Following Pluto’s ‘demotion’ to dwarf planet status, a few positive things happened. It got people thinking about this area of the Solar System, how little we knew about it and, with the discovery of a few more similar sized objects, what else could be lurking around out there. Given it’s sheer distance from Earth, are there any missions planned to return to this area of space? And just how long would it take to get to Pluto? Let’s take a look.
Pluto – Quick Facts
- Discoverer – Clyde W. Tombaugh
- Discovery Date – February 18, 1930
- Semi-major Axis – 39.482 AU
- Orbital Period – 247.94 Earth years
- Eccentricity – 0.2488
- Inclination – 17.16°
- Mean Radius – 1,188 km
- Rotation Period – 6 days and 9 hours
- Surface Temperature – ≈33 K to 55 K
- Apparent Magnitude – 15.1 (mean)
- Known Moon/s – Charon, Hydra, Kerberos, Nix, Styx
- Closest Distance to Earth: – Around 4.71 billon km
- Furthest distance to Earth: – Around 7.5 billion km
How far is Earth from Pluto?
At the time of writing, Pluto is currently 5,048,047,233 Km (33.744112) from our planet Earth. At this distance, light takes 4 hours, 40 minutes and 38.4 seconds to travel between the two objects.
The closest that Earth and Pluto approach each other is when both objects are in opposition. Opposition happens when Earth moves between an outer planet – or in this case dwarf planet – and the sun. This happens around once every Earth year,1 or 2 days later each year from our perspective on Earth. The closest approach that these planets can make, is when they are aligned (perigee), Pluto is at its closest position to the Sun (perihelion) and Earth is at its farthest (aphelion).
At it’s farthest, Pluto can be as distant as around 7.5 billion km (4.7 billion miles) from Earth. This happens when the planets are on different sides of the Sun to each other. At it’s closest, it can be as far as around 4.71 billon km (2.9 billion miles) from Earth. Pluto’s orbit is incredibly elliptical and eccentric, with a 17 degree inclination. The distance between the Earth and Pluto can vary widely during its 248 year orbit. It spends around 20 years of it’s journey around the Sun in the orbit of Neptune.
According to theskylive.com, the closest that Pluto and Earth will reach up to the year 2100, actually occurred on June 20, 2013 at a distance of 31.45 AU, or 4,704,718,037 km.
How Long Would it Take to Get to Pluto?
Given the eccentricity of the dwarf planet’s orbit, flight times to Pluto can vary. We have only sent one mission to the Planet so far, New Horizons which launched on January 19, 2006. It conducted its closest approach of Pluto on July 14, 2015 almost 9 and a half years later at a distance of 12,500 km from the planet.
If the aim was simply to conduct a flyby you could get there quicker, with a slingshot around aligning planets en route. But the quicker the approach, the less useful science you can conduct when you get there. It’s an expensive undertaking to visit such a distant portion of the solar system so we really need to maximise the science on these missions.
What is the Shortest Trip?
There is one current concept for a Pluto orbiter and lander, that would utilise a type of fusion powered engine, called a Direct Fusion Drive. This drive would use a type of fusion drive that is currently being researched and developed. If it works out, this type of drive could potentially send a craft up to 1000kg in weight to Pluto in around 4 years. It would also provide significant energy for instrumentation, significantly increasing the amount of useful science that could be conducted. This type of engine could be a game changer for space exploration within our solar system.
How Often Does The Closest Approach Occur?
A close approach between Earth and Pluto occurs a little over once every Earth year when the planet and dwarf planet are in opposition. However, given Pluto’s incredibly eccentric and elliptical orbit the distance when the two are in opposition can vary massively. Over the dwarf planets longer orbital cycle, its close approach to Earth is much rarer. In 2013 the two objects reached the closest they will be for around 200 years.
Missions To Pluto
So far there has only been one mission to Pluto. The Voyagers didn’t get a chance for a visit on their tour out into the depths of the Solar System. Pluto was left to the New Horizons mission, launched on January 19, 2006. The craft took a tour passed Mars and Jupiter, catching some great observations of Jupiter’s 4 largest moons, before going into hibernation mode for most of its trip to the outer solar system. It conducted its closest approach of Pluto on July 14, 2015, 9 years 176 days later.
New Horizons gave us the first close up images of Pluto, it’s moons – particularly Charon, and continues to explore and send back incredible information about the Kuiper Belt to this day. The extended mission is expected to continue into the next decade.
While there is nothing currently in planning, there are some conceptual missions for a return to Pluto, and potentially Neptune. We mentioned above the proposed fusion powered orbiter and lander. While this is not in development yet, there is an R&D project actively working on the fusion engine.
Two other proposed missions, are exploring the idea of ‘hopping’ a craft around Pluto’s surface making use of its thin atmosphere. Another, dubbed ‘Persephone’ would aim to investigate if there is a sub-surface ocean on the planet.
There is a real sense that we are on the cusp of some ground breaking technologies just itching to open up the solar system to deeper exploration. We can but hope that technologies such as the DFD Drive make it past the conceptual stage and into production.