From Luce Gilmore, Cambridge, UK
Leah Crane says that a probe that missed Mercury would be “trapped by the sun's powerful gravity and dragged to its doom” (22 June, p 42). This suggests the misconception that it would meet a fiery end.
A Mercury probe would try to meet the planet at the perihelion of its trajectory, when it is nearest the sun, since that is most fuel-efficient. If it missed, its orbit would take it away from the sun.
A result of this misconception is the idea that the sun would be a good place to dump nuclear waste, as if anything escaping Earth would slide straight down into the flames. In fact, the direct route would take vast amounts of fuel and has never been done. The easiest way to the sun is via Jupiter, as the Ulysses solar probe demonstrated. If you must shoot radioisotopes into space, the moon is far easier to reach.
Advertisement
