suggest
thicknesses of 66, 85 and 75 km for Europa, Callisto and Ganymede,
respectively. These numbers are not authoritative, but might be
somewhat defensible.
Christopher England
Technologist, New Millennium Program
Thermal and Propulsion Engineering Section
Jet Propulsion Laboratory
==
You
Bruce Moomaw wrote:
And as for tides, don't forget that Triton must have undergone tremendous
ones after it was initially captured into an eccentric orbit around Neptune.
Those tides -- during the period in which they finally circularized its
orbit -- are widely believed to have completely
A habitable Mars (by hardy people, of course) might be made by dumping a
large KBO or maybe even Pluto/Charon onto Mars. This would add
volatiles and plenty of water ... and mass too. Actually, I'd prefer
Ganymede (Callisto would be easier to deflect, is more pristine and is
already in a
Paul Lavin wrote:
Run the data loss on the Martian atmosphere composition by me again. When
did this happen?
P
Thank you for asking!
The Viking lander gas chromatography-mass spectrometer (GCMS) data is
not available anywhere.
What is taken as gospel for the composition at the
Or not. Non-equilibrium atmospheres like the Earth's are a sure
giveaway. Mars has one too, but it's not so sure, too much oxygen and
not enough carbon monoxide. Titan has methane for reasons unknown.
Maybe cows.
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(1) The ST-8 pre-announcement came this morning at
http://prod.nais.nasa.gov/cgi-bin/eps/bizops.cgi?gr=Dpin=04#104194
The response date is April 18, 2003
(2) The New Millennium program is holding a workshop in Washington DC on
Feb 5-6 to support a technology planning preliminary to the ST-9
If there is life on Europa, there is intelligent life out there. We
are hoping that environments like Europa will tell us more about what
life is, and, therefore, how common it is. Europa's oceans are not
unusual environments. Any rock-ice body with a diameter ~1000 km can
have a
The meteor crater in Arizona was formed about 45,000 years ago. I'm not
much on statistics, but an interesting guess might be that such a strike
has a probability of 1/45,000 per year. This strike was a small one.
Zodiacal dust has a life on the order of 20,000 years, so why is there
any?
Robert
It's true that some of the particles coming to Earth are extrasolar, but
that's because, after they are sputtered by their star to a small size,
they are blown out of that star system, and some of it goes here.
Zodiacal dust falls inward due to the Poynting-Robertson effect (I
haven't
Hubble's days may be numbered, and JWST may be late. Maybe an interim
little space telescope is an option. No atmospheric interference and
lots of science to be had. When JWST is operational, there is no
shortage of targets, spectra and science for an LST. What may be needed
is just to turn
with a small cone shield. Otherwise,
Prometheus would be one big shield.
Ion propulsion is efficient but low in thrust (like ounces of force).
Chemical propulsion will be needed for high thrust needs like fast
orbital capture, landing and takeoff.
Chris
Christopher England
Thermal and Propulsion
It's knowing where to look, and for what to look. I don't think we (we
Earthfolk) are there yet. If there's anything certain, it is that any
life we find off the Earth will be different, likely extremely
different.
Chris
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It's stress that causes diversity in biological systems, and I would
think that tilt, with the resulting diverse environments, would be
highly favorable. For subsurface biological systems, any guesses?
Chris
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Project
Robert, Here are my answers
Chris, has anyone done an analysis to determine whether one could
produce a high-thrust ion engine complex using nanotech?
My guess would be that there would be significant gains in thrust
due to multiple micro-engines but that this might be limited due to
I love this topic.
Europa places the same face to Jupiter all of the time, as do most
satellites. I guess that it's the tidal heating that eventually
dissipates the rotational energy. I don't know of any other mechanism.
Jupiter doesn't continually flex Europa as in the balloon analogy
Good answers! Great answers. My questioning of the models is that we
don't know the interior structure or properties of the moons so we can't
calculate the tidal heating, which is dissipative.
For Europa to have thin ice (5 km), we need something like 10^13 (10
trillion) watts being
It seems to me that surface characterization on Europa should center on
discovering where the under-ice ocean communicates with the surface. I
think that this characterization is best done by remote sensing,
possibly from Earth or Earth-based telescopes. Of course, orbiting
spacecraft have a
I heard a talk by Hoffman at an AGU meeting regarding CO2 flows, and he
was ignored. Continental drift was ignored from about 1915 to 1970 even
though convincing measurements were made as early as 1912.
Hoffman's general approach on CO2 flows is described at
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