[X] My Assistant

[Redstone]

The Chair's report from the November meeting of the Mars Exploration Program Analysis Group is now online at http://mepag.jpl.nasa.gov/meeting/nov-05/index.html.

Here are some features on their draft exploration plan after MSL in 2009.

• 2011/2013 Scout and Mars Science Orbiter with telecommunications capability
• 2016 Mid-rovers or Astrobiology Field Laboratory
• 2018 Scout
• 2020 Planetary Evolution and Meteorology Network
• 2022 MSR Orbiter with Telecom
• 2024 Mobile MSR

I'm not sure how fixed this is, or how much it dovetails with NASA HQ's plans, (pretty close, I'd guess) but it gives us something to chew on until Bruce's Astronomy article comes out.

Note that the 2011 window is now shared with a new orbiter with "telecom capability" This sounds like the return of MTO, with science instruments added. Any ideas what instruments are at the top of the wish list for such an orbiter? If it launched in 2011, it could still play a big part in the MSL mission and be ready for the next rover in 2016. Remember by 2011 MRO will be six years old.

The Astrobio lab is an MSL scale rover, while the "Mid-rover" is intermediate between MER and MSL.

Mars Sample Return has been pushed out to 2022/24. This seems a pessimistic "who knows?" timeframe to me. A manned mission could be on the way by 2030, if the Vision for Space Exploration pans out. (A BIG "if", I know.) Sample return will have to be completed before humans go, I would imagine.

[Guest_BruceMoomaw_*]

The trouble with "Nprev's theory" -- quite apart from the fact that, wherever we humans spread ourselves, we'll be able to spread our deadly little weapons (especially the biological ones) far more easily -- is that, if his scenario is possible, any SINGLE intelligent species that ever pulled it off would have spread across the Galaxy by now. I have trouble believing that the evolution of intelligent life forms in the galaxy is so rare that we're the very first -- or for that matter the tenth -- to arise in the Milky Way; we are, after all, talking about 400 billion stars. It makes much more sense to assume that, whenever intelligent beings do arise that are capable of technology, they inevitably do themselves in shortly after acquiring that technology.

[David]

The trouble with "Nprev's theory" -- quite apart from the fact that, wherever we humans spread ourselves, we'll be able to spread our deadly little weapons (especially the biological ones) far more easily -- is that, if his scenario is possible, any SINGLE intelligent species that ever pulled it off would have spread across the Galaxy by now.  I have trouble believing that the evolution of intelligent life forms in the galaxy is so rare that we're the very first -- or for that matter the tenth -- to arise in the Milky Way; we are, after all, talking about 400 billion stars.  It makes much more sense to assume that, whenever intelligent beings do arise that are capable of technology, they inevitably do themselves in shortly after acquiring that technology.

What wonderfully positive thinking. Can I have some of those happy pills you're taking?

Let me see: of those 400 billion stars (I'll accept the number, though isn't it a bit high?) maybe 390 billion are of spectral classes very unlike the sun's, making LAWKI rather unlikely.

Of the remaining 10 billion, let's say 1 in 10 has a planet in the rather narrow habitable zone.

Of that 1 billion, let's say 1 in 100 (I'm feeling generous) develops life.

Of that 10 million, 999 in 1000 permanently remain oceans of monocellular life.

Of the remaining 10,000, 999 in 1000 have a spectrum of multicellular life; there are hundreds of planets on which the most advanced creature is a kind of jellyfish the size of my hand; there are maybe a hundred on which there are large, mobile forms of animal life. In 1 out of a thousand (this is really generous) there are intelligent life forms.

Of these 10, just 1 species has formed the technology to transmit and receive radio signals (5 of the other 10 are still wandering toolless in their planets' equivalents of jungles and savanna; 2 others have developed stone tools; 2 others have developed a metallic technology, but one is illiterate and the other one is still working on the rudiments of geometry).

The 1 remaining species can't figure out how to raise enough funds to go beyond its planet's only satellite, and if this attitude is a fixed characteristic of the species, is unlikely ever to go beyond the edges of its star system.

Now, I pulled all of those ratios out of my rear, um, pocket, except for the number of stars with a G-type spectral class (or something close), which is itself a ballpark figure. But you can see that it is very easy to winnow down the apparently huge "400 billion" figure to something very small. And that has nothing to do with the supposed propensity of civilizations to destroy themselves (one may note that in our sample of one, this has not happened). But with a slightly more optimistic set of ratios, you could "prove" that a Galaxy ought to have a thousand civilizations; and with a slightly more pessimistic set, you could show that 1 civilization per galaxy is on the high end, and it really ought to be 1 civilization per 100 or 1000 galaxies.

[ljk4-1]

Let me see: of those 400 billion stars (I'll accept the number, though isn't it a bit high?) maybe 390 billion are of spectral classes very unlike the sun's, making LAWKI rather unlikely.

The data I have is that of the 400 billion stars in the Milky Way galaxy, roughly half are Sol-type stars, so this should up the ante a bit at least for life in general.

You can add more to the odds in favor of life with the current theories that even red dwarfs may be friendlier to life on any worlds they may have than once thought. They will certainly last far longer than our Sun.

http://www.emse.fr/~yukna/researchers/reddwarf.htm

http://space.com/scienceastronomy/051130_small_planet.html

http://www.kencroswell.com/reddwarflife.html

To put a terrestrial perspective on why it isn't so easy for us to find another world with life - or they us - imagine the stars of the Milky Way as grains of salt. You can hold about 10,000 grains in your hand. To equal the amount of suns in our galaxy, the equivalent amount of salt would fill an average classroom to the ceiling and pour out the windows.

Now find the one yellow dwarf grain in all of that, with the microscopic blue dot circling it.

[Stephen]

The data I have is that of the 400 billion stars in the Milky Way galaxy, roughly half are Sol-type stars, so this should up the ante a bit at least for life in general.

How are you defining "Sol-type Stars"?

If we don't count white & brown dwarfs, the overwhelming bulk of stars in the galaxy are red dwarfs, which I would hardly classify as "Sol-type" stars. For example, the table on this page (which assumes a total stellar population of 400 billion for the Milky Way) puts them at over 70%.

(Such numbers are still only guesstimates, of course. But that said if you look at lists of stars closest to the Sun, where our statistics are most complete, such as the this RECONS one of the 100 nearest stellar systems, most are red dwarfs; and many of the remainder are at the dim end of the K spectral type.)