On 3/16/2017 10:25 AM, dlzc wrote:
On Wednesday, March 15, 2017 at 8:41:45 PM UTC-7, Yousuf Khan wrote:

The article you linked to is from 2011, and
it's about a totally different issue. It's about an early warning
system for solar winds, so putting a satellite at the L1 would
encounter the solar wind 43 minutes before Mars itself does. But
due to the higher speed of light, which gets to Mars in 3.5
seconds, you have 43 minutes - 3.5 seconds of early warning
about it.

The issue here is not about early warning, but about redirecting
the solar winds completely from Mars. So early warning really has
no bearing on anything here, except that if the parameters of the
magnetic shield need to be adjusted, you have about 7 seconds of
turn around time to react from Mars.
The solar wind takes 43 minutes to reach the orbit of Mars. So a
"shadow" in solar wind created by an object at the L1 point, crosses
Mars orbit 61,920 km BEHIND Mars. Mars is only 7000 km in diameter.

David A. Smith

I don't get what you're saying here! Presumably, they can angle the
magnetic field far enough in advance to aim the solar wind "shadow",
right as Mars is passing through it.

Yousuf Khan