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Solar System Busses



 
 
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  #1  
Old January 20th 04, 06:29 PM
John Buehler
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Default Solar System Busses

Getting massive objects moving seems to be one of the biggest
challenges that we face with exploration of the solar system. With
manned missions, the paraphernalia that processes the environment to
make it habitable contributes quite a bit of extra mass to a vehicle.

My Bright Idea:

Get the reusable mass of a spacecraft moving and keep it moving
between two or more destinations.

For example, a vehicle that travels between Earth and Mars could be as
massive as desired, continually travelling between the two planets.
The consumables for the vehicle, such as fuel for a NEXIS-style
engine, as well as transferred cargo, such as passengers and freight
would be accelerated to dock with the vehicle during its next pass.

The engines would keep the ship on course as the geometry of the
course between Earth and Mars changes. Highly efficient and low
thrusting engines, such as NEXIS engines, should be able to handle
such a task. When the orbital dynamics work out such that the vehicle
is going to have to follow a path that will take it back to its
starting point without having reached an interesting destination, the
vehicle can be abandoned, and subsequently recovered when it next
returns.

The basic idea here is to get the most massive parts of a spacecraft
moving once, and then kept moving, while the 'disposable', lighter
parts of the missions - the crew, cargo and fuel - are added at the
source and removed at the destination.

I'm thinking BIG here. Big enough that the biological needs of the
crews are self-contained and self-sustaining. With enough shielding
to avoid having to worry about significant radiation exposure.
Whatever we want, because the whole thing is going to be accelerated
one time, and then kept moving with clever swings past source and
destination with fine-tuning of paths accomplished with efficient,
low-impulse engines.

Is this notion fundmentally flawed in some way?

My biggest assumptions a

1. Transit systems (power plant, engines, shielding, life-support,
various electronics) is the largest portion of the vehicle mass.

2. Human consumables can be preserved in the vehicle through recovery
and recycling.

2. A vehicle can be continuously looped between destinations in the
solar system that are both interesting and practical to reach.
Perhaps not always the same two destinations for a given vehicle. I
assume that the transit time between Earth and Mars (for example) will
be excessive during certain periods.

3. Engines such as NEXIS can be used to tweak orbital trajectories
where simple passes of massive bodies (planets, moons, etc) cannot do
the whole job.

Yes, I'm handwaving tons of other things, but I'm wondering if, in the
most coarse view, whether this is a 'good idea'.

JB
  #2  
Old January 21st 04, 09:42 AM
Manfred Bartz
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Default Solar System Busses

(John Buehler) writes:

Getting massive objects moving seems to be one of the biggest
challenges that we face with exploration of the solar system. With
manned missions, the paraphernalia that processes the environment to
make it habitable contributes quite a bit of extra mass to a vehicle.

My Bright Idea:

Get the reusable mass of a spacecraft moving and keep it moving
between two or more destinations.

For example, a vehicle that travels between Earth and Mars could be as
massive as desired, continually travelling between the two planets.


Is this notion fundmentally flawed in some way?


No. What you are describing is a "cycler".

Googling for earth mars cycler will turn up lots of matches.

From
http://www.marsinstitute.info/rd/fac...rtr/in07.html:

Versatile International Station for Interplanetary Transport
(VISIT) cyclers were developed by Niehoff and his SAIC colleagues
in 1985. A VISIT cycler orbits the Sun four times while Earth
orbits five times and three times while Mars orbits two
times. This means that it encounters Earth every 5 years and Mars
every 3.75 years. A VISIT cycler launched from Earth on April 30,
2001, encounters Mars on November 1, 2001, then flies past Earth
again on April 16, 2006. After 20 years (five Mars and five Earth
encounters) the VISIT cycler's orbit must be "re-tuned" using
rockets. Niehoff envisions establishing a "network" of three or
more VISIT cyclers to permit frequent transfers.


My biggest assumptions a

1. Transit systems (power plant, engines, shielding, life-support,
various electronics) is the largest portion of the vehicle mass.

2. Human consumables can be preserved in the vehicle through recovery
and recycling.

2. A vehicle can be continuously looped between destinations in the
solar system that are both interesting and practical to reach.
Perhaps not always the same two destinations for a given vehicle. I
assume that the transit time between Earth and Mars (for example) will
be excessive during certain periods.

3. Engines such as NEXIS can be used to tweak orbital trajectories
where simple passes of massive bodies (planets, moons, etc) cannot do
the whole job.


Heck, by the time we are ready to have regular two-way traffic with a
Mars base we probably will also have even better and bigger propulsion
systems. So why not capture a few smallish NEOs, hollow them out, fit
a nuclear reactor, engines, life support etc, and then put them into
cycler orbits?

Sounds like a good idea to me.

--
Manfred Bartz

  #3  
Old January 21st 04, 09:24 PM
Anvil
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Posts: n/a
Default Solar System Busses

John:

The basic idea here is to get the most massive parts of a spacecraft
moving once, and then kept moving, while the 'disposable', lighter
parts of the missions - the crew, cargo and fuel - are added at the
source and removed at the destination.

I'm thinking BIG here. Big enough that the biological needs of the
crews are self-contained and self-sustaining. With enough shielding
to avoid having to worry about significant radiation exposure.
Whatever we want, because the whole thing is going to be accelerated
one time, and then kept moving with clever swings past source and
destination with fine-tuning of paths accomplished with efficient,
low-impulse engines.

-----
Moving out of gravity wells is the main fuel cost for both build and
supply.

The shear size in materials and cost to have such a vehicle manned
for Mars seems wasteful. A robotic craft should move consumables and
most equipment one-way only. Packing only additional sensors,
communications, navigation aids, and emergency supplies continuously.
The large manned systems supporting Mars exploration would be better
sited on Phobos/Deimos. The exploration crews should fast transit,
although a first slow manned transit could be made to set up such a
base and support crew.

The resources for the huge self-contained craft should be held back
until we commit to manned exploration outside Mars' orbit, but would
be essential in that role. Again I would keep this craft out and use
robotic craft to supply it, however it would loop back for refurbishing
at need.

One problem will be long-term crew selection. I don't think NASA will
commit to the profile necessary for distant station keeping. A loner,
craftsman, artisan, and engineer is very distant from a military, PhD,
social, and political personality. Doing long-term "PhDs in a can"
tests seem of limited value in developing the specification(IMO).
Crew profiles are better served interviewing desert prospectors and
the people who solo-crew Antarctic research stations during the
off-season. Any person who functions productively for years alone
and is still nice to visitors. These will be the people who must host
and at need rescue the exploration scientists.
 




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