Gemini: We can rebuild it, we have the technology

[gunsandrockets]

"If I understand correctly the 'reuse' of the Falcon 1 first stage will be more like 'salvage' how will this compare to the Falcon V? "<br /><br />Elon Musk of SpaceX has stated an intention to win the Americas's Space Prize. Presumably the Falcon V will therefore comply with the rules of the competition.<br /><br />"Musk told Wired News that he intends to win America's Space Prize, and that he can do it by the Jan. 10, 2010, deadline (that's when Bigelow wants to open his commercial space station for business). The space prize is right in line with Musk's business plan. "We hope to be the company that takes people back and forth from Earth to either the International Space Station or to Bigelow's space station, or to applications we don't know about today," said Musk. Ultimately, though, his ambitions extend beyond even orbit. "I think it's very important that we become a spacefaring civilization, and that we eventually become multiplanetary."<br /><br />http://www.wired.com/news/space/0,2697,66308,00.html<br />

 

[ve7rkt]

An idea I had before finding this thread was that the capsule would have batteries for just a couple days operation, and heaters/coolers to keep the capsule ready for immediate launch would be run from a power feed from the station. If the station couldn't supply that power, then there could be a docking tunnel permanently attached to the station for the express purpose of having a place to mount a solar panel wing dedicated to keeping the capsule charged.<br /><br />As for flying in a shirtsleeve environment, Soyuz 11 returned to Earth from its lengthy space station mission, the capsule was opened up, and the crew had died. A valve let go of the cabin pressure during reentry. From that point on, cosmonauts were suited up on all flights, even though that meant for most of the 1970's -- until they could shrink other systems to make room again -- they could only fit two men aboard. I'm in favour of full pressure launch/entry suits. They don't have to be real space suits (no need for six inches of hard plates to protect against debris, etc.) but air = good.

 

[mrmorris]

<font color="yellow">"Do fuel cells develop problems when sitting around for months? Perhaps the hydrogen fuel slowly leaks away? Can't have that. "</font><br /><br />Long-term storage of hydrogen is indeed an issue. To provide for the most compact and lowest-mass storage -- cryogenics are best -- but are also the worst option for long-term storage (of course). A discussion on the problems of hydrogen storage (although not specific to space-applications) can be found here. With the talk of shifting to a hydrogen-based economy, big R&D bucks are being spent on developing and improving storage technologies.<br /><br />There's also the oxygen storage to consider -- whether a fuel-cell is used or not. The craft can use either supercritical storage like Mercury, or LOX storage like Gemini/Apollo (I don't know what Soyuz uses -- or the Shuttle for that matter). If it uses LOX -- similar long-term issues exist as with hydrogen.<br /><br />I don't really expect a fuel cell to be advisable at all. I eliminated it early in the thread because the flight durations were so short that batteries obviously were the superior option. I re-introduced the possibility when I was talking about the RWRCS. However, I have grave doubts about utility of the RWRCS -- mainly I liked exploring it as an outre concept.<br /><br />Right now I have a nominal power usage of ~150 watts for G-X3. I've found COTS Lithium-ion batteries with densities of ~110 Watt-hours/kg. Given a worst-case normal mission scenario of two days from launch to dock and six hours from undock to ground, there's 8,100 Watt-hours required, for a battery mass of ~73kg. I really <b>expect</b> the craft to have a mission scenario of <=16 hours from launch to dock, and fourhours from undock to ground. This would be 3,000 Watt-hours and a battery mass of 27 kg. I've been budgeting 64kg for the batteries to have a reasonable exce

 

[nacnud]

I agree with the Li-ion aproach but it might be worth keeping an eye on methanol fuel cells as they have less issues with fuel storage, especialy if a LOX methanol RCS were to be used.

 

[mrmorris]

<font color="yellow">"They don't have to be real space suits (no need for six inches of hard plates to protect against debris, etc.) but air = good. "</font><br /><br />Suits -- whether EVA-capable or simplistic ones like are used in Soyuz flights, are a pain in mass and space-restricted craft. I've envisioned something more along the lines of a flight suit and/or helmet similar to what fighter pilots use minus the 'combat' aspects (i.e. Bio/Nuke/Chem protection, high-G bladders, etc). This would prevent a tragedy like that of the Soyuz flight. It wouldn't save the crew from a long-term exposure to vacuum -- however, if things get that bad... it's unlikely <b>anything</b> will.

 

[nacnud]

How would you stop the suits expanding in low pressures? The suits we have may not be perfect but they are good, and necessary for some abort modes. Suits for launch and re-entry are needed for a while yet IMO. Don't ignore Soyuz 11 and Challenger.

 

[ve7rkt]

<font color="yellow">This would prevent a tragedy like that of the Soyuz flight.</font><br /><br />Would it? Soyuz 11 depressurized way up high; that valve opened at 168km, and the crew was likely dead about 30 seconds later (source). A fighter pilot's helmet would not keep someone alive in a vacuum. A full pressure suit would.<br /><br />Yep, it's bulky, even simple ones (Soyuz' SOKOL, modern Shuttle's ACES), and it seems pretty odd that something could go just wrong enough to be a critical problem for the crew, but not wrong enough to destroy the vehicle; seems to me anything that should go bad, goes really bad. But of all the ways people could die in the course of spaceflight, this is one of the few ways that people actually have.

 

[rancamp]

mrmorris:<br /> />Suits -- whether EVA-capable or simplistic ones like are<br /> />used in Soyuz flights, are a pain in mass and space-<br /> />estricted craft. I've envisioned something more along<br /> />the lines of a flight suit and/or helmet similar to what<br /> />fighter pilots use minus the 'combat' aspects (i.e. <br /> />Bio/Nuke/Chem protection, high-G bladders, etc). This<br /> />would prevent a tragedy like that of the Soyuz flight. It<br /> />wouldn't save the crew from a long-term exposure to<br /> />vacuum -- however, if things get that bad... it's unlikely<br /> />anything will.<br /><br />Google search keyword(s) Mechanical Counter-Pressure Spacesuit, Space Activity Suit, BioSuit..<br /><br />We've actually had the ability to produce perfectly acceptable space suits for little more than we produce standard clothing items for decades. Just no one has done the 'leg'work to get it done. Fits all your criteria, using a tube and capstan system for hard vacuum the passengers can not only survive, but you can put the cost of the suit towards it being thier 'sovineer' of the trip.<br /><br />Randy

 

[rancamp]

mrmorris:<br /> />I was indeed visualizing things differently than you --<br /> />at least inasmuch as what I visualized didn't look<br /> />anything like that. Unfortunately -- the diagram<br /> />doesn't do much for me in terms of figuring out what<br /> />you're thinking, or where docking takes place, etc.<br /><br />I've not found a 'good' pic of the G-X3 with the nose docking adapter (to size) so I'm guessing here. If anyone has one, I can do some drawing to add the nozzels and see how it turns out.<br /><br />Randy

 

[nacnud]

Obviously I’m not mrmorris but I’m still visualising the GX-3 as being very similar to the BAe Multi-Role Recovery Capsule

 

[gunsandrockets]

"In (3) we learn that the crew noticed a leak immediately, probably from the hissing noise it generated, rushed to the front hatch thinking that this earlier problem was related to the sound. To locate the source of the noise the crew turned off all radios. They probably located the leaking valve under one of the seats and tried to close it manually. All this must have happened very quickly, possibly in less than 20 seconds because that is how long the crew would have remained capable of work after the start of the leak. Two minutes after the start of the leak the pressure had dropped to zero and the crew were dead. In (3) we also learn that the valve in question was not a pressure equalization valve but a fresh air valve to be opened after landing"<br /><br />According to the description of the Soyuz 11 disaster, the crew were still conscious 20 seconds after the leak started and the cabin took 2 minutes to reach zero pressure. If the crew had working oxygen masks, even without pressure suits, it's possible the crew could have found the leak and plugged it quickly enough to save themselves.<br /><br />Space flight is dangerous and reasonable risks are acceptable. Of all the spaceflight deaths I think the Soyuz 11 is the only case where pressure suits would have made a difference.

 

[mrmorris]

Yes -- the BAe capsule is the probably the closest to what I'd envision as well -- essentially an Apollo shape with a docking ring on the front. The exact dimensions of both the capsule and docking ring are indeterminate, so I can't produce a picture of <b>exactly</b> where/how the 'cone' would end and the 'cylinder' of the docking ring would start -- but that's a reasonable approximation.

 

[mrmorris]

<font color="yellow">"As a starting point I begin with a scaled up Gemini style RM outline, configuration and structure because the Gemini was the most efficient manned LEO vehicle ever made. The Apollo CM has a higher than needed lift to drag (neccessary for return from the moon) and an ablative coated forebody which is heavier than the hot shingle construction of the Gemini RM forebody. "</font><br /><br />I have nothing against the Gemini (obviously... I started out with it for the same reasons). However -- the only real 'downside' to the Apollo CM vs the Gemini RM is the mass. However, it must be taken into account that this is the mass <b>only</b> of the 1960's versions of the two craft. There are numerous factors that will shrink or possibly even eliminate the mass difference between the two once the base shape is fleshed out with 'the rest of the spacecraft'. The ablative forebody you already mentioned. An ASP-CM would not use this, but instead would likely use thermal blankets -- I've already suggested TABI or DuraFRSI (this would be even lighter than the Rene-41 shingles of the Gemini). In addition, the rear-ablative was thicker and heavier than would be required for an ASP/LEO version. The Apollo had several subsystems that were not present in the Gemini -- the subsystems for an ASP craft would be identical, regardless of base shape. The Apollo had docking capability -- an ASP-Gemini craft would have to add the mass of a docking system. The Apollo CM is already large enough for a crew of five -- especially with the volume reductions of modern electronics. The Gemini RM would have to be scaled up -- making its mass significantly closer to that of the CM (the AM and EM modules of Gemini were shells, with much less structural integrity than the RM -- plus no mass from a pressure vessel, of course).<br /><br />Once all this ios tallied up, you'll find the two shapes have much less difference than the mass of the originals would suggest. Once

 

[rancamp]

nacnud:<br /> />Obviously I’m not mrmorris but I’m still visualising the<br /> />GX-3 as being very similar to the BAe Multi-Role<br /> />Recovery Capsule<br /><br />Actually that was what I was picturing from the last few threads... the problem is I need a 'plan' (3-view) of the vehicle to see if the nose deorbit thrusters are possible.<br />I'd see them mounted below the docking coller as part of it.<br /><br />Randy

 

[gunsandrockets]

Very interesting. The MRC is a much better starting point for ASP than Apollo. This capsule is even intended to be reusable. <br /><br />Odds are the MRC has a rocket tower launch escape system combined with a launch shroud that covers the nose of the reentry module, shielding the docking mechanism and hatch during ascent. I doubt the LES is reused.<br /><br />The reentry module has a very generous docking hatch but only 6 cubic meters of living space. That's pretty cramped for 6 people. A Soyuz reentry module holds 3 people and has 4 cubic meters of space. I imagine the MRC is not intended to house it's crew in pressure suits. <br /><br />And where is the main engine located? According to the stats the reentry module has that engine, so where is it? On the blind side of the reentry module's nose?<br /><br />The service module is very small. So small it's main justification seems to be a mount for the solar power system. And why does it have a heat shield? Strange.<br />

 

[nacnud]

If anyone out there has access to a decent library it might be worth looking up the reference given in the astronautix entry for the MRC<br /><br />Hempsell, C M and Hannigan, R J, Journal of the British Interplanetary Society, "Multi-Role Capsule System Description", 1989, Volume 42, page 67. <br />

 

[mrmorris]

<font color="yellow">"...might be worth looking up the reference ..."</font><br /><br />As meticulous as Mark is -- I seriously doubt there's any meat in the article that he left out. Best case is that it would list <b>another</b> reference for its data which might have more. <br /><br />*edit* I emailed the British Interplanetary Society and asked about the possibility of getting a reprint of that edition, or a photocopy of the article, or just a list of the references used to compile it.

 

[nacnud]

Cool, I'll be interested to see what they turn up.

 

[mrmorris]

Interesting. I was just reading the Block II Apollo Operations handbook. I'm going over the first section where it's describing the various elements of the spacecraft. One quote that jumped out at me was:<br /><br /><i>"The interior volume is 366 cubic feet. However, the lower, right, and left equipment bays lockers, counches, and crewman occupy 156 cubic feet, leaving a usable volume of 210 cubic feet."</i><br /><br />I've been using the figure com Astronautix for the CM which is: <b>Habitable Volume: 6.17 m3</b>. The rough calculation in my head didn't match (I remembered to mentally carry the one this time), so I used a conversion calculator to convert the handbook figures to metric:<br /><br />366 ft3 = 10.36 m3<br />210 ft3 = 5.95 m3<br /><br />Soooo -- what you generally would consider to be 'interior volume' is actually about 33% less than what I have been working with. The question then becomes how much space will be freed up by reductions due to new tech and different mission requirements, and how much additional volume will be taken up by two more crewman. <br /><br />Answering the second part first, we can approximate the volume of the astronauts by calculating the volume of an equivalent amount of water (the human body is just under the density of water... ergo we float... but barely). The density of water is 1g/cm3 and we'll take the average weight of a single astronaut at 75kg. this yields 225kg for three crewman or 225,000 cm3 (0.225 m3). Therefore of the 156 cubic feet mentioned above -- only about 8 cubic feet was the volume of the crewmembers.<br /><br />To provide the same amount of open volume per crewmember as existed for Apollo, the ~6 m3 would have to be increased by 5/3. This yields 10 m3, which is obviously unattainable as the *entire* pressurized volume is only 10.36 m3. However, G-X3 is also a much shorter-duration craft than Apollo, and so this level of space isn't required. The massive reduction of volume required for electronics, plus t

 

[gunsandrockets]

I might be able to find the JBIS article on the MRC tomorrow at the local reference library. But in the meantime I found some chatter in the newsgroups about the MRC.<br /><br />"Multi-Role" comes from the intention to use the capsule in several different roles: for month long unmanned scientific missions such as microgravity experiments, for 4 man missions lasting up to 5 days and carrying up to 500 Kg of cargo, and as a Space Station lifeboat carrying up to six people.

 

[gunsandrockets]

" There are numerous factors that will shrink or possibly even eliminate the mass difference between the two once the base shape is fleshed out with 'the rest of the spacecraft'...<br /><br />...Once all this ios tallied up, you'll find the two shapes have much less difference than the mass of the originals would suggest."<br /><br />I disagree. The titanium structure of the Gemini is superior to the stainless steel honeycomb structure of the Apollo. <br /><br />"The Gemini RM would have to be scaled up -- making its mass significantly closer to that of the CM "<br /><br />Big Gemini is the only example of a scaled up Gemini I could find. With a Reentry Vehicle (RV) mass comparable to an Apollo CM it has three times as much room inside and can carry three times as many people.<br /><br />http://www.astronautix.com/craft/bigemini.htm <br /><br /><br />"The ablative forebody you already mentioned. An ASP-CM would not use this, but instead would likely use thermal blankets -- I've already suggested TABI or DuraFRSI (this would be even lighter than the Rene-41 shingles of the Gemini)."<br /><br />The shingles on the Gemini were more than just a surface layer of temperature resistant materiel such as ceramic tile, they formed the aerodynamic load bearing outer skin of the Gemini spacecraft. Thermal blankets may have advantages over ceramic tile, but it also has serious limitations compared to other types of TPS...<br /><br />http://64.233.187.104/search?q=cache:9fM9l02s86QJ:amptiac.alionscience.com/pdf/2000MaterialEase11.pdf+DuraFRSI+test&hl=en&ie=UTF-8<br /><br />"Blanket insulationis -- typically a low density, low thermal conductivity mate-<br />rial made of high purity silica, high-purity alumina fibers, or some combi-<br />nation of the tw

 

[mrmorris]

<font color="yellow">"I disagree. "</font><br /><br />Always your prerogative. I don't feel any burning need to convince you. However -- arguing against the Apollo CM shape based only on the specific metal used in the construction of the original doesn't really hold much weight. The honeycomb structure was used largely to provide additional insulative capability against the heat of re-entry and the use of thermal blankets will reduce or eliminate the need for this.<br /><br /><font color="yellow">"With a Reentry Vehicle (RV) mass comparable to an Apollo CM it has three times as much room inside and can carry three times as many people."</font><br /><br />BG has been linked to this thread so many times it has stopped being funny. You'll note that the mass being compared against the Apollo CM is one with essentially no subsystems. Comparing the mass of the two without noting the vast gap in capabilities is not really kosher.<br /><br /><font color="yellow">"Thermal blankets may have advantages over ceramic tile, but it also has serious limitations compared to other types of TPS..."</font><br /><br />The serious limitations being... what? I foresee the CM being constructed of an AL or Ti framework and outer hull, with the blankets bonded directly to the outer hull. The waterproofing is a significant issue with something the size of the shuttle, but pretty much an afterthought with something the size of an SUV. Meanwhile -- it has ridiculously low installation and maintenance costs, has been shown to be an extremely robust reusable TPS by the shuttle orbiters and provides both thermal protection and insulation.

 

[rancamp]

mrmorris:<br />We may have already touched on this in the past, but I recall we were bouncing ideas around for slowing down the vehicle landing speed.<br />(Wow, 51 pages of messages and still going)<br /><br />I recall when my Uncle was a paratrooper back in the 60s, they almost always 'deployed' with thier gear bags. They jumped out at 300 feet with auto-pull chutes that were sized for fast drop. (For minimum dispersment)<br /><br />At around 100-50 feet up they released the bag on a line. It fell hitting the ground first which slowed the person down a lot. (If you didn't release the bag you were sure to break your legs... at the very least)<br /><br />We could do this with the heatshield and it's support structure. Gas operated internal clamps and springs would seperate the heatshield at somewhere around 500+ feet on a long cable. That would give somewhere to deploy airbags/floatation devices from also.<br /><br />Of course we'd design the vehicle so that the passengers would survive a landing without releasing the shield, but I think we were already doing that.<br /><br />Randy

 

[nacnud]

That's how the Soyuz works. The impact mitigation rockets are hidden behind the heat shield which is jettisoned at a low altitude.

 

[mrmorris]

<font color="yellow">"At around 100-50 feet up they released the bag on a line. It fell hitting the ground first which slowed the person down a lot. (If you didn't release the bag you were sure to break your legs... at the very least) "</font><br /><br />While a variant of this device using the heat shield would reduce descent speed somewhat -- the benefit would be nowhere close to what is achieved for the paratroopers. Terminal velocity is a function of the mass being dropped and the area of the parachute (plus outside factors like pressure, etc.) Since the rucksack isn't <b>accelerated</b> downward (i.e. giving the paratrooper an upward push), the only thing that is slowing the terminal velocity is a reduction in the mass being slowed by the chute.<br /><br />A rucksack such as a paratrooper would have might be on the order of 60-80 pounds. With the weight of the paratrooper being on the order of 180 pounds -- this means the rucksack is ~1/3 of their body mass (reducing the overall mass being descended by ~25%). This would not only have a significant effect on the terminal velocity but also means that the paratroopers ankles/legs/knees don't have to account for another 60 pounds being supported by the trooper's shoulders & back on impact. <br /><br />The heat shield for the spacecraft is a <b>much</b> smaller fraction of the weight -- on the order of 3-5% as I've calculated it. Dropping it would slow the terminal velocity a bit, but not hugely. Besides that -- unlike a ruck -- the mass of the heat shield is at the bottom of the craft, and won't transmit additional shock downward on the supporting structure below it. In fact, by making a heat shield and supporting structure which crumples -- much of the impact can be absorbed/redirected as noise and heat as the shield bends. The Apollo CM had a crumple zone at the base to perform this function.