Fresh Idea to Achieve LEO

I totally agree with you on the ET issue. No matter how many times
it is stated, or how many times I read about the waste of ETs in
space, I am baffled by the short-sightedness of the NASA
administration. There is at least one company trying to change all
of that. I think that we should put our energies into one company
who is bent on turning that dream into reality, and that is the Space
Island Group: http://www.spaceislandgroup.com

--- In spacesettlers@y..., "Ed Minchau" wrote:
> --- In spacesettlers@y..., phoebos@w... wrote:
> > I personally believe that it would be cheaper just to design and
> launch
> > inflatable modules, as recovering these wasted tanks would be
such a
> > pain in the butt. Inflatable modules would not take up much
cargo
> space
> > and would be relatively lightweight. What would the costs be to
> launch
> > a conversion facility and propellant to boost the orbit of one of
> the
> > external tanks? I'll bet I could lower that cost with an
inflatable
> > station. Tether it to the Iss, or let it free float, whatever.
> > Inhabitable volume at the lowest cost possible is really more the
> issue
> > than if we can salvage and recover these wasted tanks. Could we
> salvage
> > them? Sure. Could we convert them into useful habitats? I have
> faith
> > that we could. But is that truly the most cost effective and
> practical
> > way?
> >
> > Everything boils down to cost. I, personally, would be in favor
of
> a
> > slightly higher federal tax, if it funded NASA.
>
> I agree, an inflatable habitat makes a lot of sense; only thing is,
> nobody's built and flown one before (although the Russians have
> inflated a large ballon in space). It would certainly reduce the
> mass of the overall structure, as well as the size of the payload
> launched.
>
> Right now, external tanks are being wasted at the rate of about ten
> per year. There will be about another 200 shuttle flights during
the
> working lifetime of the International Space Station, and present
> policy dictates that all those tanks will be wasted, too.
>
> The current launch trajectory of the Space Shuttle is decidedly sub-
> optimal: the orbiter and external tank reach about 98 or 99% of
> orbital velocity, then the engines cut off, the tank is released,
and
> the orbiter starts up its engines again, using on-board fuel. If
> they simply went directly into orbit and took the tank with them,
> then there would likely be fuel left in the external tank (and
surely
> in the 17-inch lines). Furthermore, the orbiter's on-board tanks
> would be full.
>
> NASA needs to make this energy-wasting maneuver to ensure that the
> external tank will tumble into a remote area of the Indian or
Pacific
> Oceans; as they presently have no orbiting tank salvage system,
they
> need to ensure the ET enters the atmosphere at a predicatble
> trajectory. If they simply released the ET in orbit, it would make
> about 200 orbits before re-entry (about 10-15 days), depending on
the
> orientation of the tank, whether or not it was tumbling, etc., and
> the re-entry point, angle, and velocity would be unpredictable, as
> would the impact zone.
>
> There is enough space in the intertank along the ring frame to
mount
> small booster engines, fuel line adaptors, small tanks, a covering
> for the SOFI, communications equipment, maneuvering thrusters,
hoses,
> folded solar panels, a folded passive heat dissipation panel, and
> snake robots to put it all together (either semi-autonomous
> teleoperated, or completely autonomous). It could be done in under
> 4000 kg.
>
> Such a system could use residual fuel and oxygen (there would be
> about 10000 kg of Oxygen and 1000 kg of Hydrogen left over) to fuel
> the maneuvering thrusters and small booster engines and thus
> circularize the orbit (higher up than the ISS), and still have
either
> Hydrogen or Oxygen left over. Once two or three tanks are in orbit
> together (rendezvous may take many orbits), residual fuels can be
> pooled in one ET, parts of the existing orbital salvage system can
be
> re-used to build an orbital maneuvering vehicle. This could be
used
> to retrieve other ETs that were not equipped with a full salvage
> system (maybe just the SOFI covering and other cargo in the place
of
> engines etc). Even if only half the tanks that would otherwise be
> wasted on the remaining shuttle flights to the ISS were instead
> salvaged, that would be 100 tanks in orbit.
>
> Once there are two or three in an orital cluster, it makes sense to
> start launching rockets directly to the cluster; my first choice
> would be a tank of liquid Nitrogen, launched by SeaLaunch (max
> payload about 10m long by 4 m diameter, max 5250 kg); the N2 and
> residual O2 could be used to provide an atmosphere in one of the O2
> tanks, and the N2 tank could be re-used, perhaps as a cargo airlock
> positioned at the nadir of a hydrogen tank.
>
> An earlier post mentioned that there was only one hatch on the ET,
at
> the bottom of the LH2 tank (and of course the intertank access
door,
> which does not enter either the LH2 or the LOX tank). It turns out
> that there are two man-sized (3ft diameter) hatches on the bottom
of
> the LH2 tank (one is blocked by the Hydrogen funnel); there is also
a
> 3ft hatch at the zenith of the LH2 tank, at the nadir of the LOX
> tank, and at the zenith of the LOX tank (blocked off by the
> nosecone).
>
> Perhaps a good use of an inflatable structure might be an airlock
> that could be fitted through the intertank access hatch, attached
to
> the LH2 and LOX tanks, and a second airlock between the first and
the
> intertank access hatch. The only solid structures would be the
seals