We Meant to Do That

The European Space Agency successfully crashed its probe into the moon after its three-year mission. (Yes, they meant it to crash.) Astronomers hope to examine the cloud of dust raised by the impact. Also, this is only the second use of the smaller, xenon-fueled, plodding ion engine thruster, which does not have the roar and media va-va-voom of the more familiar chemically-fueled rockets, but lasts longer and builds slow momentum. (The first use of the ion engine was last summer, for the probe that impacted into Tempel I.)