ISS cutbacks

RobertDyck · 2004-07-29 14:09:34

Adding a top hatch means entering the seats from above, no nead for an isle. Yup, shoulder to shoulder. Interior space in front is wider than the back, check this top view http://www.astronautix.com/graphics/h/h … 20full.jpg I said extend the cabin into the "cheeks" of the lifting body, that means not a perfectly cylindrical pressure hull. Center of gravity will have to be recalculated, but batteries, landing gear systems, air tanks, rocket engines, escape motors, RCS engines, booster adapater, control surface solenoids, and wiring mass do scale down. Radar/lidar, sensors and control electronics do not. Remember the life support system must provide for 4 crew, not 10, so oxygen tanks can be smaller.

When calculating ratios, watch your numbers. Reducing "to 40%" means reducing "by 60%", reducing "to 54%" means reducing "by 46%".

The question is whether congress wants to continue operating ISS using Soyuz spacecraft. If not then America will need a space taxi of its own. A craft optomized for lunar travel is far from economical as a space taxi. They'll probably end up with a 30 tonne vehicle like the Apollo command and service module. Soyuz was designed to go to the Moon with the addition of a TLI stage, but the space station taxi version (Soyuz-TM) masses 7.15 tonnes.

GCNRevenger · 2004-07-29 14:52:35

Abandoning the cylindrical pressure hull will cost you some mass since it now has to be built thicker to withstand the non-uniform pressure. Air tanks get heavier per volume as they get smaller. Electronics, batteries, guidence/navigation, etc are going to stay about the same mass as the original HL-20... But you get the idea. I think that 8,000kg is pretty reasonable for the mass with a ton for crew and OMS fuel, plus another 1.5-2.0MT for adapter and escape systems. In any event it doesn't really matter, since it will have to ride on the biggest EELVs available any which way to reach the highly inclined ISS orbit, as there is no way the vehicle will get down to 8,000kg range that it can ride on the Delta-IV Mediums.

I don't really see why the CEV Lunar class vehicles won't be suited to ISS missions either, overkill certainly but not unsuitable. And is it any less economical to spend about $5Bn on a spacecraft like a baby ($3B devel + $2B ops w/ launcher) HL-20 that you don't need and will be throwing away when the CEV is built only a few years after Shuttle's retirement? So what if each CEV-to-ISS mission costs a bit more? The ISS won't be around long enough to realize the cost savings anyway, and the money going to the "Taxi" won't be going to getting us to the Moon or Mars.

The Apollo CM, with all its relativly anticent technology, only weighed around 6MT by the way... it all depends on the service module. An ISS-only version could probobly be built to minimize weight.

Mad Grad Student · 2004-07-29 15:26:34

And yes you do really need the guidence for the docking port. You can only get range information with radar or lidar systems and not attitude, and for lidar like the ATV uses you will need docking port modifications. Any cargo vehicle has to have automatic docking/docking-abort capability, if for no other reason a safety measure in the event of remote control failure or mistakes, and that means docking port modifications. The Shuttle doesn't need it because it is already docked at the Shuttle port and can just use its arm to move pieces/containers around the ISS since it isn't free floating anymore. Shuttle BTW doesn't have any worry of remote control failure, since it isn't being remote controlled.

Oooooookay then, put a beacon on the docking port. That way you always know exactly where the port is and from the camera's perspective you can tell where you are in relation to the rest of the station. You're leaving out one other way to deterimine distance, stereo vision, MER-style. Place two cameras a few feet apart from each other at the front of the vehicle and transmit that data to an IMAX-style true-color computer screen and whoever's operating the thing can tell exactly where they are and how far away everything is. Want extra redundancy? Why not place six simple radio transmitters at the ventral, dorsal, port, starbord, fore, and aft positions of the ISS? It would work like GPS, the computer can tell where it is based on how far away each beacon is.

GCN, think about it, you're arguing that only the shuttle can ever ever forever service the ISS beacause only it is allowed to use the correct door. It's kind of ridiculous.

Let's stop for a second and think about how much of a jump a resupply vehicle is from a regular high-tech corporate jet. In case you're unfamiliar with it, the http://www.starshipdiaries.com/]Beech Starhip was a ground-breaking new business turboprop when it was developed in the 80s. Scaled built an 85% scale proof-of-concept version that was just as capible, just a little bit smaller and made of fiberglass rather than carbon fiber. You won't need turboprops in space or their fuel tanks, but can replace them with the rocket engines and tanks needed for rendezvous. Fortunately, these are actually vastly simpler machines and need not cause any headaches if some insanely simple ones (like those being made at http://armadilloaerospace.com/n.x/Armad … Armadillo) are used. The docking port and equipment is about as complex as the avionics that are already installed on any Cessna Citation (entry-level bizjet) and the weight saved by not needing wings frees up room for plenty of cargo and a TPS. Speaking of TPS, well that will be toughy, right? NASA is very good at making a big deal out of not much as it has done with heat shields. Yes, people point at Columbia and say that they're very difficult to do properly, but in a less-well-known incident, a Soyuz capsule actually hit the atmosphere backwards and still survived. The original Mercury capsules used a simple slab of Beryllium bolted on to the back, and while that's rather heavy is could get the job done here as well.

Even if we throw all that out and say that it takes a billion dollars to develop this heavy ATV, wouldn't it be worth it to retire the shuttle? A billion is a lot, but it's a lot less than just one year's worth of operating the shuttle, and by preserving our investment in the ISS it would be money well spent.

Grypd · 2004-07-29 16:31:50

Apart from the X38 what American company has built any functioning spacecraft designs since the shuttle and the 1980s. There have been test beds and a lot of interesting designs but no real change in spacecraft since the shuttle appeared and beacame the great financial sponge it is.

The ISS does not count as it being a space station from an engineering point of view should be a lot simpler to build as it does not need aerodynamics and large engines etc.

So for over 25 years there have been no American scientists building and refining new space crafts, this is a wasted generation of talent.

We could have made an ISS that worked but to save costs we didnt, We made it a makework for the shuttle. It is not too late but really it would be hard to turn it to doing something useful. The ISS was supposed to be the spaceport for further exploration but all that would have made this has been cut.

Euler · 2004-07-29 20:42:13

You are significantly overestimating the mass penalty for getting to ISS orbit. Despite getting the maximum penalty due to it's equatorial launch, Ariane V will be able to launch the 20.5 MT ATV. The dinky little Japanese H-2A will also be able to launch the 15 MT Japanese transfer vehicle to the station (not sure how they will manage this as the H-2A is only supposed to be able to launch 11 MT into LEO). 40%? It's more like 10%.

RobertDyck · 2004-07-29 23:39:49

To hide the strings?

Does it matter if it is republican or democrat as leader but the point is the leadership now isn't that great and economics are not great. Indeed there are some who say its the saudi royals who are holding the dollar to ransom and the mega corps within the US who pull the strings, before it was the USA that used to put great inventions out, lead the world economy, and launch satellites for other nations. But now the employment is getting shipped to other areas and China is launching stuff for the EU now, the ESA is very small but the euro zone has become stronger taking in an extra goups of nations which makes it 25 and creates a new economic super power with the euro now an alternative to the dollar for investors, the dollar has also been shakey and uncertain. Many electronics, manufacturing and techincal types of jobs are going over to China while the Chinese try to focus on education for their people. The president's plan for the budget year, which proposes spending $2.4 trillion for all government activities, up 3.5 percent from the current year. Revenues will total $2.04 trillion, a sizable 13.2 percent increase that the administration forecasts will occur from growing tax receipts The estimated population of the United States is 294,033,049 so each citizen's share of this debt is $24,281.66. The National Debt has continued to increase an average of $1.58 billion per day since September 30, 2003!
Concerned? Then tell Congress and the White House!
President Bush sent Congress a $2.4 trillion election-year budget on featuring big increases for defense and homeland security but also a record $521 billion deficit.
http://www.csmonitor.com/2004/0128/csmi … g/p12b.gif
To battle the soaring deficits, Mr. Bush proposed squeezing scores of government programs and sought outright spending cuts in seven of 15 Cabinet-level agencies. The Agriculture Department and the Environmental Protection Agency were targeted for the biggest reductions, and NASA got slahed recently. I think it was a terrible shame to see those cuts to NASA on the aniversary of the Apollo landings, I think it was a terrible insult. NASA has done some incredible things that the US should be proud of it is a shame to turn away from science and exploartion and it would be good if the economics were better.

Euler · 2004-07-30 00:36:10

I am talking about when GNCRevenger said:

-Estimated penalty for launch to ISS orbit & altitude as opposed to lower equitorial orbit: 40%
-Payload mass for Atlas 501 to ISS orbit: 6200kg
-Payload mass for Atlas 551 to ISS orbit: 12,000kg
-Payload mass for Delta-IV 54 to ISS orbit: 8200kg
-Payload mass for Delta-IV HLV to ISS orbit: 15,500kg

I think that his payload mass numbers are off by a significant amount.

Yang Liwei Rocket · 2004-07-30 02:41:30

they are still trying to push the ISS on, there is much work to do and they are trying to go forward even more now there could be a shuttle visit

Expedition 10 commander Leroy Chiao, a veteran shuttle astronaut, and Russian cosmonaut Salizhan Sharipov are in their final 10 weeks of training before stepping inside a Soyuz spacecraft and kicking off a six-month ISS tour. Their launch will be staged from Baikonur Cosmodrome in Kazakhstan on Oct. 9 if all goes well
The new station crew is hoping to greet the shuttle astronauts from Discovery during STS-114, NASA's first return-to-flight mission expected to launch sometime in March 2005, and have trained specially for such a rendezvous.
""We're very excited about the possibility of STS-114's arrival," Chiao told reporters during a pre-launch briefing held Thursday at NASA's Johnson Space Center (JSC) in Houston.
Hoping for visitors
According to NASA shuttle officials, the space shuttle Discovery is expected to roll out of its maintenance bay in January

space tourist is also maybe going to try and visit the space station

RobertDyck · 2004-07-30 07:43:26

I think that his payload mass numbers are off by a significant amount.

Ah. According to http://www.astronautix.com/lvs/shuleiss … cyclopedia Astronautica the Shuttle can lift 27,500kg to 204km orbit @ 28.5° inclination, or 16,050km to ISS. Launch vehicles like Atlas V or Delta IV are usually quoted to 185km orbit since that's the lowest usable orbit, therefor greatest mass (looks good on a sales glossy). According to http://www.spaceflight.nasa.gov/shuttle … .html]NASA the Shuttle can lift 28,803kg to LEO, which I assume is the same 185km orbit. So using that figure we get a ratio of 16050/28803 = 0.5572336 which means a pentalty of 100% - 55.72336% = 44.27664%. That sounds even worse than GCNRevenger suggested. However, Shuttle has to carry the mass of its orbiter as well as payload so add 104,326kg end-of-mission mass. The total orbiter + payload to 185km is 28803 + 104326 = 133129kg. The total to ISS = 16050 + 104326 = 120376. The ratio is then 120376/133129 = 0.9042057 or a pentalty of 100% - 90.42057% = 9.57943%. I think last time I estimated Atlas V 401 lift I had used Proton figures, but let's see what this one gives us:

vehicle - price - LEO - ISS
http://www.astronautix.com/lvs/atlasv.htm]Atlas V 401 - $77M - 12,500kg - 11,302.57kg
Atlas V 501 - $110M - 10,300kg - 9,313.3kg
Atlas V 551 - $170M - 20,050kg - 18,129.3kg
http://www.astronautix.com/lvs/deledium.htm]Delta IV Medium - $90M - 8,600kg - 7,776kg
http://www.astronautix.com/lvs/delium42.htm]Delta IV Medium+ (4,2) - $95M - 11,700kg - 10,579kg
http://www.astronautix.com/lvs/delium54.htm]Delta IV Medium+ (5,4) - $110M - 13,600kg - 12,297kg
http://www.astronautix.com/lvs/dellarge.htm]Delta IV Large - $170M - 25,800kg - 23,328.5kg

BWhite · 2004-07-30 08:12:52

Now, Robert, add Proton to your list. ???

clark · 2004-07-30 13:43:05

Robert, those numbers made me think...

Anyone have any thoughts on this:

Updated Gemini as the basis for a CEV design.

http://www.astronautix.com/project/gemi … gemini.htm

http://www.astronautix.com/craft/gemini … gemini.htm

Crew Size: 2. Length: 3.35 m. Basic Diameter: 2.32 m. Maximum Diameter: 2.32 m. Habitable Volume: 2.55 m3. Mass: 1,983 kg. Structure Mass: 638 kg. Heat Shield Mass: 144 kg. Reaction Control System: 133 kg. Recovery Equipment: 98 kg. Navigation Equipment: 63 kg. Telemetry Equipment: 51 kg. Electrical Equipment: 126 kg. Communications Systems: 26 kg. Crew Seats and Provisions: 426 kg. Crew mass: 144 kg. Miscellaneous Contingency: 100 kg. RCS Fine No x Thrust: 16 x10kgf. RCS Propellants: N2O4/MMH. RCS Isp: 283 sec. RCS Impulse: 9,226.19 kgf-sec. Main Engine Propellants: N2O4/MMH. Main Engine Propellants: 33 kg. Main Engine Isp: 283 sec. L/D Hypersonic: .16. Electrical System: Batteries. Electric System: 4.0 kWh. Battery: 180.0 Ah.

Update it with new materials, perhaps reducing the weight somewhat, and make it a little lagrer to accomdate 4 people (assume 100% increase in mass size and it is well within EELV)

http://www.astronautix.com/craft/gemelt … melter.htm

Use the "modular" approach with this version of the gemini and we have a temporary lunar base...

I might add that Jeff Bezos Blue Origin group has been rumored to be developing a 7 person sub-orbital/low earth orbit space ship (named New Shepard) based on the Gemini.

clark · 2004-07-30 13:47:25

Idon't want to derail the thread, so I copied my previous post into the CEV thread over in human missions. I don't mind talking about it here, unless of course anyone else does. I appreciate any others thoughts...

RobertDyck · 2004-07-30 20:16:55

This thread was started with a news article about ISS cutbacks. Current plans are to complete ISS with the exception of the Crew Return Vehicle, and US Hab module. With 2 Soyuz we can get 6 crew on ISS instead of 7, but we need life support for them. A US Hab module wouldn't cost much more and could eliminate the need to supply water, reducing the cost of operations. We have discussed here various options to supply the station and transport crew. There are a few options and all cost less than Shuttle. If we're going to spend the money to complete ISS we should get value for that money, actually use ISS.

GCNRevenger · 2004-08-03 11:40:21

Heeey now I didn't say that the HL-20 couldn't be lightend, i'm saying that it can't be lightend by the same or greater amount by simply scaling down the design.

Okay okay, so the 40% number is probobly a little high, but if its a measly 9% I don't see why NASA would go through the trouble of lightening the STS main tank by 8MT if the payloads could just be squeezed a few percent. A polar orbit shot cuts the payload by about a third I think, so it ought to be somewhere a little less than this.

The CEV's early models probobly will be somwhere between Big Gemini and Apollo, with a little Soyuz thrown in perhaps. I don't see the need to run off and build a "space taxi" when CEV will be available before too long and additional Soyuz vehicles can accomodate a crew of six. The trouble really is the HAB module and getting supplies up there.

Speaking of which, yes it IS pretty hard to build an unmanned cargo vehicle, and its quite a bit more difficult than slapping a radio beacon onto a docking hatch... the Beech Starship or the pathetic toys coming out of Armadillo Aerospace are not anything even remotely beginning to skirt the edge of perhaps maybe contemplating the possibility of such a space vehicle... The door really is a problem too, the ISS was designed to be tended by Shuttle, and it is not designed to be tended by anything else. Changing this arrangement will require signifigant modifications to the docking nodes any which way.

The Soyuz as reference to a "simple reentry vehicle" aren't terribly relivent either, since the thing must carry a few tons of cargo in bulky equipment racks and still be light enough to fly on a medium launcher, not carry a few hundred kilos of people and go up on a light launcher.

Using optical cameras for allignment is how the Progress vehicle's automatic docking works if memory serves, but there must still be backups to the automatic and some sort of emergency abort logic.

clark · 2004-08-04 09:06:48

http://www.space.com/missionlaunches/sh … 40804.html

CAPE CANAVERAL-- NASA plans to have a rescue shuttle ready for just the first two post-Columbia missions. After that, they might go back to business as usual.
If the first two flights make NASA confident the safety fixes to the shuttles are working, agency managers said they might determine it's no longer necessary to have a rescue vehicle on standby for future missions.
"After that, we will take a look and evaluate . . . and see where we need to go from there," said John Casper, a former astronaut now leading NASA's effort to implement recommendations made by the Columbia Accident Investigation Board.
When Discovery blasts off on the first return-to-flight mission, as early as the spring, NASA says Kennedy Space Center will be ready to launch Atlantis on a rescue mission within 45 days. On the second flight, a rescue shuttle will be ready to go within 58 days.

That's not the only post-Columbia change that might only last two launches. A requirement to launch during the daytime so that tracking cameras can get clear images of possible debris strikes also may go away after the first two launches, NASA has said.
Getting rid of those two requirements would be a big boost to meeting President Bush's directive to finish building the space station and retire the aging shuttles by 2010. Doing so will require flying four to six times per year, a rate that was difficult to meet prior to Columbia.

Back to business as usual if the first two flights go well... perhaps they can do it then.

Mad Grad Student · 2004-08-04 22:00:09

Well, some guys are obviously going to have some problems ahead of them, GCN. Some crazy engineers at Lockheed are planning on adding some huge artillery pieces to a C-130 (Big four-engined cargo prop plane often seen in Vietnam movies, think Operation Dumbo Drop), turning it into a GUNSHIP. Not only do they plan on doing that, these guys in the Navy are planning on landing one on an aircraft carrier, this in an airplane that has no tailhook and was never ever in its designerss wildest dreams meant to land on a a floating platform out in the middle of the ocean. Oh, yeah, and there are these lunatics in the Air Force trying to turn the B-1A, a high altitude Mach 2 bomber into a low altitude but still supersonic strike plane, even after the guy who used to be president cancelled the idea because it was so ridiculous. Crazy!!

And let's not forget the most insane ones in the lot; These NASA scientists (They ought to know better, right) are trying to make the Lunar Module of Apollo 13 guide the whole getup to splashdown, with no help from the CSM. This in a vehicle never meant to operate more than two days with two people!

Look, the point is that things can do things that they weren't originally made to do. The AC-130 is now one of the biggest stars on CNN prime time, and its parent plane, the C-130 was never meant to carry weaponry, just inert (For the time being, anyways) cargo. Yes, a C-130, a very heavy landlubber was succesfully landed twice on an aircraft carrier, with hundreds of feet to spare. And the B-1A, originally a replacement for the B-52, became, with light modifications, a low altitude supersonic cruise missle carrier that now frequents Baghdad, the B-1B. And it's doing this even after the whole project was terminated by Jimmy Carter, then revived by Ronald Reagan.

The door is absolutely not a problem. We're talking about a new, clean-sheat, blank slate spacecraft, it's designed from the ground up to use the American docking nodes. There is no conversion needed. The visual docking will work well enough, but if that fails lidar and a docking beacon will be plenty of a redundancy if you combine it with a simple kill switch. "Press this button to shut down the ATV engine and have the RCS neutralize any motion." A button that says that in so many words, perhaps by being red, could save the day if both systems fail. And yes, it is that easy to modify the American docking ports. Have you seen any pictures of the inside of Mir? It's a huge mess of cables and wires all over the place, things plugged here, jury-rigged here, a labrrynth of improvisation. Equipment in space is often made to do stuff it wasn't meant to do, some good improv wiring and a $59.99 Bendix unit could get the job done.

I can understand the argument against using the space shuttle+hab in cargo bay approach to solving the hab/ERV problems, but this is utterly ridiculous. GCN, you are terribly underestimating the skills of our engineers and vastly overestimating the difficulties involved here. If spaceshipone had its TPS replaced with a shuttle-type tile system and were launched on something like a Delta 2, provided it were wired with some Radio Shack-quality elecronics, it could transfer stuff to the ISS. Okay, that's not really true, but it could reach the ISS, dock with it, and return to land at any airport you like. If Scaled had designed it from the ground up to be a station servicer you could actually get some practical use out of it. Spaceshipone is on the same technology level as somethign like a glassair or a lancair plus the engine of a rocket dragster (For the GA laymen, glassairs and lancairs are homebuilt aircraft with pressurization systems that can bring up to six people in comfort to Mount Everest heights). Space is no longer the exclusive realm of expensive government programs, technolgoy has come far enough for it to be within reach of commercially availible hardware and those that use it creatively.

GCNRevenger · 2004-08-04 23:45:17

Relativly simple structural modifications to an overbuilt airplane in a hanger on the ground with all the tools you could ask for and loads of manpower: easy.

Moderate to substantial modifications to a delicate space station hatch in orbit that you can't dismantle or cut or weld or drill or otherwise depressurize, in zero gravity while wearing a space suit with rigid 1" wide fingerd gloves, with only minimum of tools that must be pre-planned... and do it relativly fast with only two people: not so easy.

Again with the references to Mir... Mir was a death trap, an accident not waiting but begging to happen, it was stupid of the Russians to keep it manned that long. It is a wonder that nobody was killed several times over... Oxygen generator fires, hull punctured, Cosmonauts stuck in the airlock, solar pannel failures, in-cabin toxic coolant leaks, biological contamination galore... Mir is a great example of how not to run a space station, jerry-rigging the ISS is a sure fire way to screw it up.

"technolgoy has come far enough for it to be within reach of commercially availible hardware and those that use it creatively."

No, no it has not. Orbital space travel is as far beyond SpaceShipOne and the like as the SR-71 Blackbird is beyond the little kit-build airplanes... SS1, Armadillo, all the X-Prize vehicles are worthless toys. It is simply a matter of scale... currently, the physics of rocket technology demands that the mass of the vehicle be very small compared to its fuel. This is not an "engineering challenge" for engineers to overcome but rather a problem of chemistry. At the moment, only chemical combustion can practicly provide the energy to reach space, and chemical fuels are limited in their efficency by the essentially unchanging mass of their constituent particles. The lightest and most efficent fuel, liquid Hydrogen, is the lightest stable element possible in the universe. There isn't anything practical thats better and there won't be anything better, because there aren't any molecules of lower mass... A few percent here for adding metal powder, a few percent for aerospike engines, a few percent for lower tank mass by slushing the LH2... but nothing signifigant.

Thus, nobody can afford to build a vehicle large enough to reach orbit and still have a little dry mass left over for payload. SSO would have to be 200 to 300 times more powerful. Thats hundreds of times more, in order to put a vehicle of reasonable mass on orbit... Ultimatly, this is why rockets must be huge flying skyscrapers that use every trick in the book and the latest materials to shave every last dry pound... while flying inverted pendulum style at Mach-25 on a barely controlled explosion into an environment with wild temperature swings and firey reentry... and so cost hundreds of millions of dollars to build.

Until somebody comes up with somthing better than chemical rockets, then it doesn't really matter how much everything else progresses, it still isn't going to happen without nine-digit investments... Turbine combined-cycle engines would help, but the vehicle would still be gigantic and have to fly high-supersonic. Nuclear engines are a non-starter for small time commertial outfits... And there really aren't many other options, other than the Scramjet. Scramjets that work this well are still a long ways off, limited to around Mach-10 at the moment, and this is definatly not going to change rapidly.

Mad Grad Student · 2004-08-05 20:09:42

Relativly simple structural modifications to an overbuilt airplane in a hanger on the ground with all the tools you could ask for and loads of manpower: easy.
Moderate to substantial modifications to a delicate space station hatch in orbit that you can't dismantle or cut or weld or drill or otherwise depressurize, in zero gravity while wearing a space suit with rigid 1" wide fingerd gloves, with only minimum of tools that must be pre-planned... and do it relativly fast with only two people: not so easy.

Wrong. Many planes have been substantially modified time and again and still used to the fullest of their new abilities. For example, the Supermarine Spitfire airframe was never meant to handle an engine larger than ~1,500 hp. Postwar it was used with a monster 2,500 hp Griffin engine with contra-rotating props and as a carrier fighter. Back in the '60s, Darryl Greenamyer took a stock F8F Bearcat, gave it an engine with double what the airframe was designed to use, clipped 10 feet off the wings, and replaced the canopy with the headlight from a P-3 Orion ASW search plane. As you might guess, the Bearcat flew around the racetrack at Reno at 450 mph easily and could rocket to well above its redline speed in forward flight. Now that is a major modification.

Putting a beacon on a docking port is not a substantial modification. Granted, the conditions for doing the rewiring are a lot harder to work in, but it would be a far simpler task than many other EVAs that have been done, like those on the Hubble service missions.

Again with the references to Mir... Mir was a death trap, an accident not waiting but begging to happen, it was stupid of the Russians to keep it manned that long. It is a wonder that nobody was killed several times over... Oxygen generator fires, hull punctured, Cosmonauts stuck in the airlock, solar pannel failures, in-cabin toxic coolant leaks, biological contamination galore... Mir is a great example of how not to run a space station, jerry-rigging the ISS is a sure fire way to screw it up.

Hi, welcome to space, GCN! Despite putting its astronauts through rigorous, massive amounts of extended training, preparing them years in advance for a two week spaceflight NASA has still found a way to make going into space as dangerous as fighting a war. It's a dangerous place, no matter what you do to protect yourself. Eventually, jurry-rigging will be a fact of life on the ISS, just as it was on Mir, weather we like it or not. Systems don't work forever and just as you said earlier, it's hard to replace or repair them while keeping everything spick and spotless. The only way to keep the station running after a certain point will be by improvising new wiring, new systems, and rerouted systems. Adding one docking beacon won't hurt or effect things to much in the great scheme of things.

Orbital space travel is as far beyond SpaceShipOne and the like as the SR-71 Blackbird is beyond the little kit-build airplanes.

Most likely true. But let's asess that statement for a second, how far behind the SR-71 are the "little kit-build airplanes?" There are many on the market made of carbon fiber, which is even stronger and lighter than the SR-71's titanium. The immense heat made by going at those Mach 3 speeds isn't a problem, a TPS like the one on SpaceShipOne could keep that in check. Avionics have come a long way in 40 years. What was state-of-the-art back then is stuff you could find on eBay now. Ah, but the engine. The SR-71 engine was made for a very specific purpose, and the only engines that can do the same job are othe SR-71 engines. Clearly some work can be done here.

So, other than propulsion, the SR-71 isn't actually a huge leap beyond a Lancair of today. Engines for orbital space flight can be made solely by private industry right now, as Spacex has proven.Your comments about the difficulties of getting to orbit don't seem to counter anything I've previously said. I was never saying that SpaceShipOne or the like could go to orbit right now, I was saying that they could do that if they were the tip of an availible orbital launch vehicle. However, I'll take a stab at a few of your points.

It is simply a matter of scale... currently, the physics of rocket technology demands that the mass of the vehicle be very small compared to its fuel. This is not an "engineering challenge" for engineers to overcome but rather a problem of chemistry. At the moment, only chemical combustion can practicly provide the energy to reach space, and chemical fuels are limited in their efficency by the essentially unchanging mass of their constituent particles. The lightest and most efficent fuel, liquid Hydrogen, is the lightest stable element possible in the universe. There isn't anything practical thats better and there won't be anything better, because there aren't any molecules of lower mass... A few percent here for adding metal powder, a few percent for aerospike engines, a few percent for lower tank mass by slushing the LH2... but nothing signifigant.

But in a sense it is an engineering challenge, overcoming the natural difficulties to achieve the final goal. Liquid hydrogen may appear to be the ideal fuel because of its high specific impulse and low weight, but it is definately not. Even though you "only" need to have 90% of the starting mass to be fuel, LH2 is the least dense of all the pallet of fuel choices. The fuel tanks need to be so giant it defeats the purpose, and in addition to its low density, hydrogen must be kept extremely cold, adding even more weight to the tanks.

The Centaur upper stage has an extremely good mass ratio of 10, done with LOX/LH2. If that stage were filled with hydrogen peroxide and kerosene it would have a mass ratio of 40. In fact, it gets even better because the engine for an H202 rocket can be far simpler than that for a conventional bipropellant rocket. Simpler means lighter, simpler means cheaper, simpler means faster. The isp isn't as good, but the benefits of better mass ratio far outweigh that. This is a propellant that can actually get you somewhere, not that hydrogen/oxygen can't.

Thus, nobody can afford to build a vehicle large enough to reach orbit and still have a little dry mass left over for payload. SSO would have to be 200 to 300 times more powerful. Thats hundreds of times more, in order to put a vehicle of reasonable mass on orbit... Ultimatly, this is why rockets must be huge flying skyscrapers that use every trick in the book and the latest materials to shave every last dry pound.

You're forgetting that SS1 uses a dinky little hybrid engine with an isp of maybe 160 on good days. That's not seriously viable as orbital propulsion. Scale spaceshipone up ten times, using H202/kerosene rockets, and it could reach orbit. That's quite reasonable.

You and I both know that the rocket industry has passed up opportunites to make space flight affordable and better countless times. In 40 years the Delta has barely been improved, that's not because it was perfect when it was made, it's because nobody ever had the guts to say "Hey, this rocket's a piece of crap! Let's make something better." 40 years later, Spacex makes a rocket five times as efficent that's mostly reusable in two years. Today's technology will always make it difficult to get into space, but with some out-of-the-box thinking skills it can be done affordiblly.

Euler · 2004-08-05 23:04:01

I was never saying that SpaceShipOne or the like could go to orbit right now, I was saying that they could do that if they were the tip of an availible orbital launch vehicle.

Space Ship One would not be able to go into orbit on top of a conventional rocket because it's heat shield is not nearly strong enough to survive reentry. It also does not have sufficient life support to stay in orbit long, and it probably couldn't dock with other spacecraft.

In fact, it gets even better because the engine for an H202 rocket can be far simpler than that for a conventional bipropellant rocket.

H2O2/Kerosene engines are still fairly complicated. They seem to have a T/W ratio that is not much higher you would expect from an LOX/LH2 engine. This means that the engines for the H2O2/kerosene vehicle would probably be bigger, heavier, and more expensive that the engines of the H2/O2 vehicle because they need to be much more powerful due to the greater weight of the H2O2/kerosene vehicle.

GCNRevenger · 2004-08-06 15:48:14

Excuse me? Are you kidding?... the SR-71 is far beyond any airplane built today, any plane, short of fighter jets. It is infinatly more complex than any kit-build planes, reguardless of what materials its made of. No less than six or seven times as fast, able to fly at double or tripple the altitude, experiencing the bolt-snapping gauntlet of transonic and supersonic flight, exposing the skin to hundreds of degrees of atmospheric heating that would make composits burn... and still be able to fly reliably again and again without substantial serviceing. THAT is the kind of gap that exsists between suborbital spacecraft and orbital ones. Comparing dinky private jets to the SR-71 is an insult to Kelly Johnson & Co.

SpaceShipOne uses ablative paint for a "heat shield" like the X-15, which at high supersonic speeds failed and almost destroyed the whole ship. An orbital vehicle would be going three or four times as fast and reach temperatures of 2000-3000K+, and experience the nasty effects of ionization that will eat through almost anything, much like a welders' plasma torch. And it gets better, the force imparted on the vehicle by the hypersonic air pressure would simply rip the wings right off of SSO, which "would end your trip real quick." SSO also has no LSS system, only compressed air tanks which also operate the control surfaces, landing gear, and RCS systems. Battery power enough only for hours. No thermal rejection capabilities at all. No docking hatch. No restartable OMS engine. No water supply... You get the idea. Even with Peroxide/Kerosense fuel, the SSO would still have to be 50-100 times bigger i'd imagine because of the higher mass of the vehicle needed.

Burt's rocket is a toy and nothing more, so get the grand ideas of Scaled making flights to the ISS out of your head...Let me introduce you to an aborted 1980's Russian project: http://www.astronautix.com/craft/maks.h … t/maks.htm

This is the MAKS spaceplane, launched in similar fasion to SSO from an airplane. It weighs about 18MT and would have enough room to seat 8-10 or carry 9-10MT of cargo to a useful orbit. About 8MT of its dry mass is taken up by its engine, the RD-701, which is unique because it burns LOX, Kerosene, and LH2 to minimize fuel carriage. But guess what? The fuel tank that it rides on is 31M long, nearly 7M around, and still weighs 248MT wet. The airplane that it is launched from is the An-225 Mirya, the largest aircraft in the world... if you built one flying with only LOX/kerosene it will be too heavy to fly. Even if you cut the thing to half that size and fly only tourists, I doubt it could fly it on a 747, and nobody is ever going to be able to afford to build it privatly. You do need a vehicle the size of MAKS to deliver Delta-II sized payloads and be reuseable.

"But in a sense it is an engineering challenge, overcoming the natural difficulties to achieve the final goal.

Wrong, you are missing my point. It is not an engineering challenge, because you CAN'T overcome the natural difficulties, only live with them better. Its against the laws of physics to do so. As long as we rely on chemical rocket engines with sane propellants, the mass fraction is thermodynamicaly limited by the amount of energy you can derive from the chemical bonding per mass of propellant. And our engines right now are so good, they operate at 90% of the theoretical maximum efficency of available rocket fuels.

"but the benefits of better mass ratio far outweigh that. This is a propellant that can actually get you somewhere, not that hydrogen/oxygen can't."

Huh? Mass ratio? What are you talking about? The Thrust/Weight ratio has nothing to do with the fuel, it is a concern of the engine(s) and vehicle dry mass. Sure thrust is a more important and Isp less at launch, but the rest of the time the lightest fuel per-energy wins since fuel mass decreases geometricly with Isp... Which is why it beats the crap out of Peroxide/LOX & Kerosense for upper stage fuel so badly the extra tank mass is unimportant since you need so little of it. Don't forget about composit tanks, which are 30% lighter too.

The thrust of cryogenic engines can be optimized at low altitudes too like on Delta-II and IV by shaping the rocket nozzle which makes it competitive with heavier fuels, and the use of an aerospike engine makes SSTO vehicles possible. I'd like to see you build a DC-X that burned Peroxide & Kerosense! I bet the Russians sure wish they had cryogenic engines back in the Space Race days, get your facts straight before you turn into Jim's parrot.

"Simpler means lighter, simpler means cheaper, simpler means faster."

No, no it doesn't. The more complex solution that offers the higher performance is often justified. The notion that the KISS solution is always best is a great soundbite for entertaining docu-drama shows on TV, but unfortunatly its A LIE... Before you make more "Big Aerospace is Evil!" steriotypes, I suggest you get your facts straight about the modern Delta and Atlas rockets, and realize that they are stuck with the same chemical fuels we've had for the last fifty years... SpaceX and Elon's rockets, five times more efficent? No, five times cheaper perhaps, but considering that he still hasn't flown his engine, you might get what you pay for. Oh, and guess what? The upper stage on the Falcon-V will be burning Hydrogen with a RL-10 engine!

Again, you can't think outside the box, because the box's walls are made of things like "gravity" and "proton/neutron mass" or "bond energy" that engineering can't change.

Mad Grad Student · 2004-08-06 18:59:41

GCN, you're still missing the point, it is an engineering challenge to create a low cost orbital LV, in the same sense that it's an engineering challenge to build the Strait of Messina Bridge. Obviously the engineers aren't going to try to turn gravity off around Sicily or make some magic metal that can suspend millions of tons of material from a single thread, but they are going to have to be creative about the shpe of the bridge deck, the design of the towers, etc to make a one-span suspension bridge cross two miles of water. There are set rules in the laws of the universe that can't be broken, but they can be used to their fullest.

I'm not saying that SS1 per say would be effective in orbit. I'm saying that a derivitive of it modified for work in orbit would be effective. Life support could be taken care of by a simple unit like the one in the ol' Vostok capsules, I'm sure that they could be made much lighter and compact now. SS1 does have an effective OMS system, a hybrid rocket that can be throttled, shut down, and re-started and is capible of around 1.5 km/s of delta-V. Not much, but good enough for docking and de-orbiting.

According to http://hobbyspace.com/AAdmin/archive/Sp … .html]this, NASA has developed a simple woven heat shield made of high strength fabrics and woven ceramics, it wouldn't be very heavy and would be highly effective. It does say that the setup is somewhat hard to work with, but since we have plenty of throw capacity from our LV, the areas that couldn't be covered by the quilt could use the simple brute-force approach used by the Mercury capsules, a slab of beryllium. It would weigh 25 pounds per square foot though, so it would be desirable to use other setups on as much of the area as possible.

By covering the top of the spacecraft in solar pannels you could solve the power problem. Need more RCS? Get a bigger nitrogen tank. If that's still not enough or too heavy some simple hydrogen peroxide engines could be used. Fortunately, we don't have any of the alleged docking woes of the ATV and can just use the same hatch as the shuttle. Place it wherever you want, for all I care, it doesn't really matter. Random guess, how about on the roof of the cabin? That would muck up the aerodynamics on landing, though, so how about this, place it in a small bay behind the cabin with folding doors above like on the shuttle. For missions that don't involve rendezvous, an airlock could be placed there instead, or some science equipment, extra LSS, or a payload.

As far as I can tell, there was nothing fundamentally blocking the MAKS from working, it was stopped because A) Russia already had the Buran and B) Russia had and has no money. Just FYI, the An-225 is bigger than the 747.

I'm not talking about thrust to weight ratios when I say that hydrogen peroxide rockets have better mass ratios than LOX/LH2 rockets. Mass ratio, I'm sure you've heard of it before, is the gross weight of a rocket (Or airplane, cruise ship, etc.) divided by its empty weight. So a rocket that weighs 1,400 pounds and carries 12,600 pounds of fuel has a mass ratio of 10. Sorry if I'm patronizing you.

hydrogen peroxide rockets can have much higher mass ratios because the propellants are far denser. So even though they don't have specific impulses as high as hydrogen engines, a given weight of peroxide mixed with a little kerosene actually contains more latent energy. Somewhere in the ballpark range of three times as much energy. They are far simpler than standard biprop engines because, well, here's a rundown of how the two work. A LOX/LH2 engine takes the propellant (hydrogen) and oxidizer (oxygen), sprays them both into a combustion chamber, uses what ammounts to a spark plug to ignite the mixture, and the resulting explosion is rushed out the back to produce thrust. Sounds easy enough, but the fuel and oxidizer propellant lines must have complex turbopumps (Unless you want to use pressure-fed rockets, not considered a viable option on big engines) to move the stuff around. The immense heat made by the engine requires the fuel to move first into a jacket around the engine to cool it off, adding complexity. And for more efficent engines, the two chemicals are mixed together in a "pre-burner" before entering the combustion chamber, making even more headaches.

In an H2O2 engine, hydrogen peroxide is mixed at about a 10:1 ratio with kerosene in a feul tank. On ignition, the mixture is blasted into a cooling jacket around the engine and then into a catalyst pack. The catalyst pack splits the hydrogen peroxide into water and oxygen, liberating a lot of energy and heat, and the heat created by the reaction ignites the kerosene with the newly-created oxygen. And, that's it. No complicated turbopumps, bre-burners, etc. Instead of the complex network of pipes and plumbing that are engines like the SSMEs, H2O2 engines are increadibly simple.

The KISS principle does work. It's Occom's razor, the simplest course is the best and most likely to work, don't add epicycles. People will eventually realize that the best approach to a problem is with the least technology possible, not the most. Yes, we're stuck with the same fuels we had 50 years ago, but airplanes still use the same fuels they did back then. There are other ways to work around a problem then by waiting for new fuels to arrive. Do you really think that the Deltas and Atlases are the pinnacle of possible efficency at their $5,000 per pound to orbit price? Of that price, only a buck fifty (Less than a Big Mac) is the fuel. I suggest you get your facts straight.

RobertDyck · 2004-08-07 10:54:30

We do have magic metal that can support tons from a single thread; it's called carbon nano-fibre. We just haven't figured how to make fibres long enough to be useful, but researchers are working on it.

MAKS-OS as a space taxi? Great idea. The AN-225 has a cargo capacity of 275,000kg and the MAKS in any variation weighs exactly that much with fuel tank full. The 747-200F can lift 112,490kg and the 747-400QXLR Freighter can lift 112,810kg. The standard MAKS configuration could carry 2 cosmonauts and 7.0 tonnes to ISS, or an unmanned configuration could carry 8.2 tonnes to ISS. However, that doesn't include an airlock or docking adapter to permit cosmonauts to enter the station. The configuration for Transport Maintenance Service would include an airlock with docking port and optional passenger compartment. TMS-1 would carry 4 passengers for a total of 6 crew, while TMS-2 could carry no additional passengers and unpressurized cargo bay with 3.6 tonne capacity. Could that be scaled down to 4 astronauts and no cargo with a dorsal docking hatch and no airlock, and be small enough to fit on a 747? I think so.

I think the MAKS-OS unmanned configuration is silly. If you're going to launch unmanned, why not use MAKS-T that replaces the orbiter with an expendable upper stage that can lift 17.4 tonnes to ISS.

Designing a spacecraft is an engineering problem. For example, the Shuttle has a big orbiter so a 9.5% mass penalty for ISS orbit vs 185km @ 28.5° significantly reduces cargo capacity. After safety enhancements following Challenger, Shuttle could lift 24,400kg to 204km @ 28.5°. That would permit only 12,070kg to ISS without the upgrades. So we can achieve a lot by choosing appropriate alloys like lithium-aluminum, designing the vehicle be optimal for its mission, using air breathing engines whenever possible to eliminate carried oxygen, etc.

::Edit:: NASA has two 747 aircraft to transport Shuttle. Odd, Astronautix says one is a modified 747-100 and the other is a modified 747-100SR (Short Range). A kit builder says it's a 747-200, NASA web sites just call it a 747. According to Boeing the maximum takeoff weight for a 747-100 is 333,400kg, for 747-200 it's 374,850kg; but that isn't broken down into aircraft, fuel, and cargo. Either way it would be financially good to reuse the Shuttle service fleet.

A new craft based on MAKS could reduce tank weight by using lithium-aluminum alloy like the upgraded Shuttle ET. Either scale down RD-701 or use a single chamber version. SpaceShipOne uses a single engine. I'm sure Burt Rutan's knowledge of aircraft composites could be applied to reduce orbiter weight.

GCNRevenger · 2004-08-08 21:20:56

"There are set rules in the laws of the universe that can't be broken, but they can be used to their fullest."

But there is your problem right there! Sure you can knock a few percent of tank mass here, squeeze another second of impulse out of an engine there, but even with substantial reductions in vehicle dry mass, you still can't make the rocket an order of magnetude smaller, because the mass ratio is still largely dependant on the fuel which you can't change. Take the Delta-IV Medium for instance... did you know that the entire rocket empty mass, including its oversized LH tanks and heavy RS-68 engines, is only 30MT, of which 8MT is engines? I don't think its going to get much better than this, and high efficency rocket engines today are already flirting with 90% of the theoretical maximum energy content of rocket fuels.

For a modest payload, your rocket is always going to be BIG, no matter how hard you try or engineer... and since the more margins are pushed (CNT composit vs Aluminum vs Steel) or the larger you scale the vehivle, the more expensive the vehicle gets, so yes you ARE bound by the physics.

The reason I picked out the MAKS vehicle as a comparison to what Private Space has to come up with, is that they CAN'T do somthing like this, the investment required would be absurd because there would not be anywhere near enough money made to pay for it. And it really can't be made that much smaller, the Russians already did a fine job with it, and you need aproximatly that much payload to send up satelites. Burt & Co or anybody doesn't have a prayer of building somthing like this.

Don't even get me going about all the stuff Burt's puny toy would need to survive on orbit. The batteries for dark side and LSS alone would really bite into its mass budget, and its rocket though restartable, can't be restarted or shut down quickly and reliably since it is a solid rocket. Meaning, no accurate OMS burns... But more then that, Burt's rocket simply could not survive the trip, the whole concept of SS1 is increasing the wing drag on purpose to slow down from mid-supersonic speeds. Coming in at Mach-25, and the wings would rip clean off... Completly changing the wings, aerodynamics, structure strength, TPS, engines, fuselage size, LSS, power systems... It wouldn't be an "upgrade" or "derivitive" anymore. I don't think Burt can build a vehicle that would take it.

Oh, and did you know the Shuttle hatch is way way too small for payload racks? The only ISS hatch big enough is the US node module hatch, where the MPLM carried in the Shuttles' bay can connect guided via robot arm. So no, you can't just "dock to the Shuttle hatch," its not that easy.

On to rocket physics...

"hydrogen peroxide rockets can have much higher mass ratios because the propellants are far denser. So even though they don't have specific impulses as high as hydrogen engines, a given weight of peroxide mixed with a little kerosene actually contains more latent energy"

Iii don't think you are following... your mixing concepts all over the place, confusing theoretical mass ratio (which only concerns fuel mass and total vehicle dry mass) with practical mass ratio (the amount of fuel mass and the mass of the payload)... Density is only a concern of fuel volume where H2O2/RP1 does have a substantial advantage by weight, but I am pretty sure that LOX/LH2 contain quite a bit more energy by mass... The mass advantage of LOX/LH2 over H2O2/RP1 depends on how much Delta-V is called for, where with a small Delta the mass ratios of the H2O2/RP1 is close enough to LOX/LH2 that the extra structure of the larger fuel tanks does take away the LOX/LH2's dry mass advantage. For instance...

Wet/Dry ratios LOX/LH2 Isp: 460sec, H2O2/RP1 Isp: 319sec
Delta-V of 1.00km/s: 1.25 vs 1.38
Delta-V of 10.0km/s: 9.18 vs 24.5

The lower the ratio, the better, meaning you can have more dry rocket per pound of fuel, right? So, when you get to higher Delta-V (or when stage wet mass is vital), and since fuel tanks get lighter per volume as they get larger (and now moreso with the advent of composit fuel tanks or pressure stabilized structures etc) the extra Isp for LOX/LH2 really decimates the H2O2/RP1. Its also worth noting the USAF has tinkerd with Slush Hydrogen, which is about a third denser. So yes, H2O2/RP1 can have a better mass ratio for small Deltas (like the initial liftoff burn) but with the high Delta-V's needed for spaceflight the geometric decrease in the mass of fuel needed for Hydrogen, wins... And in some cases, like upper stages or interplanetary transfers, wins big time, making the cost of the more complex engines worthwhile.

I know full well how rocket engines work...oh, and since the catalyst packs probobly aren't made of materials that resist high temperatures, how do you intend to keep them cool without any cryogenic propellant? Uselessly low engine temperatures would doom this catalyst rocket real quick.

Liquid hydrogen has been adopted by almost everybody in the launch biz, the US (Apollo, Shuttle, Centaur, Delta-II & IV cores, DC-X/I), the Russians (Onega, Energia, Angara uppers), the Europeans (Ariane core and new uppers), even the Indians (cryogenic upper). They obviously aren't stupid, so LOX/RP1 must have some severe drawbacks to go to the extra trouble of using Hydrogen. Add aerospike engines, composit tanks, slushed hydrogen, and the practical mass ratio of Hydrogen gets way better too.

KISS superior my foot... And Occom's Razor is another great sound-bite thought experiment, but it isn't any enshrined golden path to truth by any stretch either. The best solution is NOT always the simplest, in fact it is often quite the opposite.

Mad Grad Student · 2004-08-08 21:55:18

Where do you get this stuff? I'm starting to wonder if there's even a problem about getting the science racks through the Russian ports, I've just been taking your word for it the whole time. One minute you say that the US docking nodes are the only way to get the stuff in, the next it's the Unity nodes.

Okay, so maybe we don't want to regeneratively cool H2O2 engines. So what? It's not like weither or not I slipped up in their description detracts from their value. Thanks for your calculations, they actually seem to prove my point. Let's throw out all the terms and jargon of rocketry for a second just to ensure that nothing is lost in translation. If the fuel tank you describe is filled with hydrogen peroxide It could orbit itself. If the fuel tank is filled with LOX/LH2 it would fall short of that. Remember that the Centaur has a mass ratio of 10 with LOX/LH2 but 40 with H2O2/RP-1. It's certainly possible to make SSTO work with hydrogen peroxide. Weither it can be done with LOX/LH2 is questionable, but most likely possible.

Because of the way winged vehicles come back from space the stresses exerted on spaceshipone actually wouldn't be too much greater coming out of orbit than they would be coming back from 100 kilometers. The g-forces are just traded for intense, firey heat. I think that it is certainly possible for private industry (Most likely Scaled Composites) to make orbit given a few years time, you're very skeptical of it. Time will tell who made the right bet.

GCNRevenger · 2004-08-08 22:07:42

No no, you don't understand Mad... the LOWER the ratio, the better, not higher. Thats mass wet devided by mass dry, just like it is in the natural log of the rocket equation. The Hydrogen rocket at Delta-V of 10kms is about 89% fuel, while the Peroxide/RP1 is about 96%. That is, the dry mass is about three times higher for the Hydrogen, which even if the stage mass is much higher then that of H2O2/RP1, Hydrogen still wins. An SSTO powerd by such lousy fuel as H2O2/RP1 is a non-starter, as your entire vehicle empty would have to weigh less than 4% of what it does fueled. Get it?

And if you don't regenerativly cool your peroxide rocket, then you are going to have a very hard time keeping it from getting so hot, the catalysts will melt or disintegrate... and if you can't run your engine at high temperature, your Isp gets even worse.

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