New Mars Forums

It is just too tempting to get the 6.4 km/sec delta vee for "free".  The problem is that the mass ratio (inital/payload) is an exponential function of delta vee.  All else being equal, your payload will be reduced by a factor of 1/10 (or your rocket has to be 10 times bigger initially).  You'll always take the aerobrake risk if it's available.  For chemical rockets anyway.

***EDIT to use a more reasonable specific impulse.

Actually they are quite efficient.  Chlorophyll only responds to these frequencies ...

... so a two color LED array wastes very little power ...

Hi Major Tom (I love that song), welcome to New Mars.

Speculation has it that the object is the heatshield that separated from the lander during EDL.

This is the polygonal terrain they were looking for (similar ice modified terrain occurs in Antarctica)

A false color image ...

http://www.unmannedspaceflight.com/inde … 5&start=15

What!?  Minorities have rights?  That's quite a big step for you Terraformer.  Careful though, next you'll be imagining what your life would have been like if you'd been born into a minority, and we all know where that leads.

The Soyuz TMA-11 ballistic re-entry was caused by the failure of the equipment bay to detach ...

http://abcnews.go.com/Technology/story?id=4901625

Einstein understood Quantum theory very well.  He just didn't like the implications.  In particular that Bell's Theorem ...

http://en.wikipedia.org/wiki/Bell%27s_Theorem

... requires that we abandon locality (allow "spooky action at a distance") or counterfactual definiteness (things exist even when you're not looking at them).  Most physicists choose to abandon locality, but Einstein didn't want to give up either - and who can blame him?

Here is an article that talks about how far out TV signals may be detectable ...

Aliens Can Watch `I Love Lucy', Lou Scheffer
http://contactincontext.org/cic/v2i1/lucy.htm

Here is a web calculator for other types of signals ...

SETI Range Calculator, Eric Johnston
http://www.satsig.net/seticalc.htm

Note that we think that _very_ large "virtual dishes" can be constructed using  VLBI techniques ...

http://en.wikipedia.org/wiki/VLBI

Is it really?  Isn't a God of the Gaps even less satisfying that Creationism?  At least "Let there be light" has poetry.  This whole "scientists can't explain that, so God did it" and then, when science explains that, "well ... you still can't explain this different thing, so God did it instead."  I mean it is just embarrassing.  They are shooting themselves in the foot by making God just another name for ignorance.

You can use the same formula, but you run up against a pretty important limit - the age of the universe.

It's that first figure that is the kicker.  On average, galaxies are 1 million light-years apart.  So travel times alone could easily be on the order of 10 million years.  But suppose that 1% of populated galaxies colonize a new galaxy every 10 million years.  Then, you'd need 25 billion years (and that's not even counting dark matter galaxies http://en.wikipedia.org/wiki/Dark_galaxy ).  But the estimated age of the universe is 14 billion years, so even if some civilization began an intergalactic colonization program soon after the big bang, they'd still only have colonized 1 in a million galaxies.  And if life didn't arise anywhere until, say, 8 billion years ago (after supernovas had some time to create the heavier elements) then they'd have colonized only 1000 galaxies. 

On those timescales though, who can know?  I mean, 100 years ago, it was thought impossible to travel in a vacuum because there'd be nothing to push on.

Yes indeed.  But this seems to suggest a higher lower bound on the chance that a random star system is inhabited. 

Doesn't your figure suggest that there are only (400e9)(1/400e6) = 1000 habitable star systems?