MARS - Water and Life

"Where there’s water on Earth, there’s life. Is the same true on Mars?" PBS NewsHour 9/28/2015

Excerpt

SUMMARY:  NASA has found evidence of liquid water on Mars.  Science correspondent Miles O’Brien joins Judy Woodruff to discuss the inevitable question:  Does this mean there could be some form of life on the red planet?

JUDY WOODRUFF (NewsHour):  Finally tonight: big news from outer space.

NASA today announced that it has found evidence of liquid water on Mars, at least during certain seasons of the Martian year.  The discovery was made through satellite images, which revealed darkly shaded streaks on slopes of craters and hillsides.  They darken and lighten over time as water seeps across the surface, and then evaporates.

For more on what it all might mean, I’m joined by science correspondent Miles O’Brien.

Hello again.

MILES O’BRIEN (NewsHour):  Judy, good to see you.

JUDY WOODRUFF:  So, how do they know it’s water, Miles?  They don’t — there hasn’t been a human there to look at it.  They’re looking through satellites.  What — how do they know?

MILES O’BRIEN:  The HiRISE instrument, which is on the orbiting Mars Reconnaissance Orbiter, is a very sophisticated instrument and has the ability to do spectral analysis.

So, it can actually look at how light moves through whatever is flowing there.  And it gives unique signatures of water and in this case a lot of salt.  It’s the salt that is the key here, because Mars is cold and has an atmosphere which is almost nonexistent.  So, the idea of water flowing there is hard to imagine.

JUDY WOODRUFF:  But this flies in the face of what scientists thought for a long time, or have they been building up to this?

MILES O’BRIEN:  Well, there is a huge body of evidence that Mars at one time was warm and wet, and we think probably a cushy birth for life.

So, we have been looking for evidence of ancient life, fossils, for example.  There has always been this thought that maybe the water is underneath in an aquifer.  Could it somehow rise to the surface on certain occasions in certain ways?  That’s been a big question.

They first spotted these streaks back in 2010.  It sure looked like water.  But what would keep it flowing?  And the key was, they found these percolates, these salts in there.  It’s extremely salty water.  Think of why do — how do we get snow off our roads in the winter?  We use salt.