Wednesday, August 31, 2005

How to travel to the planets cheaply (and in style) !

How to travel to the planets cheaply (and in style) !

It is most easily explained by a simplified example :
We have a hundred ton satellite that is orbiting Earth at 18 000 mph .
This is made up by 50 tons of mass-driver , power and guidance which we can call the Orbital Reusable Reaction Mass ( ORRM for short ) and the passive payload of 50 tons .

The ORRM satellite’s mass-driver accelerates the payload to 36 000 mph in the direction of orbiting . In reaction , according to Newton’s Laws , the ORRM satellite is now orbiting in the opposite direction at 18 000 mph .

Our payload is on its way , but the important thing is that the reaction mass ( the ORRM satellite ) is intact and still in orbit . It can be re-used over and over again . Energy can be obtained from solar power . Orbital rondezvous are an established technology . The software for orbital calculations required to keep the ORRM’s in orbit ( whether around Earth , Mars , Venus , the Sun , etc ) is off-the-shelf .

We can send ORRM’s into solar orbits to be available for fast-transit voyages between planets . For instance , Earth to Mars can be done by sending unmanned ORRM payload packages ahead . The manned trip will be a rather intermittent acceleration affair , but it sure beats months of weightless travel .

Rather like sailing ship between supply-ports in the old days .
But it will be cheap . And the style will depend on whether you go first-class or steerage .

Furthermore , no ORRM need ever to be decommissioned ! It can always be parked in a reusable orbit after speeding it’s latest cargo on it’s way .

We can envisage a solar system filled with millions of ORRM satellites , orbiting the planets and the sun , using solar power to fling the traveller to his destination in whatever style he desires .

At first , every pound of mass will have to ferried up from Earth’s gravity well . Expensive! But costs will nosedive as access to materials in orbit and vacuum (where mass-drivers can be economically used) become available . The debris-fields around Earth , then the Lagrange points spring to mind . After that , the Moon is an ideal platform for mass manufacturing and launching of ORRM’s .

To get into a vacuum-orbit from a planetary surface will be the most expensive part , but after that it will be very cheap .

We can see some interesting sociological effects :
A high entry-cost but cheap maintenance thereafter was the driving force of Western maritime expansion . (eg the Caravelle,Carack) , enabling adventurers to seek fortune where they could find it .

But what will be the treasure of space ? It is mass in vacuum .
First-off , the stuff in orbit . Earth debris will be snuffed up . Historical items like Hubble or ISS will be in grave danger of ending up in an ORRM . Lagrange debris will be next . Then the Moon . But the real value will lie in locations that give optimum transition times between sites . Not just the start and end , but the the whole orbital path . (In a low-cost environment , even small advantages count for a lot .)

We can envisage that the whole Solar Volume is owned by various parties , with the value fluctuating according to orbital dynamics . (Eg owning ORRMs on the shortest route between Earth and Mars will be more valuable than elsewhere . Economics will then ensure that the most profitable routes are serviced extremely well and cheaply .)

Warfare will also be cheap . Competition over the control of lucrative orbitals , ORRMs and mass in vacuum will be sharp .
The Moon will probably remain under some sort of Earth control
Phobos and Deimos should be very valuable . Also the airless moons of Jupiter and Saturn . Asteroids near major trade routes will also be of value .

Insolation and terraforming :
Cheaply moving large masses in orbits gives us the capability of controlling the intensity of sunlight on a planet . A thin screen of reflective dust-particles pumped from mass-drivers on the Moon in a hyperbolic orbit in front of the Earth will reflect any desired degree of sunlight . So Earth will be the first to be terraformed , political considerations permitting .

Mars will be even easier : a dynamic reflector layer behind it can warm the planet without worrying about the indigenes . And it has moons in vacuum! (I told you they are valuable!)

Venus will need a bit more beef : maybe using Mercury material and energy for the dynamic shield . Only real men need to apply !

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