 7-CCB+Mega-Upper-Stage Russian Angara simply can't launch large enough payloads to be practical. The weight, complexity, and safety penalty of on orbit construction of a large craft with many smaller launchers should be Jay Leno grade material, proven by the insane trouble of building ISS compared to Skylab.
What isn't really clear is if the EELV fleet could make efficenct-enough supply/fuel launchers for already assembled bases or beyond-earth-orbit ships.
As far as the next shuttle or the next-next shuttle, I think that a shuttle replacement based on current rockets or engines just isn't worthwhile. Why? We are pushing the limits of practical efficency for fuel/oxidizer chemical propellants, the SSME engines on Shuttle are already running at 6000F and above 90% efficency, we just can't make it that much better. So, we skip the next-generation craft entirely since it would be limited to "classic" rocket propellants and go directly to air-breathing rockets to cast off the mass penalty of oxidizer entirely, which makes staging of rockets a nessessity.
Hmmm from my rudimentary understanding of orbital mechanics, the SRB+SSME/RS-68 combo puts the payload/engine module section into an excessivly eliptical path, and thus requires the OMS engines to circularize?
If we aren't planning on making the engine module reuseable, and the OMS engine would only need to fire once or twice for a known time/thrust, then how about dropping the OMS engines with their expense and complexity and use scaled up cheap solid rockets, like the ones used to boost smaller satelites to GEO. I would think that the fewer moving parts involved, the better the reliability would be and the lower the cost. It would be ~really bad thing~ to send up a several billion dollar NTR/NEP transfer stage or Mars surface payload and lose it on the way up.
Lastly, I would have to agree that we ought to avoid any redesign of the SRB/fuel tank as much as possible outside more powerful boosters that are already half way here, including ommitting top-mounted payload setups or Shuttle-Z upper stage, and even though Russian hardware is more efficenct for Big Dumb Booster arrangements. Changing what we have already will add big money and big delay... A serious trip to Mars or a small Lunar city will be an expense thats hard to swallow already. The technology for Mars and Moon exsist TODAY, adding more unessesarry delay and expense make these future glory days that much further off.
I think that a HL-20 style lifting body or even maybe a scaled up X-37 would be light enough to go on top of a "single barrel" Delta IV Medium or Atlas V, if the design were kept small enough and simple enough. The Delta IV Medium+ with four small SRBs can loft about 10,000kg-11,000kg to an ISS orbit without breaking a sweat which would cost $60m less and cut in half the number of liquid-fueled engines you would have to rely on... Anyway, the original HL-20, sans adapter/escape stage, would weigh around 10,000kg, and that is for a ship with room for ~TEN~ people, with landing gear. If the HL-20 were scaled down to seat 4-6, even with an adapter/escape module weighing 25% or so could still be accomodated. With living with the "Space 747" Shuttle as the only manned launcher for so long, it is difficult to convince people how small a winged OSP could be!
It is even possible, X-33 style, that the heat shield could be entirely made of metal and re-used many times with a minimum of inspection, unlike having to replace an ablative shield, a major and delicate componet of a capsule, every flight or three. Even if a plane-OSP used Space Shuttle style thermal protection, the much much smaller area coverd would be pretty easy to inspect and refurbish without the need for total replacement. Have a look at my longish post about the ease of handling and processing a horizontal ship with wheels.
The nice thing about not needing parachutes is, well, one less thing that can go wrong that would doom the crew. Another factor i'd like to mention is that a capusle decent would expose the crew to fairly high G-loads; while this isn't a big problem for a fresh crew going up, it might not be such a good idea for a deconditioned/injured crew coming back down. Even if Soyuz-TMA worked properly, the crew would still be hit with 4G's during reentry... And you have to worry about coming down where you don't want to.
The HL-20 areodynamics have been pretty throughly explored, Russia even flew one (the BOR-4 military plane), and X-15 pilots that flew the simulator had no trouble landing it. With the know-how gained from the X-37 project, 100% automatic operation shouldn't be too hard to integrate relative to a capsule system.
Hmmmm I think i'll have to put my weight behind a SDV setup... Shuttle right now is the only vehicle that can lift 100 tons or so needed for a reasonable Mars ship, the only big problem with it is the insane fixation on reuseability, the boosters are a little underpowerd, and the fact that its main engines are unfortunatly built inside of a 80-ton airplane.
If old "used" SSME engines, the ones swapped/being swapped out for safer ones are laying around, lets use them... otherwise, instead of three SSMEs I would redesign to accomodate a pair of the nicer and cheaper RS-68s. The Shuttle-C concept ought to go on a diet as much as possible; if it doesn't need OMS engines drop them, if the Mars ship or Lunar base module can withstand liftoff or even better main engine torque, then omit the entire Shuttle-C design except for a nose cone and the engine "pod".
Lastly, use the updated "stretched" SRBs if at all possible, and if they can be made expendable and lighter like the Graphite/Epoxy motors on Delta IV/Atlas V, all the better. This would be especially nice if it would permit dropping the OMS engines off the Shuttle-C.
Current functioning infrastructure without having to make serious changes to the VAB or launch pad, only modest changes to the booster section, and 100 tons to orbit is all we really need to get us to Mars. In the future, a new super booster would obviously be nice, but chemical rockets are already pushing the limits of practical fuels themselves, so such a program might be better postponed until we create air-breathing scramjet boosters or the like.
A capsule might be quicker and easier to ~build~, but the cost of constructing the things, even if the capsule is resuseable, is only a portion... perhaps a minority portion... of the total cost to fly them. Building Shuttle was not all that expensive compared to what we've sunk into flying it to date.
One of the arguments i've heard against is that a capsule has no ability fly in the atmosphere; in the event of a catastrophy and you had to come back ~right now~, a crew member suffering a serious injury lets say, you would have to pay a hefty sum to operate more numerous landing sites to get care quickly. Also, since ease of maintenance factors big in the cost of operation, working on an airplane with a heat shield standing/rolling on its own landing gear with convienant equipment hatches jet fighter style would be a much less involved proposition than half-dismantling the capsule to access a deeply burried componet or to move/turn the thing around. And when your OSP plane does land right, you roll to a hanger, have a few Boeing/LM/USA engineers inspect and prepare it for the next shot almost as easily as a Leer Jet, roll it to the VAB, roll it up horizontally to the EELV, attach the bolts/umbilicals and fuel her up. Delta IV is processed horizontally, and just recently Lockheed badly damaged a satelite being readied for integration when trying to turn it over? Simple things with complex fragile craft are difficult. Speed is also an issue, in case you need to launch a 2nd OSP quickly for rescue like in a Columbia-style senario, or for the simple fact that time is big money when you are paying engineers, horizontal integration might be easier for a plane. The more airline-like it is to operate any reuseable spacecraft the better, cost wise.
Plus, recovery itself could be a somewhat more dangerous process than runway landing... what if you came down in water or forest a few miles off course at night for instance? Precious minutes tick away that you could have spent gliding at hypersonic speeds to a major airfield. The advances made in the strengthening heat shielding of a winged or lifting body craft have also made the "mini Columbia" disaster issue moot relative to capsules, and infact the OSP itself would be safely mounted on top of the EELV launcher, whereas a pure Apollo-copy capsule would have to ride under an escape tower which itself is a collision hazard and engine failure mode. Oh and speaking of heat shield, a good winged OSP heat shield wouldn't have to be replaced at all as opposed to the ablative shield on a capsule. Another improvement in modern aircraft design that mitigates the "heavy dumb wings" problem is the use of small wings made of Titanium or other "fancy" alloy and composit with control surfaces operated electricly instead of hydraulicly. These are things flying today on fighter jets; alot of things have changed since Shuttle was designed that mitigate the plane=heavy/unreliable issues. Plus, once you are out of the atmosphere the shape of your craft doesn't matter alot if you are intending to use the OSP for travel to higher orbits or near-Earth space. Even though a winged OSP would not be a good Mars decent vehicle, a capsule OSP would have to be highly modified for Mars atmosphere entry with a completly redesigned heatshield and possibly retrorockets for landing, which might as well be designing a new vehicle. Oh and speaking of which, another point where a winged craft has an edge is that it doesn't rely on parachutes at all. Another thing I thought of, wouldn't it be easier to put a docking/collision radar in the nose of an airplane than somehow trying to mount it to avoid the docking collar of a capsule were one to be included?
Although we have alot of experience with intermediate sized capsules, we also have quite a bit of experience with spaceplanes like the old X-Planes, Dyna-Soar, and the beautifuly efficenct new X-37 which Boeing may only have to scale up for their OSP entry. I think the 15-20 year timescale is a poor estimate considering that building such a craft won't be that hard. I will admit it is harder to put a airplane on top of an EELV than a capsule, but I think the payoff is worth it... Though I do long for the Saturn heyday, I think a warning over letting "capsule sentimentality" influence such a major decision is also prudent.
Okay I see a feeew problems that are somthing of an issue with a NTR SSTO vehicle (which are also on the NuclearSpace message board)...:
A nuclear reactor when its fueled for the first time with fresh Uranium 235 isn't very radioactive, but when you switch the thing on in order to take off from Earth or a handy nearby Lunar launchpad, its going to put off a -silly- large amount of radiation without shielding of unreasonable mass. Plus, you would need a very large and heavy reactor to produce enough raw thrust to get off the ground; the original NERVA engines topped out at 250Klb of thrust and as far as launching go would be used as a Saturn-V UPPER stage, after you have momentum.
It simply isn't practical to use the engine near a Moon base or in Earth's lower atmosphere. Further, when a reactor is turned off it will keep on radiating for a while (read: at least a year) due to leftover extremely radioactive fission fragments, so you really can't bring it back to Earth's surface at all or near a Lunar base easily. It will be enough trouble to dock acent/decent vehicles or space stations to a nuclear transfer stage to avoid frying an unwary crew in orbit. Space reactors belong only on orbital transfer vehicles or uninhabitated surfaces unless they are heavily (eg burried, concrete/HDPE/lead, large water shield, thick steel etc) shielded.
On to the Lunar base concept... since it is so much trouble to launch masses into LEO as it is, the hefty payload penalty to get to the Moon would make a sizeable base difficult even with a 100-150 ton LEO chemical launchers which we are stuck with in the near term, so at the moment a LEO station makes more sense. In the near-distant future, after Project Prometheous has given us a nuclear-electric ion engine or a reuseable NTR engine, then sending up an initial base on heavy chemical launchers to get to the Moon becomes practical. When/if the Moon's polar ice starts yeilding signifigant amounts of water, then the REAL Moon city can begin... Lunar LH2/LO2 powering reuseable acent/decent lifters to refuel a waiting nuclear-powerd transfer stage... and anywhere we want to go without having to bother with 1G gravity or an atmosphere.
Of course, getting to Mars if we have a NTR engine and Moon Base technology would be easier than making a big enough Lunar base to mine enough water to fuel sizeable rockets...
Oh, one last note, you can't pollute the Moon with any pitiful tiny amount of oxygen we could waste, most of it would probobly just waft away into space due to the low gravity (hence the Moon being airless), but if you WERE really concerned about it, you could just mix it with Lunar metals and trap it on the ground as a solid oxide by heating.