This week New Horizons beamed back some amazing images of the not-a-planet-anymore, Pluto. Of course, being a physicist I couldn’t let this opportunity to write about science slip by, so here’s some interesting facts about the mission along with a few nice images.
Launch (and other techy stuff)
NASA launched New Horizons over nine years ago on January 19, 2006 as part of NASA’s New Frontiers program. About the size of a piano, the probe launched aboard a fast-moving Lockheed Martin Atlas V rocket from Cape Canaveral, Florida. The rocket reached speeds of around 16 kilometers per second (58,000km/h; 36,000 mph). New Horizons left Earth faster than any other spacecraft to date! It didn’t get off to a very smooth start however, as the first two launch attempts failed earlier that week. The failures were caused by high winds at the launch site and a power outage at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., which operates the spacecraft during the mission. New Horizons carries a payload of seven instruments used to investigate the global geology, surface composition and temperature, and the atmospheric pressure, temperature and escape rate of Pluto and its moons. Three optical instruments, two plasma instruments, a dust sensor and a radio science receiver/radiometer. Although not all instruments are used simultaneously, only a tiny 21 Watts is used for instrument operation. That’s around the same power used by a desk lamp!
One of the most sophisticated cameras ever made
There are three cameras aboard New Horizons, but Ralph is the guy that’s sending back the pics we have been seeing most. Despite being built over 10 years ago, New Horizons’ Ralph camera is one impressive piece of technology. It weighs about 10.3 kilos and uses a tiny amount of energy. Ralph captures visible and some infrared light and sent back the highest resolution image of Pluto ever captured. It can resolve features on Pluto’s surface as small as 60 meters across.
Apart from its instruments, New Horizons carries the ashes of Pluto’s discoverer Clyde Tombaugh
Clyde Tombaugh discovered Pluto on February 18th 1930 at the age of 24! He made the discovery after pouring through millions of images of stars. The discovery was a big deal for science and helped us understand more about our own solar system. It is the largest known object in the Kuiper belt, which the probe also confirmed the existence of. Tombaugh died in 1997 at the age of 90. Nine years later New Horizons was launched.
“When he looked at Pluto, it was just a speck of light,” Annette Tombaugh, his daughter, said. “To actually see the planet that he had discovered and find out more about its atmosphere, find out more of what it is and actually get to see the moons of Pluto, he would have been astounded.”
The canister bears an inscription from Alan Stern, head of the New Horizons mission: “Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system’s “third zone.” Adelle and Muron’s boy, Patricia’s husband, Annette and Alden’s father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh (1906-1997).”
New Horizons Mission is Powered by Space Radioisotope Power Systems
Essentially the probe is running on nuclear fuel. Its Radioisotope Thermoelectric Generator (RTG) uses Plutonium-238 as a source of heat as it decays. The reason this is needed is because Pluto is around 7.5 billion kilometers from the sun, more than 30 times farther away than earth. As a result, solar energy is too low to power the spacecraft unless it had enormous solar panels. Similarly, chemical fuel or batteries would be too large a payload for the spacecraft so nuclear was the best option.
New Horizons also flew by Jupiter
In 2007, New Horizons made a tactical flyby of Jupiter with the aim of using the massive gravitational pull of the gassy giant as a slingshot. The flyby was a success and the spacecraft got a boost in speed of around 14,400 kilometers per hour. If it didn’t get this speed boost we wouldn’t be seeing these fantastic images of Pluto for another three years! On its trip through Jupiter’s gravitational well, it also spotted a volcanic eruption underway on one of Jupiter’s moons, Io.
Powered by a PlayStation CPU
Yes the original PlayStation. New Horizons was launched 9 years ago in 2006, long after the first PlayStation came out. There were more advanced consoles and computers out at that stage, but NASA weren’t aiming for a high speed CPU. They wanted stability. The CPU is a MIPS-based Mongoose-V CPU, directly derived from the MIPS R3000, which powered the original Sony PlayStation. It was in fact even slower that the PlayStation, clocked at a mere 12MHz whereas the PlayStation ran at 33MHz. The chip was perfect for low power consumption and radiation hardening as the probe would be bombarded by cosmic rays and other stellar phenomena.
What’s next after Pluto?
All things running smoothly with the Pluto flyby and if the probe has enough fuel left it will leave Pluto behind to try and explore another object in the Kuiper belt. Unfortunately the other large object we know about in the Kuiper belt, Eris, is the other side of the Sun to Pluto, so we won’t catch a glimpse at that, but between the years of 2016 to 2020, New Horizons will be on the lookout for anything interesting. The best is at the edge of our solar system and is around 20 times wider than the asteroid belt that separates Mars and Jupiter. Objects in the Kuiper belt are more or less unchanged since the formation of our solar system, so studying objects from here gives us a look in to the past.
So there’s some interesting facts you didn’t need to know about Pluto. You never know, something from the article might come up in a table quiz and you’ll be thanking me then! Instead of putting up a gallery, take a look at this fantastic gif that NASA shared of pluto throughout the years. Four of the first images were taken by Hubble and the rest by New Horizons.