Views and Statements expressed on this site are personal opinions of Oxford University and are © Oxford University 1999-2003.
Pai, TH 2009-013
LEO-Port is a "Port" In "L.E.O." - Low Earth Orbit and is a GravSat facility - slow spinning of 3 large habitubes - basically large Gas pressure tanks with the mass - shielded ends pointing at the sun,
It is of the same design as Haven1 … this is a much older website, being updated. More up to date stuff is on www.Haven1.com
LEO-Port is at 200Km equatorial orbit, main assembly point, Haven1 is at 900Km. All operate under United Space Agency
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
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
orbit, High at launch! is constructed from 14 "water tank type"
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
is a "Port" In "L.E.O." - Low Earth Orbit - specifically the orbit Eastward, DIRECTLY above the Equator at a height of about 300Km and Velocity of 7.5 KM/sec circling the Earth every 90 minutes. It is principally a place for handling "goods" or "cargo" to and from Earth and elsewhere, mostly, the moon.
It is designed to work in conjunction with Sky-Port - an extremely large permanently flying AIRCRAFT also flying East above the equator, at a height of 15KM and speed of 300 Metres/second (conventional sub-sonic high altitude passenger jet speed)
Although a LARGE amount of energy and reactant is required for getting materials from Earth Surface to Earth Orbit, and from there to Lunar transfer point, A much smaller amount is required to get from Lunar surface to Lunar Orbit and from there to Earth transfer point. - There is a much larger "return" from Lunar transfer point to Low Earth Orbit than that needed to get from low lunar Orbit to that point, so, by usinf a staged momentum exchange, material can be brought from Lunar Surface To Low Earth Orbit at close to zero cost, enabling both LARGE constructions there, "Inertial exchange" boosting of cargo from Earth, and/or delivery of moon rocks to Earth at great (inertial) energy available for powering things on Earth.
ENERGY (inertial) , E = ½ M V squared.
This means that it takes a LOT of energy to get things to move really fast. The MINIMUM Earth Orbit speed is 7½ KM/sec. It takes a lot of energy to get things there, and a lot of energy has to be dispersed to slow down again, in returning to Earth. The COST of that energy is very high, especially as "the reactant" (fuel burnt and thrown out the rocket engines at great velocity) has to be carried (and supported against gravity during ALL the time that it takes to get to orbital speed) requiring very large engines and fuel tanks even for a small payload
LEO-Port's Main component is a "linear accelerator" tube of at least 1 metre diameter and 250 Metres in length, and massing 50 tonnes. It can either accelerate a 1 tonne package to about 500 Metres/second, or Decelerate a similar package a similar velocity.
The "Package" has to be capable of accurately navigating and standing forces of 50 gravities.
There are two types of "Package" initially - One is the top stage of an up-coming cargo delivery from Sky-Port (The equatorial flying Space launch centre), and the other is one of several "Ion Drive" boosted "counterweight" craft.in an elliptical (Equatorial) Orbit between 300Km and about 2,000Km
The Up-coming 1 tonne craft is "captured" from its boost to "only" 7KM/sec - 500 Metres/sec less than needed to orbit, and slows LEO-Port down by about 10 Metres/second in doing so. Slightly later (or a bit before) the "counterweight" craft arrives to re-boost LEO-Port to correct orbiting speed.
The Up-Coming rocket Craft left Sky-Port with about 30 Tonnes of fuel, and arrives as little more than a rocket engine and an empty fuel tank, massing 1 tonne - all "useful mass", though the actual "delivered hardware" may only be 200Kg ... but these Up-Coming craft can be received every 90 minutes* as LEO-Port passes over Sky-Port.
The "counterweight" craft uses "Ion-Drive" to accelerate to a higher orbit. Ion Drives are unsuitable for the launch phase, because they need a lot of power, and produce only a tiny thrust. To change orbits, something must be "ejected" as "exhaust" to react against - either gasses from a chemical combustion at perhaps 2KM/sec or charged Particles - "Ions" electrically accelerated by solar (or nuclear) power. at maybe 200Km/sec We use Solar. The "Cosmos" series of ('70's) Russian spy satellites used a PIG generator (Plutonium-Inert-Gas) and when reactant ran out, the satellite split in two and reacted to cause the "camera" bit to slow and re-enter (or burn up on re-entry) and the PIG to accelerate to a higher orbit, where they will remain for more than 100 years. One (Cosmos 495) split the wrong way, and the PIG landed on Alaska poisoning large areas with plutonium. we were all ducking for several days, until only the Inuit tribe of Alaskan Indians copped it.
Using that "E = ½ M V squared" it can be seen that to eject mass at 200KM/sec rather than 2KM/sec needs 10,000 times the (chemical) energy of the former. the Inertial rule is M1xV1 = M2XV2 - and this means we require only 1% of the mass (that has to be brought from Earth) to provide an equivalent net Delta-V (change in velocity) to our LEO-Port. In orbit above 300KM there is essentially NO air drag or "weight", so very large, very thin parabolic reflectors can collect as much power as we need for our Ion Drive "ship" being either "The actual counterweightcraft" or a craft that "Pumps them up" to higher orbit (As the high gravity capture would require sturdy stowage of such collectors)
Building LEO-Port #1
It is possible to build the first LEO-Port using the Up-coming craft with more fuel to get that last 500Metres/second by conventional rocket reaction, but arriving at perhaps only 600KG total, 50Kg "payload" per trip, However, there will be a need for getting Humans to a habitat pre-built at LEO-Port. This would entail lifting extra "safety" mass (multi engine, and (emergency) re-entry shield and chutes) this would need to be a 2 tonne payload, kept to a maximum of 3G acceleration. Instead of a 30 Tonne departure from skyport to deliver 1 tonne mass, 200Kg "Payload", a fueled departure from Sky-Port would be of the order of 500 tonnes to deliver a payload of 2 tonnes, + rockets/empty tank of 3 tonne - (total 5 tonne, including emergency re-entry pod shields and chute) Used for (rocket only) cargo at up to 8G acceleration 10 tonnes may be delivered, 7tonnes being payload.
6 launches of these craft may be enough to construct LEO-Port#1. Another 6 enable some rescue capability for other space users. later they will be launched regularly when needed to carry people UP ONLY, so we'll need 8, plus one a week. Note that (barring accidents) these crafts Engine and fuel tanks, etcetera NEVER return to Earth.
The first craft to orbit contains a number of "counterweight" ships and their Ion Drives / solar collectors, as they take some time to boost to operational orbit. and the telechir tools to assemble LEO-Port.
When LEO-Port #1 becomes operational, the initial frequency of cargo acquisitions from Sky-Port is limited by the time it takes the "counterweight ship" to get up to speed (several days) and how many there are.
Initial Optimisation is to receive cargo every 90 minutes, needing either more "counterbalances" or more rapid "pumping" - perhaps by putting out more (delivered) mass at a lesser velocity with available energy. LEO-Port is designed to boost 16 one tonne up coming rockets per day.
Presume it's 2010 - SIX years from now, though it need not take that
10,000 small port facilities orbit the Equator at 300Km, 90 minute orbit - about 4km apart. They are as described in LEO-Port.com Mass 100 tonnes each and can accelerate or decelerate Packages of 1 tonne or more to or from a relative velocity of 500M/sec. They orbit at about 7 ½ Km/sec.
1) moon rock from (higher, faster, elliptical) orbit is caught from 8Km/sec - LEO-Port gains speed. 2) A package from not-quite-orbital 7Km/sec is boosted to LEO-Port speed, balances #1 3) same as #2 again - LEO-Port loses speed 4) LEO-Port decelerates moon rock to 7Km/sec, balances #3
The process has "Swapped" TWO packages from Earth up that last step, and has brought the lunar rock down 2 steps for a total of zero change in LEO-Port orbit or need for other accelerating forces.
In an elliptical orbit above LEO-Port a similar craft called Transfer1 approaches LEO-Port at relative 1KM/sec or 8½KM/sec, relative to Earth. It Is from this that the moon rock #1 was decelerated to 8Km/second. In doing so "Transfer1" was accelerated (and LEO-Port too, as in #1)
5) "Transfer1" is now too fast, and has to be decelerated either by receiving "upcoming" at 7 ½ KM/sec ... or Ejecting at 8½Km/sec. This does not have to happen at that time or Orbital point.
"Transfer2". Craft's ellipse at 9KM/sec does similar transfers between 10KM/sec orbit "Transfer3"
"Transfer3" orbit of 10KM/sec is approximately "Lunar Transfer" or 28 day "LaGrangian" orbit - well above the "Geo-Stationary" or "Clarke belt", 36,000 KM above the equator, past which navigated transfers are made.
"Transfer3" is "Lunar-Stationary" remaining in a fixed point above the lunar surface, rotating around it, as it rotates, once every lunar day (28 earth days.) This boint is "GRAVITATIONAL" half way to the moon - i.e. A LOT closer to the (much lighter) Moon than the Earth - although 10Km/sec relative to Earth, it is only travelling at about 4Km/sec relative to the Lunar surface and its much smaller "gravity well" .
6) "Transfer3" receives Lunar Rock upbound from moon via "Transfer4" thereby losing velocity.
7) "Transfer3" regains velocity by reaction from slowing to 9 ½ KM/sec package bound "down" the "Transfer2"chain to Earth.
8) "Transfer3" also works in reverse, receiving moonbound cargo from T2, and sending to T4
T4 is at 3KM/sec, lunar relative, T5 is at "Low Lunar Orbit" 2KM/sec, Lunar relative. There is no T6 - a substantial (lunar surface) accelerator gets rocks to 1½KM/sec
16:50 no help for window move...
Constructing "the stairway"
7KM/sec is NOT fast enough to orbit, so to remain at this velocity, above the equator, a thrust reaction equal to a PART of the weight not balanced by centrifugal force has to be continuously applied :-
The square of 7 is 49. The square of 7½ is 56(and ¼) 49/56 so only 87% of the required "gravity balancing force" is available - and 13% of the weight of any craft wishing to linger there has to be provided by downward thrust.
There is a similar "advantage" in "Mass-to-Orbit" gain - approximately 17% more mass can be got to 7KM/sec than can be got to 7½KM/sec - AND maybe 20% extra rocket propellant/ reactant (gas) mass would have to be carried - 37% increased Mass-To-Orbit means a similar 37% cut in rocket take off size, approximately.
Savings "At the top end" are much bigger than at the bottom, weight for weight.
Sky-Port - a 50,000 tonne permanent East Equatorial high flying launch platform is sub-sonic (less than about 340 Metres/second) but enables easy high Gravity accelerator launches every 90 minutes to ONE LEO-Port, or every 540 milliseconds to each of 10,000 LEO-Ports.
The embryonic Sky-Port of five 747 aircraft (or even less) connected together with a LEO-Port like accelerator capable of launching 30 tonne cargo craft, with an in-flight recovered re-usable robotic winged RAMJET hypersonic stage makes best use of high altitude air for support and acceleration before rocket use.
The Full fledged (big, heavy) Sky-Port provides a much larger proportion of orbital velocity acceleration, and eventually Lunar material aquisition, eventually reducing or eliminating the need for jet engine fuel.
All "Transfer" ports are presumed to be able to accelerate to, and decelerate from, 500Metres/second at about 50 gravities (50G for 1 second = 250 metres of accelerate or decelerate length) as such, they are unsuitable for DIRECTLY accelerating humans, or anything not robust. Higher accelerations, and/or longer tubes would enable higher relative velocities and/or fewer stages.
Human access to space from skyport uses only a ramjet stage to mach6 (2KM/second) during a 2Gravity boost of about 100-15 = 85 seconds before a 3G liquid fuel rocket boost of the remaining 5½KM/sec (183 seconds).
The (delta winged) ramjet stage is remotely piloted back to Sky-Port with enough fuel for air-air docking automatically or by remote pilot (on board Sky-Port). Most operations, however, are done by Telechir (remote handling robotic operators on Christmas Island, Equador and Sky-Port. These "human carriers" have no wings and are not designed for re-entry or re-use from Earth to Orbit. The requirements for taking people TO orbit are quite different to the requirements for returning them FROM orbit.
The human habitat, and all its supplies - and substantial solar flare shielding, previously unavailable - are sent up by (much cheaper) high acceleration launches, and assembled by telechirs, so that only a minimal extra mass than the people and their short term needs and emergency needs are "slow launched".
The "return" heat shielded human re-entry modules are constructed initially from High gravity delivered cargo, and eventually, from lunar materials.
A second "habitat" module is built at other "Transfer" locations up to crossover, and down to LLO, to which humans travel via re-fuelled "Human carriers" (stripped of no longer needed emergency re-entry bits) (possibly) enlarged and able to "over" boost at 1 to 3G for minimal trip time. Fuel is Liquid H2 and O2 produced from solar power and water brought from earth by high gravity boost.
The "Human carrier" ships that bring passengers up remain in space, and have a lot more rocket thrust power for transfers between orbits and from LLO to and from the lunar surface (water is delivered there as high gravity cargo and again, electrically split to form liquid fuels for humans to leave the moon, allowing less decelerate and landing mass and associated dangers.
Lunar Base 1
Lunar Base 1 is robotically built, with operators either on Earth (initially) then at the Lagrange point until substantial accelerator packages are in operation. The "single use Human Carriers" rocket engines, navigating and control gear carry the Lunar landing robots at relatively high gravities to the surface - a rocket set that has initially accelerate a 30 tonne craft at 3 gravities from Earth is capable of landing a similar mass at 12 gravities to the lunar surface, minimising fuel usage in the early missions.
Primary construction is an accelerator / decelerator similar to LEO-Port, initially permitting a delivery and collection using High G + 1KM/sec of rocket usage rather than the 2KM/sec of rocket burn for initial landings.
Lightweight components from Earth are reinforced with processed moon rock to get this initial accelerator - and then extensions to both it, and the LLO transfer accelerator to minimize or eliminate rocket usage.
A Hole is dug to a depth of 15 metres, then outwards to a diameter of 15 metres and height of 5 metres (the 10 metres of undisturbed "rubble" (or whatever) above is supported by a bladder inflated to Earth Normal pressure with nitrogen brought from earth, to which Oxygen (from split water) CO2 etc. Are added. The mass of 10 metres of Moon rock above balances that (Sea level, Earth) air pressure and provides radiation shielding.
Digging that hole is part of the mining process for MASS to send back along the stairway to Earth, where it provides inertial energy to lift cargo, and ALSO industrial energy to Sky-Port and Earth. A Very large LEO facility can be built of mostly lunar materials getting delivered there "Free" at some economic stage, refining of those lunar materials - possible at any transfer point - may choose to make aluminium foam sections that may ONLY be producible in zero gravity, Zero Oxygen places ... These may be delivered for construction on earth, in orbit, or for the very large vessels more suited to long duration interplanetary flights.
When lunar base one "hole" is dug, 15 metres diameter, 5 metres high the 883 cubic metres of rock removed is replaced with air and is reasonable living space for 10 people and sufficient plants to balance air needs, given power supplied from solar collectors in orbit by microwave or laser that also supplies the boost accelerator.
As We have to dig up rocks anyway to make the system work, doing so 10 metres underground for the cost of importing Liners and air - and thereby making human living and growing space there at the same time is worthwhile. There is no reason why a 5KM diameter "cave" cannot be built, and, so long as there is a 10Metre layer of moon rock or dust covering it, and air does not leak it is safe, and can be any height of air even 500Metres, if the sides are firm and slope at a reasonable angle. Main limit is the cost of importing its 80% nitrogen content from Earth - and that cost is set by how much rocket fuel has to be used (rather than accelerators) and the quantity of material that HAS to be brought to LEO to decelerate it from it's reception of moon rock from "Transfer1"
© Oxford University 2001