Impulse transfers for interplanetary travels
What is best to send humans to Mars? A lightweight station with few
commodities that makes the travel in a few months, or a big and
comfortable station that takes nearly a year to arrive? In the first
case you spend the money on high technologies and propellant. In the
second you spend the money to assemble a big cruise station. The second
possibility is not that comfortable since it implies a longer travel.
A compromise could be to launch a big and comfortable station towards
Mars, with lots of redundancies and spare room, and shoot loads at it
electromagnetic linear accelerator, from Earth orbit or from Moon
The station would carry an electromagnetic decelerator to capture the
loads. By sending that way bits of impulse towards the station it would
accelerate towards Mars. Arriving at Mars it can rely on
aerobraking to be caught by the planet. On the way back, again it can
be shot at to fall to Earth orbit.
Many scenarios exist for the loads being shot towards the station:
- They can be simple Moon rocks or utilitarian
items like propellant, structures or equipment and food for the
- They can be lots of fast grind or slower and bigger structured
- They can be accelerated using other means than a linear
accelerator. Reciprocally they can be captured back by an impact
shield, a rotating tether...
- The device that captures the loads can be separate from the
station. For example it can be sent slowly towards the incoming load
then drift back to the station to share the impulse and possibly
transfer the goods that arrived. A ladder of station pieces can
be established, that inflates and deflates for each incoming load. The
echelon that catches the loads should be the most sturdy one.
- The loads can be shot directly towards the station or be shot
along elliptic trajectories, either away or towards the Sun, even
before the station starts its journey. That way they can arrive at the
station from lots of different angles and benefit from gravitationally
- Either the loads can be equipped with trajectory control tools or
the station can be equipped to move its catching device
on a large array.
- The station's linear decelerator can be used as an accelerator to
shoot back either
caught rocks or empty containers. Those loads can either be aimed
towards a catching device on the Earth or only serve to get more
- If a load is being received by a linear decelerator it will
produce a flash of electric energy. That energy can be stored in
electric condensators or supraconductive coils. It can also be used to
simultaneously launch a load using a linear accelerator. This somehow
ressembles a cable car system. If the electric yields of the linear
devices are high, the speeds of the loads are kept relatively low and a
high flux of masses is maintained, quite a strong impulse can be
transfered to the station with a low electric energy investment.
I like the idea of the astronauts constantly receiving fast deliveries
and be able to send items back to Earth (for example medical samples).
also like the idea of the station having sealed habitable parts for
emergencies and safety, altogether with many different sources of food,
water and air. Part of these items can be left in Martian orbit, for
the next to come.
What kind of orbit would be best for the station once around Mars? If
still rely on loads shot from the Earth (or from Mars' moons) this is
a secondary problem. Otherwise, I suppose best is to leave most of the
station in very high orbit above Mars, get a part to low orbit and
descend to the ground with landing and return devices. Another way
round is to use one station to get to Mars and another station to
travel back to Earth. Then none of these two stations would have to get
into orbit around Mars. Maybe in a near future a set of stations will
constantly travel from Mercury to Mars, along elliptical orbits. Their
paths would constantly change, using several methods altogether.
Astronauts would embark and leave as they pass near Mercury, Venus, the
Earth and Mars. It seems around Venus only a space station would be
habitable. On Mercury, the Moon and Mars, scientific stations can be
established and later on permanent settlements. I suppose industrial
activities can be held aboard the cruise stations to pay for at least a
part of their costs, just like industrial activities are currently
being held aboard the ISS. Once the technology involved in the stations
is deemed reliable on the long term and their size grew sufficiently,
those drifting villages can be sent further away, to Jupiter, Saturn
and their inhabitable moons.
Stations can shoot at one another to transfer loads and to help each
other change trajectories. Two stations traveling towards each other at
high speed can exchange loads to slow down and be able to dock. Two
stations continuously exchanging loads can make one fall down to close
Sun orbit and the other to leave the solar system. A station with a
giant electromagnetic accelerator can land on an asteroid and shoot its
dust towards another station to allow it to leave the solar system at
Can a station shoot loads towards a planet or moon, have the loads
accelerated or decelerated by the planet or planetoid and catch the
loads back? I suppose yes. That way a station can change its trajectory
or orbit autonomously. This may take years in some circumstances...
September 10 2006 till October 4 2006