The biggest reason that NASA—as well as other western space agencies—has not attempted a solar sail flight is that the cost of launching even a small spacecraft is so high that they are unwilling to carry out a mission with very modest goals.
During April 2005, the Mars Global Surveyor happened to pass relatively close to Odyssey and Mars Express. What resulted were remarkably clear pictures of human-made spacecraft orbiting and alien world.
74 years after Clyde Tombaugh discovered Pluto as a faint dot on a pair of photographic plates, a modern group of astronomers made another remarkable discovery. On March 15, 2004, Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale announced the discovery of Sedna – the furthest object ever detected in the Solar System.
The discovery of Planet X was announced to the world on March 13, 1930, which marked the anniversary of William Herschel’s discovery of Uranus in 1781 as well as Percival Lowell’s birthday. The observatory’s communiqué emphasized that the discovery was no coincidence, but the vindication of Lowell’s predictions made years before.
Since his teenage years Clyde Tombaugh had been an avid amateur astronomer and a gifted telescope builder. Based on instructions contained in an article from a boy’s Sunday school paper, he built a series of telescopes of increasing power and quality on the family farm.
The discovery of Neptune accounted for nearly all the unexplained motions of the outer planets of the Solar System. Nevertheless, several astronomers insisted that some unexplained residual motions remained, pointing to the presence of a ninth planet beyond the orbit of Neptune.