The Voyager probes were a huge part on my childhood. I was 7 years old when they gave us the best images of Jupiter and its moons we'd ever seen. The following year, we received unprecedented data on Saturn.
Uranus and Neptune remained somewhat mysterious. In the ground-based telescopes of the time, they were just big, white dots. Voyager 2 reached Uranus when I was 14, and it revealed a more colorful, active, and strange world than we'd imagined. Neptune was predicted to be remote, cold, and serene. My senior year of high school, Voyager proved that expectation wrong. Neptune is warmer than we though it would be, and it has storm systems with winds faster than the speed of sound. Its moon Triton is large enough to suggest it had been captured from somewhere else, and it has geysers of liquid nitrogen.
In short, the more we knew, the stranger things became.
That left Pluto. An original flight plan for Voyager 1 was to take it past Saturn to the little wanderer, but when we discovered Titan's atmosphere, that made it a more pressing (and practical) target. Pluto was out of the picture.
To rub salt in the wound, the IAU decided to demote Pluto in 2006. It was no longer a proper part of the Solar System. It was reclassified as a "dwarf planet," now just one of the little planetisimals in the Kuiper Belt. What a rip.
Whatever its status in the nomenclature, Pluto's still important. Its composition gives us a glimpse into the earliest composition of the solar system.
In 2006, NASA launched the New Horizons probe. Its mission is to get better pictures of the planet than Hubble can take, analyze its properties, then continue on to study other bodies in the Kuiper Belt. So far, it's been a resounding success.
Here's what we've learned in just the last few days:
- Pluto has a temperature of -387°F
- its north pole has a methane and nitrogen ice cap
- it has a tenuous nitrogen atmosphere, which appears to be escaping into space
- its geographical features are given appropriate names, such as Balrog and Cthulhu
- its moon Charon has extensive geological formations, including a crevice deeper than the Grand Canyon
- Pluto is a rock with a bunch of ice, while Charon appears to be an even mix of rock and ammonia/water ice
- because of their relative size, Charon doesn't exactly revolve around Pluto. The two bodies actually orbit a central point between them
- Pluto's other four (!) moons may have more chaotic and unstable orbits than we thought
- New Horizons is programmed in raw assembly language
The probe still has plenty more science to do. Its downlink is sending data back to the Goldstone Deep Space Network at a trickle of 2,000 bits/second. At that rate, it's going to months, to send everything back.
There's a fun talk between Neil deGrasse Tyson and Stephen Colbert here, in which Tyson observes that Pluto has gone from the "tiniest planet" to the "king of the Kuiper belt." They even have Tang, although (like me) they refuse to drink the powdery swill.