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I've been pondering the feasability of a bullet shaped spaceplane (think a much smaller version of that Lochked CEV thats been floating around) launched on a Pegasus-like booster that can send a refridgerator sized, 1-2 ton piece of cargo, or a single astronaut to a space station. On reentery wings pop out and it glides down, possibly on landing gear or skids.
The advantage is the boosters could be popped out like cruise missiles, and the thing would be so small that reprocessing the thing would take no time at all. It could rush suppies and workers to a station, and since its dropped off the wing of a B-52, or a White Knight, launching several at a time would be affordable, and it could launch and return experiment quickly and cheaply.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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If you want the ideal, use a SCRAM jet spaceplane for access to LEO. The lunar vehicle can be made fully reusable with advanced propulsion.
I just did another calculation (I found a great trajectory calculator and I'm not telling you which one, pttt). The Apollo LM separated from the Apollo CSM into a lunar orbit of 111km apolune and 14.5km perilune. The idea was if something went wrong they could get back to the CSM just by waiting, but in normal operation at perilune they de-orbited for descent to the surface. So I calculated a transfer trajectory from 407km circular Earth orbit at 51.6° inclination directly to lunar orbit. The current focus appears to be lunar poles, so I used a lunar orbit inclination of 90°. The RD-160 engine uses LOX and liquid methane, it has a specific impulse of 381 seconds and 2,000 kgf thrust, RD-167 has 379 second Isp and 36,000 kgf thrust; so I used 380 second Isp. The result was 35.36853% of the total departing mass arrives in lunar orbit. Transfer time 4.61977 days. That doesn't include descent and landing then ascent directly into trans-Earth trajectory. Ascent would throw 9.254% of the landed mass into trans-Earth trajectory (lunar escape velocity 2.38km/s). That's why I said you need an expendable TLI stage using LOX/LH2, and a reusable lunar vehicle with LOX/LCH4 and aerocapture into Earth orbit. Delta 4-2 has Isp 462 seconds; if insertion into lunar orbit used the same Isp then 42.53359% of departure mass would arrive in lunar orbit. The calculator doesn't separate TLI from LOI.
When you change the specific impulse to a solid core nuclear rocket, it changes everything. Timberwind had 1000 seconds; recalculating with that results in 67.37119% of departure mass arriving in lunar orbit. Same transit time. This permits an entirely reusable vehicle. Timberwind also had a relatively light engine. Nerva 2 was 11,860 kg engine mass for 88,451 kgf thrust, Timberwind 75 was 2,500 kg engine mass for 75,000 kgf thrust. Nerva 2 also had 825 second Isp instead of 1000 second. This dramatic difference in engine mass was due to moderator; Timberwind was a particle bed reactor that operated without moderator. A reactor can only work without moderator if it's enriched to 10% U235 or greater, but both engines used >99% U235. Timberwind had the problem that particles would create a hot spot between them, creating a pocket of hydrogen gas that pushed out liquid hydrogen propellant. That permitted the hot spot to get hotter until the particles melted together. That agglomeration of particles meant Timberwind did not have engine restart capability; it was single-use only. Could you develop an axial flow NTR like Nerva that operated without moderator like Timberwind? Another feature of Timberwind was rapid reaction of nuclear fuel, permitting less uranium for the same heat but shorter burn time. Uranium wouldn't be consumed before propellant was exhausted, so this further reduced engine mass. Could you design a nuclear engine with uranium for multiple lunar trips, and make it safe enough to aerocapture into Earth orbit?
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"Could you design a nuclear engine with uranium for multiple lunar trips, and make it safe enough to aerocapture into Earth orbit?"
No. It would take at least a year or so for just the top-level short half-life daughter particles to decay and years longer for the bio-absorbed ones. There is no possible type of reentry armor that could sufficently mitigate this extreme world-wide risk. Portable shielding for rendezvous or Lunar surface operations will also basically eliminate your payload too.
I am normally the nuclear fan boy, but not this time: bringing back a hot reactor to Earth orbit that has just recently fired, so that basically all of the really really nasty hypra-radioactive waste has not yet decayed, on a trajectory which will cause deorbiting in less then a few years is unacceptable.
Edit: Idealy, no nuclear reactor would ever be in or be placed on a nonmaneuvering trajectory into Earth orbit that would decay for ~200-300yrs.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Just saw this comment on space.com concerning SRB safety:
An O-ring leak -- assuming one were still possible with the new seals, wouldn't cause a catastrophic failure for the stick. A loss of thrust, but no explosion.
The ET is what exploded.
Slaps self on forehead. . . Well do'h!
So tell me again WHY are solids inherently unsafe?
Especially if we add small explosive charges to blow open the sides to accomplish thrust termination in the event of abort (as GCNRevenger mentioned)?
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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Apparently us liquid-lovers were mistaken... until liquid rocket engines reach next-generation level reliability, I can't see any obvious reason why a single large solid rocket is a problem.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Reading about Brian Feeney's X-Prize contender I learned that paraffin wax (ordinary candle wax) produces a higher ISP that the Thiokol SRB if combusted with LOX rather than 78% nitrogen ordinary air.
Shut off the LOX flow and the stuff burns as rapidly as a table candle. Nice.
Few toxic by-products as well.
Its a shame the stuff would melt while being erected on a Canaveral launch pad. :;):
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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Follow up from space.com message board:
Re: Griffin Favors Shuttle SRB for Launching CEV new [re: mrmorris]
> The ET is what exploded.
[najab?]Cue Mr Pedantic (that's me). The ET didn't explode, if it had there would have been a much more energetic event. What happened was the plume from the SRB leak burned through the lower support structure of the SRB, which then pivoted around the upper support into the ET. The bottom of the LH2 tank fell out as a result of the impact and the rapid expansion of the fuel drove the top of the tank into bottom of the LOX tank. The two mixed with the resulting rapid combustion.
As it was, the Orbiter was destroyed by being yawed sideways into the air stream, and aerodynamic forces broke it apart (the crew compartment was seen exiting the conflaguration relatively intact).
As you said, if a 'Challenger-style' leak was to occur during the launch of the CEV, it would likely have no impact on the mission, other than resulting in a first state underspeed. If the leak progressed too far, the first stage would fail and the escape tower would drag the second stage/crew module clear of the booster.
Doesn't this say that a "small enough" Challenger-style O-ring leak would still allow the mission to reach orbit? Especially if the 2nd stage had reserve fuel for on-orbit operations.
Hmmm. . .
If this is true, as for the SRB CEV proposal, Thiokol's SRB has over 200 successful launches with ZERO mishaps that would lead to loss of CEV crew.
Sounds like we are very far down the "man-rating" road already.
Edited By BWhite on 1120674273
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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No one said a new NTR could be developed quickly. If you want a lunar vehicle operational by 2010 then it will have to be chemical. A chemical rocket vehicle could be built that quickly but it means every piece of the system must start development now.
Here's a challenge for our resident nuclear guy: design a fuel element that's composed of materials that will not melt at atmospheric entry temperature. The original Nerva achieved 5500°F exhaust temperature. Timberwind achieved 3000°K (4940°F). Hmm, why lower temperature and higher Isp? Anyway, the operating range of reinforced carbon-carbon used for the nose and leading edges of the Shuttle's wings are -250°F to +3000°F. Fuel elements must endure higher temperatures during engine operation than atmospheric entry so fuel elements should make it all the way to the ground. Nerva used uranium zirconium carbide (U,Zr)C as its fuel, as fibres embedded in pyrolytic graphite. Now find a material that remains intact at atmospheric entry temperature, and isn't a capsule but rather a solid material that incorporates uranium, but has minimal mass other than uranium. Solid material means uranium won't be dispersed into the environment even if the element cracks or breaks apart.
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Ok ok ok, Bill. You guys convinced me. As long as there's no liquid fuel tank beside SRB segment seals, and the escape rocket has higher acceleration than the SRB, then you could use The Stick.
I saw a TV interview with another astronaut who said riding the Shuttle was scary. It shook with vibration so strong he was worried the Shuttle would fall apart. Just as he convinced himself it's supposed to be this way, the SRBs separated and the Shuttle flew perfectly smooth without vibration. The Stick will use the same SRB but without the mass of the ET or orbiter to dampen it. The mass proportion of SRB to the entire launch stack will be greater, so expect more intense vibration. Astronauts will have a rough ride.
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Ok ok ok, Bill. You guys convinced me. As long as there's no liquid fuel tank beside SRB segment seals, and the escape rocket has higher acceleration than the SRB, then you could use The Stick.
I saw a TV interview with another astronaut who said riding the Shuttle was scary. It shook with vibration so strong he was worried the Shuttle would fall apart. Just as he convinced himself it's supposed to be this way, the SRBs separated and the Shuttle flew perfectly smooth without vibration. The Stick will use the same SRB but without the mass of the ET or orbiter to dampen it. The mass proportion of SRB to the entire launch stack will be greater, so expect more intense vibration. Astronauts will have a rough ride.
Good reasons to hope t/Space manages to actually fly, soon.
t/Space may very well be why Griffin wants the stick to have both cargo-only and crew variants.
As I recall, the problem with NASA paying for t/Space is that they want to retain their intellectual property rights rather than transfer those rights to NASA in exchange for development funding. That suggests t/Space may very well have alternate funding available which would allow NASA to use the stick CEV only for genuine exploration missions and not as an ISS taxi, buying rides to ISS on a per seat basis, like airline tickets.
Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]
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Does anyone here subscribe to the Mars Society Newsletter? Robert Zubrin sent a fascinating Op-Ed, I'm told it was published on Space News but I can't find there yet. Dr. Zubrin makes some convincing arguments.
Basically, he calls for a 4 person CEV launched on an SDV directly to the lunar surface and back. He argues for lunar oxygen for the return trip. This permits a manned mission to the Moon with a single throw. He makes a strong argument to ensure the capsule is not sized for 5-6 astronauts, but just 4. He says that using a LOX/LH2 for the TLI stage as well as lunar orbit capture and landing, but LOX/LCH4 for ascent you can have a 7.4 tonne CEV. As he points out the Apollo capsule massed 6 tonnes. I would add that Apollo normally carried 3 astronauts but also carried lunar samples back; a rescue version designed for Skylab could carry 5 astronauts and no samples. This is certainly do-able. He also points out "The same lander used to deliver the CEV and its ascent stage could also deliver heavy cargo such as a 20 tonne habitation module (ISS modules weigh 20 tonnes), making long duration lunar surface stays possible right from the start of the program." He also recommends a financial incentive for contractors to deliver 5 CEV modules to NASA in 2008.
I've argued strongly for maximizing reusable equipment, but if contractors can make the CEV capsule reusable (as the article Bill quoted calls for) then that together with Dr. Zubrin's comments make a compelling argument. I would have liked a 4-person capsule docked to ISS as a life boat, and that means a CEV again. This appears to make more sense than the system I described, with the sole catch that the CEV must be reusable. My ideas started with the assumption that capsules can't be reused.
I wonder if I can salvage any of my ideas. I would have made the lunar capsule lighter by using an aluminum alloy hull with DurAFRSI on the upper surface. A capsule still needs an ablative heat shield on the bottom. Would DurAFRSI not only permit an aluminum hull, but reduce thermal stress so it can be reused?
Ps. I still want SDV/Orbiter combination flights to complete ISS. Let's get the damn thing done fast.
Pps. This feels like Robert Zubrin himself has joined out debate. Cool!
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No one said a new NTR could be developed quickly. If you want a lunar vehicle operational by 2010 then it will have to be chemical. A chemical rocket vehicle could be built that quickly but it means every piece of the system must start development now.
Here's a challenge for our resident nuclear guy: design a fuel element that's composed of materials that will not melt at atmospheric entry temperature. The original Nerva achieved 5500°F exhaust temperature. Timberwind achieved 3000°K (4940°F). Hmm, why lower temperature and higher Isp? Anyway, the operating range of reinforced carbon-carbon used for the nose and leading edges of the Shuttle's wings are -250°F to +3000°F. Fuel elements must endure higher temperatures during engine operation than atmospheric entry so fuel elements should make it all the way to the ground. Nerva used uranium zirconium carbide (U,Zr)C as its fuel, as fibres embedded in pyrolytic graphite. Now find a material that remains intact at atmospheric entry temperature, and isn't a capsule but rather a solid material that incorporates uranium, but has minimal mass other than uranium. Solid material means uranium won't be dispersed into the environment even if the element cracks or breaks apart.
The problem isn't just the temperature Robert... you have to worry about ablation too, from the high-hypersonic Mach 30+ entry (massive asymmetric pressures too), which isn't just plain Hydrogen anymore... you've gotta worry about the super-mega-hot oxygen plasma in the atmosphere chewing at the corners of the fuel elements, spreading fission fragment oxide dust around...
Then there is the question, what happens on impact? If the fuel elements don't hit the ocean and hit anything but very soft ground, there is the risk that the fuel elements will shatter and disperse at least some. Heck, the elements themselves, even if they don't shatter, will contain enough high level waste to kill anybody within a city block... Its hard to describe in words just how much more deadly mostly & freshly spent highly enriched Uranium is compared to whimpy RTG fuel elements, or even more then commertial power reactor rod segments.
Plus, your vehicle will have to carry some pretty heavy (tonnes) radiation shielding to protect the crew, it will need bigger fuel tanks, and the Hydrogen propellant is difficult to store (without a heavy cryogenic condenser) for any length of time.
There is also a question of thrust: if you want to use the NTR engine for landing/takeoff from the Moon, you will probobly need quite a bit of thrust, thus increasing the mass of the reactor (and shielding) alot, and making the lousy thrust/weight problem nontrivial.
The easiest thing to do for the moment, until we are ready to do more then a Martian McMurdro, is NOT try and bring a reactor back to Earth at all. Go with Timberwind style reactors, one-shot throw away maximum Isp engines, little RL-10/RL-60 class ones.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Just an observation I'd like to throw into the fray, everyone is still citing the SSMEs as the main engine for a heavy lift SDV, doesn't using and RS-68R make more sense as they were cheaper and designed to be expendable?
Also for all the talk of NTRs (I am personally in highly in favor of their use, as well as any form of lunar IRU) does anyone know if NASA has actually put any money or requests for information out about a resurected NTR program. Thus far the only NASA nuclear programs I am aware of are for next gerneration RTGs and power reactors for space.
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The problem isn't just the temperature Robert... you have to worry about ablation too, from the high-hypersonic Mach 30+ entry (massive asymmetric pressures too), which isn't just plain Hydrogen anymore... you've gotta worry about the super-mega-hot oxygen plasma in the atmosphere chewing at the corners of the fuel elements, spreading fission fragment oxide dust around...
Then there is the question, what happens on impact? If the fuel elements don't hit the ocean and hit anything but very soft ground, there is the risk that the fuel elements will shatter and disperse at least some. Heck, the elements themselves, even if they don't shatter, will contain enough high level waste to kill anybody within a city block... Its hard to describe in words just how much more deadly mostly & freshly spent highly enriched Uranium is compared to whimpy RTG fuel elements, or even more then commertial power reactor rod segments.
I just said it's your task to design a fuel element that won't pulverise on impact. Since you raised the concern of hot oxygen plasma, let's add that requirement. You're the nuclear advocate and a chemist; do you feel you're not up for it?
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If we have the ability to build power reactors, it should be a fairly short hop to dust the NERVA blueprints off to build rockets again. The designs weren't that complicated...
As far as RS-68R versus SSME, three reasons:
-RS-68R doesn't exsist, its just a hypothetical upgrade to improve performance some, but probobly would increase cost signifigantly per unit and still not have the same Isp as SSME. Thats also development money that NASA would rather not spend at the moment to make SDV fly. Lower performance could cut 10-20MT or so off the payload of SDV HLLV.
-SSME is available now, and a simplified downgraded nonreuseable version would probobly be easier to make then an upgraded RS-68R, and still have better performance. However, I imagine that RS-68R would still be considerably less expensive... which suggests to me that Griffin & Co are going the SSME route because:
-SSME employs several hundred or a thousand people at MSFC/KSC. Griffin, being a weak congressional appeaser and possible stealth Shuttle-hugger, would then not have to fire them.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Just an observation I'd like to throw into the fray, everyone is still citing the SSMEs as the main engine for a heavy lift SDV, doesn't using and RS-68R make more sense as they were cheaper and designed to be expendable?
Actually, I would use SSME for a Shuttle-C recoverable engine pod. For the big in-line expendable SDV I would use RS-68. I know GCNRevenger has pointed out the 'R' version has a regenerative exhaust cone, but the Boeing web site lists that only for the version fuelled by slush hydrogen. I have no idea why web sites advocating expendable engines would use SSME. No wait, that's because they're more expensive so therefor more profit.
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The problem isn't just the temperature Robert... you have to worry about ablation too, from the high-hypersonic Mach 30+ entry (massive asymmetric pressures too), which isn't just plain Hydrogen anymore... you've gotta worry about the super-mega-hot oxygen plasma in the atmosphere chewing at the corners of the fuel elements, spreading fission fragment oxide dust around...
Then there is the question, what happens on impact? If the fuel elements don't hit the ocean and hit anything but very soft ground, there is the risk that the fuel elements will shatter and disperse at least some. Heck, the elements themselves, even if they don't shatter, will contain enough high level waste to kill anybody within a city block... Its hard to describe in words just how much more deadly mostly & freshly spent highly enriched Uranium is compared to whimpy RTG fuel elements, or even more then commertial power reactor rod segments.
I just said it's your task to design a fuel element that won't pulverise on impact. Since you raised the concern of hot oxygen plasma, let's add that requirement. You're the nuclear advocate and a chemist; do you feel you're not up for it?
*Laughs*
Robert, I don't think you've got a clue what you are asking... dozens and possibly hundreds of professional materials scientists and chemists the world over (particularly at Sandia Nat'l Lab) are working on ultrahigh temperature ceramic compounds day and day out... its waaay out of my corner of the chemical sandbox.
I think it very likly that no such material exsists, and that there is a good chance that no such material is even possible. There is a finite upper limit to what kind of thermal punishment that chemical bonding (ionic or covalent) can withstand, but no such upper limit for kenetic energy. It may simply be that the energies involved with reentry are so severe, that no material could handle it.
To review, fuel elements must be able to withstand the following due to their high-hypersonic reentry:
-Temperatures well in excess of 3,000K, likly up to 5,000K
-Bombardment by corrosive oxygen plasma under very high pressures without substantial ablation
-Not be smashed by its own weight under the G-forces, either normal to one face of the element or centrifugal force from spinning
-Survive supersonic impact on hard ground without shattering
-Be insoluble in salty sea water for years
-Survive temperature swings, from sudden space sunlight/darkness or water immersion without cracking
And do this while also resisting supersonic atomic Hydrogen ablation or Hydrogen embrittlement at very high pressures and temperature up to 3,000K for an hour or so in space plus the vibration & g-force of launch.
Something of a tall order, and even if the fuel element does survive, it will still kill whoever lives nearby.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Just an observation I'd like to throw into the fray, everyone is still citing the SSMEs as the main engine for a heavy lift SDV, doesn't using and RS-68R make more sense as they were cheaper and designed to be expendable?
Actually, I would use SSME for a Shuttle-C recoverable engine pod. For the big in-line expendable SDV I would use RS-68. I know GCNRevenger has pointed out the 'R' version has a regenerative exhaust cone, but the Boeing web site lists that only for the version fuelled by slush hydrogen. I have no idea why web sites advocating expendable engines would use SSME. No wait, that's because they're more expensive so therefor more profit.
SSME is the known variable, and one less thing to worry about if Griffin is in a rush to the Moon and maximizes the payload of SDV... but more importantly, keeps Congress happy by preserving 5%+ of the Shuttle Army.
RS-68R, as I have mentioned, doesn't exsist other then in Boeing glossies for uprated Delta-IV, labeld "RS-68 Regen." Even with the new nozzle, they won't have the same Isp as SSME, but will still be cheaper for total thrust most likly.
And its not slushed Hydrogen most likly (though it is possible), its more likely just extra para-enriched liquid Hydrogen
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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"Basically, he calls for a 4 person CEV launched on an SDV directly to the lunar surface and back. He argues for lunar oxygen for the return trip. This permits a manned mission to the Moon with a single throw. He makes a strong argument to ensure the capsule is not sized for 5-6 astronauts, but just 4."
Ah, he's just rehashing his "VSE = BAD!" treatise essay trilogy from a while back... Problems:
-Obliterates surface payload due to direct trajectory, requires lifting TEI fuel off Lunar surface, higher thrusts too
-Lunar LOX won't be available, nor should be relied upon, for early missions
-Requires man-rated HLLV, which is a non-starter as per M. Griffin (and sanity)
-Penalty for non-direct flight from Earth, orbital circulization of large (>100MT) vehicle is nontrivial.
A larger capsule would be a real boon too, that the bigger capsule could be carried over to NASA-DRM with few modifications later, increase Lunar surface personell, or offer extra cargo/living space for 4-5 man crews. More room for ISS crap if we are saddled with the station until 2017 too.
Again, I remind you about how important that carrying at least some payload with the crew, and the lander having room for a two-week stay, are both non-negotiable. Hydrogen should be likly used for Lunar acent, to simplify the vehicle by reusing the lander as the acent vehicle, capitalizing on Lunar LOX better later with the higher oxidizer mass fraction, and increasing overall performance. Oh, and making a reuseable lander more practical later on... Such a lander would be big enough to haul one of Bob's big payload too to boot.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I saw a TV interview with another astronaut who said riding the Shuttle was scary. It shook with vibration so strong he was worried the Shuttle would fall apart.
The Stick will use the same SRB but without the mass of the ET or orbiter to dampen it. The mass proportion of SRB to the entire launch stack will be greater, so expect more intense vibration. Astronauts will have a rough ride.
Would changing the exit nozzle shape to an aerospike style lessen the amount of vibration?
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Solutions to the vibration problem:
-Change fuel grain shape to have lower surface area to reduce thrust, without having to modify the rest of the booster
-Build shock-absorbant seats into the capsule. Obviously.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Would changing the exit nozzle shape to an aerospike style lessen the amount of vibration?
I don't think so. I believe the vibration is caused by uneven combustion of solid fuel, not anything about the nozzle.
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http://www.boeing.com/defense-space/spa … 1.pdf]This document is the only thing I found from Boeing that mentions RS-68 Regen. It describes 7 Delta IV Heavy upgrade cases that use the existing pad, 2 of which use RS-68B and 3 use "RS-68 Regen + Dens." which I assume means densified hydrogen. You should get excited, reading from the graph the largest of the upgrade cases would lift 47 tonnes to ISS or 18 tonnes to C3=0. The term "C3=0" means escape from Earth with 0 forward momentum, enough for trans-lunar insertion.
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Uneven combustion of the solid fuel? I doubt that... then why did the Saturn-V have such nasty vibration?
I am familiar with that document, and thats 47MT to LEO and not ISS orbit... With small SRBs and RL-60 upper stage engines, it is the rocket that NASA would employ if it went the EELV route.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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If you read the legend it says "LEO (407-km, 28.5-deg) (mt)". Ok, that is the the altitude of ISS but not the inclination. The line graph appears to be 47 tonnes but the text at the bottom says "upgrades could potentially allow up to 45 metric tons to be launched into low Earth orbit."
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