[ExI] ?Existential hysteria

[Keith Henson]

On Sat, Aug 2, 2014 at 5:00 AM,   John Clark <johnkclark at gmail.com> wrote:

snip

> People have been talking about hypersonic ramjets for years but they have
> proven to be enormously difficult to make;  I'm starting to think they will
> always be 20 years in the future, just like fusion power.

The Reaction Engines people agree with you.  However, Skylon engines
are not hypersonic ramjets.  They are precooled combined cycle engines
where the technology (except for the precooler) is very similar to
conventional turbine engines.
https://en.wikipedia.org/wiki/SABRE_%28rocket_engine%29

>> The second slide shows the cargo under way using VASIMR engines making
>> the purple glow.  The engines are powered by microwave from the ground.
>
> First use this technology to put a paperclip into Low Earth Orbit and then
> maybe we can talk meaningfully about how much it would cost to put a
> supertanker sized object into Geostationary Orbit.

Ion engines do not work in the atmosphere, not at all.  But they work
great in a vacuum.  That is what the Dawn spacecraft used to visit
Vesta and is using on its way to Ceres.
https://en.wikipedia.org/wiki/Dawn_%28spacecraft%29#Propulsion_system
It has been flying for almost 7 years now.  I.e., ion engines are not
new technology.

And while 15,000 tons of payload is considerable (about half the mass
of one power satellite), it's a long way from a 250,000 tons
supertanker https://en.wikipedia.org/wiki/Oil_tanker#Supertankers_.28VLCC.29_and_.28ULCC.29

Keith