... One possible application of a solar sail is a spacecraft to warn Earth of approaching interplanetary disturbances and shocks. ... Spacecraft that can provide such a warning are currently stationed at (or near) the Lagrangian L1 point , between the Earth and the Sun--at about 4 times the distance of the moon and 1/100 times that of the Sun. ... Because of the greater distance from Earth, the Earth's pull there is weaker, not enough to make the spacecraft match the Earth's motion around the Sun. ...
... But there also exists a practical angle: in a world increasingly dependent on electricity and electronics, the "space weather" outside the atmosphere can have serious effects, in particular on human communications. Currently more than 200 communication satellites circle the Earth in synchronous orbit . ... For a view of NOAA's "space weather report," click here ; another such report, from the University of Michigan, is linked here . ... Another such event occured April 7-11, 1997 . ...
Ice Volcanoes Reshape Europa's Chaotic Surface . Ice-spewing volcanoes and the grinding and tearing of tectonic plates have reshaped the chaotic surface of Jupiter's frozen moon Europa, images from NASA's Galileo spacecraft reveal. ... Although the images do not show currently active ice volcanoes or geysers, they do reveal flows of material on the surface that probably originated from them, said Galileo imaging team member Dr. Ronald Greeley of Arizona State University, Tempe. ... Europa . ...