6 questions you want answered about Pluto

Pluto is the most famous planet on Earth right now.

The New Horizon spacecraft which was launched by NASA almost a decade ago is currently flying by the dwarf planet.

Though we missed the ship to deliver eight interesting facts about Uranus, the mission represents a new frontier of space exploration.

The universe is quite literally too big to comprehend, but here are some facts to put things in perspective for you.

1. Why was Pluto no longer considered a planet?

Image courtesy of Reddit user /u/chrismusaf

Image courtesy of Reddit user /u/chrismusaf

There’s a common misconception Pluto was no longer classified as a planet because of its size.

Though the debate started when objects in the Kuiper Belt beyond our solar system were found to be a similar size. 

This resulted in the International Astronomical Union changing its criteria for celestial bodies to be qualified as planets in 2006.

While Pluto was indeed round and orbited the sun, it had an erratic orbit; while other planets need to stay clear of other planets, Pluto’s trajectory suggested it had issues with personal space. 

Pluto did not ‘‘clear its neighbourhood’’, meaning other objects in the suns orbit were within a certain distance of it.

It was reclassified as a dwarf planet — one of five — and the classic rhyme to remember to order was changed to: 

My Very Educated Mother Just Served Us Nachos

It's just not the same...

2. What have we found so far?

Expectation vs Reality. Photo courtesy of @thijsroe

Expectation vs Reality. Photo courtesy of @thijsroe

Scientists predicted the surface of Pluto would be uniform and relatively featureless, but they were surprised to discover otherwise.

New Horizons detected a rich diversity of terrain types, particularly on its biggest ‘‘moon’’, Charon.

Dark poles, or darkened terrain, were found on the moon. Though scientists can only speculate what it is, it does suggest the dwarf planet is "active".

Active in this instance implies there is some geological activity occurring on the celestial body, though this is due to atmosphere rather than tectonics shifts.

As confirmed by NASA, the planet has snow but it is vastly different to what we're use to on our little blue planet.

Snow on Earth is part of a natural water and precipitation cycle, but snow on Pluto is actually comprised of methane, which is what gives it its brownish colour.

The extreme cold mixed with the thin atmosphere sublimates - turns the gas into a solid without turn it into a liquid - the methane and other gases into snow.

3. Why don't we land?

It may seem odd the window to observe the dwarf planet is so brief, considering it took us over nine years to get there.

Sadly, the fuel required as well as the extra time it would have taken would have held the mission back by a few decades.

While today's ion engines are theoretically effective enough for a landing, slowing down enough to enter orbit would have required massive amounts of fuel.

To carry more fuel, the spacecraft would need to be bigger, which in turns requires more fuel.

This is compounded by the fact that a landing would require the spacecraft to be travelling significantly slower.

This leads on to the next question...

4. How difficult was this mission?

It cannot be understated how much of a logistical nightmare it was to get the probe in the position it is in.

A fair comparison would be trying to launch a golf ball from Cairns and then getting a hole-in-one in Melbourne; though this would still be conservative.

The probe is travelling at 58,536km/h and Pluto is over five billion kilometres away, meanwhile Pluto orbits the sun at 17,096km/h over 248 years per rotation.

NASA managed to calculate its arrival from here to there, even arriving 72 seconds early.

5. What next?

Illustration of New Horizon. Source: NASA

Illustration of New Horizon. Source: NASA

While the flyby will be brief, instruments on the spacecraft will collect a range of data, from pictures to chemical analysis of escaping gases, and it will take between 16 to 18 months to transmit all that data back to scientists on the Earth.

It takes 4.5 hours for signals from NH to reach back to Earth, and at time of writing NASA and the world are eagerly awaiting for the transmitted images.

For the first time in history we will have clear photos of three out of five of Pluto's moons which include Charon, Hydra and Nix. Unfortunately not Styx or Kerberos.

We have a satellite dish, about 70 metres wide, pointed to a dot about five billion kilometres away.

At the current bandwidth rate (the probe doesn't have Fibre To The Premise either), NASA is expecting about 11 images a day to be returned - this does not include topographical data.

The dwarf planet is only the first step for New Horizon. After the probe collects what data it can, it will continue on.

Pluto is actually part of a region known as the Kuiper Belt, which scientists think contains hundreds of thousands of rocky, icy objects.

6. Why are we doing this?

"... This mission has really shown how far away from home our spacecraft is - Pluto is deep, deep out in the black. It will be years before the spacecraft reaches a KBO for a flyby, and then nothing, ever. It redefines lonely and helps you better appreciate your companions." - Curt Niebur, NASA Program Scientist

Though there are countless scientific reasons to spend decades on this project, the New Horizon project is merely a symptom of human nature.

We do it, because we can.

Tablet - Narrow
Tablet - Wide