exact composition

Dave Stevenson has spent his career working on “swing-by” missions to the other planets. Now he has a modest proposal he’d like to swing by some government agency with a few billion dollars in available funding. According to Stevenson’s calculations, it should be possible to send a probe all the way to Earth’s core by combining several proven technologies with a few well-grounded scientific assumptions about the workings of the planet. The probe would sink straight to the core in an envelope of molten iron, sending temperature readings, compositional information, and other data along the way.