Well, I have written extensively about Shuttle Launch Systems derivatives since the 1980s.
For about $6.5 billion we take the MAF External Tank tool set and the Rocketdyne SOB (Saturn Omnibus Contract) for the LTB (Linear Testbed Program) using the tools and skills developed for the Aerospike engine and adapting both to work efficiently together as an improved ET to create an integrated flight system. This is the low hanging fruit.
Recovery of the tank uses an advanced RCC shock based thermal protection system of exceptionally low mass combined with ILC Dover inflatable wing technology deployed after subsonic speeds are achieved in the upper statosphere to provide adequate cross range capability.
Downrange recovery when needed, is achieved via tow plane.
The ability of an annular aerospike engine to operate over a broad range of thrusts and application of vector control is exploited to bring the unit back to a vertical landing in a manner similar to the tail sitter aircraft designs of the 1950s and 60s, and proven with the DCX in the 1990s, following horizontal flight with inflatable wings.
The design I've developed there are no landing gear on the powered ET, and landing occurs with a specially built reactive landing platform to absorb shocks and catch the vehicle at touchdown. This maintains low mass and high performance in the launch vehicle while improving reliability.
In the end a highly reusable 50,000 kg inert mass improved ET is built. It carries 112,300 kg of hydrogen and 617,700 kg of oxygen propelled by a 9.79 MN annular aerospike engine with zero height spike that doubles as a TPS. A single stage element is capable of placing 47,390 kg into LEO.
Using this as a starting point, we design as a second kick stage in parallel with the main vehicle. Here we have an RL-10 based high expansion, highly reusable upper stage. This kick stage carries significant payloads into deep space.
Properly loaded, it carries up to 5,960 kg of hydrogen along with 32,780 kg of liquid oxygen which makes it capable of carrying 6,200 kg of useful payload to the surface of the moon's surface and back to Earth.
Upon its return to Earth the stage re-enters the Earth's atmosphere, and executes a powered touchdown on Earth after re-entry.
This ability to re-enter the atmosphere and execute a powered touchdown, as well as touchdown on an airless body like the moon, gives this stage the capacity to fly to mars, enter the atmosphere there and execute a powered touchdown one way, while carrying a similarly sized payload.
Carrying a small power supply to convert water found on Mars into hydrogen and oxygen, allows the system to return to Earth next synodic period - ala' Zubrin.
This launcher and upper stage could have been done any time since 1973 onward at a cost of $6.5 billion or less, had we the will to do so.
From the business angle, the single stage to orbit vehicle would have been useful in deploying a communications satellite network that turned the world into a wireless hotspot and earned $50 billion per year for its owners and provided a means to project soft power throughout the world. Retaining a portion of that revenue would provide sufficient capital to expand on this initial design.
The easiest way to improve capacity is to use the two stages as a two stage vehicle to place 65,000 kg into LEO with recovery of both stages. The ET derived first stage is recovered downrange by an aircraft loitering in the recovery area, and then towed back to the launch center where it is released to carry out a vertical touchdown. The second stage, releases its payload, and deorbits so that it is recovered at the launch center as well.
Once the downrange recovery process is well defined, the expansion then includes turning the ET derived SSTO into a Common Core booster element. Here three element booster with two strap on boosters made of modified ET as described, operating around a central element of the same design, equipped with cross feeding is made. This three element two stage highly reusable system is capable of putting 225,000 kg into LEO. This gives us a capacity to place 29,400 kg of useful payload on the moon and return it safely to Earth. It also gives us the ability to send 30 tonnes to Mars.
308,100 kg may also be placed into LEO using this larger lunar vehicle as a three stage launcher, in a manner described above.
With 225 tonnes to 308 tonnes in LEO, we can do significant solar power satellites. With 30 tonnes on the moon we can support bases there. With 30 tonnes and a power plant on Mars, we can support bases there as well.
Adding energy sales to communications sales lets the launch provider enter into the profitable energy markets earning trillions of dollars. Conversion of a portion of these revenues to your infrastructure allows them to build a 7 element launcher and associated upper stages using the same infrastructure.
A seven element system puts up over 600 tonnes in LEO, and allows the deployment of multi-gigawatt solar power satellites along with Lunar and Mars expeditions placing 80 tonnes on the lunar surface and Mars surface per flight.
Industrial development of these two worlds are now possible.
This could have been done any time after 1973 for $6.5 billion. I could not be done at that price after 2010 when the ET tool set was removed from MAF in favour of the SLS program approved after that time.
https://vimeo.com/37102557
http://www.scribd.com/doc/30943696/ETDHLRLV
http://www.scribd.com/doc/30877060/E...Launch-Vehicle
http://www.scribd.com/doc/31261680/Etdhlrlv-Addendum
https://www.youtube.com/watch?v=-0Y0FS8Z1Qk
http://www.scribd.com/doc/35449912/S...tellite-Orbits
http://www.scribd.com/doc/35439593/S...-Satellite-GEO
http://www.scribd.com/doc/29948592/Proto-Progress
http://www.scribd.com/doc/130453929/Power-Satellite
http://www.scribd.com/doc/130451640/Space-Solar
http://www.scribd.com/doc/20019383/July-11-2009
An exciting SLS derived system was possible on a short development cycle as long as Michoud was still operational. That ended September 20, 2010 when the External Tank hardware was disassembled.
At present, MAF touts artist renderings of tool sets that will build 321 foot tall 5.5 million pound rockets some day. I hope they do. However, the cost of this level of retooling adds significant unneeded costs and delays to the programme I've outlined above while throwing away the skills and quality assurance built up over decades of real world construction.
However, NASA doesn't have the funds, or the commitment for a complete system today, along the lines described on the MAF website and likely never will.
That is why as the end approached for MAF based ET tooling, I proposed a compact, minimum mass system to achieve a lunar landing soonest using totally private funds.
http://www.scribd.com/doc/20053585/M...space-Overview
http://www.scribd.com/doc/40549127/Disk-Moonship
http://www.scribd.com/doc/40623446/Disk-Moonship-2
Here we use arrays of chemical micro-rockets built into a propulsive skin to send astronauts in long duration space suits equipped with MEMS based fuel cells and life support, to the lunar surface and return them to safely to Earth.
This could still be done within the 5 years remaining. Just. The SLS based system cannot.
LOX/LH2 is the propellant of choice, however, recent success with H2O2/C combinations in making high density monopropellants, suggest that research should also be supported with the focus of reducing tripropellant combinations to bipropellant combinations feeding MEMS rocket array systems. This includes Lithium/Hydrogen/LOX combinations converted to a bipropellant system with Lithium particles suspended in LOX mixing with LH2 in the system. This not only improves exhaust speeds to the 6 km/sec range it also increases propellant density! 5.6 km/sec is possible using this system.
Recent revelations regarding Jetter cycle fusion suggest Zubrin's Nuclear Salt Water Rocket might be easily updated using that. A very compact and capable system is possible, as described, which could be developed privately in the time remaining, if work began now. The High Flux Isotope Reactor produces 85 MW of neutrons and is quite compact. Modifying this to support Li6D Jetter cycle provides a means to produce 85 GW of jet power quite simply. With a 20 km/sec exhaust speed, a 57.3% propellant fraction gets a single stage vehicle to the moon and back, using nothing more than water laced with Lithium-6 Deuteride as propellant. At this power level 866.7 metric tons of force is produced at 85 GW power level and this exhaust velocity. With a 1.75 gee take off acceleration a 495 metric ton take off weight is supported. 285 cubic meters of Li6D laced water is the size of the propellant tank. 100 tonnes is the inert mass 110 tonnes is the payload. This is 5 TEU capacity.
Such a system could not be built in the USA or Europe today.
It could be built in Asia.
Built by Cheoy Lee shipyards in Hong Kong, since they have spare capacity now. Avionics built in India by ISRO and in China. The propulsion system built and tested at Lop Nur and integrated at that base as well.
Lop Nur is where the finished ship is launched.
This could still be done in the time frame allotted, if adequately funded, for less than $1 billion.
The Chinese after all built a hydrogen bomb from scratch in 32 months in 1967.
A ship can be built by Cheoy Lee in as little as 240 days.
Super computing platforms already exist that allow us to model this in great detail (I happen to have one). So, detailed plans can be generated rather quickly. Relevant tests and sub systems proven in short times as well by experienced personnel.
This size of system would be adequate to build four suites for 8 passengers and a crew of 6 to provide luxurious service - of the type described here;
http://www.superyachts.com/luxury-ya...e/ab-116-1155/
A fractional ownership plan for 4 persons who invest $250 million each is possible. They also own the rights to half the profits from the first 1 GW of electrical generation capacity built around the core energy process. 1 GW x 8766 hours per year x $0.10 per kWh = $876.6 million per year. Discounted at 6.25% over 30 years this has a net present value of $11.75 billion. With a $1.75 billion construction cost, this leaves $10 billion - half of which is $5 billion. That's $1.25 billion returned for each $0.25 billion invested.
This in addition to what is earned after operating costs, selling excursions to the moon on the vehicle just described.
http://i.telegraph.co.uk/multimedia/...e_1626416i.jpg
Finding the right parties to back this might get us to the moon and back in less than 5 years.