23Feb2010 re-design - GRAVSAT 12 is an (updated) orbital living environment. it is the first to provide GRAVITY in an orbital environment, suitable for humans, livestock and plants. In 50 years of access to space, nobody has "bothered" to provide this, yet it is the first step for survival beyond earth's atmosphere. It is part of the larger plan described in UnitedSpaceAgency.com
HeavyShips.com
This proposal avoids the need for hazardous orbital assembly by Launching 3 large GAS TANKS To be converted and connected together in orbit.
An 18mm THICK duraluminium tube, 12 Metres in Diameter, 100 metres Long
..Long in orbit, High at launch! is constructed from 14 "water tank type" units 12 metre diameter 7 metre high - perhaps from several manufacturers, assembled and brought to the offshore launch site when ready for fuelling and launch.
This thick aluminium tubular skin weighs 180 tonnes, and with its dividers and internal structures. It's capacity is 10,000 cubic metres, and it is strong enough for 1.5 atmospheres of internal pressure. When the End plates, internal plates and column are added it's 312 tonnes, and with 50 tonnes
of rocket engines thats 362 tonnes of about 420 maximum - although not leaving a huge allowance for nose cone and cargo,it is sufficiently strong.
After being "The tough outer hull" to support and accelerate 10,000 tonnes of liquid propellants on 15,000 tonnes of rocket thrust from 49 engines during the (HeavyShips) ascent to orbit, it becomes the tough outer hull of a HabiTube - see
HabiTube.com one of the 3 major GravSat components
The HabiTube is a long, strong, duralumin tubular gas tank, 12 metres in diameter and 100 metres long. whose axis is maintained pointing at the sun on its fully solar storm shielded end. the 18mm thick alloy hull is more than adequate shielding at the side. solar alignment is maintained by minute thrust bursts to counter the precession of this spinning trio, Spinning one-end-always towards the sun as it orbits both the sun and Earth.
Through the centre of this fuel tank is a central support column 3 metres in diameter, that can later be removed in orbit, in sections and recycled as the needed connecting spokes Passageway(s) between main tanks, or other purposes later. It's also the first "safe" (or "safe-ish") air filled area for the first adaption crew to use. at 3m diameter and 6mm wall it adds 56 tonnes to the total mass, now 312 tonnes, and also reduces tank capacity by 675 tonnes from its 10,800 tonne theoretical maximum
LEO-Port.com - the most useful port on (or only just off) Earth.
3 such habitubes are connected in paralell (via airlocks and a bridging tube) and are spun up to produce an effective 10% gravity in the two outer tubes, spinning at 5RPM or less (if wider spaced)
1) The central HabiTube with zero gravity in the (axially rotating) central, sports and docking HabiTube,
2) A Human HabiTube for human accommodation, 40 cabins, 6metres x 4m x 3m on 2 passenger/crew decks, cavernous ends.
3) Agricultural/work HabiTube for agriculture and manufacture
4) Additional habitubes need no extra screening, so 6 more tanks (launches) may be used to extend LEO-PORT from an outpost to a busy village.
5) "the rear end" is fully shielded, and further (HeavyShips) are brought up, fitted out, shielded and crewed here prior to their departure to new orbits.
less obvious (above and below the 40 cabins, and below the caverns, is addition "grass crops" growing areas.
Only by being LARGE at takeoff (10,000 tonnes) can we get a 400 tonne package to orbit, (including 50 tonnes of spent rocket motors, NOT dropped off)
We'd prefer larger living and working diameters than 12 metres, but it will do, and the extra fuel load at take off would be an even greater explosion risk. This size works as a "bus" to get large masses to orbit once a week from one of several launch sites - and TheSpa.Biz describes how frail passengers, animals and plants can get up to orbit in a purpose built "Spa" or warm water tank, with scuba gear on a Heavy Ships weekly ascent. we need the (5 to 30 tonnes) of water anyway!
By sticking to the MODULAR, s12 metre "disposable-to-orbit" HabiTube /Fuel Tank / ship we can provide a regular WEEKLY trip to space for people, supplies and "safe" hardware. 3 months between trips is too long, especially when other "projects" are to be launched for cash customers during our construction schedule. We charge as low as US$2.5M/tonne to LEO, and onward handling in and out to Clarke belt from there.
Your servicemen can hire a living suite and workspace :-)
Cost and Benefits
Each of these modules costs US$300M to build and fuel, excluding launch facilities, Bureaucratic overheads and orbital conversions. Such a low price does not include any insurance other than TESTING, and MULTIPLE REDUNDANCIES only possible on a large SSTO (Single Stage To Orbit), nor of the multiple factory setups to fabricate and handle 7 metre lengths of 12m heavy pipe - 18mm thick. (for US$1M)
Joining and testing the 15 sections is done on a horizontal Jig, mounted on a converted Oil-tanker, which transfers it to an offshore launching rig for completion, fuelling and launch. that ex-tanker would be working on the next assembly as soon as we're unloaded. With a single jig on a single tanker, it MAY be possible to assemble the 100m long HabiTube in its launch tankage mode in 2 weeks (it can be largely automatic, computer controlled welding) and a second such tanker is a good backup for weekly runs! ditto with launch sites in several different geo-political sites.
The first 15 successful tank launches may take 2 years, rather than 15 months... and 9 are likely to remain at LEO-Port for adequately LARGE facilities. meanwhile :-
* 2 other basic GravSat (of 3 tank unit) or
* 1 medium GravSat (of 6 unit) assemblies
..are still in fitting out, and when ready will depart for higher orbits, initially 300/900 and 900/900. where inertial energy transfer via cargo/mass exchange pods released and captured by rotating tethers RotatingTethers.com prove the technology for Gravity-Pumped boosting. This saves on (Earth Supplied) Argon for VASIMR drives INITIALLY and otherwise needed.
The reason to send a GravSat to "The pumping orbit" (Where it passes BEHIND the moon in its orbit, Or the Earth in its orbit and returns (same side) with increased velocity is to pump INERTIAL energy into our system without expending reaction mass. Our returning "Pump GravSat" comes in with quite a bit more velocity and is 1,000 tonnes - capable of transferring considerable acceleration to another craft in order to slow back down.
This transfer to other (upcoming) craft is via Mass Exchange Pods (MEP ) and RotatingTethers.com on both craft. The MEP has to ACTIVELY make mid course corrections, but with precise timing this may be minimal. The MEP may be used to transfer inertial energy (acceleration) to bring cargo (or a GravSat) all the way to lunar-insertion orbit, or at various steps. It all has to be very well choreographed!
These MEP transfers are likely to experience 10 gravities, So are not a direct way to send people, at least at this early stage. We can use less massive ships than a GravSat around the pumping orbit (about 6 days), but for a lesser inertial return. People living aboard "Pump GravSat" are not likely to notice it. ... and it's on a trading route...
The Cost? - not finished at 45 launches for the 3 GravSat as above, 15Bn + tankers and launch stand $3Bn =
US$18Bn
"Permits", Insurances, losses, cleanups, Bureaucracies and Politics ... Treble it? US$60Bn
Well , we shouldn't have to as an NGO (non-government organization) but if we hae to pay that, it's still well worth it and more... Why?
SPIRIT is one thing - that of humans going forth boldly... co-operatively, to "New Lands" of opportunity.
R-O-I isn't measured in these terms. it should be.
The cost of NOT GOING far exceeds the cost of going
(previously)... (it's now a straight tube, narrower and longer)
prebuilding the large liquid hydrogen tank needed for such a mission - this is a HEAVY SHIP of about 600 tonnes in orbit - mainly the thick aluminium tanks that previously contained fuel and oxidant. Its launch mass is 12,000 tonnes. a bit heavier than the "smallish" 10,000 tonne passenger liner that brought me from England to Australia in 1969.
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NO PARTS "drop off" during ascent. The complete ship arrives at LEO* It's a SSTO*
EXHAUST is just "new water" born of pure Hydrogen, and pure oxygen
EVERYTHING taken to orbit will be useful there, except the main booster engines, which we'll return to earth later.
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The Oxygen cylinder ( a 25 metre sphere) becomes a workplace that can be evacuated to "elsewhere" and re-pressurized after some
plates are replaced by airlocks. The 2 hemispheres can be unbolted (from inside, but depressurised - use a pressure suit, or use telechirs, big parts brought in (the motor array and hex shield) and then resecured.
For smaller ops, a smaller plate may be replaced by a resealable port. for an airlock
* LEO = Low Earth Orbit, 300Km : * SSTO= "Single Stage To Orbit" - No "Dropped off" boosters or tanks
There are 4 main parts.
1 : Rocket Motor Array
The Cryogenic rocket motor array (yellow) consists of 6 (or 7) MAIN motors in a hexagonal pattern. These are large motors producing 4,000 tonnes of thrust each, or arrays of smaller ones such as SSME equivalents. They will be returned safely to earth months LATER. - or recycled in orbit. The central engine/array has a number of smaller engines down to 1 tonne thrust. the cryogenic oxygen tank is SHIELDED from the motors by a substantial hexagonal shield (white)
2 : The Oxygen tank
The Oxygen tank (purple)is a 25 metre (80 american feet) sphere whose LOX capacity is 8,000 tonnes. Of hefty aluminium (10mm thick) this sphere is inflated to 100Kpa (1 atmosphere, 14.7 american pounds per square inch) and is the majority of the ships mass, at 8,000 tonnes when full of LOX. it may have internal structure if needed to support the collar and the rest of the ship
3 : The collar (green) and load spheres (white)
The collar (green) is 8m in diameter and supports the much larger (but lighter) LH2 tank (Red and yellow) this also connects to up to 6 * 8m diameter spheres which carry crew and/or supplies in these non-cryogenic spaces.
Access to the ship is from (or via) the "crew" sphere - one of the 8m diameter (white) spheres into the green collar region - thence, via removable plates, which the crew will replaced with airlocks into both the LOX and LH2 tanks (now habitat outer shield) after they have been filled with air.
4 : The Hydrogen tank (Red and yellow)
The LH2 tank (Red and yellow) will become the main habitat "tank" in which up to four 20M habitat rotors are spun. These rotors are fully welded and all the ALUMINIUM parts assembled and secured immersed inside the Liquid hydrogen. There are no airlocks or any other non-aluminium parts so (cryogenically) immersed, and these all will be fitted by the crew once it is empty and warmed up. the LH2 tank carries about 4,000 tonnes of Liquid hydrogen
Once stabilised in orbit, Access to the now 1/2 pressure air filled hydrogen tank from the 1/2 pressure filled collar is had for overalled tradesmen and goods... polythene bag water tanks are attached inside the "top" of the LH2 tank and filled with water for mass shielding
20m x 8m x 1m (160 tonnes) or a narrower strip (20 * 4 *1 (80 tonnes) for initial screening of HALF of gravsat.
The bearings for the rotors are then fitted and its airlocks and fittings are then installed in the tank in a breathable atmosphere of at least 50% of normal air pressure. once the rotors are fully sealed they are increased to sea level pressure and spun up to 5RPM and fitted out for comfortable living.
The FOUR 20m diameter * 12m thick ROTORS are fabricated on Earth, then the LH2 fuel tank is built around them, secured for 3G acceleration to orbit, then eventually mounted in bearings in orbit before spinning up. in each rotor there are 16 rooms 6m * 4m and a deck above them for horticulture and a 10m diameter "low to zero" gravity hub space. These 64 rooms are not all for guests, but in an emergency we could cater for 100 people for a limited time, or several dozen permanent or in transit passengers
For now though, here is the original entries
The first concept Gravsat (superceded) looks like this model :-
The Main habitat is the rotating Disk, which is 12 metres diameter, and 4 metres thick, spins at 5 R.P.M to generate about 0.1 gravities, so an 80Kg person would "weigh" 8kg at the perimeter. In the centre, there is almost no gravity in the 7m diameter, 4m wide core. access is via an airlock to the connection corridor shown below the disk in the picture above.
the box to the left is 4m x 12m and is 4 metres thick, the first (sunward) metre is always between the disk and the sun, regardless of what gravsat orbits around, (earth, moon or sun) and contains a 1 metre thick array of tanks or boxes at the front (sunward side) made of any material including waste, sewage or anything of similar mass - 48 tonnes of such mass are needed to shield the entire ship, its crew, passengers and crops against solar flares, waste from the ISS and salvaged space debris will be collected for this. it needs to be anyway!
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(previously, superceded) :-
the disk is the main habitat, and is constructed of 6mm thick aluminium plate, rather than the more typical 1 or 2 mm of the ISS and shuttle craft. this is for a much greater penetration resistance to the few small particles crossing the orbit from previous misuse of space by humans, including specks of PAINT which very nearly destroyed STS24 (the one before "Challenger" STS25) when it hit the windscreen - and those fragments of glass that are still in orbit. We plan to have minimal ceramics and such orbiting, and would encourage others to do likewise...
Inside the disk
Inside the disk the "carpeted" sections shown (with some "roof" removed) are each 15 degrees or 1/24 of the circumference (about 36m) or about 1.5 metres per section, by 3 metres wide, to give (on the exampled 3 section space)4.5m x 3m of living space for a "unit", plus a "corridor" 1m wide which is a cycle, buggy, conveyor or running track, for exercising in higher gravity, up to or exceeding earth normal gravity, if one cycles fast enough!
Although 8 such private accommodation units could be provided, leaving only the cycleway in communal "gravity space" it is planned to have only about 3 such "twin-share" spaces, leaving room for crew of 2 or 3 and agricultural / farming space (and machinery) that also needs gravity - such as toilets and showers!
It can be built within 2 years for less than 1Bn.US
GRAVSAT 2 is much bigger, multi-decked and more substantial, and requires lunar resources to build both its shield 120m x 50m x 1 tonne/square metre = 6000 tonnes and the aluminium for the 4 disks showm.
Because, at the distance that the Earth and moon are from the sun, the sun occupies 1/2 a degree of arc, and there is a square pyramid shadow from the shield. the disks will either need to be smaller as they get further from the shield, or some intermediate "tip shielding" may be required. the configuration of 4 large disks, as shown may need slight size or shielding adjustment. and their direction and/or speed of spin may vary from the 5RPM of the prototype - that would give about standard earth gravity at the rim, but still have a fairly high corriolis force at 30 degrees per second.
GravSat 2 = 300 acres of variable gravity space
a slower spin would reduce corriolis , allowing about 15 degrees per second and 1/4 G (2.5 Metres per second, per second) for greater comfort. rather than the "single deck" (plus hub) of the proto, up to 30 decks could give a considerable "acreage" (up to 4 acres per deck) for agriculture, plus a large low gravity hub area in each of the disks. the two 6M diameter (zero gravity) connecting tubes may be fully shielded or used only in planetary shadow. the extra mass for shielding is probably worthwhile though, and a good idea as with 4 or more disks, and hundreds of people on 300 acres of "land", and possibly livestock full shielding is preferred
Construction of gravsat 2 starts with a smaller disk (or contra-rotating pair of disks, better for stability) behind a smaller shield, and when another is built (constructed in shadow but zero gravity at the right) it is bigger, but initially not fully shielded, then the shield is extended, and the new disk mounted behind it - moving very heavy structures in orbit is EASY!.
"Parking" for transit craft or constructions can be had in the shadow to the right. or "teed off" from the connection tubes /"axles" for ease of access. Power generation is from an aluminium parabolic reflector (not shown) on the LHS that concentrates a LOT of solar energy to a focus for THERMAL collection to run a "conventional" steam turbine generator, with cooling finsin the shadow behind it. many megawatts of power are available, without having orbit-hazardous fragile ceramics exposed to space as in P.V. Photo-Voltaic collectors
Gravsat 2 is a stage towards a rural township - holding many skills, spaces and amenities, and a low G (and zero G) environment ideal for paraplegic and elderly people nursing, as well as "the hardy outgoing" types one usually associates with space fiction - though, of course, GETTING to LEO is (at present) not a trip for the feeble, or frail. It will get better though, with the demand (and funding) for it to do so. this will be expanded on a link from UnitedSpaceAgency.com shortly
© Lord Oxford 0109-2008
Oxford@UnitedSpaceAgency.com