Comments on: Scientists ponder next 50 years of space exploration

NASA holds two-day conference to look at the last--and next--50 years in space exploration.

[Lolo Gecko]

but, where is ...

Buddy Holly when we really need him :)

[indedave]

4 percent of matter

Hmmm, I know that politicians are dense, but I didn't think they had swollen up to the size of 6 billion galaxies ("all the matter on earth makes up 4 percent of the universe"). This probably should read "all the matter detected from earth makes up 4 percent of the universe." BTW, "dark matter" is theorized to comprise an additional 20 percent, the rest is ascribed to "dark energy."

[zero_point]

I thought so

Thanks for that indedave, as I too couldn't believe my eyes when I read that in the article. What's more, the guy who was quoted saying "all the matter on Earth makes up 4 percent of the Universe" is the "chief technologist at JPL and professor at Caltech." Go figure...

[skrubol]

Maybe 4 percent of unique matter?

Maybe he meant 4 percent of all the different elements and compounds?

[mastermaq]

4% = baryonic matter

Presumably he means "familiar matter"...from Wikipedia:

"Cosmological observations suggest that about 73% of the universe consists of dark energy, 23% is composed of dark matter and only 4% corresponds to the visible baryonic matter which constitutes stars, planets and living beings."


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

[grey_eminence]

Interplanetary and Interstellar Travel

cannot be based on what is today's technology and
the nuclear detonation Orion program will pollute
the space environment as well as Earth.

Some green propulsion must be developed. Here is
one example amoung many that could work.

http://nlspropulsion.net