If you've been paying attention to the New Horizons mission, you may have noticed that the probe won't be going into orbit around Pluto. It will only be doing a single flyby ... at a relative speed of around 14 kilometers per second! This isn't a mistake, or some jury-rig solution. This is how the mission was planned from the beginning. It all has to do with fuel and weight and space, (that's space aboard the probe). The more fuel you capacity you design into a space probe, the less room there is for scientific instruments. So, as you might have guessed, without huge fuel tanks, New Horizons has space for lots of instruments, and boy howdy, does it ever!
New Horizons is packed with seven instruments that give it nothing short of super powers. Yes, super powers. Can you see an object with decent resolution from a million miles away? New Horizons can, in two different ways! Using its Long Range Reconnaissance Imager (or LORRI), a high powered telescopic camera, New Horizons has been sending black and white images of ever-increasing detail over the past months, ever since the probe hit the million miles to Pluto mark. Both to enhance the LORRI images and to allow scientists back here on Earth a whole other data set, Ralph a visible and infrared camera, is both adding color to the LORRI's black and white images and taking infrared images reveal temperature variations on and around Pluto.
As New Horizons gets closer to the dwarf planet, it will start sampling its atmosphere using an instrument called Alice. Now, a little background on this one, ‘cause it's kind of fascinating. First of all, Pluto has an atmosphere? Yep. ... Well, sometimes. What? Stay with me. Pluto's orbit is far from circular. It's elliptical (think of a football, an american one, and then round off the two ends. So it doesn't maintain a constant distance from the Sun. As it gets closer, it warms up, a little, just enough for bits of its surface to evaporate and create a temporary atmosphere. As it gets further away this atmosphere starts to condense into clouds and even a kind of snow. Scientists are pretty sure its all methane instead of water, but still, it's a kind of snow. So, as New Horizons gets closer to Pluto (the closest it will come is about 12,000 kilometers) it will use Alice, an ultraviolet spectrograph to sample the composition of Pluto's atmosphere. Wait a minute! you may be thinking. How can anything sample an atmosphere from a distance of 12,000 kilometers? Well, remember that Pluto is a lot smaller than the Earth. It's a lot smaller than the Moon. So, low gravity means that it doesn't keep its atmosphere anywhere nearly as close to its surface as Earth does.
Oh, and check this out: Another instrument called the Radio Science Experiment (or REX), will actually use radio waves sent from Earth, through Pluto's atmosphere to further analyze its composition.
Two other instruments, the Solar Wind At Pluto (or SWAP) and the Pluto Energetic Particle Spectrometer Science Investigation (or PEPSSI) will work together to capture and study particles that Pluto's atmosphere is losing to space. By analyzing these particles, these two instruments will determine the composition of Pluto's surface. Remember, surface melts just a little, turns into atmosphere, hence: sample the atmosphere, sample the surface. SWAP and PEPSSI will also help us to understand how Pluto's atmosphere interacts with the solar wind.
Finally there is the Student Dust Counter (or SDC). This instrument was designed and run by students, and unlike any of New Horizon's other instruments, it has been working continuously since the probe was launched in 2006. The whole time it's been keeping track of interplanetary debris striking New Horizons as it flies ever further from Earth, providing a totally new understanding of the dust spread throughout the solar system.
Andrew J. Dunlop lives and writes in a little town near Boston. He's interested in space, the Earth, and the way that humans and other species live on it.
