Rare earth

Isn't that the name given to the land mass millions of years ago before it split into the Continents we have now?

It was actually called Gondwanaland, and was indeed the supercontinent that existed about 600 million years ago. It was one half, actually, of a duo of supercontinents - the other being Laurasia. The primary landmass was Pangea before the split.

S.

"You were dragged into existance for that purpose,and when the DNA molecules have done with you you will die.
Know anybody over 150 ?

Well, I don't personally know anyone over 95 but the oldest human age reached is 122.5 years. However, extensive research is ongoing into extending the human lifespan, such as stopping oxidative processes (oxygen free radicals cause a gradual deteoriation of tissue and cells), caloric restriction (eat less!), hormone treatment and gene manipulation. Researchers have already increased the lifespan of dogs by 20% using caloric restriction, and with gene manipulation, have increased the lifespan of mice by 50 to 75%. Unfortunately, at the moment, there's no such thing as a free lunch and most of this research leads to sterility or reduced fertility but it's a young science so I wouldn't put a limit on the human lifespan just yet.

DNA will figure large in discussions about getting to Mars and elsewhere. Cosmic Rays cuts DNA to pieces. There is no protection from Cosmic rays half way between here and Mars !

Most cosmic rays get stopped at the heliosphere, only the fastest get through to the inner solar system (those moving at +0.5c) so interstellar spacefarers will be at more risk. Cosmic rays do of course pose a threat to astronauts but those who landed on the Moon were exposed to cosmic rays and survived very well. The thickness of shielding necessary to stop cosmic rays precludes its use on spaceships but current reasoning is that exposure to cosmic rays on astronauts during a two year trip to Mars is likely to increase the risk of fatal cancer by a few percent. It's not cutting DNA to pieces.

Thanks for spotting the typo dmcdona.
Never spotted myself dropped the "na" typing Gondwanaland.
Why didnt U tell me before ?

Peter.

Just One trip Gorgdon!
Risk goes up a few percent !

After 5 years in that environment you and your DNA are cut to shreds.

One meter of lead shielding only serves to smash up the incoming protons to riddle you only even more efficiently.

Where does that leave Martin colonies except buried deep under the martian surface.

Who wants to live like that ?

(P.S. After my unspotted typo I've migrated to Pangea..easier to spell!)

Peter.

Just One trip Gorgdon!
Risk goes up a few percent !
After 5 years in that environment you and your DNA are cut to shreds.
One meter of lead shielding only serves to smash up the incoming protons to riddle you only even more efficiently.
Where does that leave Martin colonies except buried deep under the martian surface.
Who wants to live like that ? Peter.

Petger, there is a vast amount of ongoing research into how astronauts can be shielded against cosmic rays. NASA set up a working Group in 1995 and you may wish to have a look at the document published in 1997 titled "Shielding Strategies for Space Exploration" at: www-d0.fnal.gov/~diehl/Public/snap/meetings/NASA-97-cp3360.pdf
Due to weight, you can rule lead out as a form of cosmic ray shielding. There are more efficient methods being researched. One exciting research area is the use of superconducting magnet technology, in other words, creating a magnetoshpere to envelop the spaceship or habitat. Hybrid systems such as plasma shields (a combination of magnetic shields and electrotrostatic shields) are also being studied. Systems such as these could be even more effective if used with a solid mass shield.

I am quite optimistic that science and human ingenuity will eventually overcome whatever problems lie in the way of space exploration, including those pesky GCRs.