The Cassini-Huygens probe now orbiting Saturn attracts the interest of, say, 100 million people to an extent equivalent to perhaps 1 hour of their lives, for a total of 100 million / 1/365 x 1/24 = 11,000 life-year. In addition, the probe's study of Saturn's satellite Titan may lead to a greater understanding of, say, global warming, or the origins of life on Earth, or of geological processes that may have taken place on Earth. If the increase in understanding of those phenomena is 0.1%, and if their complete understanding would affect all 6 billion people to an extent equivalent to 1 month of their lives, then the Cassini-Huygens mission would affect 0.001 x 6 billion x 1/12 = 500,000 life-years.
Human News aims to devote 1 character to each 40,000 life-years, or 1000 average lives. Thus, this story can have about 500,000 / 40,000 = 12 characters.