Blog #9: New Horizons Makes it to Pluto!!

New Horizons has made it to Pluto! And with it, we have uncovered a wealth of knowledge about the former planet never discovered before. What was once just a single pixel, the new high definition images of Pluto returned by New Horizons will literally write the textbooks for this little dwarf planet.

So, what do these images look like?

The Pictures: 

The picture above is the true color image, while
the picture on the right uses an infrared filter to highlight certain geographical features.

One of the first things to note about these pictures is that neither of them are true color images, since New Horizons does not contain a green filter. Preliminary research about Pluto suggested that Pluto barely reflected any green light, so scientists opted to include an infrared filter instead, rendering the picture on the right. However, because Pluto does not reflect any green light, the image above, despite lacking a green filter, is the closest true-color image of Pluto that we have. In other words, if you were able to personally fly to Pluto to see it with your own eyes, it would look very similar to the image above.

The Spacecraft: New Horizons:

The spacecraft that travelled to Pluto for a flyby, New Horizons, was launched on January 19, 2006, when Pluto was still considered a planet to complete the tour of the Solar System following the two Voyager probes. New Horizons contains seven instruments, which included Ralph, Alice, REX, LORRI, SWAP, PEPSSI, and SDC. A quick breakdown of each of these instruments are as follows:

• Ralph: Visible and infrared imager/spectrometer. Provides color, composition, and thermal maps
• Alice: Ultraviolet imaging spectrometer. Analyzes composition of Pluto/Charon atmosphere
• REX (Radio Science EXperiment): Measures atmospheric composition and temperature. Passive radiometer. 
• LORRI (Long Range Reconnaissance Imager): Telescopic camera .
• SWAP (Solar Wind Around Pluto): Solar wind and plasma spectrometer used to measure the effects of the solar wind on Pluto's atmosphere. 
• PEPSSI (Pluto Energetic Particle Spectrometer Science Investigator): Measures composition and density of particles and plasma escaping from Pluto's atmosphere. 
• SDS (Student Dust Counter): Tool designed and built by students to measure the space dust New Horizons encountered during its journey to Pluto. 

The instruments on board New Horizons were designed to help scientists visualize and analyze Pluto in ways that were impossible to do so with space and ground based telescopes. One of the most impressive feats of the New Horizons mission was the speed at which the spacecraft was launched. To date, it is the fastest launch speed ever achieved. In fact, New Horizons is considered is considered the second fastest probe, only rivaled by the speed of Voyager 1. New Horizons achieved this speed and arrived at Pluto is such a relatively short time due to its relatively small mass, and a large boost from the Atlas V rocket launch system. The ion propulsion system did the majority of navigating through space, and a large gravity assist from Jupiter helped New Horizons achieve the speeds necessary to reach Pluto within 9 years.

On July 14th, 2015, New Horizons made its closest approach to Pluto, and used it's instruments to capture as much information as it could as it flew by the dwarf planet. New Horizons was never intended to stop and orbit Pluto due to the lack of fuel necessary to change its course. The spacecraft was moving too fast to ever slow down enough to enter the Pluto-Charon orbit, and was instead designed to gather as much information as possible during the fly-by. Now that the closest approach to Pluto has passed, NASA scientists hope to reroute the spacecraft as it goes through the Kuiper Belt to do a fly-by of a Kuiper Belt Object.

What we have learned:

The photos and other data returned by New Horizons have unveiled the mysteries of Pluto that were unknown due to the fact that ground and space based telescopes were not able to resolve Pluto to anything larger than a few pixels. However, looking at the pictures, it seems that Pluto has active geology that is shaping surface features, such as mountains made of methane and nitrogen ice as well as flat planes. Pluto is also confirmed to have polar ice caps. It is unclear as of yet what is causing the geological processes on the dwarf planet.

The color of Pluto, which appears to be a reddish brown color, is similar to that of Titan. The reddish brown is the result of an abundance of tholins. Tholins are organic compounds that form when cosmic rays and solar ultraviolet interact with methane. Since Pluto's thin atmosphere and surface is full of methane, the interaction with the solar wind and interstellar cosmic rays with the methane creates a chemical reaction the results in this reddish "gunk" that falls onto Pluto's surface, making it a reddish brown. Similar processes color Titan's surface, one of Saturn's moons with a thick methane atmosphere.

New Horizons wasn't just tasked with observing Pluto, but rather to get a better understanding of the Pluto-Charon system as a whole. Looking at Charon, it appears that Charon may also be geologically active. There are large crevices on the moon's surface, as well as fewer craters than expected. Also, Charon appears to have polar ice caps as well, with a large dark spot at its north pole.

Since New Horizons is still transmitting data back at the rate of 2 - 4 kb per second, it will take some time to get all of the data back. In the meantime, NASA is in the process to find a new Kuiper Belt Object to redirect New Horizons to in order to get a better understanding of the post Neptunian world.

Source: 
http://www.nasa.gov/mission_pages/newhorizons/spacecraft/index.html
https://en.wikipedia.org/wiki/New_Horizons