Re: starship-design: Tau Ceti, It and Planets

[KellySt@aol.com]

In a message dated 6/9/97 10:02:30 AM, stk@sunherald.infi.net (kyle) wrote:

>I am new to this project, so try to bear with me.
>
>I read that you are planning the mission to be for the star tau ceti. I
>would
>like to express my feelings about this choich, and voice my findings
>regarding
>the star and its solar system. I think tau ceti is a wonderful
>destination. It is
>quite sunlike, and the first planet seems good. I have some info on the
>star itself:
>
>Spectral Type: G8V
>Mass: .82 suns
>Distance: 11.9 ly
>Apparent Magnitude: +3.5
>Main sequence lifetime: 16.43 Gyr
>Age (current): 5.38 Gyr
>Radius: .80 suns
>Surface gravity: 341.7 m/sec^2
>Escape Velocity: 621 km/sec
>Luminosity: .41 suns
>Absolute magnitude: 5.7
>Surface temperature: 5144K
>Peak wavelength(micron): .56
>Outer Ecoshell radius: .64 au
>Inner Ecoshell radius: .79 au
>
>Tau Ceti I:
>Mean orbital distance: .72 au
>Eccentricity: .00 (why not?)
>Axial tilt: not established
>Year: 246.4 earth days
>Star system escape velocity: 44.97 km/sec
>Angular diameter of star: .60*
>Rotation period: not established
>Mass: .21 earths
>Radius:3800 km
>Density: 5464 kg/m^3
>Albedo: .33 (why not?)
>Inertia Factor: .34? (an educated guess)
>Gravity: (typical) 5.80 m/sec^2
>1/ellipticity: 294.1 (why not?)
>Escape velocity: 6.64 km/sec
>Shortest possible rotation: 2.64 hours
>Geosynchronous orbit: 21274 km (something like that)
>End of major plate tectonics: 1.68 Gyr (we don't have to worry about
>alien Mt.St Helens!)
>Maximum mountain height: 28067 m (probably lower than that)
>Atmospheric composition: O2, N2, CO2, H2O vapor, percentages unknown
>Atmospheric Pressure: What, you're asking me??
>Temperature range of orbit: -32.4 to -37.2C
>Surface temperature: (45*) about -7C or 19.4F (assuming good greenhouse
>effect) Bring jackets!
>Mid ocean tide height: .22 m (something like that)
>
>Conclusion: Sounds good, a bit chilly but survivable. Oceans probable
>from H2O signature in atmosphere, Life probable due to O2 and CO2
>signatures. I would recommend that we find out the atmospheric
>percentages ASAP. (after all, this is 2050, and in 1997 they've already
>discovered over a dozen planets. I think we could do that) Pressure
>could also be helpful. (Maybe we have an advanced platform studying
>extrasolar planets, like NASA's GAEA concept, or the DARWIN concept.
>Take jackets, as the weather report shows cold for another 10 billion
>years. (a little humor). 
>
>Well thats it. Respond when you have a chance.
>				Kyle R. Mcallister

Welcome to the group Kyle.

Where are you geting this info from?  From what I remember we never defined
the place in this much detail.  (I also remember very little grav or air on
planet 1.)

Kelly Starks