Gemini: We can rebuild it, we have the technology

[cdr6]

I used the MOL as reference only for dimensional purposes, it was part and parcle to the Gemini legened, sort of speak, and I thought it would trigger a size image in everyone's mind. Of course the interior would be "civilian-ized" as the original was intended as a military recon vehicle. <br /><br />MOL had its own rcs and propulshion systems, abet somewhat less capable than is possible today. Further by using the "tug" concept a pilot could do his or her own flights/missions. Not unlike the agena was envisioned for the original. <br /><br />Reading some of the posts here, I sort of get the impression that the aim is more or less toward designing the "Cessna of Space" simple, easy to fly, and cheap to keep. I think given the advanced state of avionics and computers today the New Gemini could easily be a single pilot spacecraft.<br /><br />Imagine the thrill of piloting a spacecraft to certian point in space. And see something oh lets say like Hubble hanging there in space a short distance out your window. <br /><br />It's simply a case of "This is what we've got. Now what can we do with what we've got?"

 

[mikejz]

<font color="yellow">Imagine the thrill of piloting a spacecraft to certian point in space. And see something oh lets say like Hubble hanging there in space a short distance out your window. </font><br /><br />Someone screaming in Hubble control "Get out of the way you idiot...your blocking my view!"

 

[grooble]

Yeah, tiny 1 man craft would be cool. Imagine if it was like the PC gaming industry, where u could swap out old hardware and install new and improved components - new avionics, thrusters, computers. <br /><br />It'd be a hobby for the rich thrill seekers, but if they ever get launch costs to like $1/lb you could have 1000s, 10,000s of folks in little pods doin stuff.<br /><br />Its good to dream.

 

[mrmorris]

<font color="yellow">"Here again you run up against the same problems that have hobbled Shuttle, if you try to make it do too much it does nothing well and the weight grows with every additional capability added. " </font><br /><br />Dang! I've always realized that the Gemini was a heckuva lot smaller than the shuttle. But I really didn't quite grasp <b>how much</b> smaller until I made a scale diagram of the two...<br /><br />It's no wonder the shuttle costs so much to get into orbit.<br /><br />

 

[scottb50]

If you go back and look at some of the early Shuttle designs it ballooned dramatically. <div class="Discussion_UserSignature"> </div>

 

[scottb50]

How about this: <div class="Discussion_UserSignature"> </div>

 

[arobie]

mrmorris,<br /><br />This is a great thread! I have been reading it, but not posting in it. I really have had nothing of use to put into it. I just don't have enough knowledge of the subject matter to input anything constructive.<br /><br />Well, I love the idea. Everything is working out very neatly. I want to ask if you could complile the changes that you have made to the initial idea and the information that you have gained from this brainstorming exercise and compose a post adding it all to your design. A post with all the updated weights, designs & plans for the capsule itself, and even the computer system that you have decided upon into one nice, neat post. <br /><br />This would make it easier for me to review your plan, and to remind myself of anything if I can't remember instead of searching through this entire thread to find it again. This thread has grown long with all the new ideas and brainstorming that is occuring. It would be easier to have a reference post to look at for info on your design as you have it now.

 

[grooble]

Scott, that is EXACTLY what i had in mind for a 1 man pod. For the operator to essentially become 1 with the machine. My idea would be with the operator completely enclosed and he can see outside via cameras, he would wear video goggles. I think that may be an advantage of zero g, there is no up or down, whether he was watching the forward cam video or back cam video, it'd always be "in front". I also agree with the gloves thing.<br /><br />Engineering pods would be great for space construction and repairs.

 

[scottb50]

My idea is to basically replace a Space Suit with a self propelled Pod that can do what a Space Suited Astronaut can do along with other options.<br /><br />Another version would do away with the arms and RMS and serve as a private sleeping area and escape vehicle if a problem occurs. Climb in close the hatch and go to sleep, if anything happens you're protected and can undock and move off. <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

<font color="yellow">"A post with all the updated weights, designs & plans for the capsule itself, and even the computer system that you have decided upon into one nice, neat post. "</font><br /><br />Well "decided on' is a wee bit strong of a term, as I'm not actually building said capsule. I checked the cushions in both of my couches at home, but didn't manage to locate a few tens of millions of dollars to begin funding such a project. In addition, I haven't *decided* on the final form of even the virtual craft residing somewhere between my ears. I'm continuing to research the possibilities for this concept in particular, and I also want to expand my general knowedge of spaceship design by picking up a little light reading on the subject, including:<br /><br />Griffin, M. D., French, J. R. "Space Vehicle Design", AIAA Pub., Washington DC, 1991.<br /><br />Kane, T. R., Likins, P. W., Levinson, D. A., "Spacecraft Dynamics", McGraw-Hill Book Co., New York, 1983.<br /><br />Pisacane, V. L., Moore, R. C. "Fundamentals of Space Systems", Oxford University Press, New York, 1994.<br /><br />I'm also searching through patents filed on spacecraft to see what research has been done by others with more experience than myself (I'm just a computer nerd with a space hobby). Patent 5,064,151 is interesting. I don't doubt that I'll find several others. You can do a full text search for patents here.<br /><br />I am gathering all of the data I'm locating through my research into the possible design elements and subsystems for Gemini-3X. However -- it shares more in common with a loose assemblage of post-it notes than a coherent report at the moment. I'll try to come up with a quickie listing of my base assumptions in the next couple of days.<br /><br />

 

[arobie]

I checked my sofa also for you, I almost came up with enough. I found a total of 17 cents. <img src="/images/icons/wink.gif" /><br /><br />Wow, those books are pretty big...and expensive. Good luck with your 'light reading'. <img src="/images/icons/smile.gif" /> <br /><br />Looking forward to future posts about this idea.

 

[mrmorris]

I've been doing some research on what kind of communications capability must (can) be built into the X3 to make it functional. Direct ship-to-ground signalling isn't practical for orbital craft as a sole means of communication due to line-of-sight issues. NASA has antennas worldwide to handle their S-Band communication, but a private firm can't <b>rely</b> on being able to use this at will. <br /><br />However -- I recently ran across a suggested upgrade to the shuttle orbiter system that should be able to fill the bill nicely. Boeing has tried to get the orbiter fleet to upgrade to a Ku-band phased array antenna to replace their existing deployed-antenna Ku-band system and potentially the functionality of the S-Band system as well. The phased-array antenna allows a fast-moving object to focus on a communications satellite in GEO and provides high-bandwidth communications (~75MBs). <br /><br />Boeing uses this technology in their Connexion service for commercial aircraft to provide high-BW internet access to planes in flight. Gemini-X3 could use essentially the same system to gain an internet connection while in flight. This would grant multiple capabilities to the X3:<br /><br />- Real-time upload of information from ground-based computers. This could supplement on-board processing and increase accuracy of burns, etc.<br />- Real-time download of telemetry, on-board audio, video, etc.<br />- Voice-over-IP (i.e. telephone access) while the Gemini is in orbit ("Hi, Mom -- I'm an astronaut."). <br />- Secure communications. Communications from ground control to the Gemini-X3 can make use of secure servers and 128-bit encryption.<br /><br />Having the internet access on Gemini also opens up lots of marketing possibilities. I see marketing bucks being used to pay back some (or most -- or all) of the R&D money.<br /><br />- Vonage (or another such firm) could be tagged to be a multimillion dollar sponser for the voice-over-IP. <br />- They could tag GoldenPalace.COM.

 

[mikejz]

I'm not sure we even need to get that fancy for communications. After all basically, we need a data and voice link---nothing we can't borrow from Ham radio satellite technology. You data rate requirements are not huge (under 19,200bps should do the job) as you don't have a great deal of subsystems to monitor. You should simply launch a couple of small relay satellites to GTO that would serve as the basic data link---or even just have ham radio operatiors around the world link up on the internet to form a massive ground-tracking system. <br /><br />Or Plan-B. Why not just use a couple of Iridium phones?

 

[mrmorris]

<font color="yellow">"You should simply launch a couple of small relay satellites to GTO that would serve as the basic data link</font><br /><br />Spending a couple hundred million launching three geosynch satellites (the minimum for guaranteed global coverage on an orbiting object) is better than renting bandwidth from an existing satellite system? Also, you still need a means of communicating with them -- which is going to be something along the lines of a phased array antenna as I suggested.<br /><br /><font color="yellow">"---or even just have ham radio operatiors around the world link up on the internet to form a massive ground-tracking system. "</font><br /><br />Communications with a manned orbiting spacecraft is just a wee bit critical. This should be placed <b>by design</b> into something as kludgey as a network of ham radio operators?!? <br /><br /><font color="yellow">"Or Plan-B. Why not just use a couple of Iridium phones?"</font><br /><br />1. Obviously you've never used one of these if you're of the opinion that they are reliable. Several directors at my company got them at one point and no one kept theirs for more than three months before dumping it. <br /><br />2. The Iridium network was never made for something moving at these speeds. It's **extremely** unlikely that one of the handsets could aquire and hold a link to one of the satellites for long enough to have a conversation.<br /><br /><br />I don't understand why you consider my solution 'fancy'. It uses an existing technology, and existing satellites. It gets high-powered <b>results</b> from this -- but that's not due to anything particularly complex or dificult about the method being used to obtain them.<br /><br />19.2 won't allow for video transmissions to the ground. You can consider this extraneous if you'd like, but there are numerous possibilities if it's available. It would be extremely useful to be able to send real-time video to the ground (like video feeds

 

[mikejz]

I’m sorry I was speaking in a more tong-and-cheek approach, not exactly meaning to be taken seriously. However I do stand by the communications satellite idea. I’m not talking about massive communications satellite, but instead something along the lines of microsats, after all relaying voice and low speed data is a drop in bucket compared to what tradition comsats handle—Basically Orbcomms in a higher orbit. Video is important, however I was under the impression was that this subject was more along the lines of making things as simple as possible, If they really wanted live video they can use wait until the spacecraft passes over a continent and use a few tracking stations.

 

[grooble]

Have you rebuilt it yet morris? Show us some pics.

 

[mrmorris]

<font color="yellow">"however I was under the impression was that this subject was more along the lines of making things as simple as possible, If they really wanted live video they can use wait until the spacecraft passes over a continent and use a few tracking stations. "</font><br /><br />Simplicity *is* king. I truly don't see where you're getting the impression there's something complex here. Boeing already has its Connexion service that I'm <i>reasonably</i> confident would work with Gemini-X3. It gives broadband internet -- which gives the global communication I was looking for (i.e. one that doesn't require the firm building this craft to build up a global infrastructure). It was only afterwards that I thought -- "Hey -- broadband internet -- what <b>other</b> capabilities does this provide them?" Once you have BBI -- adding one or more webcams to Gemini-X3 is simplicity itself. Actually -- one of the benefits Boeing touts about Connexion is the ability for executives to engage in videoconferencing while in flight. With a multi-Megabit connection to the internet -- all kinds of data transfer possibilities become possible between ground and spaceship. These come as essentially 'free' extras above and beyond the need for uninterrupted ship-to-ground communication that the internet connection fulfills.<br /><br /><font color="yellow">"...spacecraft passes over a continent and use a few tracking stations."</font><br /><br />But that's the <b>point</b>!. This isn't NASA or some government doing it. It's (in my head) Blue Origin/SpaceX/Whoever. They don't own tracking stations on multiple continents. They shouldn't need to (or plan to) rely on the goodwill of someone that does. They don't need to (or want to) pay through the nose to use someone else's hardware. The space-based/Connexion Internet connection bypasses the need for them to own/control <b>anything</b> on the ground except a connection to the internet. This seems to be bot

 

[mikejz]

Different Idea set: If the entire goal of the G-X3 is to dock with a space station, why not keep most of the communications gear on the station. Minimal communications would be used prior to where the capsule gets within Line-of-sight of the station, after which the station would serve as a rely to the Boeing system you talked about. After all, I am willing to bet very seriously that good ole' wifi network adapters could be modded to serve as a data link between the two-- And I am not kidding! <br /><br />On the issue of tracking stations: While I understand your concerns it in many ways depends on how it is implimented. For example, lets assume that the communcations will be to LEO on UHF, such a tracking station would be very simple, and in all odds you could find schools that would be willing to partner with you to help run it.

 

[mrmorris]

<font color="yellow">"Have you rebuilt it yet morris? "</font><br /><br />I have a preliminary diagram I made to see if a pressure vessel (henceforth PV) large enough for six people would fit within the exterior dimensions of the original Gemini and still leave room for propellent, oxidizer and ECS. The answer is 'probably'. The diagram is attached below. The dimensions of the pressure vessel are built around those of the Cessna Citation-Mustang executive jet. <br /><br />In this diagram -- I've minimized the size of the PV to provide the maximum space possible at the sides for propellant, ECS, etc. Below the PV -- I have four 24" diameter spheres and two 18" diameter spheres, plus room for another 3-5 18" diameter ones. All of the electronics, power supplies, etc. will be placed in the foremost portion of the PV. <br /><br />However -- I'm working at the moment on a significant redesign. There are several things that I think would improve the design.<br /><br />1. I <b>really</b> want the docking adapter to be on the front of the capsule. This will involve a considerable movement of subsystems and abandoning the 'exact' Gemini capsule shape. Not too worried about abandining the exact shape -- I've been using it primarily as a known mass value. So long as I keep the changed shape in the same basic range -- it matters little that the exact dimensions no longer match. In particular -- the diameter of the elongated nose has to be increased.<br />2. I'd like the PV to extend all the way to the sides. I'm considering several ways to make better use of the space. I would expect the seats to fan out to the sides in a 'V' as the capsule widens, and the 'walkway' between the seats would actually be raised (much like the driveshaft 'hump' in a rear-wheel drive car). Unlike an aircraft, there's going to be no 'walking' done in the X3. In this space I can see the ECS being placed. At that point -- all of the space outside the PV below the seats can be used f

 

[mrmorris]

<font color="yellow">"...why not keep most of the communications gear on the station. Minimal communications would be used prior to where the capsule gets within Line-of-sight of the station, after which the station would serve as a rely..."</font><br /><br />Because the X3 needs to be able to communicate with the ground from launch to docking. The <b>most important</b> times for communication are UNTIL it's in sight of the station. Its at this time that the critical burns that move the capsule toward an object they can't see will occur. These burns determine how much propellant gets used and how fast the operation occurs. On X3 -- to minimize ECS requirements -- the burn accuracy is very important. Ground-based tracking telemetry results, and uplinked commands can optimize this -- but only if there is a good communication link with the spacecraft.<br /><br /><font color="yellow">"After all, I am willing to bet very seriously that good ole' wifi network adapters could be modded to serve as a data link between the two-- And I am not kidding! "</font><br /><br />I'm willing to bet very seriously that you have no idea how short the range is on WiFi adapters. You'd have better luck using two tin cans and some string for a transatlantic phone call.<br /><br /><font color="yellow">"For example, lets assume that the communcations will be to LEO on UHF, such a tracking station would be very simple, and in all odds you could find schools that would be willing to partner with you to help run it. "</font><br /><br />And if this were a payload containing some student experiments -- maybe some carrot seeds and a few white mice -- that would be great. However -- this is a manned spacecraft and the communications link is critical. If things go wrong in orbit -- people tend to die. You don't cut corners here.

 

[arobie]

<font color="yellow">I need to calculate how much LOX/Ethanol is required to generate the Delta-Vs required for this craft.</font><br /><br />How much Delta-V will G-X3 need?

 

[mikejz]

I guess your right for the most part. The only issue I can think of is if the RCS system failed or the spacecraft where in an orentation where the only way to communicate would be via an Omni-directional antenna. <br /><br /><br />That said you really should look into the potential of WiFi, People have managed to get ranges of up to several 100 miles on a few watts of power. Maybe not for space...hehe...but its really neat

 

[mrmorris]

<font color="yellow">"How much Delta-V will G-X3 need? "</font><br /><br />Yeppers -- gots to come up with a figure on that too. The original Gemini had 101 m/s from the SRBs, and 222 m/s on the RCS system for a total of 323 m/s. The Endeavor has 700 m/s of dv. The closest craft to the purpose we intend G-X3 is the Soyuz TMA. It has 390 m/s of dv according to Astronautix. That's probably the closest figure to what we need. However -- it leaves us with a number of questions on how relevant the number is.<br /><br /><br />Is that reaching for a craft of this nature? Probably a bit, since it takes quite some time to match orbits (the Soyuz take an energy-efficient route to minimize burns). On the one hand, the G-X3 needs to get there faster. On the other, presumably it would be launching from a better inclination to reach the ISS/BSS.<br /><br />Also, as with the Gemini, the SRB deorbit boosters would also be providing a good portion of the required dv for the X3 (the Soyuz uses its hydrazine thrusters to provide retrograde thrust). <br /><br />How closely does the Soyuz (rocket) get the Soyuz (TMA) to the required orbit to match velocities with ISS? Does the TMA have to expend a lot of propellant raising the height of the orbit? If the Falcon-V second stage can get the G-X3 to a closer altitude/velocity -- the OMS will be used primarily for matching orbits -- rather than for raising the orbit. During the retrograde phase -- the SRBs will provide the majority of the thrust, with the RCS/OMS used to provide steering and fine-tuning of the retrograde thrust. Therefore -- the G-X3 <b>might</b> need a very small amount of dv from the LOX/Ethanol system. Best not to bet the farm on it, though.<br /><br />The end answer is 'heckifIknow'. However -- you could consider 390 m/s as an absolute upper limit for the LOX/Ethanol RCS/OMS subsystem. A more likely figure would probably be 150 m/s provided by the SRBs and 200-300 m/s provided by the LOX/Ethanol syste

 

[arobie]

Ok, I did some research on the Soyuz so we have something by which to have a basis on figuring out propellant needs.<br /><br />Soyuz<br /><br />Propellant Mass = 900 kg (About 150 kg of propellant is used for rendezvous/docking, and about 200/400 kg is used for Earth return.)<br />The 900 kg of propellant feeds both the Main Engine and the AOCS thrusters.<br />Isp = 305 sec<br />Launch Mass = 7,070 kg<br />Docking Mass = 6,790 kg <br /><br />After finding this data, I wanted to figure out how much dV the Soyuz goes through for rendezvous and docking.<br /><br />I used this equation and rearranged it to solve for dV:<br /><br />mass fraction = e ^ ( dV / Ve )<br /><br />log (mass fraction) = log (e) * (dV / Ve) <br /><br />log (mass fraction) / log (e) = (dV / Ve) <br /><br /> />>dV = Ve * log (mass fraction) / log (e)<<<br /><br />Ve = 9.807 * 305 = 2991.135 m/s^2<br /><br />mass fraction = mo / mf<br />mo = original mass ; mf = final mass<br />mo = 6,790 kg + 150 kg = 6,940 kg<br />mf = 6,790 kg<br />mass fraction = 6,940 / 6,790 = 1.022091311<br /><br />dV = 2991.135 * log (1.022091311) / log (e)<br />dV = 65.359 m/s^2<br /><br />So to answer your questions about the Soyuz, it spends 150 kg of propellant on rendezvous and docking with a dV of approximately <br />65.359 m/s^2. The Soyuz burns anywhere from 200-400 kg for reentry, which is 155 m/s burn. The soyuz then has 350 kg of propellant<br />left over for any corrections, adjustments, and to keep the solar panels facing the sun.<br /><br />[edit]<br />Calculations for remaining 350 kg of fuel:<br /><br />mo = 6,790 kg<br />mf = 6,790 - 350 = 6440 kg<br />mass fraction = 6,790 / 6,440 = 1.054347826<br />dV = 2991.135 * log (1.054347826) / log(e)<br />dV = 158.298047 m/s<br /><br />So according to my calculations, the Soyuz has <i>approximately</i> 378 m/s dV altogether.<br />[/edit] <br /><br />Sources:<br /><br />Soyuz Specifications Webpage<br />http://w</safety_wrapper

 

[mrmorris]

Yes -- I worked it from a different angle. Assuming a 300 m/s dv -- I wanted to determine how much Ethanol would be required. I'm not sure I did it right, as I used the resulting propellant fraction to determine *only* the mass/volume of the ethanol. Dunno if the LOX mass should have been included in the mix. At any rate -- it results in a worst-case scenario.<br /><br />Dv = Isp * g * ln (W0/Wf)<br /><br />300 m/s = 330s * 9.8 m/s2 * ln (Wo/Wf)<br />300 m/s = 3234 m/s * ln (Wo/Wf)<br />0.09276437847 = ln (Wo/Wf)<br />1.09720318012 = Wo/Wf<br />Wf/Wo = 91.1% (i.e. 8.9% propellant mass required)<br /><br />Figure 4200 kg dry weight for Gemini-X3<br />8.9% propellant would be 374 kg<br /><br />Ethanol @ 20 degrees C is 789 kg/m3 <br /><br />Volume Needed for 300 m/s:<br /> V = 374 kg / 789 kg/m3 <br /> V = .474 m3 or 474018 cm3<br /><br />A 24" (61 cm) sphere holds 118850 cm3. All four 24" cylinders would hold 475400 cm3. The required 474018 cm3 would then be 99.7% of this volume which wouldn't allow space for the ullage. Either there would have to be an additional tank, or the dv would need to be reduced. I think 300 m/s is overkill, so the second option is probably best. Going back to the ACRV patent 5,064,151 where they were discussing the selection of propellant tanks, they say:<br /><br /><i>"Tanks were selected with an "off-the-shelf" philosophy to keep costs to a minimum. Tanks with a 28-in. diameter (2-tank system) and a 22.1-in. diameter (4-tank system) were considered. In these categories, the most current models were a 22.1-in. Atlas-Centaur tank and a 28-in. Space Shuttle auxiliary power unit (APU) tank..."</i><br /><br />The Atlas-Centaur tanks would then be a likely candidate for the Gemini-X3. Four of the A-C tanks then should hold sufficient ethanol for Gemini-X3. The LOX volume required should be considerably less (how <b>much</b> less is a problem for another night), but it would likely fit in the space allocated to the 18" cylinders. <br /><br />Of course i