New Year, New Science

Next week, as we ring in the new year, a spacecraft called New Horizons will push the boundary of human knowledge by being the first spacecraft to preform a close flyby of a Kuiper belt object. This isn’t the first time the grand piano sized spacecraft has embiggen human knowledge. From it’s gravity assist at Jupiter to it’s flyby of Pluto let’s reintroduce our selves to New Horizons, the craft, its spectacular scientific achievements, and what it plans on accomplishing next week.

New Science, Old Idea

In 1991, just after Voyager flew by Neptune, the USPS released a set of stamps commemorating the fact that we had flown by 8 of the 9 (at that point) planets. Each stamp had a drawing of the planet along with a caption listing the craft that explored it. Pluto’s carried the caption “Not yet explored.” As those stamps were being introduced at JPL, talks were already underway as to how explore Pluto. Fast forward 10 years to 2001 when New Horizons was official selected by NASA to go into development. The story of it being designed, cancelled, and then revived through a massive outcry of public support was told in Alan Sterns book Chasing New Horizons which I highly recommend!

The Science and it’s Tools

New Horizons had 3 primary mission objectives once it reached the Pluto-Charon system

Characterize the global geology and morphology of Pluto and Charon

Map the chemical compositions of Pluto and Charon’s surfaces

Characterize the neutral (non-ionized) atmosphere of Pluto and its escape rate

In order to accomplish these goals it had onboard 7 scientific instruments.

LORRI – Long-Range Reconnaissance Imager – LORRI is basically a telescope of a similar design to Hubble. It’s much smaller in size to Hubble, but allows New Horizons to capture distant objects. It also allows for close up views once New Horizons flies by a body. SWAP – Solar Winds Around Pluto – SWAP analyzes the solar wind by measuring the amount of ions and electrons that that go through it. Only 3 other spacecraft, Voyager 2, Pioneer 10, and pioneer 11 have measured the solar winds 10 Au out from the sun. PEPSSI – Pluto Energetic Particle Spectrometer Science Investigation – Like SWAP, PEPSSI also measures ions and electrons, but instead of investigating the solar winds PEPSSI is designed to investigate particles coming from Pluto. This is useful for investigating Pluto atmosphere. Alice – This is an ultraviolet spectrometer designed to detect noble gasses in Pluto’s atmosphere as well as water, carbon monoxide, and carbon dioxide. Ralph Telescope – This is the second telescope on New Horizons. If you see any images from New Horizons and it’s in color it’s from Ralph and if it’s in black and white it’s from LORRI. VBSDC – Venetia Burney Student Dust Counter – This instrument is designed to measure the dust in the outer solar system. This will help us determine how likely planets are to form in the outer solar system. One of the coolest things about this instrument is that it’s named after Venetia Burney, the 11 year old girl who in 1930 suggested the name “Pluto” for a newly discovered planet. REX – Radio Science Experiment – This instrument is designed to explore the pressure, temperature, and ionosphere on Pluto. It’s the smallest experiment on the spacecraft and because of this two were placed on New Horizons.

Getting an Assist from Jupiter

New Horizons was finally launched in 2006. It took advantage of a gravity assist from Jupiter to cut down on it’s flight time to Pluto. LORRI got the following photo of Ganymede’s shadow on Jupiter, Ganymede (top moon), and Io (bottom moon).

LORRI also took high quality photos of Jupiter moons. This following one of Io is especially good. If we look at the top and left of Io we see two bulges. These are plumes from active volcanoes.

Ralph captured this composite of Jupiter’s atmosphere. It looks like an oil painting!

Pluto, Finally

On July 14th 2015, New Horizons had it’s closest approach to Pluto. Our best image of Pluto went from this

to this

It revealed the truth behind whole new worlds like Kerberos. We thought Kereros was an extremely large dark object, but it turned out to be an extremely small reflective object, which likely indicates the presence of clean water ice.

Pluto, instead of begin a simple large rock floating in space turned out to be much more complex. Here are some of the biggest discoveries New Horizon found.

Pluto once had liquid water (and still might below the surface!)

Unlike cold dead moons like Triton or our Moon, which is mostly covered by craters, Pluto has lots of geographically interesting features. This likely means that our understanding of geology for icy worlds is incomplete.

Pluto’s moons, are smaller, brighter and weirder than we expected. Most of their axes of rotation 90 degrees off of what we were expecting.

If we went to Pluto and found that it matched our predictions that would be nice albeit boring. Because the results are different than our models, that’s also cause for celebration. It means there’s still more fascinating things out in the universe that we can’t yet explain.

Gone so Soon

Just as quickly as New Horizons got to Pluto, it was gone again. It’s trajectory was a fly by, not a permanent orbit. If we had gone to Pluto with a traditional Hohamn transfer that allowed us to stay in the vicinity of Pluto it would have taken about 35 years (+/- 10 years Note the large error bars, this was just a quick estimation ) instead of the 9 it actually took. New Horizons trajectory is taking it out of our solar system, in the direction of Sagittarius. It’s flight-path is taking it through the Kuiper belt, a much larger asteroid belt (20 to 200 times larger than the one between Mars and Jupiter), which has not yet been explored. In 2011 a massive searched kicked off to find a Kuiper belt object that New Horizons could visit. It was only with the help of the Hubble Space Telescope that 3 possible targets were found. These were then whittled down to just one that New Horizons would adjust it’s course to fly by. The New Horizons team chose 2014 MU69, nicknamed Ultima Thule. Next week, 13 years after it left Earth, New Horizons will visit Ultima Thule.

Ultima Thule or Ultima Thules?

Here’s some fun facts about the encounter

It will be humanities first close encounter with a Kuiper belt object

New Horizons will fly within 2,175 miles (3,500 km) of Ultima Thule, that’s closer than it got to Pluto.

Ultima Thule may actually be two smaller bodies close to each other and not one larger body!

Ultima Thule’s characteristics have led us to believe it was formed in the early phases of our solar system.

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