Atomic ramjet for exploring Titan

Rick Jones wrote:
Or I suppose load the thing with a classic Tomahawk-esque radar
terrain map of Titan obtained from an orbiter?


Since it is going to take a long time for whatever you send to Titan to
arrive there, you might as well combine the balloon and orbiter into a
single mission, rather than using two separate launches.
Even if the balloon doesn't work, you will still get good data from the
instruments on the orbiter.

Pat

On Mar 19, 4:39*pm, Van Chocstraw
wrote:
Rick Jones wrote:
Frogwatch wrote:
In the late 50s and early 60s, the USA had "Project Pluto" a nuclear
reactor powered ramjet whereby a reactor directly heated incoming
air to provide thrust. *It could be capable of flying for months but
emitted a lot of radiation, maybe even a lethal dose to anything
nearby.
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies
around for months sending back data. At the end of its life, we
could simply allow it to crash OR we could use onboard solid rockets
to accelerate it to escape velocity from Titan and allow it to
either go in orbit about Saturn or to drop into Saturns atmosphere.
Such a flying machine might be just what we need to explore Venus
too. *The dense atmosphere would allow for fairly low speed flight
there.

Apart from a present lack of humans, why would it be any better for a
nuclear reactor to be spewing radiation into the atmosphere of Titan
or Venus than it would be for Earth?

rick jones

The sun is spewing much more radiation than a jump engine would.

--
//--------------------\\
* * * * Van Chocstraw
*\\--------------------//

How much of it makes it to Titan?

On Mar 19, 4:53*am, wrote:
You'd have both. *A payload would aerobrake into orbit around Titan,
using a lifting aerobrake involving multiple passes

http://adsabs.harvard.edu/abs/1986STIA...8713820D

You would release an orbiter which would circularize its orbit at the
apo-apsis *of one of the passes, while the lander continued its
descent, releasing the nuclear powered drone - which communicates with
the orbiting satellite.

http://www.youtube.com/watch?v=f1Y3ohmn-OU

Of course, a hydrogen filled balloon is also possible in this
atmosphere.

Any topic or contribution by Pat Flannery is a one way ticket. So,
even when you are right and being perfectly constructive, it doesn't
matter. Pat Flannery only replies to others of his kind. Don't feel
bad, because I'm treated the same way.

Most of Pat Flannery's topics are actually bogus to start with.

~ BG

On Mar 18, 12:26*pm, wrote:
The radiation need not spew anywhere - much of that was mis-reported
to make the ideas contained in the project seem outlandish. *That was
done to prevent folks from working on them when we decided not to.

Fact is, we can build nuclear filaments as easily as we now build
light bulb filaments and surround them with TPV stacks of tremendous
efficiency to create very powerful very lightweight very clean power
sources - to drive all manner of electric engines. *The Navy is
already working on a miniature nuclear sub and adapting this
technology provides a means to power lots of different vehicles and
appliances without any central power or fuel supply - for periods of
decades or more.

Why don't you design the entire mission of Titan or Venus using
nuclear thermal energy?

~ BG

"Van Chocstraw" wrote in message
...
Rick Jones wrote:
Frogwatch wrote:
In the late 50s and early 60s, the USA had "Project Pluto" a nuclear
reactor powered ramjet whereby a reactor directly heated incoming
air to provide thrust. It could be capable of flying for months but
emitted a lot of radiation, maybe even a lethal dose to anything
nearby.
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies
around for months sending back data. At the end of its life, we
could simply allow it to crash OR we could use onboard solid rockets
to accelerate it to escape velocity from Titan and allow it to
either go in orbit about Saturn or to drop into Saturns atmosphere.
Such a flying machine might be just what we need to explore Venus
too. The dense atmosphere would allow for fairly low speed flight
there.

Apart from a present lack of humans, why would it be any better for a
nuclear reactor to be spewing radiation into the atmosphere of Titan
or Venus than it would be for Earth?

The sun is spewing much more radiation than a jump engine would.

Apples and oranges. Not all radiation is the same. There is a world of
difference between visible light radiation and, say, gamma radiation.

The whole argument is awfully silly though. If engineers can't build and
fly nuclear ramjets on earth, how can engineers design, build, and test one
to fly on Titan? Not to mention the hazard of launching the thing.
Launching RTG's encased in protective cases designed to withstand a launch
accident and subsequent reentry is not the same thing as nuclear reactors.

Jeff
--
"Many things that were acceptable in 1958 are no longer acceptable today.
My own standards have changed too." -- Freeman Dyson

On Mar 17, 1:14*pm, Frogwatch wrote:
In the late 50s and early 60s, the USA had "Project Pluto" a nuclear
reactor powered ramjet whereby a reactor directly heated incoming air
to provide thrust. *It could be capable of flying for months but
emitted a lot of radiation, maybe even a lethal dose to anything
nearby.
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies around
for months sending back data. At the end of its life, we could simply
allow it to crash OR we could use onboard solid rockets to accelerate
it to escape velocity from Titan and allow it to either go in orbit
about Saturn or to drop into Saturns atmosphere.
Such a flying machine might be just what we need to explore Venus
too. *The dense atmosphere would allow for fairly low speed flight
there.

Seems a wee bit overkill, especially for accomplishing the planet
Venus.

There's always the Rn222 ion thruster that'll kick serious thrust (by
far the most ion thrust per kg and per applied kw.h), easily sustained
from a cache of radium that's worth 1650 years half life. Radium
decay should also make helium.

You do realize that arc-jets can burn CO2, and just about anything
else, therefore creating thrust from whatever's available.

~ BG

Pat Flannery wrote:



Alain Fournier wrote:


Only partially true. Your maneuverability is limited but you do have
some. A hot air balloon pilot doesn't just land where he happens to be
when comes time to land. Wind direction will usually vary at different
altitudes. So to steer a balloon you go up or down according to which
wind you prefer. In the case of a hot air balloon going up or down can
be as simple as giving more or less heat. In a hydrogen balloon, you
can compress a little bit of the hydrogen or let it expand to control
your height. Of course, this maneuverability is nothing like powered
flight but you do have some control.


But if you get up too high, that's where you start to run into the
turbulent atmospheric conditions on Titan; and one of those is violent
vertical wind shear, which could destroy the balloon:
http://en.wikipedia.org/wiki/Huygens_probe

But that is much higher than what I had in mind. A ballon pilot here on Earth controls his flight path (or at least
tries to) by just going up or down something like 100 m.

"Doppler Wind Experiment (DWE)
This experiment used an ultra-stable oscillator to improve communication
with the probe by giving it a very stable carrier frequency. This
instrument was also used to measure the wind speed in Titan's atmosphere
by measuring the Doppler shift in the carrier signal. The swinging
motion of the probe beneath its parachute due to atmospheric properties
may also have been detected. Failure of ground controllers to turn on
the receiver in the Cassini orbiter caused the loss of this data.
Earth-based radio telescopes were able to reconstruct some of it.
Measurements started 150 kilometres above Titan's surface, where Huygens
was blown eastwards at more than 400 kilometres per hour, agreeing with
earlier measurements of the winds at 200 kilometres altitude, made over
the past few years using telescopes. Between 60 and 80 kilometres,
Huygens was buffeted by rapidly fluctuating winds, which are thought to
be vertical wind shear. At ground level, the Earth-based doppler shift
and VLBI measurements show gentle winds of a few metres per second,
roughly in line with expectations."

Even a wind of a few kilometeres per second may make it impossible for
the vehicle to land and stay in one place for long enough to either
analyze the soil or take a sample, as the envelope of the balloon will
act like a sail and drag the probe around, particularly in the very low
gravity and with the dense atmosphere.

Yes. In fact that would even be true about a wind of a few meteres per second.
Oh! is that what you meant to say instead of a few kilometeres per second :-)

It might be smarter to have the balloon drop small surface probes as it
flies along without landing itself, and have the probes relay signals up
to some sort of satellite in Titan orbit for transmission to Earth.
The same landing problem would apply to any sort of winged
aircraft...you probably get it to land in one piece, but taking off
again could be a real problem.
Maybe a atomic-powered helicopter is the answer?
In that low of gravity with that thick of a atmosphere maybe that could
be made to work, and it probably would be heavy enough to stay in one
place once landed without the wind blowing it around till it finished
its surface examinations and lifted off again.
The combo of a thick atmosphere and very low gravity is so odd that it
makes it hard to figure out what is possible and impossible in those
conditions. You don't know if you want to go with aircraft or submarine
type analogies in regards to designs of things.

The way I would see it happen would be that you only make rather high altitude measurements when you cover an area the
first time. Before you cross a path already covered, you decide which attainable spot deserves special attention and go
down to that place. You could have a "probe on a rope", you throw it to the ground let it do what it can for a minute
and pull it back in.

But let me be clear. I don't think that ballooning is the best method to study Titan. Just because it could be done
doesn't mean it is the best way to do it.


Alain Fournier

Rick Jones wrote:

Alain Fournier wrote:

Only partially true. Your maneuverability is limited but you do have
some. A hot air balloon pilot doesn't just land where he happens to
be when comes time to land. Wind direction will usually vary at
different altitudes. So to steer a balloon you go up or down
according to which wind you prefer. In the case of a hot air balloon
going up or down can be as simple as giving more or less heat. In a
hydrogen balloon, you can compress a little bit of the hydrogen or
let it expand to control your height. Of course, this
maneuverability is nothing like powered flight but you do have some
control.


That would have to be autonomous though given the timelags. So, how
would such a thing "navigate" - by that I mean know where it was and
which way it was going relative to some desired destination? Does
Titan have a magnetic field to use as a reference? Occasional signals
from something in orbit?

Yes a serious problem. That would be a problem also for an airplane probe or a helicopter probe. Given that a hot air
balloon pilot here on Earth tries to control where he will land but doesn't always succeed very well, doing it by an
artificial intelligence system on Titan would probably be harder for a balloon than for an airplane or helicopter.


Alain Fournier

On Mar 18, 12:23*pm, wrote:
TPVs are capable of 30% and more -

http://www.appliancedesign.com/CDA/A...ogy/21925cf0a0...

Electric light bulb filaments are capable of 3,000K and more -http://hypertextbook.com/facts/1999/AlexanderEng.shtml

Though not in the open literature, small self-heated nuclear filaments
that self regulate (neutron cross section changes with temperature)
and operate stably in a background - provide a means to create a tiny
very powerful very long lived very robust power plant - that with a
TPV stack turn into a very compact safe reliable etc., electrical
energy source with very high power to weight - to drive all manner of
electric engines.

http://en.wikipedia.org/wiki/File:Bo...trator_AB1.JPG

Those TPVs are in fact terrific, and by all means we could put such to
work rather nicely (especially in cold environments) once having
included the "GaSb infrared-sensitive photocells and wavelength-
selective mirrors". TPVs and a Stirling engine process and/or
directly powering the CO2 arc-jet could even be ideally suited for the
Venus application, whereas the rigid airship buoyancy of 64+ kg/m3 and
90% gravity is going to go a long ways without demanding all that much
energy.

Odd that no one else seems to have your atomic lightbulb filament
interpretation of TPV applications.

Once again, we're talking about decades old technology that may never
get utilized. At this rate, you and I are going to die long before
anyone here figures how to use fire, much less of any complex realm of
synfuels and h2o2.

~ BG

On Mar 17, 1:14*pm, Frogwatch wrote:
In the late 50s and early 60s, the USA had "Project Pluto" a nuclear
reactor powered ramjet whereby a reactor directly heated incoming air
to provide thrust. *It could be capable of flying for months but
emitted a lot of radiation, maybe even a lethal dose to anything
nearby.
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies around
for months sending back data. At the end of its life, we could simply
allow it to crash OR we could use onboard solid rockets to accelerate
it to escape velocity from Titan and allow it to either go in orbit
about Saturn or to drop into Saturns atmosphere.
Such a flying machine might be just what we need to explore Venus
too. *The dense atmosphere would allow for fairly low speed flight
there.

Seems a wee bit overkill, especially for accomplishing the planet
Venus, whereas Mook's TPVs might be sufficient.

There's always the Rn222 ion thruster that'll kick out serious thrust
(by far the most ion thrust per kg and per applied kw.h), easily
sustained from a cache of radium that's worth 1650 years half life.
Radium decay should also make helium.

You do realize that an atomic arc-jet can burn CO2, and just about
anything else, therefore creating thrust from damn near whatever's
available.

~ BG