Gemini: We can rebuild it, we have the technology

[mrmorris]

<br />Does anyone know where I could find specs on the APAS-89 docking assembly? Specifically I'm trying to locate dimensions and mass.

 

[mrmorris]

OK -- I was able to Google up a bit of info -- but not much:<br /><br /><i>"The 632-lb docking mechanism is an androgynous peripheral assembly system (APAS) built by RSC Energia in Russia and purchased for NASA by Rockwell International. The unit is alternately referred to as an androgynous peripheral docking assembly or system (APDA or APDS). The mechanism, based on a concept developed for the Buran space shuttle, will connect to the APAS-89 unit on the Kristall module.69 It includes a capture ring and three guide petals, each with two capture latches. The capture ring is mounted to a base ring by six ball-screw shock absorbers that allow 6-degrees-of-freedom movement of the ring, and serve to damp out residual motion after capture, or soft docking. Twelve structural hooks on the base ring secure the mechanism to the docking unit on the other vehicle. The guide petals interact with those on the target APAS to align the two systems. After capture, the latches on the guide petals secure the two units, which are sealed by redundant silicone rubber O-rings. In the undocking procedure the latches are disengaged by a control switch on the Orbiter flight deck, and the two units are slowly pushed apart by preloaded springs."</i><br /><br />That was in reference to the APAS made for the Shuttle-Mir docking. I don't know if there have been improvements/changes since then.<br /><br />632 pounds at least gives me a working figure. I believe the inner diameter of the APAS-89 is supposed to be 90 cm -- so I have a very fuzzy starting datapoint for the dimensions. Given the diagram (below), and extrapolating, I can figure the outer dimensions to be about 120-130% of the inner diameter. So it's somewhere in the realm of 108-117 cm across.<br /><br />I'd <b>still</b> like to find harder figures if anyone can point me to such...<br />

 

[mrmorris]

<br />Of course the Chinese would probably sell their reverse-engineered APAS-89 for pennies on the dollar. They'd love to be a supplier of space hardware of this type, and they need someone to test it in any event. They can't test it themselves without docking at the ISS or putting two Shenzhous in orbit simultaneously. It's even possible they'd supply the first one gratis in return for test results.

 

[grooble]

Would that thing fit in with the updated gemini design then? Getting crews into space and docking would be a breeze with the X3. I want one.

 

[mrmorris]

An APAS-89 is one of the two possible docking designs. The other is the probe & drogue used by the Soyuz. I haven't found a model number on that. The APAS-89 is the newer style and is the one used by the shuttle orbiters. <br /><br />I'm redesigning the capsule now to have the docking ring in the nose cone. I really didn't like the downsides of the other options (top, back, or side). This requires increasing the diameter of the nose section somewhat. Since I've determined that I don't need the room at the sides of the PV in my earlier design, I'm also widening it.

 

[mrmorris]

It's entirely possible that I'll never be able to wrap my mind around the dollar figures quoted for various space subsystems. I found an interesting article while I was looing for figures on battery systems: Easy Low-Cost Lunar Explorer (ELLE). BTW -- the lunar portion is <b>completely incidental</b> -- I don't want to take the Gemini-X3 thre on a tangent about lunar missions!!!<br /><br />They were looking into using the STAR-10 (a Thiokol booster about 1/4th the size of the STAR-17 I'm looking at for the DO stage of Gemini-X3). In the doc, they state:<br /><br /><i>"in order to kick the apogee of the orbit out to the moon a STAR 10 would be suitable (see Table 9-4). The maximum cost of this motor would be approximately $500,000, with a power requirement under 24 volts and negligible current."</i><br /><br />Half a million dollars for a podunk 18kg booster? Even if the STAR-17 boosters could be purchased for the same dollar figure -- that would mean $1.5 to $2 million burned up in DO boosters alone on every flight. <br /><br />I suppose right now each of these engines created is essentially a one-off. The price per engine would probably drop considerably if they were ordered in a larger quantity.<br />

 

[scottb50]

Considering they have a few thousand dollars in materials and the government has paid for the research there is no reason they should cost that much. Except that the users have no choice but to pay the price when there is nothing else available.<br /><br />I still think you need to look at propullsion systems specific to your needs instead of going off the shelf if you want to keep the costs down. Just like incorporating composites wherever possible, rather than simply duplicating the metal structures. I also think, one way or another you need to achieve the maximum posssible re-usability wherever possible to keep costs as low as possible.<br /><br />As long as it is compatible I also see no reason to simply slap on an existing docking adapter. I would think it would be easier to duplicate the interface parts, so they are compatable, but significantly reduce the weight of the support structure. It might even be easier to develop an entirely different system and use an interface adapter between the two that could be added to existing docking ports on the ISS. After all that's the only thing up their now, why make everything compatable with it, instead of providing an interface to it. <div class="Discussion_UserSignature"> </div>

 

[najab]

><i>The price per engine would probably drop considerably if they were ordered in a larger quantity.</i><p>Yes it would. The price would also be a lot lower if you dropped the stringent paperwork requirements that come with Government contracting procedures. Of that $500,000 pricetag, $100,000 is due to having someone check up on the person who checks up on the workers who built the rocket. Another $100,000 is probably attributable to the 10 test firings of other motors built from the same batch of propellant and another $100,000 was probably the 'plus' in the 'cost-plus' contract!</p>

 

[mrmorris]

<font color="yellow">"I still think you need to look at propullsion systems specific to your needs instead of going off the shelf if you want to keep the costs down. "</font><br /><br />The STAR-17 need not necessarily be <b>the</b> DO booster used. However -- it provides a starting point for determining mass, volume, and price. With that -- it's possible to solicit bids for competing systems and then they can be compared based on the various merits vs. the S-17. As for a propulsion system 'specific to your needs' -- that's another way of saying 'develop a new system'. This is certainly *possible* -- but if the G-X3 is being made for the ASP -- there's a very limited timeframe to do a whole heckuva lot of designing and building. Every additional part being developed from scratch adds that much more expense and time to the mix. In any event -- because the adapter module is expendable -- worst case, the STAR-17 SRMs can be used for the first few launches -- and then easily replaced with something better/cheaper down the line.<br /><br /><font color="yellow">"Just like incorporating composites wherever possible, rather than simply duplicating the metal structures."</font><br /><br />Composites are not magical materials. They have plusses and minuses. Their main plus is that they are lighter than an equivalent metal part. If Gemini-X3 ends up running close to its mass limits, then composites are an excellent candidate for reducing weight. However, this does not appear to be the case at this time. As such -- using aluminum makes manufacturing cheaper and easier given the vision as I've outlined it (i.e. using a small-aircraft manufacturer to build the structure). As with the SRMs -- I can certainly see the possibility of replacing portions of the struture with composite equivalents is there is value in doing so.<br /><br /><font color="yellow">"I also think, one way or another you need to achieve the maximum posssible re-usability wherever possibl</font>

 

[grooble]

I could do with that $50m. I'm gonna build a gemini capsule from the piles of scrap refridgerators. There are millions of tons of scrap.

 

[mrmorris]

OK -- does anyone know how to get access to Johnson Space Center docs? Specifically I want to find:<br /><br />JSC-26938: Procurement Specification for the Androgynous Peripheral Docking System for the ISS Missions

 

[najab]

Did you try calling/emailing them - specifically the PAO?

 

[mrmorris]

<font color="yellow">"Did you try calling/emailing them..."</font><br /><br />Nope -- I've been relying entirely on Google for my information locating needs. I probably should add a virtual sticker to my virtual spacecraft that reads 'Body (and everything else) by Google." <img src="/images/icons/smile.gif" />

 

[mrmorris]

OK -- well according to "SPACE STATION PROGRAM ANDROGYNOUS PERIPHERAL ASSEMBLY SYSTEM TO PRESSURIZED MATING ADAPTER INTERFACE CONTROL DOCUMENT PART 1 Core (APAS to PMA-2 & 3)", the APAS is supposed to have an outer diameter detween ~64" and ~76". It's frikking <b>huge</b>. No wonder it weighs 632 pounds (and the Soyuz uses the older probe & drogue).<br /><br />*sigh* I'll have to make that nose a bit bigger. It's going to have to be 6-feet in diameter to handle the APAS. I see why the Multi-Role Recovery Capsule designed by British Aerospace Ltd looks so stubby now.<br /><br />On a side note -- I decided last night to make the Gemini-X3 into a five-person craft. There's several major plusses to this and only minor downsides:<br /><br />- With the widening of the pressure vessel -- I can fit three crewmembers in the rear row of seats. This means I only need two rows of seats rather than three. Leg-room was one of the major problems with the capsule (especially assuming seats with shock-absorbers to reduce landing Gs).<br />- The ASP only requires five people. Six might be somewhat more useful in the long run, but in the short run, it's a handicap. Making a six-person craft when a five is the requirement and the job at hand is already on the edge of possibility is sheer hubris.<br />- Besides the space freed up, it drops about 150 kg from the craft, what with the person, their seat, their ECS requirements, etc.<br />- I hope to find space to fit a hatch between the cabin and the nose section -- creating a small airlock (dropping one row of seats makes this much more feasible). I didn't like the idea of only having one door between the crew and vaccum. If the space is there -- it would also provide for EVA capability. This is obviously not the intended role of the capsule, but it's something that could obviously be very useful in an emergency or if the capsule gets used for other roles than that of a taxi.<br /><br /><br />Of course the downside to the five-pe

 

[grooble]

SPACE STATION PROGRAM ANDROGYNOUS PERIPHERAL ASSEMBLY SYSTEM TO PRESSURIZED MATING ADAPTER INTERFACE CONTROL DOCUMENT PART 1 Core (APAS to PMA-2 & 3)<br /><br />what?

 

[mrmorris]

It's one of the reference docs outlining the protocols, etc. for the ISS. Specifically document <b>SSP 42120</b>.

 

[grooble]

Sounds like the Gemini 3X concept would meet the requirements of the american space prize, at least it is doable then, even if it's just on paper.

 

[mrmorris]

<font color="yellow">"...meet the requirements of the american space prize at least it is doable then, even if it's just on paper."</font><br /><br />Yes -- well the whole point from the beginning was a craft to compete for the ASP -- so that's been a guiding design requirement from the get-go. As to 'doable'.... that's a horse of a different color. I've tried to make the design of Gemini-X3 as realistic as possible in several respects:<br /><br /><b>KISS</b> -- Keep it Simple, Stupid -- Any time there's two ways of doing something and one is more complex -- pick the simpler of the two unless there is a **really** good reason for not doing so. This is why I have pretty much dropped the paraglider from consideration. While landing at a runway is really nifty -- the PG is not nearly as robust as a parachute landing, the avionics are ***much*** more complicated than a purely ballistic re-entry, and the failure potential is much higher. Likewise it's critical that Gemini-X3 avoid having a requirement for Unobtanium. With the PG option dropped -- the largest technical question mark is the LOX/Ethanol RCS. If that proves untenable, then hydrazine is available as a backup option.<br /><br /><b>Smaller is Better</b> -- The smaller the spacecraft the better it fits with the above priniciple. It also means less propellants, cable runs, parachutes, heat shielding, etc. are required. Later versions can always be increased in size, with the design principles and much of the hardware carried over from G-X3 MkI. So long as the various subsystems are designed well (avionics, RCS/OMS, re-entry, communications, ECLSS) and with a modular mindset, they can be ported over to a different structure with modest changes.<br /><br /><b>Flexibility</b> -- The ASP is job one -- but tunnel vision is 'A Very Bad Thing'. Making the G-X3 with other potential uses in mind (ISS, orbital operations, etc.) adds to the potential market and can reduce the time to recoup development costs.

 

[nacnud]

Hats off to you sir for this <img src="/images/icons/smile.gif" /><br /><br />I was looking into TSTO rockets and I discovered that Kistlers K1 has a LOX/Ethanol RCS that might be useful for comparison.<br /><br />Kistler K1 OMS<br /><br /><font color="yellow">One Aerojet LOX/ethanol Orbital Manuvering System (OMS) engine with a total vacume thrust of 870 lbf (3.9 kN).</font><br /><br />

 

[scottb50]

those ruskies don't know a thing about docking adapters after having built several different models over the past 30 years or so and using them for hundreds(?) of dockings with various space stations and spacecraft. Creating a brand new docking adapter from scratch should be a snap. <br /><br />Not what I said at all. Obviously it would have to be comatable with what exists today. Just because you have a standard doesn't mean different Adapters can't be built to those same standards. <br /><br />Realistically, the Gemini3x, or 3.2X, is a totally new vehicle, does it have to use every nut and bolt the original does? The flight proven configuration is the essential factor, in my opinion, and the fact it is sized to be compatable with a low cost launch system that may or may not exist in the near future.<br /><br /> Beyond that I see no difference with a Docking Adapter that can work with an existing Adapter, on ISS, Shuttle or Soyus and replacing the original avionics and flight control system with something available in a Citation Jet. <div class="Discussion_UserSignature"> </div>

 

[najab]

There are three things I wouldn't want to fart around with: the TPS, the reentry rockets and the hatch. As long as those three work the crew should survive the mission. The docking adapter is part of the hatch - mess that up and the crew breathes vacuum...let's use what's already there.

 

[mrmorris]

Adding to my subcontractor list:<br /><br />ECLSS -- Hamilton Sunstrand -- they make the ECLSS systems for the shuttle. Specifically I want to use downsized versions of their Cabin fan and CO2 absorber systems (always assuming they can build a system for a competitive price). <br /><br />(and if I ever decide to go wild and add a 'head' to Gemini-X3 -- they're the people to talk to...)

 

[scottb50]

That presents a problem to me. The original Gemini TPS isn't designed for multiple flights and the Gemini had two rather large hatches over both seats, definitely not condusive to docking with anything. To dock, and transfer personnel or cargo, is going to require a hatch that has no resemblance to the Gemini vehicles docking capability. so if you have to start over anyway why not update it, as long as it is compatable with what exists today. Or come up with a totally different design, after all ISS is the only existing destination and it's design is nearly 30 years old already. Do we want, or need, to make that the standard?<br /><br />As for re-entry rockets if there is going to be a need for a low cost vehicle, such as GeminiX? there will also be a need to get from one place to another in orbit, even if it is the same orbit at different altitudes. Using that capability to provide escape provisions for launches would be a great way to deliver the needed assets to orbit. I would look at a Gemini(?) as delivering people and cargo to a single destination where they would be transfered to other locations as needed and brought back to the location for transfer back to Earth. Maybe there would be numerous orbiting hotels, or at least research facilities that would need servicing, it would be much easier launching to a set point every time and then distributing from there.<br /><br />I think a vehicle like this would need to do more than take a few people to orbit and bring them back, without interacting with a destination in orbit, be it ISS, an independent station, or a Bigelow hotel. If that's the case getting the most mass into orbit at one time as safe as possible makes the most sense.<br /><br />If the idea is to just win a prize then fine. I totally agree batteries and low tech life-support systems makes sense, after all you are coming back to Earth quickly where everything can easily be serviced or replaced, if needed. Keep It Simple. The problem comes trying to ma <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

<font color="yellow">To dock, and transfer personnel or cargo, is going to require a hatch that has no resemblance to the Gemini vehicles docking capability.</font><br /><br />You're either deliberately or accidentally misinterpreting NajaB's post. Since he specifically linked the APAS-89 to the 'hatch' and the original Gemini hatches obviously had no relation to this -- he wasn't referring to them. The Gemini hatches in any event were specifally made to work with the ejection seat system which I've already stated in the thread makes no sense for this number of people and is therefore eliminated by default. The original hatches go as well.<br /><br /><font color="yellow">"...so if you have to start over anyway..."</font><br /><br />Ah -- but the APAS-89 is not 'starting over'. It is switching to a standard that is known to work. What <b>you're</b> suggesting is starting over.<br /><br /><font color="yellow">"...why not update it, as long as it is compatable with what exists today. </font><br /><br />You haven't read the same document I have (mentioned earlier). NASA is really anal-rententive in speccing out how the APAS has to be constructed in order to work. Not <b>too</b> suprising, I suppose, since a docking system that didn't work has the capability of killing everyone aboard the station and the docking spaceship simultaneously.<br /><br /><font color="yellow">"Or come up with a totally different design, after all ISS is the only existing destination and it's design is nearly 30 years old already. Do we want, or need, to make that the standard? </font><br /><br />If it ain't broke -- don't fix it. Especially when fixing it wrong can kill you. There's lots of space tech that is in sore need of improvement. Docking mechanisms would not top my list.<br /><br /><font color="yellow">"As for re-entry rockets..."</font><br /><br />You're welcome to think 20-25 years in the future. Be my guest. Gemini-X3 is five years (ho

 

[scottb50]

<<You're either deliberately or accidentally misinterpreting NajaB's post.>><br /><br />No I understand what he posted. How do you link the APAS-89 to the 'hatch'(s)? The Gemini docked to the Agena upper stage and that wasn't an APAS-89. APAS-001?<br /><br /><<Ah -- but the APAS-89 is not 'starting over'. It is switching to a standard that is known to work. What you're suggesting is starting over. />> <br /><br />It does work very well, but it is only used for one application, docking to ISS. My point is if there is a reason for GeminiX then maybe a thirty year old design could be upgraded, sort of like using the electronic avionics available today instead of the mechanical systems 30 years ago.<br /><br /><<You're welcome to think 20-25 years in the future. />><br /><br />I don't think this is 20-25 years in the future. If the only purpose of GeminiX is to dock to the ISS then your right. But it's goal should be to expand the envelope. You make a relatively economical means of reaching orbit you better have a reason to reach orbit, and getting to ISS is obviously not going to generate enough demand for the capabilities of a GeminiX. There needs to be a bunch of destinations, not just one.<br /><br />I'm thinking of the Model T. Maybe you're thinking of the hand-built vehicles of the late 1800's. Is that so bad?<br /><br />If nothing else an interface docking adapter would allow multiple vehicles to access different facilities. Doesn't the ISS have two different docking adapters now anyway?<br /><br /><<You haven't read the same document I have (mentioned earlier). NASA is really anal-rententive in speccing out how the APAS has to be constructed in order to work. />><br /><br />I wasn't intending to follow NASA's lead anyway. GeminiX doesn't have to be any more NASA compatable than Space Ship 1.<br /><br /><<OK -- I don't get this. The parafoil is *less* conventional than a parachute-based system. I can only assume that you are thinking: <div class="Discussion_UserSignature"> </div>